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jamesblown97
03-20-2010, 12:39 PM
i have an 86 with a ton of portwork done to the cylinder. i just pulled it off due to low compression. it had a 68mm piston in it and i was going to put a 69 in it but the local 250r guy says that if i put a 69 in it i will begin ot have head gasket issues. im just looking for a second opinion on where i should go from here. there are a few nicks in the cylinder but would easily be taken out if i put a 69mm in it what should i do.
skyhighatv
03-20-2010, 05:03 PM
I never had any real probs on the 69mm bores ive run over the years. Just use some three bond 1211 sealant on the head gasket during assembly and let it sit 48hrs before firing the motor,give it a good break in then give er hell!
1promodfan
03-20-2010, 05:55 PM
Originally posted by skyhighatv
I never had any real probs on the 69mm bores ive run over the years. Just use some three bond 1211 sealant on the head gasket during assembly and let it sit 48hrs before firing the motor,give it a good break in then give er hell!

^^^^^^what he said, 1211 is some great stuff!!
86 Quad R
03-21-2010, 05:37 PM
did the guy say what specific issues one would have with the head gasket if going to a 69mm bore?
Honda 250r 001
03-21-2010, 05:55 PM
heres my question... Why go to 69? why not go to 68.25 instead???
jamesblown97
03-21-2010, 06:56 PM
what is this 1211 stuff ive never heard of it and where do i get it. the guy said that i would continuosly blow head gaskets and i have not been able to find a 68.25 piston anywhere thanks for the info guys please keep it comin
Ruf Racing
03-22-2010, 07:53 AM
I had been running a 69.5mm with the 1211, no leaking. My local honda dealer sells the ThreeBond 1211.
86 Quad R
03-22-2010, 07:59 AM
Originally posted by jamesblown97
what is this 1211 stuff ive never heard of it and where do i get it. the guy said that i would continuosly blow head gaskets and i have not been able to find a 68.25 piston anywhere thanks for the info guys please keep it comin


ok so the head gasket blowing was the only issue then? with a nice straight head and deck surface and a good coat of (Three Bond 1211 do a search) you should be goed to go there. juss make sure you keep check on the torque specs. the thing i'd be concerned with is using a stock(sized) gasket on the bigger bore. make sure the guy knows to use an aftermarket b/b gasket for the 69.0mm hole. :cool: