xs750 starting issue

I have been working on a 1978 xs750. It was a runner when I bought it. After doing some clean up work to it I was going through tuning it up. I misread the manual and loosened the cam chain adjuster instead of tightening. Now when I go to start I don't seem to have any compression. The crank turns freely like when you remove the plugs to turn the crank by hand.

Before I dig deeper into the engine does anyone have any suggestions.

Other than new plugs and screwing up the cam chain tensioning I have done nothing to the engine since the last start up prior to the adjustment that she was running fine.


Thanks
Curtis


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First I would check for sticking valves from sitting because that would be easiest to check and fix.

I would guess that one or both of the camshafts has jumped a tooth when the chain was loose. You will need to find a manual that outlines setting the motor in time (top end with bottom end) There should be marks on the flywheel and camshafts that will line up with marks on the engine case and head castings.

The flywheel should be easy but you may have to pull the top cover off to check out the cam timing.

Thanks for the quick reply. I'll give that a shot.


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sounds like you bent the valves, they wouldn't be sticking because it was running before
if it did jump time, you see, it is easy to bend the valves
pull the top cover and check the cam timing

Don't like the sound of that!! The timing is definitely out. When at tdc both the intake and exhaust cams are off their marks.


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it sounds like you can roll the motor through several revolutions smoothly ?
pretty easy to check for a bent valve, whenever any cam lobe is in position for checking clearance,if the clearance observed there is exceptionally wide, then you have a bent valve
if it actually "jumped time" and you didn't bend a valve you got lucky
you can also check for a bent leaking valve by putting the motor in a position that both valves are closed and blow through a hose to the sparkplug hole and listen for leakage best to do this only with your lungs and pull the pipes and exhaust carbs so you can easily detect leakage

If it jumped and you are in that 0,001% chance of not hitting any valves you are very lucky!
Had a tensioner fail on startup on an xs1100 i just finished a big bore and top end rebuild on. All 8 valves got bent!
Made a bombproof tensioner and installed a new timing chain..