Hello everyone, just finished cleaning and adjusting my carbs on my '89 and am wondering about clip position on the needles. I have cleaned everything perfectly, put all new gaskets and o-rings, new diaphragms, put the floats right in the middle of spec and sync'd the carbs when put back together. I put the c-clips in what I believe is factory position in the middle notch. Bike runs perfect in all but one throttle position and I'm getting excellent gas mileage. (58MPG) Where there is a slight issue is at highway cruise which after marking my throttle seems to be the transition point between idle circuit and needle mid range circuit. It seems to be running a little lean at that exact point. I did the choke test and it seems to run a little better with choke at that exact point. I also did the kill switch test and checked plugs. Plugs at that throttle position have light gray coating on them. Before posting this I also checked for vacuum or exhaust leaks and none could be found. So my question is, I've heard that gs500's are set up lean from factory and is this what I'm experiencing and how much of an effect would going down 1 notch on the needles have to cure this?
What indications do you have of lean running?
I think theory supports the idea that moving the needle as you suggest will indeed affect this behavior. Whether it is Overkill or not remains to be seen. I'd try setting the pilot a quarter turn richer and lowering the idle speed stop to ensure it is idling at 1200 rom when fully warmed up first. Fully warmed up meaning after 20 minutes riding on the road.
My plugs closer to white than brown after pulling in the clutch and hitting the kill switch at a 3/8 throttle steady 5k cruise so I suspect being on the lean side in needle territory. Idle is perfect at 3 turns out. The only reason I am questioning is because I can feel a slight hesitation when cruising. If I twist a little more I can get passed it.
Quote from: Blueoval78 on September 17, 2017, 07:26:23 PM
Idle is perfect at 3 turns out.
Pilot does a lot more than just idle.
And it's possible you have opened the throttle stop ("idle speed") enough to draw some fuel from the main jet in effort to get it to idle above 1200 rpm, in which case the pilot could be too lean.
Quote from: Blueoval78 on September 17, 2017, 07:26:23 PM
My plugs closer to white than brown after pulling in the clutch and hitting the kill switch at a 3/8 throttle steady 5k cruise so I suspect being on the lean side in needle territory. Idle is perfect at 3 turns out. The only reason I am questioning is because I can feel a slight hesitation when cruising. If I twist a little more I can get passed it.
OK, that does sound a little lean. I'd try another half-turn with the idle screws first. It's possible to make small corrections to other areas with the idle screws.
Ok thanks everyone, I will try the pilot screws. Regarding the needles, I have seen in other posts that the "multi clip position" needles are not the greatest; could I switch to "shim style" without changing the emulsion tube or are they a matched set?
Quote from: Blueoval78 on September 17, 2017, 07:26:23 PM
My plugs closer to white than brown after pulling in the clutch and hitting the kill switch at a 3/8 throttle steady 5k cruise
If you're really at 5K rpm and 3/8 throttle then you may not be in pilot (much). What size main jet do you have?
Anyway I'd try re-adjusting the pilot mixture first since you can do that without tearing down the carbs. Just 1/4 turn on each carb and see if the problem heals.
You can't make everything perfect so there's always a little compromise. You are going to wind up with the bike running rich at some rpm/throttle combinations and lean at others. This is not EFI. So you might have to live with it being a touch richer at idle than ideal in order to get it to not have this hesitation at the transition to main. Or you might go the other way and just bump up the main jet so it will get on main a little earlier. Or try the needle thing. Thing is if it's lean at this condition then it may be lean at WOT/9K as well, in which case a bigger main jet is in order, dropping the needle won't help that.
3/8th throttle is likely needle and float height. Lifting up needle would help. But before you do that, make sure float height is correct. You're not supposed to adjust the float height. Set it correct, and jet around it. 3/8 is beginning of needle and its influenced by pilot jet, air screw and float height, if 0-1/8th is good, then pilot jet is fine, if start up and idle is fine, then air screw is OK don't touch that. Modding those 2 to get 3/8th throttle right will mess up the idle and start up range.
You cant get it perfect, but you can get it to where its not lean, there is a huge range between lean, perfect and rich. Perfect - Rich is a comfortable zone for the bike and you.
Cool.
Buddha.
I figured float height was crucial after reading many posts on here so I made sure they are set right. I bought a float height gauge and set them to spec making sure not to push on the floats while taking measurement and then I did the clear hose test after putting it back together. They are both bang on. The bike starts and idles perfect. So if that is the case, should I drop the clip on spot on the needle (raising it)?