Bonneville America Forums Forums Technical Forums General Tech Weird carb ballancing...

Ok question. Borrowing a friend's carbtune, and I hook it all up, and it seems like my carbs are well in sinc while at rest. I blip the throttle and the right side goes up and down more and settle more quickly than the left. BUT they do settle out evenly to eachother. Any ideas? Maybe I'm not getting a good seal on the hoses?

Mine does the same Benny, but I honestly think that is normal. It did it both times I've synched my carbs.

oh, btw Benny, on mine it is also the right side that peaks higher...

Have you tried running the throttle up slowly? What happens then?

Well I just tried it on the other two tubes (it's built for 4 carbs.) seems to be less finicky. The reason I'm ballancing them, aside from the obvious, is that it seems to be rough under throttle. Usually I thought this was due to the carbs being out of sync with eachother. But maybe not? Any other ideas guys? Doesn't quite "chatter" under throttle load... but it does seems to vibrate more. I could just be super sensative to everything since all the mods, but I'd like to get an idea of it's normal.

Benny, what all mods have you done? Mine is a bit rougher since I've gutted the airbox, as well as the surge/stumble in midrange, that's why I'm going to try the TBS needles.

So far for the engine....
Freak, TBS needles, no shims, 160 mains, drilled out cavuum ports, screws 3.5 out, semi-gutted stock pipes, and irridium plugs. LONG STORY but I'm still waiting on Epcos. So I know the 160s are probably a bit on the rich side.
Good to know you are having similar problems. I just took her for a spin and it seems like it just doesn't like to be held steady. IT begs to be given throttle, ya know? Love to pull, doesn't like to be steady...

Mine does the same thing. Switch the hoses side to side to make sure the left slider in the Carbtune isn't hanging up slightly. I think you'll find the right side is still different....
Check how well they rise together if you slowly increase the throttle - the right will probably jump a bit but follow the left pretty closely.

I'd be interested in the answer to this as well. My bike runs well and I'm happy, but the right pipe still tends to discolor a bit, and the right pilot screw is almost a full turn out more than the left. What is it about the right cylinder on these engines?

Honestly, about the only difference I can see between the left and right cylinders, is cooling. The left cylinder is slightly less exposed to airflow, since the engine is offset to the right in the frame(which thrusts the right side out into the airflow more, while the left is partially blocked by the frame and front wheel), so maybe there are slight differences in air density (with the carb being potentially a few degrees cooler), don't know. That's all I've got now...

Perfectly norlam, as long as they settle to the same you're good to go, don't sweat it, they all do that.

Thanks for the reassurance guys. Took it out for a chilly ride tonight, and I seem to be getting a hesitation when I first get on the throttle. I cracked the fuel cap to see if that was it and it seemed to help but I think it's still there. I know this was discussed a loooong time ago, so refresh my memory if you can anyone. Think maybe it's an air screw issue? I still need to do a plug check... Just can't seem to stop riding once I start. I was gonna take a pic of my odometer when I ticked over 15K tonight, but I just kept going...

Ben,
have you pulled the little mystery gas filter yet and cleaned it out? That will make the bike run a bit spazzy. Especially at 15k, time to do the yank and squirt.
No, the gas filter! Not that, geez man. let go of that thing! You're gonna mess up your monitor.

If you still have the chrome covers on, under the left you probably also still have the black plastic piece that covers the left carb. Try using a dremel or something and trim the front off this to open the air flow to the left side. The right side doesn't have one over it.

Actually I cut the mounting tabs off the left side cover piece just so I could still mount the chrome covers, all open in there now:)

Pat I did clean it out this spring when I was re-jetting/freaking my bike. Maybe I'll take another look. Gonna take off the tank console and seat to wash/wax the tank, etc, so maybe I'll pull the tank just to check the vent tube, etc.

Benny,
I was just looking at the picture you posted and was wondering what that was in the hole from the plastic cover?

That's the wiring harness for my Gerbings glove liners