big problem...dont know whats wrong with my lt250r

[Hillclimber361]

Ohh shit, that could be your prob. If you still have the cylinder together on, but some soapy water down at the base and even if you have just the head off you can probably see if you have a leak at the base, on the downstroke of the piston it will force some air out.

[370banshee]

oops that was dumb i guess you won't be doin that again. i thought youi just put a dab of sealer on the rip.

[johng212004]

yea bros thanks for the help...im getting the new gaskets in tomorrow so ill let yous know how it turns out
anyone from south carolina area or new jersey?

[PA_Banshee]

hopefully everything work out for you.

[johng212004]

hey well i replaced the gaskets today...guess what now? theres no compression. i could push it down with the weight of my leg...this is the first time ive ever rebuilt a quad. at first it wouldnt stay running. its getting better now but theres still no compresion. anyone got an idea. im proud of myself stil because this is the first time ive rebuilt an engine and it works ....well kinda. someone help

[370banshee]

hmmm well dude something like this is really hard to diag. over the comp i would say check to make sure that everyhing is tight. oh yeah what was your ring gap??? piston to wall clearance??? do you know what any of these things are??

[Hillclimber361]

The ring gap shouldn't really mess with compression that bad if it's a new set. Just check and make sure everything is tight, if you had compression before, then you should have it now if put toghether correctly. You put a base gasket, cylinder, head gasket, or or o-rings, then the head?? And you tightened everything? let us know.

[johng212004]

yeah guys everything is tight....and oil is shooting out of the exhaust so im pretty sure its the rings...its not like flying out but i see oil on my skid plates so im assumeing that the rings are screwed up from my freind not putting them on right...hopefully it didnt mess up the cylinder wall...i didnt bother to check the gap bc the old piston rings were doing fine. i just rebuilt it bc i didnt know how long it was before its last rebuild. im also hoping that it is the stock piston that i pulled out. i remember putting them next to each other and they were exactly the same. this is such a mess thanks for the help everyone.

[370banshee]

ok first things first. puttign the piston next to one another isn'e goona tell you shit. we are talking .010 here. for piston overbores. think of it this way a piece of paper is about .070 thick. there is no possilbe way taht you could tell the difference between a std piton and a .010 piston. heres te way you tell. after you take a piston out the first thing you do is take taht piston to the wire wheel and clean the top of it off. on teh top of the piston your gonna see some numbers. numbers like .010 .020 .030 .040. 050. an so on. or you will see STD on the top. soemtimes you might even see .25 .50 .75 1.00 these are the same as the above numbers. .25 mm = .010 in your best bet would be to locate that old piston (hopefully you didn't throw it out yet)
clean teh top and check it out to see what oversize it was. i'm gonna be tottally honest with you i really don't see there being much of a chance that a quad built in 1991 has a std bore anymore unless of course somebody resleeved that cyl. i would say that you probably wasted nio only your time but most likely about $100. if you already threw out that piston (they make great ashtrays don't throw them away) your gonna have to take it apart and locate a snap guage and a dial caliper or a micrometer that goes out to 3in. then put the snap guage into the cyl. and snap it out. then pull the guage out and measure it. that will give you your bore. thke that # minus about .003 and that will give you your bore size. you subtract the .003-.005 for piston the wall clearance. man i really wish youi would have posted to get some advice and a experiance hand before you tried to take this on yourself.. oh well just file this under "f*ck ups to learn by". find that old piston and get the size off fo the top and post again i'm reall hoping i'm wrong for your sake. (this is why i wanted to know the ring gap and piston to wall clearances if he had a .013 wall clearance then that would have popped up a red flag right there)

[Hillclimber361]

I was thinking that ring gap wouldn't make that much difference IF the pistons are the same, you do have to check to make sure that you don't have an overbore old piston and std new one. You probably had compression before because without a gasket, the cylinder was so tight that it was making compression on the upstroke, but on the downstroke, there was no suction to pull gas in. Hopefully you still kept the old piston.