TJScott Posted December 21, 2008 Report Share Posted December 21, 2008 just bought a welded crankshaft and two .90 over cylinders. first question, is .90 over unsafe? are the walls too thin? also, i just buy pistons labeled .90 over pistons right? btw, what cc does this make it? thanks. Quote Link to comment Share on other sites More sharing options...
bansheefreak Posted December 21, 2008 Report Share Posted December 21, 2008 never heard of 90 over.. its 80 or 100 over.. i thought Quote Link to comment Share on other sites More sharing options...
sheerider1026 Posted December 21, 2008 Report Share Posted December 21, 2008 yea, you can get .090 over pistons.. i hope you didn't pay that much for those cylinders.. you can only go .100 over on them. so you have one more bore left if you are lucky... lets say you get it together with the .090 over pistons and you have a bad failure, lean it out, dirt gets in, or whatever, and the cylinders get grooved real bad, they will still have grooves in them even after boring them to .100 over... if you gotem cheap don't worry about it and rock on..!!! Quote Link to comment Share on other sites More sharing options...
T_Shee Posted December 21, 2008 Report Share Posted December 21, 2008 no there is .090 over. not recommended by most tho. im at .080 over and ill proly resleeve next time i need to bore. i think if your not racing or running too hard you should be ok Quote Link to comment Share on other sites More sharing options...
firebanshee Posted December 21, 2008 Report Share Posted December 21, 2008 just bought a welded crankshaft and two .90 over cylinders.first question, is .90 over unsafe? are the walls too thin? also, i just buy pistons labeled .90 over pistons right? btw, what cc does this make it? thanks. I have a buddy that has ran his 100 over cylinders for 3 years no problems, alot of drag racing and hard dune riding.At those bigger bores you have to run a little bigger domes to keep your compression in spec. I think he uses a 21cc with staight av gas.He had a 19cc when he first put it together and it had about 225 to 230 pounds of compression :cool: Quote Link to comment Share on other sites More sharing options...
278 Posted December 21, 2008 Report Share Posted December 21, 2008 never heard of 90 over.. its 80 or 100 over.. i thought There are in between sizes like this but theyre not as common. 90 over isn't catastrophic but I'd say its on it's last bore, you can go 100 over but I usually make it a rule to get new cylinders at 80 over. You can run the 90's though Quote Link to comment Share on other sites More sharing options...
TJScott Posted December 21, 2008 Author Report Share Posted December 21, 2008 thanks guys, anybody know what size this makes it? i will definitely re-sleeve next time Quote Link to comment Share on other sites More sharing options...
firebanshee Posted December 21, 2008 Report Share Posted December 21, 2008 Here is a link to a calculator to figure engine size. Link to engine size calculator Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted December 21, 2008 Report Share Posted December 21, 2008 66.25x66.25x54x.0007854x2=372.2943cc Quote Link to comment Share on other sites More sharing options...
2slow350 Posted December 23, 2008 Report Share Posted December 23, 2008 One of my best bikes i own has now 100 over stock cylinders that and are fully drag ported by Jeff prolly 6-7 years ago. They will pull 80+hp all day on methnol, no problems :biggrin: Quote Link to comment Share on other sites More sharing options...
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