New carb manifold gasket arrived recently and whilst preparing the surfaces for the new gasket I took the opportunity to do the leak down test "the other way" by filling each cylinder with petrol.

Left side seemed to hold pretty well. After 2 hours, nothing in the right cylinder. After about 6 or so hours there was a small (20-30 mLs) which had leaked across. Left side also held pressure well with the 'air' leak down test previously so these results are consistent.

Right side not so good. After about 5 minutes I had around 30 mLs of petrol had leaked across to the left side. There are no leaks anywhere else that I can find so all other crankcase seals seem to be good. No petrol leaking out of the motor anywhere and I could not find an air-leak with the previous round of tests.

I'm a little perplexed how these things can leak more one way than the other!

So onto my question for all you wise NSR lovers out there:

Is a small amount of leakage across the center seal a major issue do I have some leeway? Any cross-leakage will be from one side of the crankcase to the other so shouldn't the "mix" be much the same. Am I kidding myself that I don't need to tear the motor down?

My thoughts are that I am up for a full crank rebuild but I'm hoping to be convinced otherwise.