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west1700

Yamaha Ty 250 Clutch Disengage

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I would appreciate some help as I am having trouble getting the clutch to disengage on a TY 250 I have just brought.

I am on the final stages in completing the rebuild of my 1974 TY and upon splitting the crank to replace the Mains I have come across a really bodge repair of the gear change return pin in the RH crank case. Fortunately I won a Ebay purchase for a replacement engine which has already been rebuilt it runs well but the clutch will not disengage.

I thought I found it when I realized that there was an additional clutch plate installed or that there was a washer missing behind the clutch basket but realize as this is a latter engine it did not have one.

I might be being incredibly thick here but surely the clutch basket and boss should turn independently but every time I tighten the main nut they lock together so the clutch is never going to work.

The two trust plates (the one between the Boss and the basket & the casing & the gear that takes the kick start drive) are in place.

Any help would be truly appreciated.

Regards

Mark

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Sounds like the bush that goes over the shaft that the clutch spins on is too short, might pay to compare it with the 1 out of your old motor, if you sit the clutch basket on a flat surface & fit the bush it should be slightly proud of the hole which gives you the clearance to stop binding

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It’s sorted!

My brother sussed it, the gear takes the drive from the kick start that fits into the bottom of the Clutch basket has 4 slots, 2 square and 2 rounded, all I had to do was rotate the gear my 90 deg and it all works fine.

Still a lesson learnt and hopefully this post might help someone else who was as baffled as me.

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On 10/7/2013 at 7:12 AM, west1700 said:

I would appreciate some help as I am having trouble getting the clutch to disengage on a TY 250 I have just brought.

I am on the final stages in completing the rebuild of my 1974 TY and upon splitting the crank to replace the Mains I have come across a really bodge repair of the gear change return pin in the RH crank case. Fortunately I won a Ebay purchase for a replacement engine which has already been rebuilt it runs well but the clutch will not disengage.

I thought I found it when I realized that there was an additional clutch plate installed or that there was a washer missing behind the clutch basket but realize as this is a latter engine it did not have one.

I might be being incredibly thick here but surely the clutch basket and boss should turn independently but every time I tighten the main nut they lock together so the clutch is never going to work.

The two trust plates (the one between the Boss and the basket & the casing & the gear that takes the kick start drive) are in place.

Any help would be truly appreciated.

Regards

Mark

I was reading on a site that sells magneto systems as a retrofit for the TY 250 A.  It was mentioned in the instructions that sometimes during a crankshaft rebuild that one or both of the main crank ends ends up shorter than it was originally because of the work on the crankshaft.  if that happens on the magneto side, it can cause the flywheel to touch or rub on the stator.  In your case, I think it's possible that the clutch basket could be sitting too high or low in reference to the engine cases because of the crank being moved out of position.  I am not a mechanic, and although my engine has had a complete overhaul, I do not know what the clearance should be behind the clutch basket, There are also several spacers that are close to the same size that go on various points on the crank or the gearbox components.  I had a pro bike overhaul guy do mine, so although it was expensive, the job has turned out fine and my clutch is working normally.  It might be possible to just measure the length of the clutch shaft in reference to the surfaces where the clutch cover gasket sits.  If someone else on here has the clutch cover off you can ask them to measure theirs and make a comparison.  That would tell you instantly if there is a crankshaft offset that is causing you problems.  

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1 minute ago, Tillerman6 said:

I was reading on a site that sells magneto systems as a retrofit for the TY 250 A.  It was mentioned in the instructions that sometimes during a crankshaft rebuild that one or both of the main crank ends ends up shorter than it was originally because of the work on the crankshaft.  if that happens on the magneto side, it can cause the flywheel to touch or rub on the stator.  In your case, I think it's possible that the clutch basket could be sitting too high or low in reference to the engine cases because of the crank being moved out of position.  I am not a mechanic, and although my engine has had a complete overhaul, I do not know what the clearance should be behind the clutch basket, There are also several spacers that are close to the same size that go on various points on the crank or the gearbox components.  I had a pro bike overhaul guy do mine, so although it was expensive, the job has turned out fine and my clutch is working normally.  It might be possible to just measure the length of the clutch shaft in reference to the surfaces where the clutch cover gasket sits.  If someone else on here has the clutch cover off you can ask them to measure theirs and make a comparison.  That would tell you instantly if there is a crankshaft offset that is causing you problems.  

One more possibility - you say the clutch won't disengage- Well mine did that too - when cold and if you put the full 1000 cc's of oil in the gearbox, there is a lot more friction between the plates because of the higher oil level.  But as soon as I reduced the oil level to about 650-700 cc's and especially after the engine is running for a few minutes- the clutch would slip fine with the clutch lever pulled in.

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19 hours ago, lineaway said:

 You are replying to a 8 year old thread?????

Could be- sorry- my mistake!

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 It can happen easily, but the OP has not been on Trials Central in 7 years. I hope your not expecting a reply!

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