dlnoss Posted March 25, 2007 Report Share Posted March 25, 2007 Just an estimate but your compression is probably closer to 145-150 Quote Link to comment Share on other sites More sharing options...
375hp banshees Posted March 25, 2007 Report Share Posted March 25, 2007 mine was lower than the chart said it was suposed to be also (if my domes are what i was told they were), but that does seem low Quote Link to comment Share on other sites More sharing options...
peak-j Posted March 26, 2007 Report Share Posted March 26, 2007 I just installed a cool head with 20cc domes and mine are 150 on both cylinders, stock bore. Quote Link to comment Share on other sites More sharing options...
fastrthnu Posted March 26, 2007 Author Report Share Posted March 26, 2007 Ill take off the gas tank and try it again w/o the adaptor. that extra 1.5cc may have dropped it a bit. Quote Link to comment Share on other sites More sharing options...
375hp banshees Posted March 26, 2007 Report Share Posted March 26, 2007 I just installed a cool head with 20cc domes and mine are 150 on both cylinders, stock bore. whats your elevation? Quote Link to comment Share on other sites More sharing options...
dlnoss Posted March 26, 2007 Report Share Posted March 26, 2007 Ill take off the gas tank and try it again w/o the adaptor. that extra 1.5cc may have dropped it a bit. But if the end of the compression tester doesn't thread in as far as the spark plug, the extra thread space inside the dome will add volume to the dome. Maybe I didn't understand everything correctly. Does the adapter have a volume of 1.5cc's between the bottom of the adapter and the check valve of the compression tester when it is threaded on to the end of the compression tester? Quote Link to comment Share on other sites More sharing options...
peak-j Posted March 26, 2007 Report Share Posted March 26, 2007 Right around 1000ft. Quote Link to comment Share on other sites More sharing options...
fastrthnu Posted March 26, 2007 Author Report Share Posted March 26, 2007 Maybe I didn't understand everything correctly. Does the adapter have a volume of 1.5cc's between the bottom of the adapter and the check valve of the compression tester when it is threaded on to the end of the compression tester? yes. Quote Link to comment Share on other sites More sharing options...
dlnoss Posted March 27, 2007 Report Share Posted March 27, 2007 Then your compression should be higher than what was indicated on the tester. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted March 27, 2007 Report Share Posted March 27, 2007 Then your compression should be higher than what was indicated on the tester. I am glad you tell people this. I tried to tell them and they acted like i was crazy. Those cheap compression gauges with the adaptors that tread on to the main hose add volume to the combustion chamber. I used a graduated glass eye doper and found with my elcheapo compression gauge the adaptor added 3cc's to the combustion chamber. I have 19 cc domes in my banshee with port work done and fresh top end. With the cheap o compressin gauge I got a reading of 125psi in both cylinders. With my snap on gauge that I bought i got a reading of 150 psi in both cylinders. The extra 3cc's explains the difference between the two readings. It is not that the cheap o gague is crapy it just adds extra volum to the combustion chamber. Here is a link to my post. Compression Tester LINK Quote Link to comment Share on other sites More sharing options...
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