Wildcardracing Posted November 13, 2008 Report Share Posted November 13, 2008 .055" is slightly on the wide side, but not enough do drop your compression that much...it will have a little less bottom end power as compared to a squish meausurement of around .045" Did you assemble the top end or have it done by a shop? Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 13, 2008 Author Report Share Posted November 13, 2008 .055" is slightly on the wide side, but not enough do drop your compression that much...it will have a little less bottom end power as compared to a squish meausurement of around .045" Did you assemble the top end or have it done by a shop? my dad and i put it together. Quote Link to comment Share on other sites More sharing options...
bbcmudtruck Posted November 13, 2008 Report Share Posted November 13, 2008 Did you line the rings up on the little tits on the pistons? Are the pistons installed facing the correct direction? What did your ring gap measure? Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted November 13, 2008 Report Share Posted November 13, 2008 Did you line the rings up on the little tits on the pistons? Are the pistons installed facing the correct direction? What did your ring gap measure? he said tits.. Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 13, 2008 Author Report Share Posted November 13, 2008 Did you line the rings up on the little tits on the pistons? Are the pistons installed facing the correct direction? What did your ring gap measure? the rings were lined up. maybe they could've moved when i put them in the jugs? they are facing the right way. i dont remember but the gap was within the tolerances of the little book that came with the pistons. Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted November 13, 2008 Report Share Posted November 13, 2008 If the bore clearance is correct, the ring dowels won't allow the piston to slide into the bore if the ring is not properly seated, so that's not the problem. Did you install the rings right side up?? Ther will be some very small white numbers on them, those go up. If all that and your reeds check out, I'm thinkin your rings didn't seat properly or the pistons/rings were damaged during breakin. It's just very odd that they are making the same psi if there is piston damage, it usually occurs in one cylinder worse than the other. Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 13, 2008 Author Report Share Posted November 13, 2008 If the bore clearance is correct, the ring dowels won't allow the piston to slide into the bore if the ring is not properly seated, so that's not the problem. Did you install the rings right side up?? Ther will be some very small white numbers on them, those go up. If all that and your reeds check out, I'm thinkin your rings didn't seat properly or the pistons/rings were damaged during breakin. It's just very odd that they are making the same psi if there is piston damage, it usually occurs in one cylinder worse than the other. yea it still has me stumped?? ha. the pakage the rings came in said there was a top or bottom. another thing im thinking is if the domes were marked wrong. but even if they were a bigger cc the comression should still more than 135? Quote Link to comment Share on other sites More sharing options...
XxMeltIcexX Posted November 13, 2008 Report Share Posted November 13, 2008 Did the shop have the pistons before they bored? I've got in the habit of having them match it directly to the cylinders, as i've had them off so far that the compression has dropped, as low as yours. Quote Link to comment Share on other sites More sharing options...
dirtfreak Posted November 13, 2008 Report Share Posted November 13, 2008 had it bored and put brand new pro-lites in it. what fuel was you running breaking it in with the 17cc domes.if you where running pump gas take it back apart.17cc domes requires race fuel.also what 2cycle mix are you using and what mix ratio. Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 13, 2008 Author Report Share Posted November 13, 2008 Did the shop have the pistons before they bored? I've got in the habit of having them match it directly to the cylinders, as i've had them off so far that the compression has dropped, as low as yours. yea they had them. but tey still could have done a shity job. i didnt think about it. but it does make sense. :wallbash: Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 13, 2008 Author Report Share Posted November 13, 2008 what fuel was you running breaking it in with the 17cc domes.if you where running pump gas take it back apart.17cc domes requires race fuel.also what 2cycle mix are you using and what mix ratio. i had 93. and it only has about 20 minutes at the most on it. im using maxima castor 972 Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted November 13, 2008 Report Share Posted November 13, 2008 i had 93. and it only has about 20 minutes at the most on it. im using maxima castor 972 Bingo Those 17's make way too much compression for 93 octane at your elevation. I would bet if you pull your top end apart that much of your piston crown has been eroded away by detonation. It is however very surprising that both cylinders are reading the same. Sorry :shrug: Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 13, 2008 Author Report Share Posted November 13, 2008 Bingo Those 17's make way too much compression for 93 octane at your elevation. I would bet if you pull your top end apart that much of your piston crown has been eroded away by detonation. It is however very surprising that both cylinders are reading the same. Sorry :shrug: fuck. ha. with that short amount of time would it cause it to read that low? and do that much damage? Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted November 13, 2008 Report Share Posted November 13, 2008 I've seen detonation punch a hole clear through a piston in less time. With those domes you're octane requirement would be at least 110 if not higher, so it was doing damage right from the time you started it. Quote Link to comment Share on other sites More sharing options...
craptorkiller Posted November 13, 2008 Author Report Share Posted November 13, 2008 I've seen detonation punch a hole clear through a piston in less time. With those domes you're octane requirement would be at least 110 if not higher, so it was doing damage right from the time you started it. damn. i told my dad it needed race fuel. well ill tear into it tomorrow and see how much damage or how little was done. ha Quote Link to comment Share on other sites More sharing options...
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