Clutch Drag Solutions

I have over time found some ways to reduce some or nearly all clutch drag.  There are two approaches to this problem.

1.  Change the primary oil to something with less drag.

Over time I have used a variety of oils. I have tried Golden Spectro Golden Gear Lube and STP.  Both are guaranteed to cause slippage.  Lots of it. The clutch doesn’t work. You get the idea. I have used BG EPC (extreme pressure concentrate). Same result. I know of one motorcycle oil that has this in its chemical package.  Bel Ray. Montesa recommends a 10W30 engine oil. Since most Montesas have a primary gear, I prefer to use a motorcycle 4-stroke cycle oil that has an additive package to provide lubrication for the transmission.

I have discovered a very good oil. Its smallest quantity is a 5 gal. bucket. It’s made by Schaffer’s Oil Company.  They usually sell to farms for combines and to trucking companies. It is #275s DI-LUX.  Fifty gallons are used in a wheat harvester. If you can find someone that uses it commercially and has a few gallons left over, you might get lucky. You can check the composition of the oil on line and purchase a similar lubricant at an auto parts store.

If your engine uses the clutch pack with the numbers 0263.023, change them to the clutch pack # 5363.023.

2.  Springs.

The clutch uses 6 springs. No two springs are exactly the same. You can balance the pressure by pairing.  You will need an accurate scale and a drill press that has a repeatable stop. Place the scale on the drill table and compress each spring to the stop. Record each reading. Pair the most equal springs for installation opposite each other during the reassembly.

I have done this on my 250 Impala. This motorcycle can be sitting for years, and I can pull in the clutch lever and select first gear with no resistance to rolling motion until I release the clutch lever. COOL!  You may not have as much success but it can’t hurt to try.

Additional Comments:

There are other types of clutches. I haven’t covered the Cota 25 or any of the 49 cc engines. These are an entirely different arrangement. Only one clutch plate is involved and it has a friction material on it.

The other clutch I have become familiar with is the one designed for the Cota 242, 330, 335, 304, etc. These have a clutch pack that is part of the clutch basket. There is a large retaining clip that holds this together. It will take a press of some sort to compress the pack to access the individual discs. This clutch pack is composed of metal and friction material discs. There seems to be only one flaw. The outer pressure plate tented to crack and will need replacement. There is also a good possibility that warpage may occur to the plates.  Replacement of the discs and/or pressure plates is necessary to return this clutch to working order. 

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Clutch Maintenance

Most of the clutches used in the vintage era, from 1963 to 1984, used metal to metal clutch plates.  This article will cover these models.  

The need for maintenance comes about because of noticeable dragging and/or slipping.  There are a number of ways to go about correcting or reducing these problems.  Before delving into the mechanical parts of the clutch, change the oil.  This may clear up many of the problems.

Most of the clutches used in the vintage era, from 1963 to 1984, used metal to metal clutch plates.  This article will cover these models.

The need for maintenance comes about because of noticeable dragging and/or slipping.  There are a number of ways to go about correcting or reducing these problems.  Before delving into the mechanical parts of the clutch, change the oil.  This may clear up many of the problems.

Tools:  SAFETY GLASSES, Common screwdriver, (and small common screwdriver if there are anti rattle springs) long nose pliers, 10 inch channel-lock pliers, 17mm socket and ratchet wrench.

Steps of Procedure: Disassembly

1.Place your motorcycle so you can remove the primary cover.

2.Drain the primary.  (This is also the transmission on the 123/172 Cota and other models in like design.

3.Remove the clutch cable.

4.Remove the primary cover screws.

Note: Place something to catch the oil that remains in the primary before removing the cover.

5.Either tap with a small dead-blow hammer or press the clutch arm to break the seal of the gasket.

Disassembly:

1. Place your motorcycle so you can remove the primary cover
2. Drain the primary.  (This is also the transmission on the 123/172 Cota and other models in like design
3. Remove the clutch cable
4. Remove the primary cover screws. Note: Place something to catch the oil that remains in the primary before removing the cover.
5. Either tap with a small dead-blow hammer or press the clutch arm to break the seal of the gasket
6. Remove the cover.  Locate the bronze plunger and 3-finger plate.  Remove and place with the primary cover

 You have now exposed the clutch assembly and primary gear.  To remove the clutch pack you will need to remove the thin nut that secures the clutch pack to the clutch basket.  This is right hand thread so it is removed like most fasteners. 

1. Flatten the lock tab.  A small cold chisel, punch, or old common screwdriver can be used.  Any light hammer may be use to drive the bent tab down. Note: If you are removing a clutch pack from a Cota 247 or equivalent with an external flywheel weight, it will be necessary to remove that weight to have clearance for the clutch pack.  Don’t worry about the pinion gear coming off.  The pinion gear is held on by a taper fit.  The weight is held by a nut and washer.  It won’t spin because it is  keyed.  If an impact driver is used to remove this flywheel there is the possibility that the pinion gear will pop off.  This is not a problem.  You can fix this later.
2. Using a 17 mm socket and appropriate wrench, loosen and remove the nut and lock tab. Note: I have folded a paper towel into a tight square and placed it between the pinion gear and ring gear to lock the two for removal of the nut and reinstallation later.  The cases and gears are stronger than the towel and will tear the towel up before causing mechanical damage.
3. If there are 3 anti-vibration springs, remove them now.  Wear safety glasses.
4. Pull the clutch pack from the clutch basket.  A small common screwdriver can be used to encourage this removal but most clutch packs can be removed by hand.
5. Place on a clear bench top.  Lay out the channel-lock pliers and long-nose pliers.
6. Grasp the clutch pack and, using the channel lock pliers, compress each spring and remove the dowel pin.  If you can’t remove the pin with your fingers, this is what the long-nose pliers are for.
7. Remove each spring, spring pin, and dowel and place them in a place you can reach later.  You don’t want to lose any of these items by knocking them onto the floor.  They grow motors and motor away to parts unknown.
8. Remove the inner and outer clutch plates and stack them.
9. Take the top two plates.  Flip one over and place it on the other.
10. Pinch them together.  If a gap forms, they are warped.  You can check all of them this way if you like.  When through, restack them in the order they were removed.
11. Clean each in turn, starting with the bottom plate, lube with a few drops of the oil you will use on reassembly, while placing them back on the hub they were removed from.

Reassembly:

1. Using the channel lock pliers, reassemble in reverse order of the disassembly.  While assembling you will notice reference notches and an angled cut on the driving plates.  They should be stacked with all notches and cuts aligned.
2. You will note that the clutch pack will not fit into the ring gear basket without alignment of the tabs.  Use the channel lock pliers to even the tabs at enough places so it will fit.
3. If there was a spacer washer behind the clutch pack, be sure to install it before the next step.
4. Now is the tricky part.  You have to align the clutch basket tabs and the inner hub grooves for the clutch pack to fit.  The pressure plate of the clutch pack has a rectangular hole where the lock tab fits.  You can see the inner driven hub through this hole.  With a little patience you will be able to see how the tabs fit together.  You may have to rotate either or both the outer basket and the inner hub before they will align.
5. Once the clutch pack is pressed home replace the lock tab and nut.
6. Torque the nut to 14.5 to 18 ft. lbs. (2 to 2.5 m/kp.)
7. Re-bend the lock tab.
8. Re-hook the anti-rattle springs if present.
9. Replace the 3 finger plate and bronze plunger.
10. Using a new primary gasket, replace the primary cover.
11. Refasten the clutch cable.
12. Refasten the clutch cable. Note: You can use a thin smear of Hylomar gasket dressing to reduce weepage.  This stuff won’t glue itself to the gasket or engine cases and you may be able to reuse the primary gasket if you have to remove it later.

 If the pinion gear had come off when the flywheel weight was removed, clean both parts of the taper with alcohol or electric contact cleaner and re-torque to 72 lbs. ft.  You can grip the weight in a vise with soft jaws. 

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Exhaust Smoke

Your motorcycle may be smoking for one or both of these reasons.  One, your carburetion is too rich.  Two, your exhaust is fouling with excess unburned oil.  Both can be rectified.  The first by a spark plug check and subsequent changes to pilot jet/air screw adjustment and main jet reduction. If the engine is running fine than the second smokier solution may be appropriate.  It involves a LOT of smoke and an oxy-acetylene torch.

The exhaust is removed and a fire is lit with a flame of oxy-acetylene mix.  Once the fire starts the acetylene gas is turned off and the oil in the pipe becomes the fuel.  The oxygen is still supplied by the torch.  It will burn until the flame consumes the last remnants of oil.  A rosebud tip or a cutting tip, without use of the oxygen lance, can be used.  The only problem with this is the heat might be great enough to burn through the pipe somewhere.  I haven’t found this to be true yet.  It will burn any aluminum that might be in the pipe and it will certainly burn any fiberglass if any is present.

Recommended ratio is 20:1.  That is a quart to 5 gallons.  This is recommended for all Impala’s, Scorpion and King Scorpion, and 247 Cota’s.  If in doubt check the Montesa parts/owner’s manual for its recommendations.  I recommend you follow Montesa’s recommendations.  Golden Spectro can be used at that ratio no matter what the can says or a parts person might say at any motorcycle shop.  These old engines have marginal bearing sizes.  Most of the Montesa engines use the same bearings as the first 175 Impala that produced about 16 Spanish horses.  A third bearing was added to the power takeoff side of the crank and is somewhat isolated from the crankcase premix on any of the 5 speed Cappra’s and Enduro’s.  Bearing sizes did not change until the VA series in 1976.

Other oils I have tried with success are Full Bore 50 wt., Castrol 2 stroke petroleum base, Yamaha R, Schaeffer’s, and Maxima.

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Shifting Difficulties

There are occasions when it is necessary to remove the shift mechanism from the engine.  Those with a left side shift can generally be removed entirely while those with the shift on the right will require the separation of the center cases to remove the shaft.  A snap ring inside the left case half retains the right side shift shaft.

The shift plate assembly can be removed in either case inside the primary after removal of the primary cover.  When disassembly is necessary due to worn parts or curiosity you will find it assembled in a logical sequence in this order:

1. Two 5 x 25 mm bolts
2. One locking plate
3. One cover plate #0266.101
4. One spring #0266.014
5. One fitting #0266.105
6. One plate #0266.102C with #0266.103 pin inserted or shaft 2166.118.
7. One plate #0266.013 or #4366.013, four or five speed respectively for the right side shift models. Etc.

What this is leading up to is the shaft with #0266.005, #3466.005, and #2166.005 for the right side shift models and #2166.036 for the left side models.  When you look at the end of this shaft you will note that it has a long slot across its face containing a light spring and engagement pawls.  You think it is centered.  It isn’t.  It’s slightly off center.  The shaft when placed upside down will give you; at the most, two gears.  Rotate it 180 degrees and reassemble.  This should bring all of your gears back.

The slot should be off center above center.  This will not be horizontal but turned a bit clockwise.  The plate suffix ….012, called a gear, with the pawl engagement notches must be placed correctly.  This plate will have the number of shifts available pressed into the front of the plate, these being 4, 5, or 6.

Another problem can occur with a damaged pawl spring.  If it has become weakened or bent it cannot provide adequate spring pressure to press the pawls into engagement.  It will need to be replaced.  Restretching it or rebending it won’t provide adequate tension.  The spring is an inexpensive item costing less than $2.00.  This is an extremely rare occurrence but it happens.

The service information advises you after the engine cases are closed to work the gears by hand to see that selection of all gears occur.  Use the shift lever on the splines and not a pair of pliers to rotate the shaft.  Pliers will damage the splines.  The detent plunger on the shift drum should be installed.  The hex head cam that is fastened with a 6mm nut and lock washer to a 6mm case stud should center the stop plate for the initial adjustment.  This adjustment is for firmly engaging the first and top gear.  Engage first gear.  Check to see if it is fully engaged.  Adjust if necessary.  Manually work through the gears until top gear is engaged.   If it is not fully engaged go back to first gear.  Readjust the cam.  Relock the cam and try again.  All of the intermediate gears should readily engage.   If you think to scribe a mark with a metal scribe on the cam to a reference point on the engine case this adjustment may not be necessary for future assemblies.

If the pawls are excessively worn they should be replaced.  You might have noticed that they do not engage along the full width wedge surface.  You may get by with installing them the other way around.  Damaged shift pawls do not allow a smooth engagement when shifting gears.  Missing gears is best suffered by other manufactures machines.

Check for bent shift shafts.  The shaft will drag against the cover and not return smoothly or at all.  This is more common to the right side shift models.  The only good way to fix this is by replacement.  Straightening the shaft is difficult.  On right side shift models it is nearly impossible.

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Seal Frustration

I have assembled a number of Montesa engines since my first Impala.  In the last few years I have found that the shift shaft seal, #0099.2232, on about one half of my rebuilds would pop out when closing the central engine cases.  This usually required the re-splitting of the cases with all of usual problems in reassembling the gears, shims, and gasket.  I would occasionally press the cases together and the lip of the seal would turn out on the shift drum.  I could ease the lip back with the aid of a used and rounded small common screwdriver.  This was not the best plan because the tension spring in the seal may not seat.  If this seal doesn’t do its job then transmission oil will contaminate the primary oil and cause the clutch to drag excessively and reducing the lubrication of the transmission.

This is caused by a sharp edge on the shift drum.  The new seal is smaller on the lips than the worn seal that was removed.  This will wear in with use but as a new seal it presents an edge that will not easily slip over the edge on the shift drum.  There are a number of steps that must be done in order for the seal to slip into place when assembling.

You will need a few items:

• A medium carborundum whetstone
• 280 grit aluminum oxide coated abrasive
• Fine, single cut, 8 inch round file
• Multi-purpose grease
• Patience

Steps should be taken in order:

1. With the engine cases separated and clean and with the seal removed, file a slight chamfer on the edge of the seal-receiving hole.  It only needs to have the sharpness removed and shouldn’t be more than 1/32” in width.  It shouldn’t have any roughness.  A fine file should be sufficient but it can be sanded lightly.
2. After cleaning press the seal into the hole without lubricant.  It should be dry.  If you have chamfered the hole properly the seal should go in without tearing.  Drive it in until it bottoms.
3. Remove the shifting forks from the shift drum noting how they came off for later assembly.  Also inspect the shift fork guide pins for excessive wear.  Replace if necessary.
4. The edge on the shift drum that must be eased is located behind the gear on the shift-plate end and behind the groove of that gear. Using the whetstone, round the area on the drum.  You can check progress by touching the edge lightly and running it around the drum.  Polish it with the abrasive paper.
5. Clean all areas of abrasive.
6. Pack the lip of the seal with grease.
7. Reassemble the shift forks to the shift drum.
8. You are now ready to close the cases.

If you have a metal lathe then mounting the drum in a 3 or 4 jaw chuck and spinning the drum while using the whet stone and abrasive can do the job quickly.

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Sleeve Nuts

Beginning about 1968 engine designs changed.  Up to this time most models had long studs that were used to retain both cylinder and head.  These 10mm bolts were quite long.  Due to expansion rates for the aluminum of the cylinder and head versus the steel stud the torque values on a cold engine were light.  The engine casting was unable to handle much torque and would distort slightly and/or the stud would want to pull out.  This torque value was 11 to 15 lbs. ft.  To have a more secure fastening of the cylinder to the engine, shorter and thinner 8mm studs were fitted and the cylinders were modified to accept a sleeve nut.

This nut (part #3360.161) was sized to fit in the 11mm hole.  To accommodate a tool one end was made to accept a 7mm Allen wrench.  These sleeve nuts also have the torque of 11 to 15 lbs. ft. but they only have to hold the cylinder to the engine cases.  They don’t have any other task.  The cylinder heads may then be torqued to 21 to 25 lbs. ft.  These engines don’t have a head gasket.  The addition torque will more likely resist leaking a bit more than the former through-bolt designs.  Neither design has a tendency to leak if proper assembled.

With the new attachment it was necessary to move the cylinder head fixing studs 45° around from the base studs to. Typically a boost port was inserted between a modified casting on the intake side allowing for a 3-transfer arrangement.  This is found on the 247 and later Cota’s as well as most of the Cappra’s.  Anytime you see the cylinder fixing nuts located front and rear and left and right on the top of the cylinder the engine will have these sleeve nuts.  The 360 Cappra GP’s and DS’s also have these nuts.  They are beneath brass inserts (3660.174).

If you are going to take an engine apart it is necessary to deal with these nuts.  The cylinder will not come off without destroying the cylinder and/or engine cases if you attempt it.  Scratch that.  The exceptions are the 360’s.  The 360 GP’s and DS’s have such strong cases you would have to use explosives to damage them.  O yes, the only likely damage you can inflict on the cylinder is breaking fins.  When you get that cylinder off you will see why.  Heft it.  These things are heavy.

Water can get into the holes and cause corrosion between the cylinder and nut as well as the nut and stud.  This will make them difficult to remove.  This is more prevalent on the 250’s.

• Ratchet Extension Tool
• Torque wrench
• Pencil Magnet
• Dead blow hammer

Procedure for removal:

Remove Cylinder Head:

1. It will typically take a 17mm socket to remove the 10mm nuts.
2. Insert 7mm Allen wrench into hole and engage sleeve nut. 
3. Turn counterclockwise and unscrew from stud.
4. Remove with pencil magnet.
5. Tap cylinder with rubber or dead blow hammer to loosen connection.  Strike against the edge of the fins, not on top or bottom of them.  You can also strike beneath the intake manifold and exhaust port.  Do not use a hard hammer.
6. Slide cylinder up part way.
7. Press rags or paper kitchen towels in crankcase beneath piston.
8. Remove cylinder.

This all seems very simple.  About 1 out of every 2 engines has a severely stuck sleeve nut.  You can soak the nut with liquid wrench or any number of penetrating oils and let it stand for a day or more.  I haven’t the patience.  Even after a week of using penetrant it only works about 1/10th of the time.  What to do, what to do?  Heat?  Doesn’t work.  Maybe the stud will pull before the Allen wrench rounds off the inside of the nut.  Been there, done that.  The sleeve nut will round out.  Once you rounded out the nut it’s time to drill.

Drilling:

1. Get some cutting oil and an electric drill.
2. Select a suitable sharp drill bit.  Make the selection of a size that will only drill the stud out.  Remove all of the sleeve nuts that can be removed.
3. You don’t want to drill into the cylinder casting.
4. Start drilling.  This will take some time but at least you will feel like you are doing something.
5. Remove chips occasionally with the pencil magnet.
6. Measure your progress in some fashion.
7. Resume drilling.  Eventually you will destroy enough of the stud to remove the cylinder.
8. Use locking pliers and remove the remains of the stud.
9. Order another stud and nut.

There are special steel washers at the bottom of those holes for the sleeve nut to press against.  If they fall out; save them.  If they stayed in the hole, leave them there.  Just remember to return the washers to the correct holes on reassembly.  Clean all nuts and loose washers.  Use a 7mm x 1.00 tap and die to clean the threads.

Reassembly: I am assuming that you have managed to get the cylinder over the piston and rings and seated onto a fresh cylinder base gasket.

1. Replace any steel washer that escaped from the sleeve nut hole (s).
2. Apply a small smear of anti-seize to the internal threads of the sleeve nut.  (You don’t want to go through all of this again)
3. Using a 7mm allen wrench turn the nut down and seat against the washer.
4. Use a torque wrench to tighten fasteners to recommended torque.
5. Assemble head to top of cylinder.

The question will come to you about where to get a 7mm allen wrench.  I purchased mine from Sears.  If you don’t have a good hacksaw blade you can get one there also.  You can also get a 7mm socket.  Sear’s has them in ¼” drive.  If you don’t have an adapter then get on of those too.  Sear’s tools are of uniform strength but are not hardened like some tools.  They are strong enough for the job.  A hacksaw blade will cut them.  Cut off the short part of the L.

Assemble this tool in this order:

1. Insert the long segment of the 7mm allen wrench into the sleeve nut.
2. Place the socket on the other end.
3. Install adapter(s).
4. Install torque wench.
5. Torque away.

Note:  The 360 GP/DS models have a bolt inserted over the sleeve nut and therefore hide it from corrosive forces.  You just have to remember the nut is there when removing the cylinder of one of these models.  They won’t fall out.  The inserts above them will retain them.  You will hear them click every time you turn the cylinder over.  Anti-seize will have to be applied to the threads on the stud before installing the cylinder instead of on the inside of the sleeve nut.

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Loose Needles

Many of the Montesa models of the late 1960’s and early 1970’s didn’t use caged needle bearings on the wrist pin in the small end of the connecting rod.  When removing the piston there is a shower of loose needles onto the bench, top of the engine case and into the crankcase.  This article is to explain a way in dealing with the removal and assembly of this unusual bearing solution by the engineers of Montesa.

Early 175 and 250 models used an oillite bronze bushing for connection of the connecting rod to the piston pin.  When this is subjected to severe service it doesn’t carry the load well.  When the engines were produced in the mid ‘60’s they were equipped with a caged needle bearing.  This needle bearing was weak because of the sparse number of needles.  The bearing needed replacement more often.  The 20:1 oil ratio wasn’t adequate with this bearing.  LaCross’s beginning with serial number 23M0231, Scorpion’s at 24M0401, and 250 Impala’s at 25M0201 were fitted with 28 uncaged needle bearings as a replacement for the earlier bushings and caged needle bearings in order to support the increased load.  They are a direct replacement for the earlier models.  The loose needles continued to be used into the early ‘70’s in all Cappra’s up to the VR and the 247 Cota’s to serial number 21M13106.  They were used in all 123 Cota’s (only 26 needles) and all Cappra 360 GP’s and DS (30 needles) models as well.

You will need at least one special tool to remove the piston and help in its reassembly.  Go find an electric paint remover.  It looks much like a hair drier but is typically adjustable for 750 degrees or 1,000 degrees.  Some go higher.  They are cheap.  I found mine for under $15.00 at Sears.  This is a much better heat source than a propane torch.  It doesn’t concentrate the heat in such a small area and is much faster.

Piston Removal

1. Place the engine over a cleared bench or table.  You might want to place a few sheets of newspaper down under the engine.
2. Remove the head and cylinder.
3. Pull the piston up and stuff rags or paper towels around the crankcase opening.
4. Remove one wrist pin-retaining clip.   Note:  The wrist pin is a very snug fit.  You don’t want to hammer the wrist pin out.  This can damage the connecting rod.
5. Secure some type of drift that will fit into or against the wrist pin that is smaller than the wrist pin hole.  I use a large common screwdriver that wedges into the hole near the wide end of the blade.
6. Put on a pair of cotton work gloves.
7. Heat the piston with setting on high for 2 to 5 minutes.
8. Grasp the piston with one gloved hand and push the pin out with the drift away from the remaining retaining clip.  It should push out easily.

When the pin and drift is removed the piston will easily lift free.  You will see a shower of needles and two location washers fall and scatter around the workspace.  Pick up the needles and spacer.  Count the needles.  If you don’t have the correct number then one or more might have fallen into the crankcase.  This is why you stuffed the rags into the crankcase.  A pencil magnet will help in the recovery.  I have measured used needles against new ones to the 10,000th of an inch and have never found any difference.  I haven’t reused any because I have access to new ones but in a pinch I would likely reuse.

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Flywheel Removal

Montesa flywheels are fastened onto a tapered shaft.  The woodruff key is only a location device.  It is used for location purposes for ignition timing.  The key does nothing else.  There are 2 flywheel pullers for all vintage Montesa flywheels.  They thread into the flywheel with right hand threads.  The flywheel nut, on the other hand, is a left-hand threaded fastener.  The two sizes are 27mm x 1.25 thread pitch and 30mm x 1.5 thread pitch.  You must have the engine number to order the correct one.  There was a change in at least one model from one to the other during its production.

If you find a part number in a parts book that doesn’t have these numbers then there are super cessions to them.  As a rule, any part number with a D prefix is a 27mm and any part number that is all numbers supercedes to the 30mm one.  Check for prices in the parts listing.

Steps in flywheel removal:

1. Hold the flywheel with some holding device.  If you have an air impact driver then a hand will do.
2. Use a socket wrench.  A 22mm or a 7/8” size will fit.
3. Turn clockwise to remove flywheel nut.  This is a left hand threaded nut.
4. Remove the lock washer.  This is a left-handed lock washer so don’t lose it.
5. Install the appropriate flywheel puller by turning it clockwise and turn it until it bottoms.  Note: This is important.  Any less and the threads will strip on the puller.
6. Fasten the appropriate wrench to the center bolt of the puller.
7. Turn the bolt clockwise until the flywheel pops free.  Here again an air impact driver will do the job quite nicely.  If you are doing it by hand then use about an 18” break-over with ½” drive and a strap wrench to hold the flywheel.
8. This flywheel should torque to 72 lbs. ft. when reassembling.  The factory installation may be a bit tighter.  All of the flywheels I’ve removed from Montesa engines have been done this way.

Heat doesn’t work.  The crankshaft and the flywheel hub are steel.  The metal was cleaned of all oils and contaminates before they were installed and both metals expand at the same rate.  You will likely damage the coils on the stator when you use heat.

Before you reinstall the flywheel you should clean all oils from the taper in the flywheel and on the crankshaft.  Use alcohol or electric contact cleaner.  Do not touch them with your fingers.

USE A 2 OR 3 JAW CLAW DO NOT PULLER, these will destroy the flywheel.

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Spark Plug heat Range

ANY SPARK PLUG WITH SPARK given it has an adequate ignition source. 

The confusion is about what are hot plugs and cold plugs.  It’s simple.  If the engine has too cold a plug it will likely foul (Cease to spark).  If it is too hot it will likely burn a hole through the piston.

The term cold plug is a description of how well the spark plug sheds the heat of combustion.  Thus the hot plug is one that holds more of the heat of combustion.   If it is a cold plug contaminates won’t burn clean the electrode and grounding tab and thus foul.  A hot plug doesn’t have the problem of contaminate fouling; it has the problem of either melting the electrode and/or ground or providing a hot spot hot enough to melt the top of a piston.

The manufacturer of the motorcycle has tested many plugs to adequately operate in the environment for which it is designed.  By following these guidelines the motorcycle should perform in a reliable manner.

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Troubleshooting the Ignition of the COTA 247

The first thing you should do is change the sparkplug.  If you go all through the following steps and discover it was a fouled plug you will hate yourself.

The initial start of the Cota can be a little difficult if it hasn’t been primed sufficiently.  Once the engine has been running for a while it characteristically starts on the first or second kick anytime thereafter during the day.

Thing to look for:

1. Are the points set at .014”-.016”?
2. Are the points clean?  You can card the points to be certain.  (Note to follow)
3. Is the wiring clean and properly installed with no broken or exposed wires?
4. Is the condenser questionable?  The test of a condenser is by using a volt/ohm meter, touch the outside of the casing and the center contact.  If there is continuity it is bad. Note: Many condensers will check good but will fail when the engine heats up.  If there is good starting but the engine stalls or stutters after it has come to operating heat this makes the condenser questionable.
5. Is the timing set at 27 degrees BTDC? (Some Cota’s respond to 21 degrees).  It will start and run anywhere between 21 and 27 degrees.
6. Is the high tension coil and sparkplug cap undamaged and connected properly?
7. Is the kill button questionable?  This is easily checked by disconnecting it from the coil and checking for spark.
8. Does the spark plug throw a spark with only a quick twist of the wrist on the flywheel with the sparkplug out and grounded against the head?
9. Is there any corrosion with the contact of the ground to the high tension coil?  Remove the coil and sand through any rust or paint to make a new ground.

If all of these check out then you have a mystery.   It could mean rewiring it entirely and replacement of the points/condenser.

CARDING THE POINTS:

This process has been around for years.  I heard about it in 1966 with my first Montesa.  It was around long before that.  Points were the method of choice for ignition.  Was there any other way?

The original method was to use a clean corner of a business card.  Open the points, insert card, and twist the card with a back and forth motion.  Open the points and remove the card.  Inspect the card for discoloration. Select an unused part of the card.  Repeat until there is no residue on the card.

I simplified this by using a 3 x 5 card.  I cut off a ¼” strip.  Each time I removed the card I sniped off a small piece and repeated.

If you pull or push it there can be paper left behind insulating the points from contact.  The result would be NO SPARK.

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How to set your timing

A SIMPLE WAY TO TIME USING A PIECE OF BAILING WIRE, AN OLD SPARKPLUG, A PLASTIC PROTRACTOR, AND A CONTINUITY DEVICE.

Tools Needed:

1. A length of bailing wire about 18” to 24” long.
2. One thoroughly used/fouled 14 mm short reach sparkplug.
3. One bolt 3 to 3 ½” long with a 3/8” x 16 threaded bolt with threads at least 1 ¾” long.  (I used an allen bolt)
4. Use of a 3/8” x 16 pitch taper tap.
5. One plastic protractor about 6” long on it long edge.
6. One 4” long piece of fresh duct tape.
7. Two alligator clipped patch cords approximately 1 foot in length with alligator clips installed at both ends.
8. One detection device such as a buzz box, continuity light or volt/ohm meter with internal battery supplied.
9. One appropriately sized flywheel puller.
10. Three common screwdrivers; one medium, one slender, and one small enough to turn setscrews in connector block if necessary.
11. One long nose pliers. (Needle nose)
12. One very small adjustable wrench. (6 inch or smaller)
13. A ½” piece of electrical tape.

Fabricating piston stop:

1. Secure sparkplug in a vise.
2. PUT ON SAFETY GOGGLES.
3. Use a center punch or small cold chisel and a small hammer, break up and drive out the porcelain center and wire core.
4. Break off ground wire.
5. Cut threads through the metal body of the spark plug with tap.
6. Remove gasket.
7. Insert bolt from the top and twist it into the spark plug shell.
8. Clean up area.

Fabrication of alligator patch cords:

This doesn’t need to be anything special.  Use light wire and alligator clips that are about an inch long.  You can find them with cramp in straps and screw tightening forms.  I prefer the cramp on version.  I also solder the wires for a more permanent connection.  You can find all of these items at your local Radio Shack.

Setting up to find top dead center:

1. Remove flywheel.
2. Loosen the small nut on the points and remove the pigtail that is connected to the points.  It is unnecessary to tighten the nut down.  Tuck the free wire out of the way of the flywheel so it won’t tear away when the flywheel is turned by hand in later steps.
3. Remove sparkplug from the cylinder head.
4. Screw in finger tight the fabricated sparkplug shell with the bolt inserted about 1/3 of its length into the plug shell.
5. Replace the flywheel by hand but do not fasten.  You should be able to remove the flywheel by hand.
6. Tape the protractor with a piece of duct tape so that the center of the protractor is over the center of the crankshaft.  The 90° should be somewhere a little to the left of the top of the flywheel and positioned so that the gap in the flywheel is positioned over the points.
7. Tie the bailing wire around two stationary points.  (I usually tie it around the shift lever shaft and the kick-start shaft.  In lieu of the shift shaft just wind it around some anchor point.)
8. Turn the flywheel with the hand back and forth over top dead center while screwing the bolt in the sparkplug shell down toward the piston until the rotation of the flywheel stops against the piston.
9. Bend the free end of the bailing wire so that it points to the 90° point of the protractor.
10. Rotate the flywheel away from the stop and turn it until it stops again.
11. Note how many degrees it is from the 90° point.  (Example: Say it reads 76°.)  The difference would be 14°.
12. Rebend the wire to half the degrees between the 90 and what ever you found indicated.  (Example: 83°) This is top dead center.

  

Setting timing:  This pertains to those models with the flywheel on the right.  Reverse the rotation for advance and retard if the flywheel is on the left.

1. Rotate flywheel until points can be seen through the flywheel hole and the points are open to their largest gap.
2. Loosen point set screw.
3. Under close inspection you will see a fixed stop on the stator and a notch on the point plate where a common screwdriver blade will fit.  Turning the screwdriver with the setscrew loosened you will see the gap of the points open and close.
4. Insert a thickness gage between the points.
5. Adjust with the screwdriver until the thickness gage will slide through the points with a little drag.  The points should not be seen to open or close when the gage is inserted and withdrawn.  Typically the gap should be .014” to .015”.
6. Tighten the setscrew.
7. Clip the alligator patch cords to you continuity device with one end connected to the frame or engine.  This is ground.
8. Wrap a piece of electrical tape around the other clip to insulate it from contacting the metal of the flywheel and surrounding metal.  Connect this clip to the points blade spring or the nut.  (You remember the nut that you loosened to remove the condenser pigtail.)  Use the long nose pliers to fasten the clip to the nut.  Your fingers won’t fit.
9. When you rotate the flywheel before top dead center you will, at some point see a change in signal.  Note the degrees on the protractor.  This is the point where spark takes place.
10. To adjust the point in which the timing is supposed to take place, remove the flywheel and loosen the 3 screws that secure the stator to the engine.
11. Rotate clockwise to retard and counter clockwise to advance.  You will have to remove the flywheel each time to turn the stator.
12. Once the correct timing has been located, remove the flywheel once more and tighten the three stator screws.
13. Replace the flywheel.  Check that the timing has not moved.
14. Remove the flywheel again and fasten the pigtail of the condenser to the points.
15. Replace the flywheel and torque to 72 lbs./ft. or to that recommended for your model.
16. Replace all pieces on the engine and tighten snugly. 

You have now set your timing.  Easy wasn’t it.  Next time you can do it in as little as a half hour.

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Checking the Timing

ELECTRONIC – INTERNAL ROTOR

There are two reasons that the Motoplat ignition does not create a spark.  First, for some unknown reason an internal short occurs and it just quits.  The second is the more likely and that is what I will address.  There is no way that the ignition can be damaged for the spark to be lost by removing the flywheel and stator unless there is physical damage inflicted on the unit by carelessness with tools.  Knocking it off with a hammer would be one of these.  Removal with a proper puller of the flywheel and removal of the stator with a common screwdriver is not.  There is a greater amount of heat and vibration occurring during engine operation then proper removal and assembly can afflict.  These are the things to look for:

1. Check and reset the timing if needed. 
2. The ignition coil on the frame must have the metal mounting tab in contact with the metal surface of the frame. 
3. Check all wiring for any breaks.  This is easily done with your volt-ohm meter on the ohm test mode.
4. The only way you can check for spark is to have the top end assembled and all of the electrical components hooked up.  Install a new spark plug into the coil cap of the high-tension wire, ground it against the engine, and rotate the engine rapidly.  This type of ignition needs to be spun faster than the external flywheel type because it has magnet proximity of lesser radius and the magnetic flux occurs with the passing of a magnet past the core to the primary coil windings.  If the kick-starter is unable to spin the engine fast enough then elevate the rear wheel, select top gear, and spin the engine using the rear tire. Note: These electronic ignitions can short in the stator if the components are connected and the sparkplug isn’t grounded when the engine is turned over. This is not a common problem but it never hurts to take precautions.
5. Disconnect the kill button and try again.  Some kill buttons will short.  The ones I use are an aftermarket copy of the two-wire Yamaha kill button.  I have not found any failure of this unit.
6. If these steps do not provide a solution then you can send it to Motoplat USA and they can test it.  It takes special equipment to do this.  The typical way a home mechanic tests the stator is to replace it with a stator on an engine that has proven spark.  Note:  You might think that the rotor may have lost its magnetism.  These are permanent magnets not provided by Lucas.  I have not found any to have lost any magnetism.  This may be a test performed by Motoplat USA.  Loss of magnetism is a rare ocurrente.

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Montesa Ignition Timing Chart

This is the most complete list that I could assemble. If you have any specs that are missing or see mistakes, I would be greatful if you emailed me. john@rmmontesa.com			# Models with CDI * Models with lighting coils
Model Number	Bike Name	Degrees BTDC	Inch/mm BTDC	Bore/Stroke
3M*	Impala Sport	25	.138"/3.5mm	60.9x60
4M*	Impala	23	.118"/3mm	60.9x60
5M*	Microscoter 60	?	?	38x43
6M*	Comando 175	23	.118"/3mm	60.9x60
7M*	Montesa 50	?	?	38x43
8M*	Kenya	23	.118"/3mm	60.9x60
9M*	Comando Impala	?	?	60.9x60
10M*	Cota 25	22	.097"/2.5mm	38x43
10M*	Cota 25A	22	.097"/2.5mm	38x43
11M*	250 Trial	23	.118"/3mm	72.5x60
12M*	Texas	22	.118"/3mm	60.9x60
13M	Impala Cross 175	25	.138"/3.5mm	60.9x60
13M	Cappra 175 (Italian Model)	25	.138"/3.5mm	60.9x60
13M	Impala Cross 250	32,36 xx	?	72.5x60
?	El Diablo (U.S. model)	?	?	?
14M*	175 Enduro	25	.138"/3.5mm	60.9x60
15M*	Sport 250	27	.157"/4mm	72.5x60
16M*	Cota 74, Trail	20	.157"/4mm	42x54
17M*	Ciclo Montesa 50	?	?	38x43
17M*	Indiana 1st & 2nd Version	?	?	38x43
18M*	Cappra 125 MX	27	.157"/4mm	51.5x60
19M*	172 Cota	24.3	.157"/4mm	60.9x54
20M*	Cota 49	?	?	38x43
21M0001*	Cota 247MK-I	21-27	.098"/2.5mm - .157"/4mm	72.5x60
21M3000*	Cota 247MK-II	21-27	.098"/2.5mm -.157"/4mm	72.5x60
21M6100*	Cota 247MK-III	21-27	.098"/2.5mm -.157"/4mm	72.5x60
21M13830*	Cota 247 Trail	21-27	.098"/2.5mm -.157"/4mm	72.5x60
21M19228*	Cota 247 Ulf Karlson	21-27	.098"/2.5mm -.157"/4mm	72.5x60
21M21482*	Cota 247T	21-27	.098"/2.5mm -.157"/4mm	72.5x60
21M25132*	Cota 247C	?	?	71x60
21M25307*	Cota 247 (1978)	?	?	71x60
21M51001*	Cota 248	?	?	69x64
23M	La Cross	33	.118"/3mm	72.5x60
24M*	Scorpion	27	.157/4mm	72.5x60
25M*	Impala 250 (USA)	27	.157"/4mm	72.5x60
26M	Enduro 75L	24	?	42x54
27M*	Mini	?	?	38x43
28M*	Cota 123, 123T	24.3	.157"/4mm	54x54
29M*	Cota 200	20	.079"/2mm	54x64
30M0001*	Scorpion 50	?	?	38x43
30M5301*	Scorpion 50R	?	?	38x43
31M	Cota TT	?	?	72.5x60
32M*	Cota 80	?	?	?
33M	Cappra 250	27	.157"/4mm	72.5x60
34M*#	King Scorpion	27	.157"/4mm	72.5x60
36M	Cappra 360-GP	23.5	.175"/4.5mm	78x73.5
37M*	Biro 50	?	?	38x43
38M0001#	Cappra 125 VA	?	.059"/1.5mm	54x54
38M1265#	Cappra 125 VB	?	?	54x54
38M2052#	Cappra 125 VB (1978)	?	?	54x54
38M2477#	Cappra 125 VE	?	?	?
38M2878#	Cappra 125 VF	?	?	?
39M*	Cota 242	?	.079"/2mm	71x60
39M*	Cota 304	?	?	71x60
40M*	Rapita 50	?	?	38x43
41M*	Rapita 50	?	?	38x43
41M*	125 Impala II	25.3	.118"/3mm	60.9x60
42M*	Crono 75	20	?	42x54
43M0001	Cappra 250-Five	23.5	.157"/4mm	72.5x60
43M0310	Cappra 250-Five	23.5	.157"/4mm	72.5x60
44M#*	King Scorpion Automix	22	.118"/3mm	70x64
45M#*	Rapita	22	.118"/3mm	70x64
46M0001	Cappra 360-GP	23.5	.157"/4mm	78x73.5
46M0600	Cappra 360-GP/DS	23.5	.157"/4mm	78x73.5
48M*	125 Enduro, Enduro L	20	.079/2mm	54x54
51M0001#	Cota 348	17.3	.071"/1.8mm	78x64
51M49001#	Cota 349 Trail	17.3	.071"/1.8mm	78x64
51M54301#	Cota 348 Trail (1982)	17.3	.071"/1.8mm	78x64
51M15709#	Cota 349	?	.085"/2.1mm	83.4x64
51M20920#	Cota 349 (1981)	?	.085"/2.1mm	83.4x64
51M24524#	Cota 349/4	?	.085"/2.1mm	83.4x64
51M26497#	Cota 350	?	.105/2.7mm	83.4x64
52M*#	Crono 125	?	?	54x54
53M	Cappra 250 GP	27	.157"/4mm	72.5x64
54M0001*#	Enduro 250	22	.157"/4mm	70x64
54M66001*#	Enduro 250A	20	.098"/2.5mm	70x64
54*#	Enduro H, Enduro 250K	20	.098"/2.5mm	70x64
54*#	Enduro 250-H6, 250-H7	22	?	70x64
55M*#	Crono 350	?	?	83.4x64
57M#	Fura	?	?	38x43
58M	Enduro 125H	?	?	54x54
61M00001*#	Coda 330	?	?	83.4x60
61M01500*#	Cota 335	?	?	83.4x60
62M*#	Enduro 75 H6/79, 80 H7	?	?	42x54
63M*	Cappra 250 MX	23	.118"/3mm	72.5x60
66M0001*	Cappra 360 VA	24	.118"/3mm	83.5x64
66M0501*	Cappra 360 VB	22	.118"/3mm	83.5x64
66M1383*	Cappra 360 VB/78	22	.118"/3mm	83.5x64
66M01799*	Cappra 414 VE	?	.118"/3mm	88x68
66M02262*	Cappra 414 VF	?	.118"/3mm	88x68
66M02575*	Cappra 414 VE	?	.118"/3mm	88x68
67M0001*#	Enduro 360-H6	?	?	83.4x64
67M04609*#	Enduro 360-H6/79	?	?	83.4x64
67M7001*#	Enduro 360-H7ET	?	?	83.4x64
67M*#	Enduro 360-H7L	?	?	83.4x64
68M0001*#	Enduro 125 H6/79	?	?	54x54
68M01305*#	Enduro 125 H7	?	?	54x54
73M5001*	Cappra VR	24	.118"/3mm	70x64
73M6001*	Cappra VR	24	.118"/3mm	70x64
73M8089*	Cappra VR-75	24	.118"/3mm	70x64
73M9690*	Cappra VA	24	.118"/3mm	70x64
73M10612*	Cappra VB	22	.118"/3mm	70x64
73M11841*	Cappra VB/78	22	.118"/3mm	70x64
73M13468*	Cappra VE 250	22	.118"/3mm	70x64
73M14928*	Cappra VF 250	22	.118"/3mm	70x64
73M15939*	Cappra VG 250	22	.118"/3mm	70x64
MH 123	Montesa Honda 123	?	?	54x54
MH 200	Montesa Honda 200	?	?	54x64
MH 349	Montesa Honda 349	?	?	69x64
?	Cota 307	?	?	71x60
?	Cota 309	?	?	74x60
?	Cota 310	?	?	74x60
?	Cota 311	?	?	74x60
VTDNT01AOM	Evasion	?	?	74x60
VTDNT03900E0	Cota 314 R (1994)	?	?	71x66
VTDNT03900E1	Cota 314 R (1995/96)	?	?	71x66
VTDMT0EA0VE0	Cota 315 R (1997)	?	?	72.2x61
VTDMT03A0VE01518	Cota 315 R (1998)	?	?	72.2x61
VTDMT03A0XE0	Cota 315 R (1999)	?	?	72.2x61
VTDMT03A0YE3	Cota 315 R (2000)	?	?	72.2x61
VTDMT03A01D3	Cota 315 R (2001)	?	?	72.2x61

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