No compression when hot

[243ron]

1976 FX, all stock, with 15,000 original miles what runs very strong. Sometimes, not always, when the bike is hot it will jusk kick-through as if it has no compression. After doing this about 10 times the compression comes back and the bike will start. ( if you hold the throttle open). I'm thinking either the lifters are holding some valves open or cylinder wash-down from a carb flooding. Any thoughts?

[Snuff™]

243ron,

Your not alone.  I've have this happening to me on my '82EG.  Haven't had time to screw around with it.  Thought its been sticking valves until the other week and thought it might be slipping clutch??  Anybody else have some thoughts?

-Snuff

[CraigArizona85248]

Sounds like a sticking valve to me.  I wouldn't think that a clutch would stop slipping after a few kicks.  But I can see a valve becoming unstuck after a few cycles.

-Craig

[243ron]

I think I'll start carrying a compression gauge with me to test it next time. Won't happen at the shop of course.............

[pappyfreebird]

id hope fer the flooded cyls.. they kin really roll ova easy when flooded..then hold throttle n she cleans up,,id hope fer floodin

[Ultrashovel]

Bad (loose) valve guides will do that. It makes any sort of valve adjustment problematical. They need to be fitted per the manual and reamed to size with the proper sized reamer after they are installed since they tend to close down when put in with proper interference fit.

The valve guide fit is the most ignored issue on Shovelheads and yet it's one of the most important. It's really critical since the guides in Shovelheads are very short.

[243ron]

Thanks for the advise. I was kinda leaning towards doing the top-end anyhow. I guess 32 years on a top-end is about all your gona get. One thing is clear, I most likely won't be around for the next one!