BansheeUSA Posted May 8, 2020 Report Share Posted May 8, 2020 4mil stock cyl. 66.50 pistons with custom domes by builder has 135 psi compression how am I able to bump this up to higher compression. He told me if I changed domes they would not fit. He said it is already at .015 and very high compression, and race fuel is needed. I am running +4 timing and 33 pwk keihn. What are some ways I could bump the compression up to 150-170 or so to get more power. I’m new at this so I’m having a hard time understand, but I am willing and wanting to learn more. Quote Link to comment Share on other sites More sharing options...
gusto Posted May 8, 2020 Report Share Posted May 8, 2020 Smaller cc domes or a thinner head gasket. 135 psi sounds perfect to me though, paying for race gas is so expensive and sometimes even finding it is a real pain. Its not fast enough? 1 Quote Link to comment Share on other sites More sharing options...
gusto Posted May 8, 2020 Report Share Posted May 8, 2020 Also, your on your last bore, just run it and don't throw more money into it. Quote Link to comment Share on other sites More sharing options...
97Screamer Posted May 8, 2020 Report Share Posted May 8, 2020 (edited) Gusto is correct, 135psi is perfect for pump gas and running race fuel on a play bike is expensive for no real reason. Who is your builder? If your builder told you to run race fuel at 135psi ask again to make sure you didn't misunderstand. That would be a very odd setup. Save your money and build a bigger engine if you want more power. 0.015" squish is stupid tight. You should be about three times that. Squish band and dome size are two different things. You can get smaller cc domes cut with the same squish but again its a waste of money in my opinion. Edited May 8, 2020 by 97Screamer Quote Link to comment Share on other sites More sharing options...
ClaudeMachining Posted May 8, 2020 Report Share Posted May 8, 2020 Your builder put a 0.015" squish???? I do not understand.Envoyé de mon SM-G965W en utilisant Tapatalk Quote Link to comment Share on other sites More sharing options...
BansheeUSA Posted May 17, 2020 Author Report Share Posted May 17, 2020 On 5/8/2020 at 9:53 AM, gusto said: Smaller cc domes or a thinner head gasket. 135 psi sounds perfect to me though, paying for race gas is so expensive and sometimes even finding it is a real pain. Its not fast enough? Does 135 compression sound to low for a 4mil ? Quote Link to comment Share on other sites More sharing options...
BansheeUSA Posted May 17, 2020 Author Report Share Posted May 17, 2020 On 5/8/2020 at 12:22 PM, 97Screamer said: On 5/8/2020 at 12:22 PM, 97Screamer said: Gusto is correct, 135psi is perfect for pump gas and running race fuel on a play bike is expensive for no real reason. Who is your builder? If your builder told you to run race fuel at 135psi ask again to make sure you didn't misunderstand. That would be a very odd setup. Save your money and build a bigger engine if you want more power. 0.015" squish is stupid tight. You should be about three times that. Squish band and dome size are two different things. You can get smaller cc domes cut with the same squish but again its a waste of money in my opinion. Yes this is what he said that it was really vital I run race fuel. I’ve just built the motor for a 4mil. Crank. I think he kinda messed it up because I have cool heads so he should have to cut the domes or anything right? Quote Link to comment Share on other sites More sharing options...
BansheeUSA Posted May 17, 2020 Author Report Share Posted May 17, 2020 On 5/8/2020 at 9:53 AM, gusto said: Smaller cc domes or a thinner head gasket. 135 psi sounds perfect to me though, paying for race gas is so expensive and sometimes even finding it is a real pain. Its not fast enough? Just want some to real kick the newer bikes butt lol. I’ve had the builder do a 4 mil but I think he messed up the Cool heads so it’s not Getting it’s full potential Quote Link to comment Share on other sites More sharing options...
SandSlingerOR Posted May 17, 2020 Report Share Posted May 17, 2020 Who built the motor? Quote Link to comment Share on other sites More sharing options...
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