Vintage Dirt Bike Q & A

Just wondering if anyone else has had a problem with the cylinder base gasket.. shifter side blowing on 78,79,80 Cr250's. Both of the ones I got were leaking on shifter side...was able to locate due to the leak down tester I made from the post on the Suzuki forum here..thanks agian Nathan and the poster.
Upon closer inspection on both motors the gasket had pulled in on the narrow edge side of the gasket causing a leak, showed up immediately with the leak down test.
Seems odd to me, after finding the first motor I assumed poor installation but after finding the same exact thing on the second motor, I am figuring it is a problem. Both motors appeared to have RTV on the gaskets, wondering if I should use some Permatex on the gasket?

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Garry Mainer
#33m (retired)
Honda Cr250r 1980
Honda Cr250r 1980
Yamaha TY250C 1976
Arctic Cat 650 H1 2007

Yes, this is a very common event for this year. I have some extra cylinders that I have purchased from other owners that show evidence of staking the aluminum gasket surface with a center punch every 1/16" in order to provide some mechanical grip to the gasket paper. I have personally blown base gaskets on '78-'80 CR250Rs over the years. In my opinion it's best to install the gasket clean and dry with no added sealant.
Once, while riding goat trails in the Gorman, Ca area I blew a base gasket and went back to the truck and tore the back cover off a Thomas Brothers map book, took a small exacto and made a gasket out of that. It worked great in a pinch and since the book cover was lightly plastic coated, the plastic melted to the mating surface. I ran that base gasket for about 6 months 'til the next ring change.

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1978 CR250R
1979 CR250R
1980 CR250R
1980 ME360
1986 CR250R

Thats funny about making a gasket...did the same thing back in the 70's with the stiff cover off phone book...got me going!
New gasket on the way, will give the dry approach a try....thanks.

_________________
Garry Mainer
#33m (retired)
Honda Cr250r 1980
Honda Cr250r 1980
Yamaha TY250C 1976
Arctic Cat 650 H1 2007