Newly found 1985 VF500F Interceptor

I have been contemplating buying a VF500F to restore, well I found one. Got it home, checked compression.....I'm wondering if it's worth saving. Would anyone have an idea why the big difference from front to rear compression. 210 L-Front, 208 R-Front, L-Rear 40, R-Rear 140. It has sat in a barn for the last 5 years, thinking this would mean rust or stuck rings in the LR cylinder?
Thanks
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Nice looking 500! Try the compression check again after pouring a little oil in the spark plug holes. If there is no significant difference, do a valve adjust and check compression again.

 

40 psi sounds really low and yet the front two sound pretty high. When I did mine I got them all in the 160-135 psi range. Warming the engine made a v small difference.
No idea if my values are right or not. Compression testers vary too. My engines run OK with those values.

Has the engine actually run, if so does it run OK? 40psi sounds barely enough to pull the skin off a rice pudding.

Edit. Manual says compression should be between 142-199psi
Some decent info here too
http://www.pumaracing.co.uk/comp.htm

 

Welcome!

For reference, if you don’t yet have a copy of the FSM:



+1 on Creaky's post. Hopefully all will work out.

 

"Nice looking 500! Try the compression check again after pouring a little oil in the spark plug holes. If there is no significant difference, do a valve adjust and check compression again. "
Nice looking bike...............
Look around and research the difference adding the oil will make. It indicates the problem area maybe valves or rings? I will try to find the information.

 

Try this test with the oil...GOOD LUCK

A quick, down and dirty test is this. Squirt some oil, maybe a teaspoon's worth, into the cylinder through the spark plug hole. Now run the test again. The oil will hold compression for several turns of the engine. If your retest with oil gives higher compression, you will know the rings are worn. If there is no change in compression, it's the valves that are leaking. If you think it's the valves, it's always a good idea to check the valve tappet clearance. If the valves are tight, they could be leaking compression. If the valves are tight, reset them to the proper clearance and test again. if your compression comes back don't thank your luck, thank Jesus ! He just saved you an engine rebuild.

 

Man, that is a nice looking bike. I hope you find the problem and get it going!