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Discussion Starter · #1 ·

I guess this is a general question however I have a 99R1, thus the post here

I stripped the cylinder head off my bike (because of a faulty crank - P4 big-end disintegrated, another post) and want to test the valves in their seats.
A friend suggested to just pour gas/petrol down the inlet and exhaust ports and see which valves are leaking. Which I did and found some to be leaking and others not.

My immediate thoughts where 'is it necessary to have the valves and seats machined and lapped again?'

I searched the www about this topioc and didn't find anything quickly that can answer my question if gas/petrol is the right substance to do a 'liquid' leak test. I've seen some youtube vids where water is used on car heads. So, I used water - and they don't leak !!

I'm getting the fealing that gas/petrol is perhaps too viscous and will leak with even a 'perfectly' (good enough) seated valve. Is there a more consistent reliable fluid I can use to test with ? I've also read/heard mineral spirits (from the bloke that posted the 2000 R1 engine rebuild vids on youtube) but haven't tried that yet.

I know I could do a compressed air leakdown test - but the cylinder is off the bike now .

Otherwise I have no suspicion that the valves are leaking out-of-spec.

Any thoughts welcome.
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