XS dies at 1500rpm

[xssiveone]

I think I asked about this once before, but will try again in the hopes that perhaps some new ideas can be brought forth.

1978 XS1100... not sure of the mileage as it's a friend of mines. After the engine is warmed up, (about 20min of riding) it will, quite literally, die, at around 1500 rpm.... just as if you turned the key off. If the throttle is feathered, he can get past the 1500 mark, if normal acceleration is used, it will die. Then, it will start right back up. Once past this rpm point, it will run like a true XS.

Carbs have been gone thru and rejetted for Mac 4 into 2
Fuek tank boiled out
Iinline filters installed
Pickup coil wires are good
Vacuum advance is working
Coil resistance is correct
CDI box has been swapped for a known good one
Fuse box replaced

**And a bunch of other stuff that I have forgotten

He is currently going thru the wiring in the neck area as he found a broken wire there before. And he is also planning bypassing the mercury shutdown switch.

I think it's a carb issue as it is right at the "off idle" point, he is convinced it's electrical.

Any ideas?

[Snow]

Check the plugs - if they are dry, prolly carbs, if they are wet, electrical - right?

[Mike Hart]

Rejetted how? What is different from stock? Ordinarily one wouldn't have to rejet when going to another 4-into-2...

[Geezer]

Adjust the idle mixture and synchronize the carbs again.

Geezer

[xssiveone]

Originally posted by Mike Hart
Rejetted how? What is different from stock? Ordinarily one wouldn't have to rejet when going to another 4-into-2...

Offhand I don't know Mike, will check with him tomorrow to get specifics. I do know that this was a European import, and had different jets then what is the norm for a North American XS.

[xssiveone]

My friend thinks the problem has been solved. One of the pickup coil wires was rubbing under the timing cover and had worn some of the insulation off. Revving the engine up to the 1500rpm point caused the advance mechanism to move enough to create a short at that point. A quick repair and a couple of short runs thru the 'hood and the problem appears to be gone. He made a more permanant repair, but then the monsoon showed up again so he hasn't had time to give a good run yet.

[xssiveone]

That appears to have been the problem. He must have repositioned the wires when he checked them for breaks and it eventually wore thru. He rode it to work today, in the rain no less, and it performed flawlessly.