Herman Melville
New member
I am sorry to ask - I have been trying to fix this for weeks.
This engine starts first time. Idles sweetly. But sneezes at 2500 rpm (with no load on the muffs)
I have done:
New plugs (putting the old plugs back in also made no difference)
New fuel filter.
Cleaned and dried the fuel tank.
Sonic carb cleaning.
Checked the float height and reset idel screws to 2 turns (stock).
Put in brand new fuel. Made sure that new fuel is in the carbs not the old stuff.
Tested the primary and secondary coil resistance - in spec.
Tested the HT lead resistance - in spec.
Tested the spark gap - jumps the specified 11mm no problem.
New CAM belt - it made no differnce (just needed doing)
Triple checked that after the new CAM belt is on that all the marks are where they should be.
Balanced the carbs - this would really affect idle so i did it mostly to make sure there was no vacuum leak after the carbs.
I have also kept the bulb pumped hard while runing to make sure the carbs are full of fuel - no difference
I have bent and poked and moved and prodded every lead in the ignition while it is running to see if I can close or open an internittment bad connection.
Compression test gives 175psi + on all four cylinders.
There is not a lot left to try...
Any clue would be appreciated.