Sick running bike

[Trev1958]

Help!! Bike was running perfectly last time out. Before next outing I took the plugs out for a quick check. All good so popped them back in. Started the bike up (GT 750), and now it’s popping and banging like a b…..d! I put a new set of plugs in, same thing. Also checked that the leads were on the correct plugs, there is a spark on each cylinder, vacuumed pipe is on, plenty of fuel. Each pot feels the same temp. Took the plug caps off and made sure they were screwed in properly. Just think of anything else. Any ideas chaps???

[canaletto5]

Is it all the pots or can you isolate the fault to one of them? Kev

[Trev1958]

The biggest ‘bang’ was from the left pot.

[canaletto5]

Have you got a spare, charged up battery, or is the battery on the bike fully charged?

[Trev1958]

I keep all my bikes on an Optimate. The battery is fully charged.

[canaletto5]

The popping and banging you describe can be caused by either low voltage at the coil(s) or a problem with the coil itself. Weak spark causes unburnt fuel to build up and then suddenly ignite. Worth checking the input voltage at the coils as a starter. Kev

[Trev1958]

Coils were my suspicion as well. Will try that. Thanks Kev.

[Trev1958]

Any idea what the correct voltage output should be?

[Trev1958]

Sorry, input voltage.

[canaletto5]

You should be seeing at least 11.5v at the coil connector plug