1997 BMW F650 El Diablo Hellride
In some not so excellent news, we’re looking at a motor showing only 70 psi compression. It sat for two years, so maybe I’m lucky enough to have stuck rings. It definitely smoked and it definitely put some oil on the plugs. It definitely got really hot.
I needed to find TDC, but without pulling covers, so I can put compressed air into motor for a leak down test. These motors have a dimple in the crank at TDC to lock the motor during valve work and whatnot. The special bolt is really just a bolt with a rounded tip. In my case, that’s the fuel tank bolt...
This bolt is removed, and gets replaced by the rounded tip jawn...
Then I rotate the motor until I can feel the piston at the TDC on the compression stroke. A screwdriver works here...
Once it’s at TDC, I crank the special bolt down about 1.5 turns and I’m locked in place.
Next, hook up the compressed air to a spark plug hole. To do this, I have the hose from one of my compression testers rigged up to utilize the quick fitting on my air hose. It’s as simple as pullling the Schrader valve out...
Hooked it up in a plug hole...
Then raised pressure to 90 psi. I wasn’t getting much at 30psi, which is why I turned it up. No air out the exhaust or intake ports, but a bunch of air out the oil filler and I even got some oil out the breather tube...
Pretty much puts us at bad or stuck rings, barring any other hidden surprises.
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