Zenerdiode

It sounds more like you have described the symptoms of a failed needle/float valve for carb #1. If the level is going much higher than what you’d expect in the bowl; the mixture is probably too rich for cyl #1 to fire. If the petcock has failed (which indeed it may have as well) when running it would have no effect, as it’s ‘on’ in any case. So when the engine is not running and petcock in ‘Prime’, the bowls should fill to their fuel height and shut off. The petcock is really just there in case the needles weep a bit. Have you checked the fuel level in all of the bowls?

So the GSX750 was bought as a non-runner. The engine in the bike has a snapped timing chain, it came with a ‘spare’ engine that apparently burns oil like petrol. So I’ve decided to see if the snapped chain engine can be repaired - it’ll need to come out either way. Removed the rocker cover; yep, no chain. Took the head off; and there’s been contact. Also, make sure you check your locknuts after adjusting valve clearances guys, I found one that escaped. It was still in the head, so I don’t know if it contributed to the chain snappage. I’ve filled the ports with fuel, the inlet valves are s