The ol' GS was running fantastic, went to start her up Sunday and she was running a little rough. Rode anyhow and had a good ride, but she feels like she's got a miss, especially at low rpm, and idle is real rough.

At first I suspected bad gas because the bike was running fine when I put it away and the only change was I filled it up with my gas can in the garage. My wife has been known to leave the gas can out in the rain after she fills the mower. I thought the gas was fresh....but I could have been mistaken.

But now I've ridden through a tank of gas and filled it up with high test and run half through that and nothing has changed. I was listening to the bike and it seemed like it was running on one cylinder. While it's running I can pull the wire off the left plug and nothing changes in idle speed or anything - but when I go to plug it back in the idle picks up and smooths out for a second - then goes rough again. If I pull the wire on the right plug with the left plugged in, the bike dies. It also will start with the left plug off, but not with the right. So I've got it narrowed to the left bank. Both plugs are light brown and similar in color - neither looks too lean or rich.

I have a parts bike, so I borrowed a coil and swapped the left coil. No change. Also checked both banks for spark and both are getting spark.

I'm going to try to get my hands on a compression tester this weekend and check compression. Anyone know what a healthy compression is? If compression is good I'll start looking to carbs, but I'm a bit baffled as to what could have changed in the 2 weeks the bike sat in the garage between rides that would have so drastically affected how it runs.

Any ideas? I'm hoping someone will come up with something simple that I've missed!! Thanks.

Sounds like an intermitant spark on the left side. Check the wires going to the ignitor for a corroded or bad connection. It may look like a good spark but it may not be consistant.

Thanks man. You mean the two coil wires? They looked fine when I swapped the coil out - or do you mean the cdi box? Or am I completely missing you?!

Quote from: octaneI'm going to try to get my hands on a compression tester this weekend and check compression. Anyone know what a healthy compression is?....

Zuki manual says compression pressure specifications are:
Standard - 142 to 199 psi; 1000 to 1400 kPa; 10 to 14 kg/cm^2
Limit (low limit?) - 114 psi; 800 kPa; 8 kg/cm^2
Difference - 28 psi; 200 kPa; 2 kg/cm^2

Zuki manual says to have engine warmed up prior to testing.
Zuki manual says to pull plugs, insert compression testor adaptor into plug hole and turn engine over with starter while keeping throttle at maximum.
Zuki manual says to note maximum gauge reading.
Zuki manual says to do same on other cylinder.

Zuki manual says to overhaul the engine if compression of one cylinder is below the 114 psi limit, OR if the difference of the two cylinders is greater than 28 psi, OR if both compression pressures are below 142 psi even if greater than 114.

That is all.  

Thanks....hopefully she'll check out.

Quote from: octaneThanks man. You mean the two coil wires? They looked fine when I swapped the coil out - or do you mean the cdi box? Or am I completely missing you?!

I am referring to the small wires in the wire harness.

The same thing happened to me. I unplugged all the connections in the harness, cleaned them and applied electrical grease. Fired right up.

Cool, thanks man. I'll check it out this weekend.

First off, check your spark, either take the plug out and connect it to the wire, take a bare wire and ground out the threads hit the starter and check if you see spark, or buy  a spark tester.

i would also check the carb.

Easy ... Auxilliary ground ...
Cool.
Srinath.

The White Owl started doing the same exact thing, same cylinder. What I found is that when I apply choke, the left side carb is applying way too much fuel for a cold start...right side is fine. If I start the thing by applying a small amount of choke until it starts building heat in the combustion chamber and then give more choke, it runs fine. I don't have the carbs off so I don't know how to adjust this from side to side, but at any rate, that's what has been causing the problems with my Baby G. I just threw this in since it is exactly what was happening to me.

Try holding the plug wire just far enough away from the plug to keep it firing and see if that makes a difference. Wider gaps cause an increase in peak coil voltage so you may just try opening the gap on the plug to see if that makes a difference. I know it doesn't cure the problem but at least it gives you another trouble-shooting tool. Love the cantankerous Baby GS, Poland (flat steam-rolled by Hitler in WWII), and this forum.

C........

Quote from: gazingwaFirst off, check your spark, either take the plug out and connect it to the wire, take a bare wire and ground out the threads hit the starter and check if you see spark, or buy  a spark tester.

i would also check the carb.

Already did this and by eye spark looks about even.


Srinath,
I don't believe I have an auxilary ground, and I don't believe there has ever been one on this bike!! And it never gave me this problem before.


Cernunos,
You know what - I was messing with the handlebar controls when I put the new headlight on...I wonder if I bound the choke cable somehow. It is feeling a little tighter than usual...hhhmmm...

Thanks guys...hopefully she'll be running smooth again by the weekend!

octane, i'm having a similar problem, left cyl is dead and has spark. i checked my choke cable, seems fine.

my idle hangs when i can ret it revved, but i can't find any air leaks.

now this is weird.

i put my palm over the left carb intake, i feel suction but bike keeps running. i put my hand over right intake, more suction, and stalls immediatly.

i'm stumped.

Church6360, I had similar symptoms a couple years ago.  Running on one cylinder, had spark on both, etc.  In my case it turned out to be a bad connection to one of the pulse generator coils.

I hate to send you to a post that will send you to another thread (which walks someone else through their starting problem) but I'm going to anyway.  :mrgreen:

Start HERE

What I'm after are the electrical readings outlined in the "chart" towards the bottom of the 2nd page of the long thread.

thanks kerry i need all the help i can get!
i'll check out that thread.

had that issue when puting the stock needles in my carbs this weak, one of the pilot jets caught a small chunk of something and it didnt like it.

Quote from: dgyverThe same thing happened to me. I unplugged all the connections in the harness, cleaned them and applied electrical grease. Fired right up.

where can i get some of this electrical grease