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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Stiff Cam Shafts
Post Info TOPIC: Stiff Cam Shafts
SteveGT


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Stiff Cam Shafts
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I have just re-assemblyed my TTR raid, after replacing the piston rings. When replacing the cam shafts, as soon as I tighten up the bolts the cam shafts become too tight to turn by hand. Even if I just do the bolts up hand tight they are really stiff. Is this normal?

I have completely re-assembled the engine now and can turn it over  quite easily using the nut on the end of the crank, but I'm a bit woriied how stiff these cam shafts are.



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TTRfan


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Good to hear that you are nearly there Steve biggrin

The only thing I can suggest is that you double check that you have the cam caps with I marked on them on the carb/inlet camshaft and the E marked ones on the exhaust side - and that the arrows on the small caps are pointing toward the timing chain. Can't think what else to suggest.

Good luck!

Brian 



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SteveGT


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Have checked the cam caps and everything is correct. Motor is turning over on the starter OK - with no spark plug in. Will fire it up tomorrow and see how it goes!!!



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TTRfan


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Good luck. That first start up after a rebuild can be a bit scary but let us know how it goes!

Brian



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TTRfan


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What news Steve - does the TTR live again?

Brian



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SteveGT


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The TTR lives, but has a bit of an oil leak. Turned over twice and fired into life - phew!!! No banging or clanking so looks like the missing dowel didn't end up in the crank case after all.

I've had a couple small runs and everything checks out ok - apart from the little oil puddle at the end of the run. Sounds OK and runs fine, hopefully all went well and she should give me a few more trouble free weeks before the next maintenance job.

The oil leak is from the cam chain tensioner which should really have had a new gasket. Any idea where I can source one locally Brian. Fowlers will cost me a fiver in postage.



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TTRfan


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SteveGT wrote:

The TTR lives, but has a bit of an oil leak. Turned over twice and fired into life - phew!!! No banging or clanking so looks like the missing dowel didn't end up in the crank case after all.

I've had a couple small runs and everything checks out ok - apart from the little oil puddle at the end of the run. Sounds OK and runs fine, hopefully all went well and she should give me a few more trouble free weeks before the next maintenance job.

The oil leak is from the cam chain tensioner which should really have had a new gasket. Any idea where I can source one locally Brian. Fowlers will cost me a fiver in postage.

Excellent news Steve and well done on your first TTR engine rebuild!

I am sure I got a tensioner gasket in stock because they are quite brittle and break easily. I can put one in the post if you want? If so, how urgent - 1st or 2nd class?

Brian



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SteveGT


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Thanks Brian. Second class should do it. I've got a busy weekend so not sure if I'll get it done then anyway. Would be nice to get out on the lanes again though. Can't beleive it's taken 6 weeks. I think I should spend less time out on the road bike... but it's been such good weather. 



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airmanbear


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i have found the same  problem with my ttr250 .it just doesnt make sense

i have not done anything to make the cams shaft  tighter. do you have any ideas what woud make  this happen  .. the only thing i can see is to shim the cam yokes a few thousands  of an inch away from  the shafts no im afraid  to assemble it so tight



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TTRfan


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airmanbear wrote:

i have found the same  problem with my ttr250 .it just doesnt make sense

i have not done anything to make the cams shaft  tighter. do you have any ideas what woud make  this happen  .. the only thing i can see is to shim the cam yokes a few thousands  of an inch away from  the shafts no im afraid  to assemble it so tight

Hi Ed and welcome to the new forum!

I have had this a few times now and I think it may be to do with creating some slight burs on the head's camshaft bearing surfaces from around the area where the "inside" head bolts have been removed and replaced.

On the basis that the camshafts worked OK before the rebuild, and that they turned over easily enough with the engine back together, I adopted a "head in thesand approach and just put them together as they were (tight) and haven't had any problems that showed on later strip downs. 

I hope that helps.

I am assuming SteveGT did the same and haven't heard that he had any consequent problems.

Brian



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Aidan


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Mine was very tight as well after my rebuild. I just left it and then after installing a new cam chain later on they seems to have settled. And were within specs if that helps.

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SteveGT


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Although I have only done about 400 miles since re assebling my engine it seems to be running fine. So Brians 'head in the sand' approach seems to work. I will be checking the value clearances soon so it will be interesting to see if the cams have eased up a bit.



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airmanbear


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WHEN I SAY STIFF I MEAN REALLY STIFF... LIKE I NEED A LEVER IN THE CHAIN COGS ..TO MOVE THE CAMSHAFT (I USE A SCEWDRIVER )
LIKE I CANT MOVE THEM WITH JUST MY HANDS THIS WORRIES ME .. WAS YOURS THAT TIGHT ????

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SteveGT


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Yes really tight. Even if you just lightly tighten the bolts. Had me worried to but seems to run fine. Have done a couple 100 mile runs and all seems OK



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airmanbear


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ITS AGAINST EVERYTHING I KNOW TO EVEN START

 THE MOTOR WITH THE CAM SHAFT  SO TIGHT.... IM AFRAID THE CAM CHAIN

WILL JUST JUMP  COGS ...OR STRIP THE SPROCKETS..

SIGNED FEARFUL..



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TTRfan


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Does it turn over easily with the kick start or using the flywheel bolt Ed?

Have you checked for burs around the head bolt holes on the head "yokes"?

Brian 



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airmanbear


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I AM GOING TO TALK TO THE LOCAL YAMAHA MECHANIC HERE IN WOODSTOCK,NY BEFORE I TAKE THE NEXT STEP ..AS MINE SEEMS EVEN TIGHTER THAN OTHERS
LIKE SITE MEMBERS HAVE EXPERIENCED ...YES I HAVE LIGHTLY SANDED ANY BURRS OR SHARP EDGES ..
HAVE YOU EVER FELT THE TURNING FRICTION AFTER YOU RAN OUR BIKE AFTER A TIGHT REASSEMBLY
JUST TO SEE IF THE ROTATIONAL FRICTION WAS REDUCED ???????????? AFTER A RUN??

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