okbeast Posted January 29, 2007 Report Posted January 29, 2007 Went home to do some work on the 'shee this wknd and put a .040 milled stock head on it and tested the compression and it was 125 for both cylinders. I should have tested it with the stock head on to see what it'd read but I didn't. I thought this sounded kind of low for havin a milled head, but the bike'll still start with 4-5 kicks when it's dead cold. Since both cylinders are at the same PSI I'm not too worried about tearing down to rebuild just yet, or should I? Quote
man27 Posted January 29, 2007 Report Posted January 29, 2007 Went home to do some work on the 'shee this wknd and put a .040 milled stock head on it and tested the compression and it was 125 for both cylinders. I should have tested it with the stock head on to see what it'd read but I didn't. I thought this sounded kind of low for havin a milled head, but the bike'll still start with 4-5 kicks when it's dead cold. Since both cylinders are at the same PSI I'm not too worried about tearing down to rebuild just yet, or should I? 125 is low but all heads are different so if you want more compression have it shaved again but I wouldn't tear it down until it gets below 100 psi or until you blow the bottom end out because you put too much compression on top thats what I did it was the best mistake I ever made!!! :biggrin: Quote
yamaha04 Posted January 29, 2007 Report Posted January 29, 2007 i myself would tear it down. since you checked it after you had your head milled the compression before could have been down to 100 or so? Quote
DADEBOYRACER101 Posted January 30, 2007 Report Posted January 30, 2007 this is a trick a real machanic would do pour oil on the head and kick till it get hard Quote
awesomeame Posted January 31, 2007 Report Posted January 31, 2007 125psi is LOW?? i just (5mins ago) checked mine, and i had 90 PSI in the left and 80 psi in the right i had 90 in both in july but i lost 10 there somehow...time for a rebuild... OKBEAST--are your bore/stroke/pistons stock size? --matt Quote
dajogejr Posted January 31, 2007 Report Posted January 31, 2007 125psi is LOW?? i just (5mins ago) checked mine, and i had 90 PSI in the left and 80 psi in the right i had 90 in both in july but i lost 10 there somehow...time for a rebuild... OKBEAST--are your bore/stroke/pistons stock size? --matt 125PSI is low at or near sea level for a .040 shaved head. 90 and 80 is low...unless you a high mofo, high in elevation... Honestly...your call. Could be fine, could be someone didn't really take off .040...maybe a little less. However...for the price of a few gaskets, you could take the top end off, mic the pistons and cylinders and check ring end gap..... Quote
okbeast Posted January 31, 2007 Author Report Posted January 31, 2007 Already got the gaskets comin, figure if I get a decent weekend I'll tear 'er down and check all the tolerances to see if I can at least make it past Spring Break ride hopefully. Quote
4strokessuck Posted January 31, 2007 Report Posted January 31, 2007 Was wondering how much of a compression increase would you get from a milled head? Also, my buddy had 85psi with a Cool Head with 21cc domes at sea level and it still ran fine. He rebuilt it soon after. Good luck. Quote
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