I believe it a Comet spacer . How can you tell the difference? Martyn
Comet - Primary Chain
- Thread starter Martyn Goodwin
- Start date
Is it feasible to move the engine sprocket inboard by the required 2mm? Keeping the clutch where it is will give maximum spline engagement, reduce load on shafts, etc. Worth a try?
Comet engine spacer 21/64" thick.
Twin clutch spacer 7/32" thick.
Both are 1.50" OD 1" ID.
I could also ask, what shaft do you have in your Burman ?
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First up my apologies for no paragraphs – for some reason I am unable to put line returns into my posts on this forum.
To those folks who have been following this thread, here is a summary of work performed and in conclusion a theory on additional work , not performed, but that may have been of benefit.
This all started out with me trying to cure almost constant "locking" of the kick start lever on my Comet. I obtained new old stock replacements for both the kick start quadrant and the engaging pinion from the VOC spares company.
Often one reads about the need to "file" the lead tooth on the Burman Kick Starter quadrant to avoid the dreaded "locking" of the kick starter. Attempting to force the kick starter once locked may result in damage to the kick start shaft, the kick start quadrant, the driven pinion, the rider’s foot or the rider’s leg – and any one or any combination of damaged items is possible.
Once the kick starter becomes locked the accepted release technique is to engage a gear then rock the bike back n forth till the kick starter becomes free, then gearbox back into neutral and try the kick starter again.
Despite extensive research I was unable to find any guidance on just how the quadrant lead in tooth should be shaped to avoid lock up - until now.
Recently I purchase a NOS Burman Kick Start quadrant from Draganfly in the UK for use in the Burman box fitted to my Comet. I also purchase a second kick start quadrant – again NOS – from the VOC Spares company for the same purpose. On both the lead in tooth is identical at about ½ height with a flat top, and its top surface slopes slightly towards the valley of the first "full" tooth. Photos are available – send me a PM – or just wait for the story in MPH.
During the reassembly of the motor/gearbox I discovered miss-alignment between the drive sprocket on the main-shaft and the driven sprocket on the clutch. Using a straight edge I measured the difference then made up a suitable spacer to fit behind the clutch, moving it outwards so that the alignment was corrected. As my Comet is fitted with a Conway’s Honda clutch conversion with very deep gearbox engagement splines this did not present a problem. I also took the opportunity to fit an oil slinger behind the clutch, as described by Ken Phelps in a recent edition of 998.
In order to provide the best opportunity for smooth engagement between the kick start quadrant and the kick start driven pinion it is advisable to polish the lead in tooth, especially its upper surface. BUT close examination of the engaging pinion shows that on many of the engaging pinion teeth there is a flat spot – and I postulate that if the two flat faces quadrant tooth and pinion tooth – come together then jamming is probable. What a shame , having polished the lead in tooth on the quadrant, I reassembled my Comet before I thought of the following!
The ultimate solution seems to be as follows: The lead in tooth on the kick start quadrant should have its top face sloping slightly towards the valley between it and the next tooth and that face should also be highly polished (to ensure a minimal friction surface). To complement the lead in tooth on the quadrant EVERY tooth on the engaging pinion need to have the small (narrow) flat on the very top of each tooth profiled so it slopes at a matching angle to that on the quadrant and that sloping flat surface on each tooth of the pinion also needs to be highly polished. This will require careful modification of each of the pinion teeth, with the aid of Swiss files and a jeweller’s loupe with final polish finishing. The effect of should be that no matter what pinion tooth engages with the lead in tooth on the quadrant it will be the meeting of polished (thus slippery) matching inclined planes and jamming should be nigh on impossible.
I came to this position only after having just reassembled my Comet, Clutch and gearbox so the solution is theoretical. I will be road testing the reassembled bike within a few days.
To those folks who have been following this thread, here is a summary of work performed and in conclusion a theory on additional work , not performed, but that may have been of benefit.
This all started out with me trying to cure almost constant "locking" of the kick start lever on my Comet. I obtained new old stock replacements for both the kick start quadrant and the engaging pinion from the VOC spares company.
Often one reads about the need to "file" the lead tooth on the Burman Kick Starter quadrant to avoid the dreaded "locking" of the kick starter. Attempting to force the kick starter once locked may result in damage to the kick start shaft, the kick start quadrant, the driven pinion, the rider’s foot or the rider’s leg – and any one or any combination of damaged items is possible.
Once the kick starter becomes locked the accepted release technique is to engage a gear then rock the bike back n forth till the kick starter becomes free, then gearbox back into neutral and try the kick starter again.
Despite extensive research I was unable to find any guidance on just how the quadrant lead in tooth should be shaped to avoid lock up - until now.
Recently I purchase a NOS Burman Kick Start quadrant from Draganfly in the UK for use in the Burman box fitted to my Comet. I also purchase a second kick start quadrant – again NOS – from the VOC Spares company for the same purpose. On both the lead in tooth is identical at about ½ height with a flat top, and its top surface slopes slightly towards the valley of the first "full" tooth. Photos are available – send me a PM – or just wait for the story in MPH.
During the reassembly of the motor/gearbox I discovered miss-alignment between the drive sprocket on the main-shaft and the driven sprocket on the clutch. Using a straight edge I measured the difference then made up a suitable spacer to fit behind the clutch, moving it outwards so that the alignment was corrected. As my Comet is fitted with a Conway’s Honda clutch conversion with very deep gearbox engagement splines this did not present a problem. I also took the opportunity to fit an oil slinger behind the clutch, as described by Ken Phelps in a recent edition of 998.
In order to provide the best opportunity for smooth engagement between the kick start quadrant and the kick start driven pinion it is advisable to polish the lead in tooth, especially its upper surface. BUT close examination of the engaging pinion shows that on many of the engaging pinion teeth there is a flat spot – and I postulate that if the two flat faces quadrant tooth and pinion tooth – come together then jamming is probable. What a shame , having polished the lead in tooth on the quadrant, I reassembled my Comet before I thought of the following!
The ultimate solution seems to be as follows: The lead in tooth on the kick start quadrant should have its top face sloping slightly towards the valley between it and the next tooth and that face should also be highly polished (to ensure a minimal friction surface). To complement the lead in tooth on the quadrant EVERY tooth on the engaging pinion need to have the small (narrow) flat on the very top of each tooth profiled so it slopes at a matching angle to that on the quadrant and that sloping flat surface on each tooth of the pinion also needs to be highly polished. This will require careful modification of each of the pinion teeth, with the aid of Swiss files and a jeweller’s loupe with final polish finishing. The effect of should be that no matter what pinion tooth engages with the lead in tooth on the quadrant it will be the meeting of polished (thus slippery) matching inclined planes and jamming should be nigh on impossible.
I came to this position only after having just reassembled my Comet, Clutch and gearbox so the solution is theoretical. I will be road testing the reassembled bike within a few days.
Just back from a 95 mile shakedown run after putting the Comet back together. Crisp but sunny winters day and dry roads.
During reassembly of the bike I reset the timing. In the past I was in the habit of setting it fully retarded at 4 BTDC to ensure an easy start. After some sage advise from more knowledgeable folks I switched to setting it with the ATD fully advanced at 38 BTDC, which gave a retarded setting of 8 BTDC. Starting was not difficult at all and the bike seemed to run a lot better and spin more freely - of course it could also be imagenitis on my part! FWIW I am using a CP piston with 7.2:1 compression, Mk1 Cam and 95 Octane (RON) fuel.
In addition to the kick start problem I was also troubled with a gross oil leak around the opening in the case where the Alton mounted. As my Comet is running a magneto I do have a bit of wriggle room in the sparks department so I made the decision to remove the Alton and refit my Miller generator (that I had rebuild about 6 months back) and the regulator that converts it to 12 volt output. Bonus with the generator is that a "proper" lipped seal is used, so there should be no oil leak. In case any are wondering I run LED indicators, park light and tail/stop light - oh and there is a LED inside the speedo as well. For the headlight I have a 35/35W halogen.
Anyway - cutting to the chase. After today's shakedown run absolutely no sign of oil leaks anywhere, other than that thrown off the rear chain. And not a trace of kick start jamming either.
Time to open a bottle of Red and celebrate while the going is good.
Martyn
(PS I switched to Firefox and the carriage return seems to be working)
During reassembly of the bike I reset the timing. In the past I was in the habit of setting it fully retarded at 4 BTDC to ensure an easy start. After some sage advise from more knowledgeable folks I switched to setting it with the ATD fully advanced at 38 BTDC, which gave a retarded setting of 8 BTDC. Starting was not difficult at all and the bike seemed to run a lot better and spin more freely - of course it could also be imagenitis on my part! FWIW I am using a CP piston with 7.2:1 compression, Mk1 Cam and 95 Octane (RON) fuel.
In addition to the kick start problem I was also troubled with a gross oil leak around the opening in the case where the Alton mounted. As my Comet is running a magneto I do have a bit of wriggle room in the sparks department so I made the decision to remove the Alton and refit my Miller generator (that I had rebuild about 6 months back) and the regulator that converts it to 12 volt output. Bonus with the generator is that a "proper" lipped seal is used, so there should be no oil leak. In case any are wondering I run LED indicators, park light and tail/stop light - oh and there is a LED inside the speedo as well. For the headlight I have a 35/35W halogen.
Anyway - cutting to the chase. After today's shakedown run absolutely no sign of oil leaks anywhere, other than that thrown off the rear chain. And not a trace of kick start jamming either.
Time to open a bottle of Red and celebrate while the going is good.
Martyn
(PS I switched to Firefox and the carriage return seems to be working)
Another 200 miles has been traveled - trouble free. Absolutly no sign of any oil from the motor or gearbox. This means that the only remaining source of oil "fling" is coming from the drive chain which, during the recent work, while I had it off the bike I soaked in a container of used engine oil for a couple of days then hung up to "drain" for a day. Before refitting I wiped it down trying to remove excessive oil - but there was still some "fling" onto the back wheel.
I am wondering of the wisdom of moving to a "o" ring chain. It would mean giving up the split link. Any opinions on how much of an issue that may be?
Martyn
I am wondering of the wisdom of moving to a "o" ring chain. It would mean giving up the split link. Any opinions on how much of an issue that may be?
Martyn
The "O" ring chain is not really needed with only 27 British horses champing at the nosebag. I use "Duckhams Chain Guard " occasionally, and fortify/supplement this with chain-bar lubricant. Works for me!
So - where do you source your Duckams???