studroes Posted May 25, 2009 Report Share Posted May 25, 2009 went riding this weekend and i blew an oring on the dome in my coolhead. this is the second time its happened to me..happened last weekend too. it only happens after ive been riding for awhile and both times its happened right after i let off from holding it wide open for a straight aways. any idea of why this is happening? Quote Link to comment Share on other sites More sharing options...
AKheathen Posted May 26, 2009 Report Share Posted May 26, 2009 are you torqing the head in the right sequence? retorqing? greasing the orings, or clean and dry. the domes should hold the oring when you install them dry Quote Link to comment Share on other sites More sharing options...
Darthwall Posted May 26, 2009 Report Share Posted May 26, 2009 make sure that the studs in the head are down all the way and is this a new topend that you had done or just bought? Is there any differences that have been made to the bike recently if its recent jugs have they been checked for deck heigth if the tops of the two are off a little bit then it will have weak spots in the seal Quote Link to comment Share on other sites More sharing options...
dajogejr Posted May 26, 2009 Report Share Posted May 26, 2009 Several things that can cause this. Did you check squish? Holding it WOT for a long ways, how long, what's done to the motor? It could be lean, it could have an air leak... When you're riding it WOT then close the throttle, remember...fuel also cools the top of the piston. Shutting that down all together can cause issues. Are you blowing the same side? How does the top of the piston look? How much cranking compression do you have? Compression ratio? What octane gas are you using? There are 5 to 10 things this could be, from a simple plug in the fuel line to improper cut dome/dome angle and too tight of clearances. Quote Link to comment Share on other sites More sharing options...
dirtclod20 Posted May 27, 2009 Report Share Posted May 27, 2009 went riding this weekend and i blew an oring on the dome in my coolhead. this is the second time its happened to me..happened last weekend too. it only happens after ive been riding for awhile and both times its happened right after i let off from holding it wide open for a straight aways. any idea of why this is happening? What does your bike act like when it blows an o-ring? Quote Link to comment Share on other sites More sharing options...
AKheathen Posted May 27, 2009 Report Share Posted May 27, 2009 What does your bike act like when it blows an o-ring? it leaks coolant. burns, making sweet, smoky exhaust, and pressurizes the coolant, making it spit out the overflow Quote Link to comment Share on other sites More sharing options...
studroes Posted May 28, 2009 Author Report Share Posted May 28, 2009 the squish is right where it should be. the engine is a 4mil with stroker domes, everything was calculated and cut by a professional builder. the head is a D&D head, dont know if many people know about them but it is a 2 piece type head that bolt down seperate onto each cylinder so as far as different deck heights that wouldnt be the problem cuz each side seals down itself. domes and compression are set to runpump gas so i dont run anything less than 93 oct. i ride basically roads only so its alot of wide open riding and both times it happened were when i was letting off from holding it at WOT for probably between 1/2 a mile to a mile. not too long but certainly long enough for everything to really heat up. when i put in the new orings they were in the grooves good and the head was torqued and re torqued. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted May 28, 2009 Report Share Posted May 28, 2009 Lack of fuel... Quote Link to comment Share on other sites More sharing options...
AKheathen Posted May 28, 2009 Report Share Posted May 28, 2009 what did you torque it to? i remember this coming up before about a head setup that doesn't tie the 2 cylinders together, and wether or not it will cause issues. i'm too lazy to search right now, but mabey dave remembers or probably has experience:biggrin: Quote Link to comment Share on other sites More sharing options...
dajogejr Posted May 28, 2009 Report Share Posted May 28, 2009 Nope. All cylinder heads I've used, aftermarket and stock covered both cylinders. Obviously, my Noss and Chariot have removable domes for each cylinder, but they bolt down together.... Me...if you're sure the torque is right, etc., I'd be checking the bottom of the head/dome and the deck of the cylinder for flatness. If your eyes are perfect, a straight edge works. Otherwise, a fine grit sand paper and a sanding block can tell you if it has high or low spots. Quote Link to comment Share on other sites More sharing options...
dlnoss Posted May 28, 2009 Report Share Posted May 28, 2009 There were no signs of detonation or running lean? Quote Link to comment Share on other sites More sharing options...
studroes Posted May 28, 2009 Author Report Share Posted May 28, 2009 i did alot of plug checks when i got the engine all together and running and they always came out with the nice brown color on them and as far as running lean i dont think that is an issue because if it was i think it would have caused a major problem alot sooner cuz the wheeler has been ridin and held wide open alot! the heads show no signs of detonation and never had a problem with plugs backing out. this may be a dumb question but when i let off from a wide open run is it best to let right off and pull the clutch in or keep giving it a little throttle so the engine keeps getting fuel or whats the best way to do it? Quote Link to comment Share on other sites More sharing options...
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