Stumbling when accel. from idle

[srwalters]

I am new to the XS1100 family. I bought a 1980 XS1100 GS that has not run for several years. To make a long story short, I finally got it running and it runs Great, but I have an issue with, when you give gas it will stumble and die or if you continue to rev it, it will pass the point of dying and rev up. I have read about pickup coils, but I had to replace the Fuel minture screws and according to the book set them to 1 1/4 out from when they felt a little snug. I do have vacuum, but am not sure how to test the amount of pressure. Any help would be appreciated,

[mro]

Can be caused by:
Debre in idle/enricher circut
Vacum leak
Carbs not synch'ed
Pilot screws not adjusted (1 1/4 turns out be the starting point for adjusting them)

pick-up coil wires:
Under the left round engine cover be the vacuum advance and pick-up coils. The wires connect there when engine is running constantly "flex" as rpm changes. This "flexing" causes the metal to fatige and one or more of the wires can break. Seems most of the time even when they are broken, the broken ends of the wire still make contact but can cause an intermitant "open" (wire not connected). When this happens there is no signal sent to the TCI from the pick-up coils which results in at least one of the coils (connected to spark plugs) not firing.


mro

[JRocket]

Sounds like the pilot jets. I had the same problem. My bike was seldom used, the gas went bad, and it would start right up, stumble, no power on the bottom until 3500 rpms. I pulled the carbs apart again, removed the bowls, and removed the pilot jets under the flat slotted plugs next to the jets. Using a very small screwdriver, remove the pilot jets which control the low speed running. Mine were partially clogged.

Works fine, now. Check out the diagrams and tons of info on the XS11.com site.

[srwalters]

Thanks Jrocket and Mro I will try this this weekend and see if this solves the problem. I was able to ride it yesterday for the first time and other than no power at bottom end I was able to get to 4th gear in a parking lot. When I hit second I had to hang on as I rocketed across the lot. I believe I will have to adjust the idle also as; I was not able to push the choke in all the way after warming up the bike for 20 min in 97 degree heat.

[JRocket]

Sounds more and more like the carb problem. The coils each fire two plugs, so you can diagnose by checking plugs and swapping the coil wires to see if problem moves.

Sounds like all 4 cylinders are firing, just need that low rpm fix with the pilot jets.

Good luck.

[Dennyz]

You might try turning the idle mixture screws out a half a turn at a time to see if the problem improves or degrades.

[John]

I would dare say the pilot (idle) circuit is at fault, and will need a complete cleaning and adjustment. If it will idle on the choke then that means that the fuel needed from the pilot is not being delivered, and the choke circuit is supplying it.

[srwalters]

Thanks for all the help. I cleaned the Pilot jets and the bike runs much better. I am able to slowly role the throttle with out stumbeling. Now all I have to do is change one needle valve (Carb #4) and I will be running on all 4 cylinders all the time.