banshee760 Posted December 15, 2012 Report Share Posted December 15, 2012 Wouldn't run anything less than a 100 octane on a plated cilinders period I don't care if you have pump gas domes I have seen it happen even w proper jetting , it's not the same , also at a 165 psi you were too close between pump and race gas should of went higher on the octane , and your bike did go lean Quote Link to comment Share on other sites More sharing options...
fastforworddad Posted December 16, 2012 Report Share Posted December 16, 2012 What kind of head do you have? When you pulled it off over the studs, did it slip right off or did you have to message it a some to get it off? Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted December 16, 2012 Report Share Posted December 16, 2012 COUGH..... Being cheap does make you stupid. So, you had wrong fuel, wrong jetting, and possibly wrong oil. These motors are not forgiving when you start playing with aftermarket goodies. Don't skimp and always run correct fuel, oil, parts. Don't be lazy, always run to the store to get the right stuff and spend the time turning wrenches till it is right. Make sure you learn how to talk to your motor like that weird Mexican guy does with dogs. A motor doesn't get lean like that and not give any signs of an issue. You got lucky this time, or did you? Are you sure that those missing parts of piston didn't wind up in the crank case? Tear down! Quote Link to comment Share on other sites More sharing options...
SpeedRacer88 Posted December 16, 2012 Author Report Share Posted December 16, 2012 I did tear it down So ur saying the broken pistons come from detonation? I and the black carbon is from running lean? Sent from my Galaxy S3 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
fastforworddad Posted December 17, 2012 Report Share Posted December 17, 2012 What kind of head do you have? When you pulled it off over the studs, did it slip right off or did you have to message it a some to get it off? Answer this question, had a similar problem but had nothing to do with detonation. Only one piston and on the intake side, just like you. Did you have any trouble removing the head with the studs still in jugs? Quote Link to comment Share on other sites More sharing options...
SpeedRacer88 Posted December 17, 2012 Author Report Share Posted December 17, 2012 never pulled the head and it was both pitons Quote Link to comment Share on other sites More sharing options...
fastforworddad Posted December 17, 2012 Report Share Posted December 17, 2012 never pulled the head and it was both pitons What kind of head for the third time? Quote Link to comment Share on other sites More sharing options...
SpeedRacer88 Posted December 17, 2012 Author Report Share Posted December 17, 2012 Stock cut. Sent from my Galaxy S3 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
fastforworddad Posted December 17, 2012 Report Share Posted December 17, 2012 Ok, the issue I had was head related, but I doubt it in your situation since yours is stock. Quote Link to comment Share on other sites More sharing options...
Jereme6655 Posted December 17, 2012 Report Share Posted December 17, 2012 Wait wait wait.....you didn't pull the head? What you blew the motor up and pulled the jugs off and left the head on? Ad THEN you pulled the cases apart and pulled the crank out and cleaned everything.......all without deciding to take off 10 bolts and look to see if there was deto damage to the head????? Quote Link to comment Share on other sites More sharing options...
SpeedRacer88 Posted December 17, 2012 Author Report Share Posted December 17, 2012 there was no detonation in the head. its pretty easy to flip over some cylinders an peak at the domes. my domes andy cylinders showed no issues Quote Link to comment Share on other sites More sharing options...
trickedcarbine Posted December 17, 2012 Report Share Posted December 17, 2012 Again...... Don't be lazy or cheap! So you tore the whole motor down? Quote Link to comment Share on other sites More sharing options...
SpeedRacer88 Posted December 17, 2012 Author Report Share Posted December 17, 2012 i was tearing the motor down for tranny related issues. i had no top end symptoms. the motor is back together now. leak down perfect. now that i try to go up one on the main jet it has a slight bog... could all these problems have just been detonation related from low octane fuel? or was i lean on both cylinders somehow. Quote Link to comment Share on other sites More sharing options...
camatv Posted December 18, 2012 Report Share Posted December 18, 2012 looks like possible head gasket leakage (coolant bypass = deto~!) and that can cause the ring land to cook out. squish i would set more like .50-.60 low 60's will run for ever.. cub's / servals like higher squish clearance for rider bikes as well as most drag setups. .048 is as tight as i would go IF it was on alky AND the rest of the motor was 100%... if its a stock stock head. might also have sharp edges that got hot and caused deto to rear up also. the head gasket needs to be NEW NEW NEW NEVER reuse an old OEM head gasket. tq the right way and make sure your squish is loose all the way across the band. you do that and the motor will run for years. ( if the rest is in good shape) i have a stack of 421 cub pistons that i "tested" clearances when these things came out ( cub).. my trail 421 is at .65 tho... pump gas. custom dome runs excellent. you DONT need tight squish clearance to create compression.... its much better to get it in the domes desing instead of milled stock head... Quote Link to comment Share on other sites More sharing options...
SpeedRacer88 Posted December 18, 2012 Author Report Share Posted December 18, 2012 The gasket was new on install I never took it off my squish is at what my builder recommended "cam" also if the head was leaking wouldn't it leak during a leak down? Sent from my Galaxy S3 using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
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