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SV650 head milling.

Discussion in 'Tech' started by track wagon, Nov 7, 2018.

  1. track wagon

    track wagon MCAS MIRAMAR

    I got a 2 mil over bore with spears thinner head gasket. Thinking of taking .010 off and redoing the cam timing. What is the most any of you have taken off?
     
  2. Champer

    Champer Well-Known Member

    Do you know if you have the 13:1 or 12:1 pistons?
     
  3. turner38

    turner38 Well-Known Member

    Depends on Piston Volume and how much work has been done to the Combustion Chamber.
    We ended up with .015” off the heads on the stock bore bike with a +5cc dome volume and .040” piston to head. That put us at 13.5/1...
     
  4. RM Racing

    RM Racing Tool user

    I've had heads come in the shop with 0.040" or more removed. As stated here, depends on the rest of the configuration. The squish is more important, IMHO, because those engines like to detonate.
     
  5. track wagon

    track wagon MCAS MIRAMAR

    678 CP pistons 2 mil over bore. Stock cyclinder as far as milling and thinner spears head gasket. St 12.5 to 1 right now.
     
  6. Monsterdood

    Monsterdood Well-Known Member

    What’s the practical limit on compression with the Sunoco APEX fuel? I want to run an MA round or two but am worried my current engine has too much compression for the APEX fuel. I have run either U4 or Sunoco 110/112 leaded.
     
  7. turner38

    turner38 Well-Known Member

    Thats a pretty loaded question.....

    It all depends on your combination really. I’ve not done a tear down yet on our current configuration but it was 13.5 like I previously said and I saw no signs of detonation on the plugs.
    I would be careful getting much over that especially if it is big bored.
    JMO
     
  8. Monsterdood

    Monsterdood Well-Known Member

    Yeah, I know there’s tons of variables but my dynamic pressure measurement was something like 210 psi (can’t recall exactly but I recall it was up there) and I don’t know what the static CR is but I think it’s pretty freaking high (kawi 650). I’m going to have the engine refreshed and mostly curious if my engine guy is going to tell me I need different pistons or if he can adjust CR down to match the fuel in other ways.

    I’m mostly looking to just qualify for a race or two and not get lapped by KT38 lol....
     
  9. turner38

    turner38 Well-Known Member

    210 cranking really isnt that high to me...
    That is as much a function of when the Intake closes as it is compression.
     
  10. track wagon

    track wagon MCAS MIRAMAR

    What does a bigger bore have to do with compression? Why cant you go 13.5 to 1 with a bigger bore?
     
  11. track wagon

    track wagon MCAS MIRAMAR

    Ever refresh it during the season?
     
  12. turner38

    turner38 Well-Known Member

    Bigger bore doesnt matter, other things that are a result of the bigger bore do.
    I don’t think 13.5/1 will be a issue with a 2 mil honestly. I’m still holding out hope they just set the limit at 700 though..
    Are those flat top pistons or a small dome?
    The Busa dome’s wont clear without a little work.
    We had a catastrauphic engine failure at Miller and the current engine hasnt been apart since then.
     
    track wagon likes this.
  13. track wagon

    track wagon MCAS MIRAMAR

    Flat top pistons. I need to do the formula to get it to 13.5 to 1.
     
  14. regularguy

    regularguy Always Krispy

    single plug or dual plugger?
     
  15. track wagon

    track wagon MCAS MIRAMAR

    Single
     
  16. regularguy

    regularguy Always Krispy

    good. dual pluggers take some tweaking to survive on the spec.
     
  17. track wagon

    track wagon MCAS MIRAMAR

    Ok cool good to know. Looking forward to seeing what power I can make!
     

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