Out on the bike toady for a ride all went well had to go to reserve then filled up, no probs stopped for tea then set off back been running for 20miles or so when backfire from one side and bikes running on two cyls and cutting in and out of three, first thought bit of muck in fuel but then wondered about coils, still on old ones, what would be the symptoms of a coil breaking down?
Further to my saga "running on Two" I have now replaced the coils and spark plugs, drained the tank and cleaned it out, had the carbs off and given them a clean up made sure all the connections are sound so time for a ride out!! First 10/15 miles all sweetness and light then the occasional miss mainly when accelerating, not as bad as it was , when cruising the bike seems ok but throttle back for a roundabout and start to accelerate it goes down onto two and coughs and splutters before picking up. im loath to take it to a garage as its going to cost a fortune for them to even find the cause. Any suggestion as to what to try next invited
Sounds like you can discount a spark issue unless the ECU is having issues - have you had it checked for any stored error codes? So that leaves an insufficient air or fuel problem. Does it misbehave if you run it up through the gears on the centre stand? If it does then I’d be tempted to remove the air filter and see if that rectifies things. if it does you need to look for a restriction in the air flow. If not then looks like it’s a fuel flow restriction.
Is it always the same cylinder that misfires, or is it random? Is it heat related i.e. hot engine only, or it can be either hot or cold? When was the valve clearances last checked?
