Strange Behavior

[D. P. Larmee]

Strange thing happened to me the other day. I rode 30 miles, stopped for about an hour to get out of the rain and when I got back on the bike I started her up and she purred like a kitten until I kicked her into first. With the clutch still in, she started trembling and wouldn't stay running without giving xsive gas. Put her back in neutral and everything was fine again. I began thinking that it was probably a clutch adjustment issue, but it did not pull forward at all and still rolled freely in gear, just ran real rough. I checked the clutch for free play and everything seemed reasonable. I decided just to bite the bullet and rev her hard to keep from stalling and get home so that I could do more diagnosing. Well about 10 miles down the road, just as suddenly as the problem started, everything was back to normal. She's been running flawlessly ever sence. Has anybody else ever experienced anything like this?

[ratbyk]

Rough Running

Sure, lots of times. Likely bad spark plug caps or plug wires or both. If you still have the original plug caps replace them with new NGK wire ends. These high tension wires and caps do not like moisture. Allows the spark to find a shorter less resistant path to ground.(instead of jumping the plug gap)
After you had ridden for awhile the water evaporated from engine heat. Many times if it has shorted to ground inside the cap for any length of time a carbon track will develop across the track the shorting charge was taking. Next time it will short even easier because a path has already been developed.
Ken/Sooke
78E Ratbyk
82 FT500 "lilRat"

[D. P. Larmee]

I had a feeling that the rain was likely was involved, although I'm still not sure that I understand why even with the clutch pulled in, it would only run rough after it was put in gear. The engine does not know the difference between being in neutral and being in gear with the clutch disengaged, does it?

[randy]

Remove, clean and replace your engine ground strap. It's just below the airbox and fastened with one of the middle gear case bolts.

HTH

Randy

[ratbyk]

Wet Ignition

The spark plugs require a require a certain amount of secondary ignition voltage to jump the plug gap. This is dictated to by compression/combustion pressures. At idle with no load on the engine this may be as low as 4000 volts. Your marginal plug wires and caps are capable of carry this voltage without finding a short cut. As you put a load on the engine, (simply by putting it in gear will increase the load slightly)now the engine requires possibly 6000 volts to force the spark across the plug gap. BUT! the weak ignition wire/caps cannot contain 6000 volts. An easier path has been established because of the moisture. The spark is not reaching the plugs but is following an easier path to ground.
Enough discussion. Replace the plug caps/keep the engine dry and your problem will go away.
A good silicon spray up inside the caps (after there dry) Will also help reduce this problem but since it has already happened a carbon track is now established (a path) inside the cap/caps.
Replace the caps.
Ken/Sooke (a very wet part of the world)
78E Ratbyk
82 FT500 "lilRat"

[skids]

Re: Wet Ignition

A couple of other things to check, if the new caps do not work out with trimming a quarter inch of the plug wires:

cracked insulation on the plug wires, and,

water getting into the ignition cover by draining into the wire sleeve, and,

if the overflow tube from the tank is clogged with a bad seal around the filler cap, water may be getting into the fuel (but if it was instantaneous I suppose this is not your problem).