500cc valve timing/cam chain question

Jeremy Wilton

Jeremy Wilton

Junior member
Location
Cropredy
This is probably really quite simple but I don't want to eff it up...

Right cyclinder at TDC (on flywheel) cam sprocket marks are a few degrees away from the marks on the blocks... how do I tighten the cam blocks down on inlet and exhaust against the pressure of the valve springs and then connect the camchain and keep it all timed correctly?

Do you force the cams down against the valve pressure by tightening the central block on each cam first then connect the cam chain - surely they'll spring apart when you try to get the cam chain linked...?

How do you keep inlet and exhaust cams pressed against the valve pressure and join the chain - how do you lock the cams?

Jezzer

 
Hi Jezzer,
      Place the cam shafts back onto the head making sure none of the cam lobes are applying pressure to the buckets , then torque them down .Short studs 16 to 18 lb/ft , long engine studs 28ft/lb.
Then you are in a position to move the camshafts to their required TDC marker.Have the crankshaft just before TDC before moving camshafts into position.The inlet cam should stay in place ,the exhaust will require a spanner to hold the cam in the appropriate position to join the cam chain together with the piston in No2 at TDC.

Take your time and if you feel you are forcing anything stop , and think about what you are doing.

Andy
 
engine is not a 500 but the principal is the same
join the chain ends together with a set of circlip pliers, hold chains with one hand, insert joining link from the back with the other hand and use the joining link to push out the plier points
is how I do the 500's and the triples, 750's, well, they are a totally different story again

 
I use one of these. Can be bought for around $25 on ebay. Doesn't block the chain pin holes and leaves both hands free to fiddle with the connecting link. Never thought of using screwdrivers to hold the chain on the sprockets though - good idea, I'll do that next time. I've always tied the ends off with tie wire until I get the connecting link in.
 

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Just a thought, do you have the rear cam chain tensioner blade out.

I use a couple of bits of heavy copper wire looped through the chain then twist them together until the chain is
close enough to fit the link. Fit the plate and locking wire then snip the copper wire and remove.

I've got a big pair of 90 degree circlip pliers that I hadn't thought to use so I'll give them a go next time.

Got my last bits of piano wire for the links from my local model shop. 
 
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