I know that it could be caused by that, but I think it would not be the exhaust gas that makes it leak, but the pressur from the cylinder, which forces the coolant into the overflow tube. I wish I could have done a compression test, to see if that was the problem, but the tester threads were too large (in diameter) to fit the Mojave's head. Where can I get one that will fit?

 

Thats basically what I mean, I couldn't think of a good way to explain it. As far as a compression tester look at Chapparel, Whit Bros., or Dennis Kirk they all sell an extensive array of motorcycle tools.

 

I bought a compression tester that would work on the mojave. I bought it at oreilly auto parts for 15 bucks. They sell one tester with different fittings and one that has a rubber nipple that you push down into the top of the head. Both work fine for any bike i have worked on.