Hulio-mv Posted March 10, 2008 Report Share Posted March 10, 2008 Last year I blew a hole in a piston and seized it up. I think it either over heated or the o-ring failed and let coolant in not sure which. The cylinders were on the last bore so I bought new factory yammaha cylinders. Now after about 2 hours of riding it starts pushing coolant out the over flow tube. I have a prodesign impellar and a vapor computer temps do not get high untill the coolant starts coming out. I have tried 2 different new sets of domes 19 and 20 both new and all new o-rings every time and the same result. I run 92 or 93 octane and maxima at 32:1 It is a modquad head. Is it possible i warped the head by heat? I am taking it to a machine shop to see if they can measure it better than I can. Is it possible the new cylinders are fouled up somehow? the o-ring doesent puhsout in the same spot every time. I took the cylinders back off and all the little dowells were there. I am lost and tired of throwing away a 30 dollar set of o-rings every day. Any info or advice you can give would be great. any info I left out that is needed ask and I will fill in the blanks. :wallbash: :wallbash: :wallbash: Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted March 10, 2008 Report Share Posted March 10, 2008 are you sure that the coolant is being turned through the system? if your rad had anti-freeze in it and the bike sat for a long period of time it is possible that it gummed up and your coolant isnt flowing very well. It is possible to warp the head being its aluminum, but temps really have to be up there to do that. have you checked the squish? normally when your squish is too tight it will cause the orings to pop out of place. Quote Link to comment Share on other sites More sharing options...
Hulio-mv Posted March 10, 2008 Author Report Share Posted March 10, 2008 (edited) are you sure that the coolant is being turned through the system? if your rad had anti-freeze in it and the bike sat for a long period of time it is possible that it gummed up and your coolant isnt flowing very well. It is possible to warp the head being its aluminum, but temps really have to be up there to do that. have you checked the squish? normally when your squish is too tight it will cause the orings to pop out of place. it was all flushed and clean when I put it back together. Is there a easy way to check squish? The o-rings sometimes have a little hump in them when i remove the head but I cant tell if it happened before I took it loose or not Edited March 10, 2008 by Hulio-mv Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted March 10, 2008 Report Share Posted March 10, 2008 to check your squish get a peice of solidering (sp?) wire and make a small bend at a 90 degree angle. insert it into the dome through the spark plug hole and put the wire where the pin slide through the piston. You dont want it over the intake or exhaust ports, because the piston can rock giving you a false reading. so insert it to the left or right. turn the motor over and the pistion will squish the wire. pull it out and messure the wire with a digital caliper and post the results Quote Link to comment Share on other sites More sharing options...
Hulio-mv Posted March 10, 2008 Author Report Share Posted March 10, 2008 (edited) to check your squish get a peice of solidering (sp?) wire and make a small bend at a 90 degree angle. insert it into the dome through the spark plug hole and put the wire where the pin slide through the piston. You dont want it over the intake or exhaust ports, because the piston can rock giving you a false reading. so insert it to the left or right. turn the motor over and the pistion will squish the wire. pull it out and messure the wire with a digital caliper and post the results Ok I have the head off right now so I will do that after i get it checked at the shop. Is there a standard measurement that is right or is it dependant on mods and different heads? Thanks for the quick reply I have to get some sleep working overnight is a crappy thing to have to do but someone has to do the crap right Edited March 10, 2008 by Hulio-mv Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted March 10, 2008 Report Share Posted March 10, 2008 idealy you want around 40 thous Quote Link to comment Share on other sites More sharing options...
Hulio-mv Posted March 12, 2008 Author Report Share Posted March 12, 2008 idealy you want around 40 thous Ok just measured them and one side is .005 and one is .006. tha is with the old o-rings and one o-ring is split. The caliper i used is pretty cheap digital and claims to be within .001. Is that too much? and if it is what should I check next? The machine shop told me my head was not warped. Just a thought could it be a stud hole in one of the cylinders not the same depth or maybe a streched stud not letting the acorn nuts not draw down tighe enough? Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted March 12, 2008 Report Share Posted March 12, 2008 is it .005 or .05?? Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted March 13, 2008 Report Share Posted March 13, 2008 Ok just measured them and one side is .005 and one is .006. tha is with the old o-rings and one o-ring is split. The caliper i used is pretty cheap digital and claims to be within .001. Is that too much? and if it is what should I check next? The machine shop told me my head was not warped. Just a thought could it be a stud hole in one of the cylinders not the same depth or maybe a streched stud not letting the acorn nuts not draw down tighe enough? Usually acorn nuts on a coolhead need to have 3/16" - 1/4" spacers for all the stuff I have messed with. Quote Link to comment Share on other sites More sharing options...
Hulio-mv Posted March 13, 2008 Author Report Share Posted March 13, 2008 is it .005 or .05?? .05 and .06 there are washers under the acorn nuts and the washers have rubber in them Quote Link to comment Share on other sites More sharing options...
Hulio-mv Posted March 15, 2008 Author Report Share Posted March 15, 2008 .05 and .06 there are washers under the acorn nuts and the washers have rubber in them What should I look at next? Quote Link to comment Share on other sites More sharing options...
C&B Posted March 15, 2008 Report Share Posted March 15, 2008 What should I look at next? I had a similar prob but it never pushed a n o-ring. turned out to be the freakin cap on the raqd was bad. I dont know if thats ur prob, maybe?? Quote Link to comment Share on other sites More sharing options...
Hulio-mv Posted March 15, 2008 Author Report Share Posted March 15, 2008 I had a similar prob but it never pushed a n o-ring. turned out to be the freakin cap on the raqd was bad. I dont know if thats ur prob, maybe?? Good to know i will check it tonight at work if I have thr correct adapter in the kit I have. Quote Link to comment Share on other sites More sharing options...
420 RACING Posted March 16, 2008 Report Share Posted March 16, 2008 Hole in the piston is usually detonation possibly taking out the o-ring also. Whats you timing at?? Compression?? and what gas Quote Link to comment Share on other sites More sharing options...
Bansh-eman Posted March 16, 2008 Report Share Posted March 16, 2008 i didnt read all of the other posts made , so this is just picking up where my last post was at. Discrd if not needed your squish could be a little tighter. you want idealy .040 of squish, but with yours messuring out farther this isnt the cause of your o rings popping out. Quote Link to comment Share on other sites More sharing options...
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