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jimbob69

HELP! more yz400f problems!

3 posts in this topic

Ok, I bought the bike about a month ago, and right away had to replace the right side cover gasket, base gasket, and head gasket due to oil leaks. While I had it apart everything looked good Mechanically and checked out within spec, I rode it for about 10 miles of hard riding and during that time it developed a head leak and was pressurizing the cooling system and blowing coolant out of the overflow. So i took the head and cylinder back off, checked them both for flattness, (they both were) so i lapped them anyhow, on a machined table saw table, with 400 grit paper and WD-40. I cleaned out the threads in the cases and on the bolts with brake cleaner and a brush, then lightly greased the bolts to get a proper tourque reading when putting it back together with new gaskets. I've since put about 4 tanks of gas through it w/o any troubles untill yesterday it slowly started dripping a little coolant out the overflow, I really wasnt concerned. Today I top off the coolant and go for a ride and throughout my ride it kept getting increasingly worse, and worse, and now the coolant gets right down to the cooling passages in the radiator within 10 minutes of riding. Im pretty sure the headgasket is blown again... :busted::smirk::ride:

Also I ruled out the radiator cap by using a few different friends caps with no luck.. :banana:

PLEASE HELP!! what do i do!?!?

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Hard to believe that two head gaskets would go bad. I second a cooling system problem :ride:

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