Valve check question

Discussion in 'WERA Vintage' started by shift96, Jan 22, 2021.

  1. shift96

    shift96 Well-Known Member

    Question: i have a cylinder that thats about 120 psi. The rest are 190ish psi. (Fzr600) Checked the valve clearances and the low cylinder is out of adjustment. The minimum clearance is .004. I can get a .002 in but not a .004. Since i can still get a .002 in this shouldn't be affecting the compression reading correct? The valve is not hanging open since i can still get a .002 in correct?
     
  2. 83BSA

    83BSA Well-Known Member

  3. shift96

    shift96 Well-Known Member

    Yes its not hanging it open and therefore not affecting the compression right? Sorry im over thinking it
     
  4. 83BSA

    83BSA Well-Known Member

  5. pscook

    pscook Well-Known Member

    However, with the valve that tight, there is a chance that the seat or the valve is burned or pitted, which can prevent sealing and therefore affect compression numbers. Food for thought.

    Have you dripped any oil into the cylinder to see if it's ring related?
     
  6. shift96

    shift96 Well-Known Member

    I did and it seems to be the same reading
     
  7. pscook

    pscook Well-Known Member

    Hmm. Seems to be a valve issue. Good thing the heads are easy to remove in the frame [/sarcasm].

    Throttle wide open? I'm guessing yes, but I have to ask.
     
  8. shift96

    shift96 Well-Known Member

    Ha yes. Good thing in this case is engine is out on my bench with carbs off
     
    pscook likes this.
  9. kenessex

    kenessex unregistered user

    How long has the engine been sitting? It is possible that with spinning it over a bunch or putting it in the frame and running it, the valves in that cylinder will seat better and the compression will come up. A leak down test on that cylinder will tell you more. Since the engine is on the bench, I would pull the head and look if this is going to be a race engine. If it is for the street, set the valves and run it.
     
  10. shift96

    shift96 Well-Known Member

    Its been siitng for a loooong time. I was thinking of adjusting the valves and running it like you said
     

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