Hi guy/girls,

first post! my bike always had a rough patch around 4-5000rpm,this got worse and started running on one cylinder cutting in and out .I went away for 10 days when i returned the bike would not rev past around 2000-2500 rpm . i checked for a spark on both cylinders and its more yellow than white/blue. i have replaced the ht caps, tested the coils(ht)resistance which was within spec.put new plugs in and checked the jets and float height which was just 9mm and adjusted it there was some improvement but its now back to running on one cylinder and seems to switch sides! .i will also add the bike has always run rich and never needed the choke to start.also i blew gently down the carb air vent (top t piece)while turning the throttle and the bike revved like normal where normally would die just past 2000 rpm.help !is it fueling or electrics,a bad ground /earth?): many,many thanks.

Carb cleaning wouldn't hurt. It would at least eliminate dirty carbs as a factor. The air vent episode is telling. For the little bit of time it takes to clean the carbs it could make a big difference. Just a thought.

many thanks,I've cleaned the jets and air passages and float bowls as best i can and they look really clean(i had hoped to see crud clogging them!) ,but there was a oring that looked like maybe fuel (or something had leaked past just below the main jet.I think i may have a fuel and an electric problem...eeeek.BTW thanks for such a rapid reply!.

You replaced the ht caps, meaning the high tension plug caps I presume, but did you check the other end of the plug wires?  The plug wires screw into the coils and are then bonded in tight.  You can't turn the wires in the coil by grabbing then and twisting them hard if they are OK, if you can turn them they are not.  One of the common causes of a GS running on one cylinder.  If you checked for spark in the conventional manner that just proves the circuits are making and breaking to produce spark but doesn't prove they are still sparking in a running cylinder.

 Thanks the sparkplug leads are not very tight and can be turned  quite easily
so that's a job for tomorrow!. Any help is very appreciated,I miss riding the Gs badly and walking to work sucks.oh one point I did not mention is that the bike would  bog down and refuse  to rev when going round a tight left turn  from a stop.

Had a loose one myself on my 02 GS.  I cut a quarter inch or so off the end of the wire, put a big dab of dielectric grease on the end, and screwed it into the coil tight and it was good to go for another year and 10k miles or so.  Got a 6' length of plug wire and I replace the wire when it gets a bit short.

I guess a proper fix would be a new coil and wire assembly, they come bonded together properly but they are a bit pricey.  I've got another 5 years and about 50k more mikes out of mine so far checking it and fixing it when I do valve checks.

The wire burning out at the coil is only a significant problem when using nylon/carbon resistor wire as opposed to copper, correct?

Quote from: Badot on April 12, 2013, 07:32:31 PM
The wire burning out at the coil is only a significant problem when using nylon/carbon resistor wire as opposed to copper, correct?

I'm only referring to copper core oem wires here plus the replacement piece I bought for the one that was loose is the same copper core type.  I can't imagine putting a carbon core resister type wire on a GS.

The problem here is the plug wire coming loose in the coil, just a little loose but the vibes soon make for a bad connection there.  The spark then takes the path of least resistance to ground and misfiring occurs.

The coils and plug wires come as an assembly from Suzuki with the wires bonded tightly into the coils, if and when they come loose the proper fix would be a new bonded coil and wire assembly but they are a bit pricey.

Never had the problem and wasn't aware of it on my 97 first GS.  When I had a loose one on my 02 after 40-50k miles I walked over to the old 97 parked in the garage and grabbed and pulled both plug wires right out of the coils.  Guess I had parked it just in time.   

LMAO jack i did the same thing. and it was a decent fix i must admit cause it worked, and never let me down.

Many thanks gsjack ,fitted new coil wires today and made sure it was super tight!.also new plugs and she started first push of the button and on both cylinders !! and sounded way better ,still did not want to rev past idle so I cleaned around the pick-up coils and the bike revved properly! And continued  to run until I switched it off.test ride after work tommorow.you guys rock.