QuestionI've come to refer to it as her "Parlor Trick." My 2000 model Yamaha XVS 1100 Classic has a quirk in that, when she's warmed up, and either in neutral or has the clutch pulled in, and is in motion, will idle up. If I'm simply in a parking lot walking her back into a parking spot, if she's still running the engine idles through the roof. It is the strangest thing. I will simply walk the bike holding nothing but the left handle bar, in neutral, and she screams and yells. As soon as I stop rolling, she calms down. In traffic, coasting to a light, same thing. When she's moving, RPM's are high. As soon as I stop moving, the RPM's return to a more sane and tolerable level. And depending on how warmed up she is, the RPM's may reach max, engine screaming. I've had her carbs tuned and sync'ed. I've had her timed and had her rings replaced. Compression is good as well. I am out of ideas. I would appreciate any suggestions. Thank you for allowing me some of what I know is your valuable time.
Answer
xvs1100_carbs
Hello Kenton,
Three reasons can lead to the problem you describe.
Air leak, lean idle mixture, clogged pilot jets. Let's take a look at them one by one.
Air leak.
The easiest way to spot, is by spraying with a spray-can (carburettor cleaner, contact cleaner, WD40) at the carburettor manifold-cylinderhead mating point, while the engine runs in idle.
If the RPM fluctuate while spraying, there is an air leak there.
Remove carbs and manifold(s) and replace gaskets.
Lean idle mixture and clogged pilot jets.
With the engine warmed-up and running at the lowest idle possible, slowly turn out (counter-clockwise) the fuel mixture screws (#14 in picture) one at a time, in half a turn steps. The idle should rise.
After each step, readjust idle speed. Repeat action until no rise in idle is noted.
You should stop turning out exactly were the highest idle is obtained.
From this point, turn the screws in (clockwise) slowly until seated, counting the number of turns. DO NOT TIGHTEN, just slightly seated.
If you count more than four turns, the pilot jets are probably partially clogged, and need to be measured/cleaned.
If by any chance the above have little to no effect, remove the carbs, clean them thoroughly and check if the choke plugs (#11) close properly and the diaphragm (#12) isn't punctured.
Don't hesitate to get back to me if something isn't comprehensive, or you need more help.
Best Regards,
Lazaros.
P.S.: I take for granted that the valve clearance is properly adjusted!
