Erratic Idle

[Anonymous]

I have a 1980 GS850, when I set my Idle wheel so it idles at approx 1200 rpms, it will Idle fine, then when I go riding it will be fine for a while, then all of a sudden when I shift gears the rpms will hang up while I shifting. Sometimes it will do this and other times it will not. Sometimes it will be idleing where I want it at a dead stop, like at a stop sign, then climb up to 3-4000 rpm by itself without touching the throttle? If I turn the idle wheel down to 800-900 rpms, it doesn't seem to do it . But that seems a little slow for idle like it will amost die, if not good and hot! I have ran a couple of bottles of carb cleaner through it. The throttle doesn't seem to be binding! I just bought the bike three weeks ago. It had been sitting at a dealership for a year. Other than that the bike runs great! and performs well! Any suggestions on what may be causing this? Please replly!

[WifeofDink]

Have you checked the adjustment and condition of your throttle cable, it may be hanging up somewhere or need replacing. The other possibility is that the carbs need further cleaning with particular attention to the idle jets

[Jay B]

Idle

Jeans points are good. Also you might want to check for air leaks. The book says that the 80 850 should idle between 900 and 1150 rpm. If you bike has set around for a long time, even inside the showroom of the dealer it could be gummed up somewhere. Take it somewhere you can wash it and spray the outside of the carbs with carb cleaner being careful not to get it on anything rubber or your paint. Let it sit for a minute or two and then hose it off. Clean and re lube the throttle cable or replace it.

[Anonymous]

Erratic idle

I had a very similar problem with my 78 GS750. After you have eliminated the obvious mechanical checks (sticking cable etc), then pay attention to the carbs. In my experiance the only way to completely clean your carbs is to strip them down then have them cleaned in a sonic cleaning tank. Its fantastic. The carb cleaners in a spray can just will not get into all the hard to reach places, no matter how hard you try. Then make sure your carbs are set right. If your mixture is too weak, then the revs will hang after revving. This was the problem with mine.

What colour are the plugs when idling, and what colour are they after a good ride. They should be a tan colour, this gives a good instant indication of mixture.

Hope this is of use.

[Anonymous]

Mine did the same thing until I changed the intake boots. The ones that were on the bike "appeared" to be in good shape, but I found out that they were slightly deteriorated and had shrunk some. This shrinking allowed air to be sucked in at various rates (depending upon the heat of the day, the vibration of different road conditions, ect.). So, instead of pulling air through the air filter, air was coming in around the boot(s) at the air box. Like I said before, the amount of air varied. So my idle would never sit still and I could never dial it in. Drove me crazy. Bikebandit has these boots for around 12 bucks. 1/2 the price of retail at the local shop.