dropping spark?

[jetmechmarty]

I had trouble with the loss of one or two cylinders after I washed the bike. It got worse to where it would happen in the rain. Now it happens even dry.

WOT I get maybe 60 mph, so I guess I might be running on two cylinders. It has been tough to troubleshoot because when I close the throttle and allow the engine to run at idle, it goes back to running on all four. I don't know what sparks aren't sparking.

[xj11john]

Sounds like spark plug wires, A good way to test this is spray water on them with a spray bottle at night and look for which ones shoot off fireworks (sparks).

[xj11john]

The reason it is worse with idle up or under load is that the wire get hotter and expand and that make the wire inside the insulation (or in some cases the silacone on most car wires) get futher apart, causing the spark not to travel through the wire-too far of a jump for the spark to jump accross the gap that is now in the wire. At idle they shrink back enough for the spark to jump accross this gap. Get some new wires and your troubles should be over.

[TopCatGr58]

Hey Marty,

Before you go investing in new wires, and trying to replace the OEM's by cutting on the coils....... FIRST try pulling off the plug caps, and inspecting the ends of the wires....look for corrosion, then cut off about 1/4" off the end of the wires, and then screw the caps back on! Inspect the screw on the inside of the caps where they attach to the wires for corrosion also, and clean as needed.

Then, if this doesn't fix it, then you know that you may need to invest in new wires. However, when was the last time you changed your plugs? Lots of residue from rain water, house hose water, can build up on the outside of the plug and short the current from the cap directly to the engine head/case instead of going thru the plug!?

But, could also be the pickup coil wires, cause at idle you aren't getting much flex in them, but with higher rpms, the timing plate is turning and flexing the wires and if cracked or broken, can pull apart and cutout the signal to 1 of the coils, hence running on 2 cylinders instead of 4!

You're a Jet Mech, get out your gauges and investigate!!
T.C.

[andreashweiss]

Yeah I agree check pickup coil for broken wire problem. New caps on a clean cut wire end. Try those first.