81 r100 idle

[bryan665]

after riding 15 or 20 minutes the idle runs about 2k she starts up good and idles 1k and does not climb untill i take her out! checked cables at stops they are on them,chokes are open,valves loose,any ideas?

[nealart]

Maybe your idle is set for a cold engine?

Idle should be set at operating temp.

[dduelin]

You have to get the engine good and hot before setting the idle speed - like a 15-20 minute ride. That's all I know.

[AnnapolisAirhead]

after riding 15 or 20 minutes the idle runs about 2k she starts up good and idles 1k and does not climb untill i take her out! checked cables at stops they are on them,chokes are open,valves loose,any ideas?

I have an '83 R100 and had the same problem. I set the idle with a warmed up engine at a couple tech days with those more smarter than I, but still it climbed (even on the way home). Completely rebuilt carbs, new diaphrams, needles, atomizer, floats, gaskets, fuel line, filters, etc. Adjusted the throttle barrels with about 2mm slack in them.

I also got a slight popping upon normal deceleration. Then I read a post (can't recall where) to warm the engine up, then back the mixture screw out about 1/8 turn, on each side. That seems to have fixed both the idle climb (for the most part) and the popping. My idle still climbs but only slightly to about 1400, might be that I need to finely tune the cables more.

BTW, one other thing I noticed was that the throttle cable splitter barrel wasn't secured. I used a ziptie to hold it in place, that might have something to do with it.

I set my idle at 1050-1100...any lower than 900 and the gen light starts to flicker. I've read and been warned about not setting the idle too low (can't pump as much oil, etc.). The older airheads are capable of idling at really low RPMs (like 500 or 600), but that's due to a heavier flywheel. I'm not 100% sure, but I think that newer bikes need a higher RPM due to a lightened flywheel (amongst other reasons, I'm sure).

Hope this helps.

[PineGreen]

Many years ago I had the same problem. I messed with different things for a year. I took it to a guy who had a bike shop and was familiar with beemers. He first pulled the plug wire on one side disabling that cylinder and the thing still idled high. Then he pulled the wire on the other side and the rpms setteled down. He adjusted the idle screw on the side he first disconnected till it slowed down. Problem solved. The bike ran fine for many years

[88bmwJeff]

Have you checked the springs on the mechanical advance? If you have a been can, then they are in the can. It's possible that the springs are worn or the pivot points need attention (cleaning and grease). You should also check with a timing light when the bike reaches full advance. I can't remember off hand (I have it written down at home), but I think if you're at full advance under 3,000 RPM, then your springs are too weak.

[bryan665]

thanks for the suggestions, it just started doing this very recently,ill find out if one side is running the idle up or if its both!

[bryan665]

it seems that 1 carb is making the idle climb,its not the cables and it only does it when ive been riding,if i stop and shut her down for a few minutes she idles right untill i take off again!what in the carb could be doing that?

[AnnapolisAirhead]

it seems that 1 carb is making the idle climb,its not the cables and it only does it when ive been riding,if i stop and shut her down for a few minutes she idles right untill i take off again!what in the carb could be doing that?

Hmm, after the bike is warmed up and still running, you might want to spray carb cleaner on the carb top, the choke and where the carb connects to the intake/head. If the idle increases, you have a leak there. If the idle remains the same whether you spray carb cleaner or not, then that's not the problem. You might have a sticky throttle cable (they should NOT be lubricated), just get a new one. They have some sort of a teflon sheath.

The carb cleaner will evaporate.

Have you verified that the choke levers (on the carb) are pressed down in the off position. Those can stick on one side or sometimes both.