float height

[mystahagy]

Hi all,
After a valve adjustment, new exhaust gaskets (huge difference), cleaning and adjusting the carbs, it's back together and running. There was something I noticed on my float height, all were around 3mm or so ABOVE the recommended spec. I figured this was to compensate for the full exhaust system and it being rejetted, but it still seemed waaay out of line. I compromised and set them all to 1mm above spec.
During my test ride the bike idled nice and smooth, but under light throttle it stumbled a little, and under heavy throttle at even as low as 2k or 3k rpm, it cleared it's throat and shot like a jackrabbit. Before I had no fuel related problems, my bike was just real noisy which was taken care by other things, so I'll probably put them back to that previous setting. I know I shouldn't have messed with them if it was fine. It just seemed so far that it couldn't be good.
My question is, is it unheard of to run so radically out of spec? One reason may be is that the engine was made to a 750 by the previous owner, and it still runs on 600 carbs. Suggestions?

[mystahagy]

Any ideas on this, I'm not sure if it would be better to raise the floats back up to where they were, or to richen the mixture screw. Really I'd be more likely to raise the floats, if I start messing with the mixture I'm bound to mess something up. Also, another thing to note, at that previous setting before I did all this work, the plugs showed normal wear, no fouling.
Dennis

[md86]

Sounds to me like you should undo what you done did .

http://66.47.68.116/tech/carbtune,CV,high_rpm_engines.html

What you describe sounds consistent with the info on this site .

[mystahagy]

Hey md,
Yeah I was studying that site and leaned out my A/F mixture to 2 turns out, while leaving the floats at 1mm above spec. It would stumble at exactly 3k rpm. According to that site, if it stumbles there at full throttle, you need to adjust the floats. As opposed to that, if it stumbles on light throttle, you need to adjust your A/F mixture. It smoothed out quite a bit, but I'm still clueless how it previously ran so well with those settings so far out. The floats were like 3 or 4 mm richer than spec, and I think the mix screw was somewhere around 3 or 3 1/2 turns out. Ya think I should try to find that combination again, or is it just a recipe for extra fuel consumption. It has a jet kit and my engine was tricked out by the previous owner, should the settings be closer to stock or more radical. It would be more clean cut if everything was stock, but no.

[Ex10DidKatana600]

It all depends on what exactly was done to the engine, exhaust, tune state of engine, etc. A good starting point is stock float hieght, adjust your mixture screws to 3 turns out and make sure the needle clips are in the middle grooves.
If the engine is now a 750, the 600 carbs are definately too small, probably the reason they went 3mm over spec on the floats, to richen it up. Check ebay, get a set of 750 carbs and you should run ok.

[stevnmd]

Sounds to me that you're too rich in the midrange. That means you need to raise the clip position on your needles a notch.

Set your float height to 15mm IIRC.

[mystahagy]

Steve,
On my '95 600 carbs it doesn't have clip notches for the needle, just a washer.
Also, I made those adjustments to the A/F mixture last night that I mentioned, and it really cleaned it up at the 3k mark. I still feel like it's not perfect right there though. About your recommendations with the needle, is that after I made the A/F adjustments and cleaned it up, or before when I was initially having the problem after bringing the floats from 3mm over to 1mm over, which led to me posing the topic.
Also one thing to note, I haven't synchronized the carbs yet, so I'm gonna grab a big fan from up here at work so I can sync the carbs at home, maybe that'll help. Previously before all this the carbs were synchronized, but that was with almost every carb adjusted differently. The float heights and mixtures were nearly all different, I have no idea how it ran that good.

[stevnmd]

Ahh, carb sync should DEFINITELY help. It's a VERY important thing to do EACH time you change anything on your carbs.