I haven't run it yet. If it was a coil miss I would have expected more carbon in the combustion chamber. Combustion chamber is clean as in the photos. All I did was wipe it out with a rag. Here it is from the exhaust valve seat out. It is probably 1/16" thick in the runner behind the exhaust valve.
Good to know. Soaking the valves in carb cleaner hasn't done anything.
Can't and didn't happen... Coil is rev limited and with that monster line I doubt that it would have enough power to run at the specified RPM let alone over rev... which may have let it get too hot.
Engine failed leakdown test which is why it was torn down. I knew that it had an exhaust valve leak which was confirmed to be carbon buildup.
Sounds like the same problem.
It may not have been a lack of oil that did the cam in. I have read about instances of these plastic cams actually melting from overheating... caused by overloading and lack of airflow.
is the cam support shaft ok, i have a high miler that wore the hole oval, and had to drill and bush it (on the right)
I'll check it but since this is a "low miler" I don't think that this would be an issue.
yes i agree, this one was closing the valves ok at startup or shim test, but was scattering the valve clearance at rpm tho
Me being the genius that I am after replacing the cam I put it right back together without the gasket. No way that it would idle. I'm like WTF .
A leak into the crankcase / valve train won't specifically keep it from running but will interrupt the pulse that drives the fuel pump in the carb.
If you look at a FS91 this is more than a leak. It's a gap. And, it goes right straight in to the mixture.
I don't have any direct experience with the updated 91 series. I did look at my 110 and it has a passage from the intake runner in front of the intake valve for the piston to suck and blow mix through the valve train and crankcase for lubrication.
It depends on the carburetor model. What was it set to before it was messed with?
That carb has tamper proof screws. I think it is the same as an S131 but with tamper proof instead of limiter caps. Try L=1.25 and H=3.5. Put a string head on it with the correct .090 line at the cutter blade length. Tune the H at WOT for max RPM. The string head load should keep it from hitting the ignition limiter at 10K. You need to fix the cable issue first though. Let me know what adjustments you finally end up with.
If that unit has another of those barrel carbs, you are in for the long haul. I spent 6 weeks researching, right here.....and 2 kits. Those bsarrel models are beyond finicky....which = junk.
