Sometimes runs on 3 cylinders on a cold day - help!

[Rumblelover]

Hiya,
My bike sometimes runs on 3 cylinders when I start it up in the morning, and doesn't get better with a little gas/choke/letting it run - it is never a problem during the day when it has been sitting in the warm... I've had it serviced, and yes they changed the plugs but the mechanic just put it down to it being old.

Sometimes you just have to fix it yourself... I was thinking I might try and replace the HT leads and/or coil. Anyone have any ideas?

Also, it is kept in the garage, so it doesn't get wet...

I just want to ride it!! Thanks...

[onearmedbandit]

Hiya,
but the mechanic just put it down to it being old.



Get a new mechanic.

[Grubber]

Oh hey,,,mine does exactly the same...oh hangon...mine is a triple. Carry on!:rolleyes:

[Banditbandit]

My carbed 650 Bandit does that when it starts after sitting for a while (couple of weeks - not a few hours) but it picks up on four cyclinders very quickly ... usually before I shut off the choke ...

I have no idea what to suggest to you - how long before it does pick up on all four cyclinders? When does it go from running on three to running on four?

This could be a carb problem - one of them is a little out iof balance with the rest? And takes a while to warm up and come on song?

Could be that oil is getting passsed the rings in one port and taking a while to burn off the sparkplug ???

Then someone is going to come along and tell me both of those suggestions are completely wrong ...

[paturoa]

Which POT?

Depending on your wiring you may be able to swap the coils and plug leads to see if the miss-behaving pot swaps with the coil HT lead swap. That will tell you if it is electrical or something else.

Edit: normally you can work out which pot is miss-firing by the temp of the header pipe. Don't burn your fingers!

[Erelyes]

I've had it serviced, and yes they changed the plugs but the mechanic just put it down to it being old.

Not calling em liars, but... did you see the old ones?

[Jjgres]

Sticky diaphragm carbs? If it has carbs, that is.