how much is enought? cylinder heads (with pics)

Discussion in 'Performance Mods' started by G-Superior, Mar 6, 2010.

  1. G-Superior

    G-Superior Member

    HI everyone!
    I was just thinking about how much material(aluminium) should i (or enyone else)take of their heads for a good compresion?
    Today i have done a suzuki lt50 head and i skimed 0.05 of it(im gona test it next week see if it works well)see pics for before, after and full view!
    how much is enought on a 80cc(66)?
    MY DAD USED TO RACE 100CC 2 STROKE KARTS AND TO MUCH COMPRESSION REDUCE DRAMATICALLY ENGINE POWER AND USED TO BLOW UP THE BOTTOM BEARINGS! and yes he did used a dino and the best tecnology avaliable with the best engine builders and best parts(costed him thousands and thousands to make him the best!)

    Attached Files:

  2. mountain80

    mountain80 Member

    Make sure you use lead and check your'e piston to cylinder clearance.
  3. motorpsycho

    motorpsycho Active Member

    use lead? clay works MUCH better and is easier to find.
    and that would be piston to HEAD clearance. the piston is in the cylinder already.
  4. give me vtec

    give me vtec Active Member

    I filed off the entire portion of the part that rises up .5mm or so.... so that it was basically flush.

    Worked great... no problems so far a couple hundred or so miles later and it made good power throughout the entire rpm range. I got it right the 1st time so I didnt file off any more... I checked for plug clearance and it wasnt an issue.

    A good comparison in power gained would be the difference between an expansion chamber and a stock exhaust.
  5. andrew88rmz

    andrew88rmz Member

    Im planning on maching my head on my 66cc. I have nt done the math yet for compression ratio but i will probably take off ten thousands of an inch. Ive already goten rid of the base gasket and that help a little but i want more.
  6. andrew88rmz

    andrew88rmz Member

    The skyhawks and flying horse 's are 6:1. Thats pretty low so you should be save playing around with it.
  7. 210061741

    210061741 Guest

    9:1 is the optimal compression.

    That = the volume of the cylinder from the top of the exhaust port divided by the volume of the (combustion chamber - the volume the piston dome takes up)

    IE: PK80 Combustion chamber in the head = 8cc
    the volume with the piston at top dead center = 5cc
    means the piston dome consumes 3cc

    And very important to note that this is corrected compression. ( True Compression )

    Going higher than 9:1 wont kill your engine unless it runs to hot and detonation occours.
    Otherwise know as ping.
    Thats when the top end of the engine is so hot the charge explodes in the cylinder wile the piston is still traveling upward befor the plug actually sparks.

    Causes a pinging or knocking or that rattling that some people think are bearings.

    Proper squish and heat range of plug can overcome ping.
    Provided the head is designed right.
  8. AussieSteve

    AussieSteve Active Member

    And, of course, higher octane fuel.
    I can only get 91 octane at my local service-station, which caused some pinging with the hi-comp head, so I've been adding a bit of octane booster to bring it up to 98. No more detonation.
  9. 210061741

    210061741 Guest

    I tried large amounts of octane booster.
    Like 3 oz per tank.

    A little better but not good.
  10. G-Superior

    G-Superior Member

    The suzuki that i put that head I also ported and mached everything, got a high flow air filter, modded exhaust, needle up, it started in 3 pulls(now it goes in 1!), warmed up in 1/2 mins(before it used to take ages), and gave it a fine carburator tuning and it now pulls like as fast as my honda c70 engined quad and its at least 10mph faster and does wheel spin :grin5:
    its to powerful now for my mates kid now:whistling: and he cant control it:grin5:
  11. andrew88rmz

    andrew88rmz Member

    Thats sweet man! I ve got a honda z50 that i put a big bore kit on, cam, ingition, new carbe, its now an 88cc and that thing rips. little bikes are so much fun!
  12. G-Superior

    G-Superior Member

    its is 10X more fun when you close to the ground compared to a car:grin5:
    My honda is like a tractor:tt1:(or probably even more torque than a tractor:grin5:)
  13. 210061741

    210061741 Guest


    Wait till you guys see my next happy time build.
    Got some super plans brewin in my head.

    Finally got the reed valve ported cylinder rippin hard.

    Time for phase 2.
  14. tacoshell4

    tacoshell4 Member

    phase 2 burn my flanges
  15. 210061741

    210061741 Guest

    Phase 2 is to build a real bicycle engine.
    Not a hopped up chineese pc of junk with a piston scorching billet head.
  16. G-Superior

    G-Superior Member

    thats how you do it Rich!:D
    NO MORE CHINESE JUNK!:rolleyes7:
  17. 210061741

    210061741 Guest


    I am starting to really dig the puch moped parts.

    Lots of compatibility and way higher quality.

    Of course a bit more expensive.

    But u get what you pay for.

    Im gonna post my upcoming plans soon.

    It's been a busy day today
  18. tacoshell4

    tacoshell4 Member

    remember gs if it werent for chineese junk this forum wouldnt exist
  19. G-Superior

    G-Superior Member

    It probably would but i would never be as big as it is:thinking:
    Most people that are in this furom are only here because they found a really cheap engine, a easy way to travel and lots of fun:D
    thats why im here!:eek:
  20. tacoshell4

    tacoshell4 Member

    fun stuff i'm switching to a 4 stroke honda