Just wanted to see if I could get some opinions or advice from the GS500 clan before I embark on a Saturday of troubleshooting. Here's the scenario:
I re-jetted my '94 GS w/ 125 mains and 40 pilots a couple months ago. Prior to the re-jet the bike ran well, other than it's cold-blooded mannerisms (long warm-up). After the re-jet, the bike would pop randomly during deceleration. I re-adjusted the mixture screws from 3 turns to 2.5 turns out in an effort to reduce the popping. Seems to have worked. Last week, I rode the bike to the local mountains nearby, and going up a slight grade in 6th, ~70 mph (6500 rpm), the bike is definitely holding back under 3/4 - wide open throttle. It seems to be lean.
I have a #4 washer under each needle. Bike is stock. I have been using paper air filters (HiFloFiltro-bikebandit) since I have owned it. Valves are adjusted and within specs. Tank is clean. Float height was checked using float height check trick located on the HOWTO pages-- no issues there. I can't remember when the plugs were last changed. I'm sure they have at least 4k miles on them.
Suggestions? I plan on pulling the plugs, but I have a feeling that they will be white and all of this will point back to lean. Is this all about the mixture screw? :dunno_white:
1st make sure there are no air leaks getting in. Spray the WD40 around the airboots/carb boots trick. And check the vacuum hose (the one between the petcock and the left carb).
Or, raise the float level, or add another washer under the needle.
If its just having problems in the mountains or all the time.. if it only happened in the mountains it could be the altitude leaning it out?? Just a thought.
Quote from: ixolas on March 08, 2007, 08:39:03 PM
.. if it only happened in the mountains it could be the altitude leaning it out?? Just a thought.
Thanks for the input. Possible that this might happen, though I took the same ride with stock jetting in the past and didn't get the hesitation. I'm going to check for air leaks as Scratch suggested, possible that there might be a lean condition from a not-so-obvious air leak.
Altitude doesn't lean things out, it richens them...less air at elevation, same amount of gas, rich.
oh ya.. had it backwards ;)
Had the day off today. Sprayed around the carbs with carb cleaner. Lo and behold, the engine picks up RPMs. Initially I thought it was the boots between carb and cylinder being a tad loose, so I loosen the clamps, double-check carbs are seated into the boots, and re-clamp. That didn't seem to make any difference, as when I sprayed carb cleaner again, RPMs would increase.
So I'm looking at the left carb and noticing the bare vacuum fitting. Could it be that I fitted the vacuum hose to the wrong carburetor? Sure enough, I spritz a little bit of cleaner on the fitting and the RPMs increase. I pulled the vacuum line off the right carb, and put it on the left carb. When I rejetted, I put the vacuum line on the wrong carb. The right carb has a fitting, it just isn't drilled.
So I put it all back together, 3 turns out on the mixture screw, and the bike is happy. No exhaust popping, either. I couldn't believe that I rode it around town for nearly a month with such a vacuum leak.
Thanks guys for your input! :cheers:
Lol, glad you found it!