3000 RPM Problem

[denysp]

Good day everybody,
I just got my 81 XS1100 back from the shop, I got them to change the main jets to 110's and clean and sync the carbs. Also got a new air filter and oil change. While the work they did seemed to have increased my range from Empty at 140KM to emty at 175KM. Im very happy about that, however the bike does not like to run at the slower RPM, it seems like its getting too much fuel. I would like to try and resolve the problem myself, but im a newbie with this sort of things. I was wondering if you guys could point me in the right direction. One of my buddies thought that the pipes I have might not be stock and could cause a problem, is this true? if so what do stock pipes look like or is there a part number stamped on them or something? Even sometimes cruising on the hiway at around 4500RPM it does it... its just very frustrating...

Thanks for your time.

[dragxs11]

Hello Mr. Denysp,
Welcome to the site. It's hard to pinpoint the cause of your issue. Did this start after the carb work, or was it the reason for service? Did this start happening after sitting all winter, last season, or after you put the pipe on? Are your spark plugs black, white, or brown?

[denysp]

Its sort of always done it at 3000rpm no matter the gear. And it was part of the reason I took it to the shop and had the carbs cleaned and sync'd but the fact that it not does it on the hiway somtimes bothers me. The same pipes have been on since I bought the bike, as for the plugs I will have a look and get back to you..

[DiverRay]

Denysp,
what did the shop do on the rebuild? did they put in "kits", with all new jets?
They should have put new plugs in when they did the carb work.
You can look at the "Tech Tips" on the left side of the page to try and find more information about carbs and running.
If you do not have a manual for the bike, you can still buy new Clymers manuals for about $25 C. That should be the FIRST thing to buy.
Try some "Seafoam" or "Berryman's B12" in the fuel for a first fix. It is quick, cheap, and may work.
I would start the trouble shooting proccess with a complete "tune up". That is, in order, Valve adjustment, cam chain adjustment, timing check/adjust, then carb sync. I hope the shop did all this, as you MUST do it in order to properly sync the carbs.
With a book, the work is fairly easy, tool needs are minimal. You will have to buy a "carb stick" or like tool for the carb sync. This is a 60cm long tool with mercury in the bottom and four glass or plastic tubes going up to the top. There are four vacum lines to hook up to the carbs.
Once on, just balance the four together, and it should run well. If the carbs seem to be running rich at the "under 3K RPM, try adjusting the pilot screws. They may have a "plug" covering them, to keep you from doing this. The shop should have removed the plug already, to help with the balance.
Good luck, and let us know!
Ray

[cokeman]

densyp
I had the same problem with my 81 midnight special. I tracked down the problem to wrong pilot jets and bad adjustment on the pilot screws, too high float level. My bike was supposed to have 42.5 pilots and I found 45's. Pilot screws were supposed to be 1.5 turns out, mine were 4 turns out or more. After i changed the pilots and adjusted the screws and float levels it ran like a charm, no more stumble and no more rich misture, gas consumption went down considerably. I too took my bike to a "mechanic" for this problem also. All that did was lighten my wallet, A LOT. Anyway that is where I would start.