Yamaha TRX850 Enthusiasts Forum

Have had a compression tester for ages but did not have the correct thread fitting to use it on the bike.

I figured I could modify an old spark plug and tap it to accept the compression tester fitting.

So got to work gutting the plug. Unfortunately I did not have the correct tap to cut the thread in the plug to accept the compression tester fitting but figured I could turn down the connector from the compression tester on the lathe to create interference fit with the gutted plug.

So turned down the fitting and put it in the freezer and then heated the gutted plug and then hammered them together and voila, tested to 200psi, so the compression fit worked well and the bike has plenty of compression

Way to go...rock on with a little enginuaty .
I bought a adaptor for $14 on ebay and that's what I made my piston stop out of.
Male end screwed straight into the plug hole and had a larger f/m diameter that the comp tester screwed into.
I just tapped a thread into the small hole in the end and placed a round headed bolt in there to rest against the piston.
What pressure did your cylinders come in at????

200psi

Cool bananas, wasn't sure if it was the joint pressure tested to 200..

i should clarify, that was with one plug in, I should test on each with both plugs out but was just testing to see if the joint was sealing