rhuebner Posted May 6, 2007 Report Share Posted May 6, 2007 I just rebuild my motor and checked my compression it is only 120psi on both cylinders. here are the mods it have it should be higher than that right? -68mm bore cheetah cub -4mil hot rod crank -hemi head with 20cc domes -35mm pwk airstriker carbs on 109 race gas - +7 timing -wiesco pistons -V-force 3 reeds Quote Link to comment Share on other sites More sharing options...
peak-j Posted May 6, 2007 Report Share Posted May 6, 2007 Well, I dont' have the mods you do. look at my mods and I have 150 in each cylinder and motor is all stock internally. It has never been reringed yet either. Mine was 120 in each cylinder before I added the coolhead also. Hope that helps a little. Quote Link to comment Share on other sites More sharing options...
rhuebner Posted May 6, 2007 Author Report Share Posted May 6, 2007 I just rebuild my motor and checked my compression it is only 120psi on both cylinders. here are the mods it have it should be higher than that right?-68mm bore cheetah cub -4mil hot rod crank -hemi head with 20cc domes -35mm pwk airstriker carbs on 109 race gas - +7 timing -wiesco pistons -V-force 3 reeds Is it cause i'm using 20cc domes? Maybe go down to about 18cc, what do yall think? Quote Link to comment Share on other sites More sharing options...
5150banshee Posted May 6, 2007 Report Share Posted May 6, 2007 its the domes stock is close to 21 or 22 so i would go with 17 or 18 and your compression should jump to about 160 or 165 maybe more. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted May 6, 2007 Report Share Posted May 6, 2007 porting on the cheetah's and your dome size is what affected it. Go down in dome size and check your squish with the new domes. Quote Link to comment Share on other sites More sharing options...
pokeatyou2 Posted May 6, 2007 Report Share Posted May 6, 2007 its the domes stock is close to 21 or 22 so i would go with 17 or 18 and your compression should jump to about 160 or 165 maybe more. thats not so true im running 21cc domes and have 160psi Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted May 6, 2007 Report Share Posted May 6, 2007 Its the exhaust duration on his cheetah cylinders, could also be his elevation. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted May 6, 2007 Report Share Posted May 6, 2007 You should have way more compression...if you're at or near sea level. first things first, check the squish on your motor... Next, what kind of compression gauge are you using? Third...did you keep kicking until the gauge didn't move? Often it can take 20 to 30 kicks. my 4 mil cub with 20cc domes, NOSS head, about 600 ft above sea level put out a healthy 185PSI with .045 of squish... Quote Link to comment Share on other sites More sharing options...
cam2 Posted May 6, 2007 Report Share Posted May 6, 2007 You should have way more compression...if you're at or near sea level. first things first, check the squish on your motor... Next, what kind of compression gauge are you using? Third...did you keep kicking until the gauge didn't move? Often it can take 20 to 30 kicks. my 4 mil cub with 20cc domes, NOSS head, about 600 ft above sea level put out a healthy 185PSI with .045 of squish... yeah, sometimes you may have to kick your a$$ off. also did you let the engine warm up first? when every thing is warmed up the piston rings will seal the cylinders a little better so you should get a higher reading then when the engine is cold. Quote Link to comment Share on other sites More sharing options...
rhuebner Posted May 6, 2007 Author Report Share Posted May 6, 2007 You should have way more compression...if you're at or near sea level. first things first, check the squish on your motor... Next, what kind of compression gauge are you using? Third...did you keep kicking until the gauge didn't move? Often it can take 20 to 30 kicks. my 4 mil cub with 20cc domes, NOSS head, about 600 ft above sea level put out a healthy 185PSI with .045 of squish... I'm at 3600 ft above sea level. This is going to sound stupid but I dont know what the squish means. My compression tester is just a Actron, yes I should just go get me a good one for a more accurate reading but this on cant be to far off. This 120psi reading I got was cold also. Thanks for your feedback. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted May 7, 2007 Report Share Posted May 7, 2007 I used to have a sears craftsman that was about 30 psi off. I also had an S&K tester that was about 20 psi off. Quote Link to comment Share on other sites More sharing options...
rhuebner Posted May 7, 2007 Author Report Share Posted May 7, 2007 I used to have a sears craftsman that was about 30 psi off. I also had an S&K tester that was about 20 psi off. What kind did you find that works the best? Quote Link to comment Share on other sites More sharing options...
06BaNsHeE Posted May 7, 2007 Report Share Posted May 7, 2007 who built your motor.You or did you take it to a shop? Quote Link to comment Share on other sites More sharing options...
rhuebner Posted May 7, 2007 Author Report Share Posted May 7, 2007 who built your motor.You or did you take it to a shop? I built it. Quote Link to comment Share on other sites More sharing options...
Michael Jackson Posted May 7, 2007 Report Share Posted May 7, 2007 higher you go, comprsssion lowers Quote Link to comment Share on other sites More sharing options...
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