Are these familiar symptoms?

[Anonymous]

My '81 1100EX with 12,500 miles has run like a champ until recently. Two weeks ago the bike started and ran well as it warmed up when I was leaving work (warm and dry). As I rolled away, it began to stumble badly. I could barely keep it running. It seemed to be running on two or three cylinders. I nursed it most of the way home (9 miles), then it suddenly began to run well. Perhaps not perfect, but well.

I drained the carbs when I got home - nothing unusual found. I started and ran the bike in the dark of my workshop (as I had done at roadside en route). No leaking spark detected. I checked the battery and charging system output - all seems well. The plugs are clean and uniform, but number four was wet when I pulled it (because of the way the engine stopped?).

The bike ran well daily for a week. I filled an almost empty tank during that time. Then, I washed the bike a couple of days ago prior to my last ride of the season. It started and ran well when I warmed it up briefly, but it was stumbling badly again when I rode off. I stopped in the dark and still couldn't discern any spark leaking. I rode for about a half-hour before it quite suddenly began to run well! I put the bike to bed for the winter at the end of that ride after all the usual winterizing stuff.

All routine maintenance is up to date.

I'm thinking coils or wires. What say you? Thanks.

[Anonymous]

Mine acted similar.

Mine is acting similarly but not so pronounced. I have gone through the coils, wires and carbs. I still have a problem of my own creation with the carbs to solve, but I don't think its related. The only thing I have yet to do is adjust the valves. I'm thinking I may find the problem then.

[nert]

i don't think you will get a wet plug from the way it turns off. That is probably your problem cylinder. You need to determine if it is ignition or carb related. I would first unscrew the hard plastic plug cap from the wire. There is a brass colored tapered screw in the wire end of the cap that the wire impales it self on. I have seen the wire burn and arc away in there. Cut the wire back 3/8 of inch to get a fresh bite and reassemble. Also make sure the resistor inside the cap is good. If you look in the plug end there is a slotted "nut" that may be loose and not connecting. You can take it apart and inspect all the parts inside or tighten it. Either way measure your secondary winding resistance across the (2) plug caps that share each coil.

[daveo]

If it doesn't do it next time you run her, I'd guess you got some water in your airbox when you were washing, maybe up under right sidecover

[Anonymous]

If it doesn't do it next time you run her, I'd guess you got some water in your airbox when you were washing, maybe up under right sidecover

That would have been my guess, too, but on the first occasion I had trouble there was no such water near the bike.

[daveo]

That would have been my guess, too, but on the first occasion I had trouble there was no such water near the bike.

I'm sorry, didn't understand it happened more than once, have you looked at the hall effect sensors and spark advance? Under right side crank end cover

[Anonymous]

I have had this same problem in the past and even today. My bike feels like it is running on 3 cylinders. The wierd thing is as I drove up a twisty road the power came back, then back on the straight it acted up again. Then finally it broke down on a major bridge during rush hour. I couldn't start it for several minutes. I am not sure if it is electical or carburator. I know my carbs need to be rebuilt, and I also have one plug that has been wet when I pulled it. The clue may be when the bike is leaned back and forth the things takes right off. It also happened as the bike died on the highway and as I pulled over I gave it gas, about half throttle, and the thing kicked in and it almost threw me off the bike.
It could be all the above. I was also thinking it could be the petcock or the fuel filter. Not sure, HELP!

[Anonymous]

Clean the carbs.

I would start with the carb cleaning. Checking the plugs and wires is a good thing to do at the same time. Cutting the wires back is good, but I wouldn't waist any of my time on those old caps. Once the resistance is out it will never be back into specs. Get some new NGK caps.

Two VBO5F and two XBO5F worked to replace my stock caps. The first letter is the syle. Just make sure they are BO5F and they will work. They were $3.25 each at the dealer, and also Den Kirk.

[redliner1973]

If you washed the bike prior to riding it, even if you started it tehn, sitting overnight can cause it to miss on one of the two coils. mine does this quite often, and have to ride it untill it gets very warm sometimes before it starts running on all cylinders. It is usually worse if I wash one day, then ride the next. On mine it comes from water soaking into the plug caps and once it gets in there it won't come out unless it gets eal warm or I pull all the plugs and blow out the caps. try this first. :twisted:

[Anonymous]

Tossing his two cents in, mopolopo said:

I had a similar problem on my Subaru. It turns out that one of my spark plug wires was totally disconnected. For some reason, it seemed like the stumbling only happened sometimes. You'd think it would happen all the time. Dunno.

There ya go. Good luck!

Michael

[silverhorse47]

This same behavior had me baffled for a long time. I had cut the wires back, new caps, changed over coils, trouble shot the whole thing and there were no apparent problems. It did not occur to me that the connection between the cap and the wire could be poor when I couldn't even budge it by pulling on the cap.
Then I started to pull the caps off one by one with the engine idling. Low and behold there was no change with the wire off #4, and a couple of others would offer intermittentend response. Funny thing was, the engine would suddenly idle perfectly when I was replacing the caps onto the plugs right up until I had actually pushed it all the way on. The connection was only good when the cap was lying on the top of the plug, not when it was pushed on all the way.
Still puzzled I recut all the wire ends, and this time left a little stub of wire sticking out the end. Bent the wire ends over the insulating rubber of the plug wire like the spokes of a wagon wheel...screwed the caps on and voila...! All is now well.
It took me several months to figure this out though. It's a simple enough thing to try.
S.

[Anonymous]

My bike was stuttering and stumbling at high speed, and died a couple of times. Turned out to be the ignition fuse. The fuse was partly broken and was getting shaken out of its socket. I'm surprised the bike ever worked.

Roger

[earlfor]

Sounds to me like the wire core of the spark plug lead on #4 is not making good contact with the spark plug cap. I would trim the rubber casing back 3/8", bend the protruding wire ends over the end of the casing and screw the plug cap back on.

Earl