Me and carburetors have a love/hate relationship. Love because there's a lot less wiring and computers involved. Hate because they can be finicky beasts ... and they are being finicky!
Filled cooling system (just with water for now), put a bit of fuel in the tank (and I just filled up my snowblower from the same jerry can yesterday, and it works), hooked up battery ground. Switched on the key - we have electrical. Hit the starter button - lots of cranking but no fire. Not a hint of firing. From the sound of the engine while cranking, compression sounds even across all four (although on initial startup with new rings, no question the compression is going to be lower than it will eventually end up).
Pulled a spark plug cap, inserted an old spark plug and arranged to ground it against the frame, crank - strong spark. Not an ignition problem.
Tried spraying WD40 directly into each velocity stack while cranking - no dice.
Took a propane torch and fed propane directly into the airbox (with the cover removed) for several seconds then tried cranking. Propane has the advantage that if you misjudge and use too much, it won't foul the spark plugs with fuel. It fired a couple of times. Tried again. It fired enough to rev up to probably 4000 rpm then quit.
It ran long enough to reveal that I have an exhaust leak at the cylinder head - that's what I get for trying to re-use exhaust gaskets. This wouldn't affect firing during cranking but it could affect whether the engine will want to keep running once it fires. I'll have to fix that, then try again.
Filled cooling system (just with water for now), put a bit of fuel in the tank (and I just filled up my snowblower from the same jerry can yesterday, and it works), hooked up battery ground. Switched on the key - we have electrical. Hit the starter button - lots of cranking but no fire. Not a hint of firing. From the sound of the engine while cranking, compression sounds even across all four (although on initial startup with new rings, no question the compression is going to be lower than it will eventually end up).
Pulled a spark plug cap, inserted an old spark plug and arranged to ground it against the frame, crank - strong spark. Not an ignition problem.
Tried spraying WD40 directly into each velocity stack while cranking - no dice.
Took a propane torch and fed propane directly into the airbox (with the cover removed) for several seconds then tried cranking. Propane has the advantage that if you misjudge and use too much, it won't foul the spark plugs with fuel. It fired a couple of times. Tried again. It fired enough to rev up to probably 4000 rpm then quit.
It ran long enough to reveal that I have an exhaust leak at the cylinder head - that's what I get for trying to re-use exhaust gaskets. This wouldn't affect firing during cranking but it could affect whether the engine will want to keep running once it fires. I'll have to fix that, then try again.