Why won't my '82 GS650 start, and how do I fix it?

[Decker]

Hey guys. My beloved '82 GS650 has suddenly become very tough to start. I can grind the starter repeatedly, and it just won't catch. And when it does, it's after some 15 tries.

I have done the usual troubleshooting: gas in tank, cock open, plugs sparking, battery wet and charged, kill switch not killing. But this one just eludes me.

This started happening when I moved from Denver to Willits, about 1 month ago. The bike was driven into the back of the Budget truck, and had to be pushed out when we got to California. My CB900 shows exactly the same phenomenon: drove it up, drag it down, lucky if it starts.

Since it happens to them both, I suspect it's either the elevation change (5300ft to 1500ft) or something jostled during its time in the truck. Any thoughts on where I should continue my bug-hunting?

[TheCafeKid]

You're probably WAY too lean to start. Altitude has thinner air, therefore, an adjustment to the carburetors is required to lean them out, because thinner air will make the bike run richer. When you went back to closer to sealevel, the air is thicker, and now your bike is not getting enough fuel. Usually its a simple mixture adjustent, but sometimes the bike are rejetted to deal with the change in altitude. I would suggest finding out what your pilot adjustment screws are set at now, and getting back with us. To find out, see how many turns it takes to turn them all the way in to a light seat. If they are less then two full turns, youre probably going to find that turning them out two or two and a half turns each might cure your problem...if that doesnt do it you may have to pull the carbs down and clean/rejet them.

TCK

Oh, also, whens the last time you've adjusted the valves? Over time, at least in your GS, the valve clearances will become tighter, and therefore, the valves will remain partially open. This will exaccerbate your lean situation. Couple misadjusted valves with a lean mixture in the carbs, and there is little chance that bike is going to fire.....Let us know!

[skidMarkNZ]

Suddenly problem like that is directly related to the elevation, you will have to adjust the mixtures unfortunately.

[buddha]

I'm at about 1500ft in AZ with a GS650. My mixture screws are at 2.5 turns out now and it starts pretty well. However, I do have the jet kit & pods installed, but they didn't seem to make much difference for startability. 2.5 turns is definitely a good place to start.

[Dave8338]

Kid and Skid...enough said. TOO LEAN.

[TheCafeKid]

Kid and Skid...enough said. TOO LEAN.

I had started correcting you, but you corrected yourself...nuff said

[Dave8338]

Its not too rich...its now too lean.

When he was up at a mile above sea level, the carbs had to be adjusted LEANER to counteract the fact that the thinner air would richen them if left set "stock"

When he brought them back down to near sealevel, the settings havent yet been changed. Thicker air will LEAN the carbs even more, so now he needs to RICHEN them to counter act that...

You read too fast and I correct too slow... too LEAN...

[skidMarkNZ]

You read too fast and I correct too slow... too LEAN...

And i ride too fast and lean too much making you too slow.

Its fun talking in sort of riddles ish maybe

[Dave8338]

And i ride too fast and lean too much making you too slow.

Its fun talking in sort of riddles ish maybe

AHHH yes, but my L is faster straight than your G's are curvy...

[Decker]

mixture, sure, but how

I figured it was thinned out by the thicker air. How exactly to fix it, I wasn't sure.

* pilot adjustment screws
So the GS does have pilot screws? Okay; I saw mention of them on the CB900, but will look deeper about the GS's.

* pull the carbs down and clean/rejet them
True, true, always a good move. A last move and a pain in the neck and parts beyond, but a good move if it fires but acts funny under gas.

* last time you've adjusted the valves
Hm, never; the previous owner may have, but unknown. I do see that in the tune-up chapter of my Clymer. I don't exactly understand what those valves do, but I'll read up on it.

Thanks a lot for these three items; I only thought of one of them, and didn't know the GS had it. When the rain breaks on Friday, I'll have some steps to try, and I will get back to this thread with a status update either way.

[Decker]

A closely related question: rejetting

A closely related question...

I intend to make runs between Denver (5300ft) and the west coast (0 - 1500ft) during the summer. Given the fairly rapid altitude changes (3000 foot drop in 3 days) how should I prepare for mixture changes?

For example, would rejetting for either high or low be a mistake when I went to the other place? Should I carry a screwdriver and expect to stop once each direction to adjust screws?

[skidMarkNZ]

A closely related question...

I intend to make runs between Denver (5300ft) and the west coast (0 - 1500ft) during the summer. Given the fairly rapid altitude changes (3000 foot drop in 3 days) how should I prepare for mixture changes?

For example, would rejetting for either high or low be a mistake when I went to the other place? Should I carry a screwdriver and expect to stop once each direction to adjust screws?

ive never had any issues on highger mountain runs,

too rich should fuss it TOOOOO much, too lean is what makes as bike go "**** off"

[TheCafeKid]

A closely related question...

I intend to make runs between Denver (5300ft) and the west coast (0 - 1500ft) during the summer. Given the fairly rapid altitude changes (3000 foot drop in 3 days) how should I prepare for mixture changes?

For example, would rejetting for either high or low be a mistake when I went to the other place? Should I carry a screwdriver and expect to stop once each direction to adjust screws?

I would set it for the lower altitude and leave it if youre not planing on staying up high for a long period of time. In WV last spring, i ran up and down then mountains there for three days, going from roughly 1000 feet or less to 4000 feet. At the most extreme altitude, the bike would bog a little bit in high gear when climbing, but otherwise it being rich didnt seem to effect it. It would in long term, but since i was up and down all day in altitude, it didnt make sense to stop, adjust, and then continue. Simply run it at the best setting for the lower altitude. Running it LEAN is WAY WAY worse than running slightly rich.

[Dave8338]

The air screws are on the top of the carbs at the front of the throat, where the intake tubes (rubbers) attach to the carbs. They may, though I doubt it...still be covered by the factory caps. If so, these will need to be removed. Adjust them to the highest possible idle (for each carb and repeat about 1.75-2.5 turns out from lightly seated) untill you can get no rpms out of the adjustment and then reset the main idle screw (large round knob) in the center of the rack (bottom) back down to 1100+-

How many miles on your bike? Honestly, it really doesn't matter...if you don't know if the valves have been adjusted, you need to do them.

Hope this helps...

[Decker]

Hey guys. The first item to take care of, is reattaching my alternator cover after I dropped the bike the one time I got it running after moving. That's waiting on a new gasket, which is waiting on my paycheck... So it'll be up to 2 weeks until I have the thing back together to try this again. I do intend to perform all three steps and to post a status report.