Air mixture screw adjustment while on bike?

[plewis51]

So i have done the rejet and pulled the brass plugs off the air mixture screw locations. I adjusted them 2.5 out and im running Yoshi slip on and lunchbox. Im having blipping and throttle issues at 5500-7500. I have 1 washer on the needle below the stopper. I was planning on trying to adjust the air mixture first but can it be done while everything is still attached to the bike? Maybe i should add another washer. But woukd i still need to adjust the air mixture?

[Big Rich]

I don't know about doing it while the carbs are mounted (I don't own a 500), but the mixture screws can be messed with all the time. Since they affect the mixture throughout the entire rpm range (more so at low rpm's) they are made to be adjusted for changes in temperature,  elevation, etc.

[The Buddha]

Diagnosis first - what is blipping and issues @ 5500 - 7500 and in either case unless you're revving it in neutral to 7500 it may be a needle/main jet problem more than air screw.
So how is the idle - you set it say to 1500, does it drop to 1000 and stall when cold, or does it shoot up to 2500 when hot - that is air screw ... I'd say dont touch that just yet. Post all the details - such as filter, pipe, and jets ...
Cool.
Buddha.

[plewis51]

FILTER = K&N Lunchbox
PIPE = Yoshimura Slip On
JETS =  20/65/147.5
NEEDLE = 1 washer under stopper

So it starts nicely and everything warm up within a few minutes and the GS is idling at 1200-1400. Great! I put it in gear and hold the clutch can rev it and the rpms fall back into idle position. Great! I start on my journey and feel the surge as I 1/4 throttle smoothly increasing speed. Great! I can flip into 2nd on the city street when i hit 5500rpm and it nicely gurggles out the exhaust and rides nicely. Great!

So i take it to the on ramp for the highway. On my approach starting in 1st gear i turn the throttle more open 1/2 or more and feel the GS surge. I went up to 9K and shifted, holding the throttle at about 3/4 now. The RPMs drop to about 7500 and it shoots up to about 9500, time to shift. Same thing with 3rd, throttle at 3/4 but felt the rpms back off before hitting 8000, drop to about 7800, then shoots to just over 9000. Now in 4th at about 70-75mph. Trying to hit 80. So I keep the throttle at about 3/4 and the GS rpms shoot to just over 8000, lots of dropping/surging going on and the rpm gauge needle is bobbing violently between 7500-8500 rpms, the GS has a sputtering feel and then BLANK..... The rpms cant make it over 8000 and the GS has a problem keeping speeds at 75 with the throttle still open near 3/4. It felt like the rpms start dropping so i let off the throttle but realize that applying throttle again is not working bike is sputtering to gain momentum.

I pull off the highway and ride around at lower gears 1,2,3 in town. It feels like the rpms are now moving into the 7000 range very quicky but my acceleration is really slow now. I was thinking of trying another washer on the needle. WHAT ARE YOUR THOUGHTS?

[Big Rich]

If Buddha says jets, listen to him. But it sounds like you're lean at the top end. Petcock on prime? Check any fuel filters you may have along with the vacuum in the tank and the carbs.

[mitch.lax]

Hey plewis51.

Did you ever get the issue sorted. I've got the same issue on my bike at the moment.

Cheers.
Mitch