On two cylinders, then back again. Cdi, wiring or coils maybe?

[Metoo]

Hey all, I searched found some similar things but no resolution etc..

Ok in a nutshell, my bike will run on two cylinders sometimes. It will happen occasionally on start up but then randomly kick back to four while riding if I'm lucky, if not I have to pull over, turn off, turn on and hope it will be on four. This works sometimes but like I said its all a bit random.

It will however, always (in the last few weeks anyway) run on two cylinders if I rev it to 7/8,000 rpm, does not matter of its in neutral or in any gear while riding. It all happen instantly, no warning.

I had the carbies cleaned and balanced, oil, spark plugs, fuel filters removed and maybe one or two other things I can't think of right now.

It's been to the mechanics multiple times and finally they said its either the wires or the Cdi, as it was running on two cylinders, they wriggled the wires going into the cdi and it ran on four. I have just spent tonight testing this and no matter what wire I pull/push whatever, I can not get it to run on four unless the bike just decides it wants to. Same as I cant get it to run on two by playing with the wires going into it.

Would this problem definitely be the Cdi? I thought maybe coils but the fact two die at 7 or 8,000 rpm makes me think the Cdi is packing it in. Also how sometimes when it runs on two I can just turn the ignition off, back on and straight away it will start on all four..

Is there a sure fire way to test the Cdi or coils to find out what it is? (I don't have any special tools, just a multimeter and a test light)

Thanks everyone

[Badfaerie]

The question would be which 2 cylinders is it dropping. If it is consistently either 1 and 4 or 2 and 3, I would look to the coil. If it varies, I'd look to the cdi.

[Nut-Nut]

Agree^^ you need to know which two, and also verify that it is in fact 2 cylinders, not just one.

If it is just one it could be a spark plug wire, if it is 1,4 consistently, or 2,3 consistently, then the problem is more likely a coil.

And as already stated, if it varies which two, then I would suspect the CDI.

I had a similar problem and that may be the one you were referring to but it is unlikely it will be the same as yours because I have an aftermarket ignition which uses two seperate pick-up coils, as it happens, one of them was cutting out and not sending a signal. Stock on a KAt, at least the 1100 i know for a fact had only one signal generator.

[Metoo]

That sounds fair enough, pretty sure it's 1 & 4. How would I check though.. (I have no idea on somethings, sorry)

[Slofuze]

That sounds fair enough, pretty sure it's 1 & 4. How would I check though.. (I have no idea on somethings, sorry)

Swap the coils and see if it's 2&3....... then it's the coil.

[Nut-Nut]

Carefull, cause you will get burned, but I checked mine by touching my "gloved" hand to each exhaust pipe. The cold ones are theones not firing...

[SOS]

Spray water on the manifold hot pipe means fire in the cylinder and no burned hand.

[Metoo]

Thanks for all the replies guys, it was only 1&4 not firing, but I didn't need to swap the coils to see why.. All it was was the bottom orange wire going into the left coil was hanging off.. So me and my mate who was helping me out to swap the coils just taped it on with electrical tape so if definitely wouldn't pop back out and everything is great now. I can't believe the mechanics tried to tell me it was the Cdi and parts and installation would be about 2000... I seriously considered selling my bike all over a loose wire, glad I checked it for myself.

Thanks a lot everyone

[Slofuze]

Rule #1: When you actually find a great mechanic who knows his sh*t and not simply trying to pump cash into a dealer's coffers...... cultivate the relationship as it will serve you well with the stuff you can't do yourself. I have a stealership about 15 min. away from me, and yet I'll go 45 min. to a place whose mechanic I trust.

[jr_2431]

informational note: black tape doesnt take kindly to weather or water. So you might want to buttsplice and/or shrink wrap for a little longer lasting