Rebuilt my 1982 xl1000 with new crank, bored out jugs to 50 over with new pistons and had new valves and guides put in, But only get 50lbs of compression in both cyclinders, Why?

 

Rehoned cyclinders, new rings agin. checked timing agin, installed new gasket set agin, still same compression problem, and no one seems to have any good answer as to why.

 

This is with the throttle held wide open? Also, Sportsters are notoriously difficult to cam-gear time, so I'd check that also.

 

Compression tester in good condition? Maybe it has a leak, good luck!

 

Same reading on both cylinders? could be cam timing, or bad tester....or misaligned valve guides on both heads (nearly improbable)

 

two posts 4 minutes apart? did you put the heads back on?

You might try reposting in a tech section where it is more likely to have a good wrencher see the post. If you put the heads back on....right size pistons... then it pretty well narrows it to valve timing...or pushrods are not correct length holding valves open but that seems unlikely if engine turns ok....maybe a search would turn up some good suggestions...

 

I would check the cam timing also.
You could also remove the valve covers to see if the the valves are closed at TDC.

 

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