craptorkiller Posted November 10, 2008 Report Share Posted November 10, 2008 just got the shee running today. im in missouri and have 17cc domes. the compression was 135 for both sides. is this too low? its on a fresh reduild. thanks for any help. Quote Link to comment Share on other sites More sharing options...
Handyman Posted November 10, 2008 Report Share Posted November 10, 2008 not sure what the stock domes are but 135psi is about right for a stock motor...Also elevation affects compression...what elevation you at? Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted November 10, 2008 Report Share Posted November 10, 2008 I don't think your guage is reading correctly, even with the most aggressive porting you should be in the 180's at your elevation with 17's...Unless you have go something else going on. I would double check with an other guage. Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 10, 2008 Author Report Share Posted November 10, 2008 I don't think your guage is reading correctly, even with the most aggressive porting you should be in the 180's at your elevation with 17's...Unless you have go something else going on. I would double check with an other guage. i thought it should be higher. its a matco gauge. but its pretty old. the motor has a mild port if that would have anything to do with it?? Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 10, 2008 Author Report Share Posted November 10, 2008 not sure what the stock domes are but 135psi is about right for a stock motor...Also elevation affects compression...what elevation you at? its around 800 give or take a couple hundred Quote Link to comment Share on other sites More sharing options...
Handyman Posted November 10, 2008 Report Share Posted November 10, 2008 its around 800 give or take a couple hundred YOur compression should be considerably higher than that...may want to try another compression gauge to double check before tearing into your motor.... Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 10, 2008 Author Report Share Posted November 10, 2008 YOur compression should be considerably higher than that...may want to try another compression gauge to double check before tearing into your motor.... i just started it up today. it prolly only has about 20 minutes on it. would that have anything to do with it? Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted November 10, 2008 Report Share Posted November 10, 2008 Haha, just had a thought....did you hold the throttle wide open while you kicked it? Also, was the engine warm or cold? Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 10, 2008 Author Report Share Posted November 10, 2008 Haha, just had a thought....did you hold the throttle wide open while you kicked it? Also, was the engine warm or cold? no the throttle wasnt open. yea it was cold. Quote Link to comment Share on other sites More sharing options...
Handyman Posted November 10, 2008 Report Share Posted November 10, 2008 no the throttle wasnt open. yea it was cold. redo the compression test with the throttle wide open...The compression should be higher Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted November 10, 2008 Report Share Posted November 10, 2008 cold and warm tests will vary by a few degrees as well...cold will give you a higher reading. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted November 10, 2008 Report Share Posted November 10, 2008 Holding the throttle wide open might give it a handful more PSI. Cold to warm, same thing...warm should give you a higher reading than cold, when the engine warms up, the piston and rings expand...that's why when an engine is low on compression and worn out, it's harder to start cold, but once warmed it usually starts much easier... Either something isn't right, or the gauge is bad. Is the gauge thread depth as long as the spark plugs? That could falter a few PSI. That bike should be 170 to 190 PSI roughly.... Quote Link to comment Share on other sites More sharing options...
bbcmudtruck Posted November 10, 2008 Report Share Posted November 10, 2008 Did you check your ring gap when you put it together? Check to see what your squish is also. Where at in Missouri are you? Quote Link to comment Share on other sites More sharing options...
dajogejr Posted November 10, 2008 Report Share Posted November 10, 2008 Squish....ring end gap...what is that?? :biggrin: Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted November 11, 2008 Report Share Posted November 11, 2008 135???!!!! that motor should be upwards of 180 to 190 with 17cc domes.. something is not right. i would try another tester. Quote Link to comment Share on other sites More sharing options...
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