JL50 won't start...Running out of options

Hi, I bought a JL50 as a lockdown project. Cannot get it to start! It has a good spark & new plug. Compression feels OK. Fuel tank was full of rust & water so thoroughly cleaned it out & new fuel. New fuel filter. New carb for good measure. It sometimes splutters for a sec or 2, but just wont start. Checked carb jets. Starter button doesn't work but solenoid & starter work ok by jumping the terminals; but I use kickstart anyway. Even a blast of cold start doesn't seem to help. Am I missing something?

 

Is there any earth cable form engine to frame

 

Good question! When I tested the plug I earthed it to the battery. Will check earth cable tomorrow. Cheers!

 

Also look at choke, cable or auto.

 

2t or 4t Valve clearance ?

 

Auto choke. I'm pretty sure the default is open, then 12v is applied when engine running which closes it. Valves have some clearance when closed, will measure.

 

Check the compression with a proper tester, there is no other way to gauge it, 10psi will 'feel' ok on your finger but it wont start the bike

 

Sorted! I replaced the coil & ECU, spark didn't look any different to before, but it started first time. Thanks for all the tips!