FoxBansheeRacing Posted March 31, 2004 Report Share Posted March 31, 2004 I checked my compression for the first time tonight and the tester said each cylinder was at 120#. How can that be right? With 20cc domes and running at 500ft above sea level I would think I would be around 160#. When I took it apart a couple months ago for the porting and head, the pistons looked pretty new. Could it be a false reading because I have -2 pegs and cant really get a good kick on it? Quote Link to comment Share on other sites More sharing options...
Bigairee Posted March 31, 2004 Report Share Posted March 31, 2004 Before I started loosing compression in one cylinder I was 145 in each cylinder with 19cc domes and 160 feet above sea level. Quote Link to comment Share on other sites More sharing options...
FoxBansheeRacing Posted March 31, 2004 Author Report Share Posted March 31, 2004 So your saying my compression isnt actually bad? Quote Link to comment Share on other sites More sharing options...
dlnoss Posted March 31, 2004 Report Share Posted March 31, 2004 It depends on your porting. When the exhaust port is raised the compression will drop. I don't have my calculator out right now but if I remember, you lose somewhere around 3cc's for each mm the port is raised. You might want to check with the person that did the porting. Quote Link to comment Share on other sites More sharing options...
Leadfoot350 Posted March 31, 2004 Report Share Posted March 31, 2004 make sure that your attactment goes all the way into the dome like the spark plug would. I still have to get another attachment. Quote Link to comment Share on other sites More sharing options...
Tim C Posted March 31, 2004 Report Share Posted March 31, 2004 Are you kicking it over as fast as you can with the throttle open until the guage stops climbing? Some compression guages aren't that accurate, if you can - try another guage to compare. But like dlnoss said it depends on you porting.I have 150lbs with 21cc domes at sealevel but NO porting. Quote Link to comment Share on other sites More sharing options...
Big Blue Posted March 31, 2004 Report Share Posted March 31, 2004 140lbs ported with 20cc domes at 1100ft. Quote Link to comment Share on other sites More sharing options...
FoxBansheeRacing Posted March 31, 2004 Author Report Share Posted March 31, 2004 I think the problem was not holding the throttle wide open. I didnt know thats how you do it. Quote Link to comment Share on other sites More sharing options...
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