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Allan G, Bustednukel, chaterlea25, StephenM
Total Likes: 5
Original Post (Thread Starter)
by StephenM
so I Had the fresh built motor fired, strobed and run around the block. Felt great to be on her again. few issues that I'm trying to figure..
-Before running, at the exhaust valves/pushrod/rockers, there would be a slight click as the cam would reach it's apex. Wasn't sure if it was full compression on one side or full release on the other as it would happen on both sides.
-There developed a terrible clattery sound when I would run it beyond 3-3.5k. it wasn't there while strobe timing. when I put her up on the stand and pulled the valve cover off I see that one exhaust valve is now SUPER loose at about .035. the adjustment was still tight however. I pulled the pushrods and they don't appear to be bent. I used some extrusion blocks and a height guage to verify as best I could.

I've pulled the head off but haven't pulled the valves/springs out to check those yet.

The other issue is I had the Bob newby clutch set and working well. Ez engage and good solid bite. After getting it back on the stand and going to kick it over to check compression the clutch doesn't bite enough to turn the motor over now. Even after tightening the springs well beyond where they should be.

I will try to upload a pic but I'm curious if this bushing/sleeve shoulder is supposed to extend so far into the clutch basket assembly area and causing issues. Or if the gearbox could float and cause engagement issues. I don't know. Just guessing at this point..

I don't know how to upload photos apparently but can link to the photo in my Google drive..

Liked Replies
by gavin eisler
gavin eisler
Check for coil binding with feeler gauges between the spring coils at full lift, a 3 thou blade should pass through, I dont see how a badly seated spring will change clearances, the valve length and seat wear dictate tappet gaps, not spring pressure. When turning the motor over by hand using the rotor nut to drive it round ,coil binding will be obvious, if the crank gets very stiff at max valve opening that is coil bind,( there will be some resistance as the spring compresses but if you feel a steep hump at max opening thats coil bind, spring pressure rise should be fairly linear.) this is not a good thing, if the motor ran it would indeed be noisy as the forces on the valve train will be immense, to keep running something like Nick describes would seem inevitable. If you have spare rocker arms compare them to whats in the bike now.
2 members like this
by DavidP
Originally Posted by NickL
Sounds like your valve springs are going coil bound.
Did you check it when you rebuilt?
Could be. I got some springs from a vendor who shall go unnamed. New springs from MAP solved this issue.
1 member likes this
by Mark Parker
Mark Parker
Do the pushrods have pressed on ends? One may not have been pushed completely on and shifted.
1 member likes this
by Bustednukel
Originally Posted by Allan G
Originally Posted by Bustednukel
Valve spring fit in the hat and cup might be the issue. A fat spring might not seat in the hat or cup. After all the stress and wiggle of a running engine then the spring might find the seats and result in a wider lash.

Originally Posted by Bustednukel
Gavin, you are right about the valve length and seat wear dictating tappet gaps, not spring pressure. So, hopefully the OP sorts it out and posts an update.

Not sure if your disagreeing or agreeing with Gavin or contradicting your original statement?

Either way. Anything that will effect spring pressure (providing it is enough to keep the valve closed) should not change the gap. If there is insufficient tension on the springs that will not keep the valve closed then itโ€™ll more likely to drop the collets and then the valve.

Alan, agreeing with Gavin cause he's right. My idea that an improperly seated spring could result in a wider lash if it seats after running was wrong. On a past engine build I had an improperly seated spring which I discovered as I centered one of the valve keepers which was in contact with the other keeper. It slid around loosely with ease and alerted me that something was wrong. Made me think of the OP.'s issues.
1 member likes this
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