how much is enought? cylinder heads (with pics)

G-Superior

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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)?
BE REALLY CAREFUL WITH COMPRESSION RATIOS!
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!)
thanks
 

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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.
 
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.
 
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.
 
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.
 
Causes a pinging or knocking or that rattling that some people think are bearings.
Proper squish and heat range of plug can overcome ping.

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

A little better but not good.
 
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 :D
its to powerful now for my mates kid now:whistle: and he cant control it:D
G-Superior
 
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