A miss at idle?

[tmacey45]

Hello, I need help with a miss at idle issue that just developed on a ride this morning... Yesterday, I installed an EBC "Street Racer Clutch" kit (kevlar friction plates and heavier than stock springs) and it was running awesome. Today, after exiting the highway, I came to a light at an intersection and my 82' GS1100GK started missing at idle. The bike ran fine on the highway going home, but at every light I had to keep the throttle bumped up to keep it running. I tried turning up the idle screw but that didn't help at all. When I got home, I took off the carbs ( which I just rebuilt a month ago with new everything... jets, float seats, float needles, etc...) and went through them. I blew out all the circuits and fuel channel first with carb cleaner then with compressed air. I didn't notice anything obvious but I did notice a small amount of "junk" trapped in the inline fuel filter. I could not find a "free flow" filter so I bought a "small engine" paper media filter made by Briggs & Stratton. After putting the carbs back on and getting the linkage, hoses and clamps back in place, I tested the new filter by turning the petcock on prime. I watched as the fuel ran through the filter and it seemed to flow freely for several seconds until the bowls were full. Then it stopped flowing and left a large air bubble in the top 1/4 of the filter. I started the engine and I could see fuel flowing through but the air bubble was still there, the level never changed. Also, I didn't notice any junk in the new filter, so I'm not sure where it came from since my tank was sealed last year. Anyway, I rode for about 10 miles and everything seemed to be okay until I was about 3 blocks from home. The miss came back at idle while stopped at a traffic light but this time when I throttled up, the engine stalled out completely (acting like there was no fuel) . It fired back up right away and ran fine until I got home. It started missing again at idle. I wouldn't think the new clutch would have anything to do with this problem, it would have to be the fuel system or maybe an electrical issue? Any ideas?

 

[Guest]

You answered your own question.
You have crap floating around and finding it's way into the carbs. Did you take out the pilot jets and make sure they were clear?

 

[tmacey45]

Yes, as I mentioned before... I went through the carbs after getting home. Took out all jets, needle seats and blew out all passages. Re-checked float height. There was nothing obvious as far as "junk" in the bowls or anything that came out on to the news paper. I only found junk in the inline filter (maybe 20-25 small pieces that kind of looked like black rubber). Since the fuel lines are new, I am guessing these pieces came from twisting on the new fuel lines. Sometimes the inner edge of a fuel line that has been freshly cut will break off little pieces like this while trying to push it on to a fitting. Also, I didn't see any junk in the new filter so I'm pretty sure what ever the junk was is gone now... I am going to go get a new free flow filter from the ATV dealer here in town today and try it again... Will let yas know if it solves this problem... Tony

 

[tmacey45]

Ok, nothing I have tried has worked...Bike is still missing badly at idle. I am going to start from scratch. Carbs are off the bike and completely disassembled. Does anyone know, what size pilot and air pilot jets to try with my GS1100GK? I am using the stock airbox but with K&N air filter and stock exhaust. In my rebuild kit, I have pilot jets 40 (stock) as well as 45. Also I have two different air pilot jets, 170 (stock) and 160. I was thinking about using the smaller air pilot and larger pilot jet combo since using the K&N air filter allows so much more air to pass through... Does anyone else agree, or disagree? Oh yeah, one more thing. I have a little bit of fuel pooling in the intake boots... Float height is at 22.4mm. If gas is pooling in the boots, should I raise or lower float height? Thanks for any help...Tony

 

[Guest]

Use the stock jets. Don't use the aftermarket jets.

 

[tmacey45]

Wow, what a kicker...Problem has been solved...Turned out it wasn't a carb problem at all. Plug cap on #2 cylinder popped right off in my hand... First 1/4" at tip of wire was so soft (probably from high heat) it felt like a sponge and had NO conductor. After trimming off the 1/4" of insulation to were I could see the shine of copper I screwed the boot back on . The miss is gone and the wind is back in my face... Not sure why I could only notice the miss at idle, but just happy it's fixed... Good thing is I shouldn't have to worry about the carbs for a while!!! Thanks chef1366 for all your input. Glad I didn't change the jets or I'd still be trying to fix something that wasn't broken.:clap: