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Thread: valve shimming

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    valve shimming

    Got the head installed and proceeding to verify clearances as I always do. After installing the head I thought how much easier it would have been to bolt the cams up on the bench and shim at that time. Anyone try it that way? I hindsight I should have tried that method myself and compared after the head was installed.


  2. #2

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    EXTREMELY easier that way.... that being said most everyone who does check clearance does it as maintenance, engine in the ski, so not impossible. Leave the intake manifold off to make putting the tensioner in easier if you havent put it on already.

  3. #3
    I was wondering if the head torque down affected anything. I'm doing the valve shimming now with the manifolds off. Trying to make everything come in on the loose end of the tolerances.

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    Oh you meant to not have the head bolted to the motor at all? Guess i miss understood that part..... I've never done it that way and am sure the book doesnt show it that way..... guess it could be done but wouldn't recommend it. You're on the right track with needed to be bolted down IMO

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    Take the time to smile sirbreaksalot's Avatar
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    Quote Originally Posted by rotortiller View Post
    I was wondering if the head torque down affected anything. I'm doing the valve shimming now with the manifolds off. Trying to make everything come in on the loose end of the tolerances.
    set the clearance in the MIDDLE of the given specs, loose only makes noise and reduces performance
    why reduce cam lift for no reason

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    LindenPWC's Avatar
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    [QUOTE=rotortiller;2813016]Got the head installed and proceeding to verify clearances as I always do. After installing the head I thought how much easier it would have been to bolt the cams up on the bench and shim at that time. Anyone try it that way? I hindsight I should have tried that method myself and compared after the head was installed.[/

    i'm also interested in this procedure, i will be reassembling my head soon just waiting on piston rings to arrive. i was going to install the head and do it by the book? i measured all of the shims and lost the position of cylinder for each one and now have to readjust and do the shim calculations according to the book.

  7. #7
    I like to set them on the loose side of spec so they go the longest time before next service.Valves wear into the seats and reduce clearance. I tried them in the middle and the machine had the same acceleration and top end. If valves did get too loose which they don't, you'd hear them, if they got tight as they typically do the exhaust valve could eventually burn. It makes no difference in the 15F power output if you follow the published valve specs, however it may seem faster on paper LOL.. They are a pain in the ass so why kick yourself in the head pulling the cams more often? I have them at about .29mm and 22mm at the average. Shims I have vary by .002" (.05mm) so that is the limit for me today. Had them at 25mm and 19mm in the past it made no more power so went back to looser settings. Hell if I want to go faster I'll do the sensible thing and ride an RXP. My 15F came from the factory with loose clearances 29-30mm and 23-28mm and it still worked exactly the same even out of spec a bit. I record all my maintenance on paper if you are wondering.

  8. #8
    Hey Roto, I finally got my head pulled and I'm sending it to the machine shop for a vavle job. They said they can adjust the valves cleareance too in the shop without it being bolted to the block.

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    Quote Originally Posted by russell41 View Post
    Hey Roto, I finally got my head pulled and I'm sending it to the machine shop for a vavle job. They said they can adjust the valves cleareance too in the shop without it being bolted to the block.
    i would like to know how the process works with the bench adjustment? i have to do mine while i have the head off.

  10. #10
    Russell41,

    So you got to send the cams and top bearing block too. You are getting the valve seats recut and new guides/valves/seals too? When you get it back and reinstalled let us know what your measurements show.

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