I have a suzuki bandit pistons 1&2 have got black on the spark plugs 3&4 havnt any sugestions what it could be
Answers:
I would clean the carbs. 1&4 plugs use the same coil and 2&3 use the other coil. So that rules out electrical problems. The back firing is caused by the black spark plugs. The spark plugs are getting fouled because of the carbs.
carbs out of ballance for the soot on plugs. backfire, make sure you have the ht leads on the right plugs.
Could be valves leaking.
Firstly you have the timeing out if it is back firing swop the plug lead diagonaly across the distributor cap. if you have black spark plugs this could be caused with the head gasket gon between the pistons or the piston rings have stuck on the pistons (this could free its self when it runs) hopr this helps.
Sugest a week spark. could be the coil. swap the coils with one another and se if it swaps the problem to 2-3/ this will give an answer before laying out cash before you have to.
If it is the coil m&p do one for about 25 pound.
jetting is different on inside cylinders as they run hotter. ride harder to keep plugs clean. this is a sport tourer not a cruiser.
Kawasaki make a fuel additive called carbo clean to remove carbon from valves, pistons and cylinders of bikes that dont get ridden hard enough to stop fouling ( I think Yamaha and Honda make something similar but I havnt used them so dont know)
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