Fast idle design question:

[BubbaZanetti]

anyone have any idea why bmw uses a fast idle lever that you manually have to hold open for maximum speed increase then will only hold the idle at a single point (which on my bike is about 250 RPM higher than "normal" idle)??? other bikes i ride with (Ducs and Triumphs mostly) have a fast idle switch that you can turn "up or down" from normal idle to about 2000 RPM. you set it and leave it then turn it off once you start going. to me this makes a LOT more sense, esp on cold mornings. on real cold days, my bike struggles a bit at the detent position on the fast idle for the first minute or so. if i could idle a bit higher (and have 2 free hands), it would be a good thing

[PUDGYPAINTGUY]

I find that it is a great indicator for a valve adj/TBI synching. If one cylinder goes out of synch then it stumbles to the point of having to hold it manually, or else it stalls. A great motivator to get it seen to quicker. :laugh

[breyfogle]

....anyone have any idea why bmw uses a fast idle lever that you manually have to hold open for maximum speed increase then will only hold the idle at a single point (which on my bike is about 250 RPM higher than "normal" idle)???

Your's might be a bit out of adjustment. The holding position (first detent) on my '94 RS produces a fast idle about 2000 to 2200 RPM which is actually too fast to be useful after about 30 seconds or so. I usually ride the first mile with the fast idle set below the first detent holding position. FWIW, I have the "normal" warm idle set at about 1100 RPM.

[RiverRat280]

Like he said...your cable is probally out of adjustment when you re-adjust it it'll be much higher then another 250rpm.

[ssls6]

anyone have any idea why bmw uses a fast idle lever that you manually have to hold open for maximum speed increase then will only hold the idle at a single point (which on my bike is about 250 RPM higher than "normal" idle)??? other bikes i ride with (Ducs and Triumphs mostly) have a fast idle switch that you can turn "up or down" from normal idle to about 2000 RPM. you set it and leave it then turn it off once you start going. to me this makes a LOT more sense, esp on cold mornings. on real cold days, my bike struggles a bit at the detent position on the fast idle for the first minute or so. if i could idle a bit higher (and have 2 free hands), it would be a good thing


If you have too much slack in the left/right throttle cables, you fast idle cam won't increase the idle much.

[JCBR1150R]

You didn't ask me directly, so please pardon my interuption.

If it is very cold (or wet now that I think about it), I might have to hold that fast idle lever at full stop but only until the cyclinders get warmed up a little (usually a few seconds) then I'll let it go to the half-way position. One morning I started the bike with the fast idle halfway but then had to go back into the house to get something, once inside the phone rang. When I was done with the call (approx 5 minutes) I went back outside and my exhaust was cherry red. I guess I narrowly escaped meltdown that time.

I haven't paid any attention to the rpm in either fast idle position....sry.

[PUDGYPAINTGUY]

You didn't ask me directly, so please pardon my interuption.

If it is very cold (or wet now that I think about it), I might have to hold that fast idle lever at full stop but only until the cyclinders get warmed up a little (usually a few seconds) then I'll let it go to the half-way position. One morning I started the bike with the fast idle halfway but then had to go back into the house to get something, once inside the phone rang. When I was done with the call (approx 5 minutes) I went back outside and my exhaust was cherry red. I guess I narrowly escaped meltdown that time.

I haven't paid any attention to the rpm in either fast idle position....sry.

This is quite normal on a Boxer motor for the header pipes to get cherry red when idling for a while with no air flow blowing across...very cool to look at but scary the first time you see it. This is just one of the many benefits of single wall header pipes along with the fun discolouration that they get too...hehehehe