How much squish?

[flea49]

Whats the best amout of squish for pump gas??

[mopar1rules]

i think we need a sticky on this subject, as this question seems to come up a few times a week. i personally run .050", but some like to run .040-.045".

[Snopczynski]

Whats the best amout of squish for pump gas??

 

Whats pipes you run? Where is your exhaust duration set up at?

[00tbanshee]

usually the person porting your cylinders will tell you.your going to get all kinds of different answers.also all builders a different

[swrbansheeboy]

i'm with snop on this, there is no magic "squish number" that works on every engine.

 

what setup your running will have alot to do with what squish you should have.

 

as was said before, get with your engine builder and they should be able to answer your question.

 

the best you will get here is a ballpark of what works for everyone with there setup...

Edited August 13, 2009 by swrbansheeboy

[kr0nic]

I wouldn't necessarily worry about your squish (from a performance stand point) its more a safty margin. In other word, when the motor starts to pull rpm the internals start to stretch (minimal but measurable) you want to make sure you have enough squish so your pistons don't start hammer your head and destroy your topend/ bottom end. Some where in the 0.035 to 0.050 range. I would be more concerned with the compression (160-190psi), angle of the cut (12-16*), and the cc of the chamber (pump gas 20-24cc). Do you have a cool head, or are you just modifying your stock head?

[Snopczynski]

I wouldn't necessarily worry about your squish (from a performance stand point) its more a safty margin. In other word, when the motor starts to pull rpm the internals start to stretch (minimal but measurable) you want to make sure you have enough squish so your pistons don't start hammer your head and destroy your topend/ bottom end. Some where in the 0.035 to 0.050 range. I would be more concerned with the compression (160-190psi), angle of the cut (12-16*), and the cc of the chamber (pump gas 20-24cc). Do you have a cool head, or are you just modifying your stock head?

 

If the squish gap is too large, the bike will run like shit.

 

If he is running mid-top end port work and a mid-top end pipe, theres no way in hell I would set it at .035"!

[kr0nic]

0.035 to 0.050 is just a guide, it can be anywhere in that range. Obviously you wouldn't want anything less than 0.035 and you don't need anymore than 0.050. Besides unless you were to machine your own domes, someone that knows what they are doing will be doing it.