Help.My bike just died. Diagnosis needed!

[Anonymous]

I am a newbie and could use some advice. I have a 82 GS650G which I don't ride very often, but which has been behaving fine - until today. I rode it 25 miles to work this afternoon without trouble, and while there, checked the oil level and put in a pint or so. (It was low, but not super low: just on the lower mark).

On the way home, the power seemed to vary. It started to speed up and slow down without my control and then on the freeway it stalled. I got it started once but the next time it refused to start. I had no tools so I pushed it off the freeway, parked it and walked home. The only clue I have is that it felt as though the two outer downpipes were not nearly as hot as the inner two. I am going to go back early tomorrow with some tools to have a look. Now I am not very mechanic and I know bugger all about bikes. What could this be? I will check for spark tomorrow (I can manage that) but where do I go from there? Might this be carburation? The carbs were professionally cleaned about 6 months ago so I thought they should be okay. I once had a similar problem caused by the airbox/carb connection leaking, but that affected all the cylinders not just two.

So any help would be appreciated and if there is anyone in West Los Angeles who feels like helping a fellow GS'ite, I will buy the drinks at breakfast!

Thanks all

Dan

[Anonymous]

I forgot to mention one perhaps important point in my last message. The first symptom of the problems -for about 4/5 miles on city streets before the stalling started - was that I noticed the idle seemed to have risen to about 2000rpm from its normal 1000rpm. Might this suggest some sort of air leak or maybe a problem with the airbox leaking again?

[SqDancerLynn1]

You need three things air, fuel and spark check them If you get stuck send me a PM maybe I can help I'm in Pomona

[Anonymous]

From what you have said, it sounds like an electrical problem. Try pulling off the small right side cover where your electronic ignition is and checking to make sure nothing has come loose. Also check your timing with a timing light. If you have spark the light will flash. You can check to see if you have spark this way without disconnecting anything.

Harrison

[Anonymous]

Well today I got a ride from a friend to go look at the bike. The plugs looked fine and had spark. It would not start at first but eventually I got it started. It got half way home and cut out again. It would not rev up at all. If I gave it more gas, it would cut out. The only thing that seemed to keep it going was setting the choke very high.

The problem is that whatever is happening is somewhat intermittent which makes diagnosis difficult. One thing is clear though - when it is malfunctioning, it is the outside two cylinders that are not working. This made me think it could not be a gas issue, but maybe I am wrong: Is there anywhere in the fuel delivery system from tank to carbs where it is divided in two, i.e. wherefuel is being delivered to only two cylinders?

I cleaned the coil connections on the left side which is the side that delivers power to the outside plugs but that seemed to make no difference. Anyway, I am stumped and *@%^$*@%^$*@%^$*@%^$ed off too. It is beautiful riding weather now and the bike seems fine this minute, but I dont want to get dumped by the side of the road again. Are there any more specific things I could do to track down the problem?

Dan

[earlfor]

Fuel blockages are not usually intermittent and neither are induction tube leaks. Electrically, the ignition is paired 1,4 and 2,3. It is your outside cylinders that are quitting (1-4) Probability is high that it is an ignition problem. I had the same problem with my 1150 when the ignition module died. 1-4 would run just fine, then die completely. Couldnt start it. It would backfire and miss badly when I could get it started, then in a couple of minutes, it would run normally. Ten minutes later, same thing again.
I had spark, but due to the ignition module crapping out, it was mis-timed so the bike missed and backfired when it did try to run.
Earl

Well today I got a ride from a friend to go look at the bike. The plugs looked fine and had spark. It would not start at first but eventually I got it started. It got half way home and cut out again. It would not rev up at all. If I gave it more gas, it would cut out. The only thing that seemed to keep it going was setting the choke very high.

The problem is that whatever is happening is somewhat intermittent which makes diagnosis difficult. One thing is clear though - when it is malfunctioning, it is the outside two cylinders that are not working. This made me think it could not be a gas issue, but maybe I am wrong: Is there anywhere in the fuel delivery system from tank to carbs where it is divided in two, i.e. wherefuel is being delivered to only two cylinders?

I cleaned the coil connections on the left side which is the side that delivers power to the outside plugs but that seemed to make no difference. Anyway, I am stumped and ####ed off too. It is beautiful riding weather now and the bike seems fine this minute, but I dont want to get dumped by the side of the road again. Are there any more specific things I could do to track down the problem?

Dan

[Anonymous]

I am far from being a coil expert gentleman but is there any possibility that one coil is bad and looses power when it gets hot? maybe a bad wire or something causing that coil to overheat and stop working? It seems to me if it were a fuel problem all the cylinders would be starved for fuel. Plus the fact that he says when the bike is cold it runs normally. Just my 2 cents here. :roll:

[Anonymous]

Thanks Michael and Earl,

I dont know exactly what an ignition module is but if you can tell me where it is and what it looks like, I will try to check it.

Dan

[earlfor]

Dan, there is a test proceedure outlined for each bike model in its factory service manual. I do not have the factory book for the 650G and different bikes use different ignition (control) modules, so the test values and terminal positions may be different. We need someone with the book for your model to post the test information.

Earl

Thanks Michael and Earl,

I dont know exactly what an ignition module is but if you can tell me where it is and what it looks like, I will try to check it.

Dan

[focus frenzy]

I have to disagree, it sounds just like he is running out of gas.
possibly a petcock problem, or a petcock screen blockage problem.
or it can be actually out of gas.
when the petcock can not flow enough gas to keep up with demand the outer carbs will run out first due to the one fuel line supplying the carbs from between two and three.
the idle raising points toward the fuel level in the bowls dropping, leaning the mixture out.

before messing with the ignition system take the fuel line loose from the carb end, and also pull the vacuum line for the petcock.
apply vacuum to the vacuum line with the petcock in the on position, and see how strong the fuel stream is, (use a approved container to catch the fuel coming from the fuel line!!!)
it should be a good strong stream, let it flow for a minute to make sure that the gas cap is venting correctly.

if you do not get a strong stream, try setting the petcock to the prime position and see if it flows better there.
I am pretty sure you have a fuel flow problem, your description sounds just like my bike when it is running out of gas.