High RPM miss

[XS1100 Newbie]

Ok folks here goes another problem. While on a ride with the group a week or so back, we were pulling a pass upgrade. I was cruising about 60ich is a little over 4000 RPM. When i tried to accelerate, the bike just crapped all over itself. It would hold at 60, and below 5000 RPM though. When we returned to camp i checked the plugs. All four were burning the same. We checked the pickup coil, which appeared to be fine. We didn't pull on the wires very hard, because we were a way from home in the hills. I did find the vacume hose to the advance with a big slit in the hose and repaired that. The thought of fuel starvation crossed my mind, so i ran the bike on prime, no difference. When i got home i checked the octopuss, and the diaphram seemed to hold good. The vacume hose looked good. I noticed on a short ride the other day when i throttled her up in 3rd gear, that it started cutting out about 4300 RPM. As i tried to go higher, at about 4900, the tach dropped to nothing, then started working as soon as i released the throttle a little. The action of the tach would lead me to believe that i have an electrical problem rather than fuel. What i need to know is a sequence of checks to make, and if the ignition control can be checked, and if anyone has had a similar problem and cured it. I don't want to start just replacing things to find it. Throwing parts at something just doesn't allways pay. I looked in the repair and mod sections, and searched, but have not really found much of anything to help me. Maybe i am just missing it. Any help is greatly appreciated. I forgot to mention, that the miss starts at about 4000, even sitting still.

[tw1980]

Hey Bob I'm starting to think maybe I didn't check your pickup wires close enough.That wouldn't explain the tach problem though.I'll have a look at the wiring diagram tonight and see if I can come up with anything.

Terry

[XS1100 Newbie]

I was thinking about pulling on those wires harder and see what happens. We have nice weather coming this week though, and i hate to miss out on some riding.

[Ken Talbot]

I was thinking about pulling on those wires harder and see what happens.

Don't be shy about pulling on the wires. If you can get them to pull apart with your fingers, they were bad in the first place. To get a good reference, take a piece of good wire of the same gauge, and try to pull it apart, even with it wrapped securely around both hands. The good wire isn't going to break, and you're sure not going to get that kind of force with just your fingers.

[Ivan]

The tach is a pulse counter off one of the legs of the alternator's AC stator winding. If the tach stops working after 5000, check with a volt meter on the battery while running, and see if the voltage drops. at 10.5V the TCI quits working. If it is close on the voltage, I could see it possibly making a miss that gets worse with RPM.

If that is the case, suspect the voltage regulator.

[XS1100 Newbie]

Thanks Ivan. Good point. I'll give that a check.

[tw1980]

Hmmmmm?

Hey if the tach runs off the alternator what's the light blue wire that comes from the pick up assy and goes to the tach for? I don't think you have a problem with the regulator because your battery is charging ok right?But Ivan got a couple of my remaining brain cells to slam together.You could have a bad plug or resister.I'd check the voltage to the tci(white/red wire)and to the coils.

Terry

[XS1100 Newbie]

Man Terry, i hope those cells didn't hit to hard. I will be checking voltages this week. It was nice today, and i couldn't resist going for a ride. Strange thing is, when i first went to start it this morning, it let out a little pop. I know it wasn't flooded. Then it wouldn't idle for a moment. Who knows. I'll do my checking this week. Thanks for the idea.
Bob

[tw1980]

Man Terry, i hope those cells didn't hit to hard. I will be checking voltages this week. It was nice today, and i couldn't resist going for a ride. Strange thing is, when i first went to start it this morning, it let out a little pop. I know it wasn't flooded. Then it wouldn't idle for a moment. Who knows. I'll do my checking this week. Thanks for the idea.
Bob

Yeah it was really nice here today as well.We went for a ride after church and I didn't get any complaints from the rear!(if you no what I mean)As for the little pop,I assume you're referring to a non violent backfire.With carborated engines we never know what's in the cylinder when we push the starter button I thinking it's of no concern but someone else may have other ideas.

Terry

[Varnae]

I'm sorry I can't be of any help right now, but if I'm reading correctly, the problem you're having seems to be pretty much the same problem I'm having. I've been fighting it for a couple weeks now. Please let me know if you find an answer before I do.