Bonneville America Forums Forums Technical Forums Performance Mods Rough idle

Came back from a ride yesterday and noticed the TBA had a bit of a rough idle. Thought it might have been bad fuel, but my husband filled his bike up with the same nozzle, same grade. To day he checked one of the plugs but said it looked good. I did leave the choke out just a fraction on the ride. Also, the bike sometimes dies at stop lights, but not often, maybe a couple of times on long rides. Could it still be the other plug, or dirty carbs, or what? Just need some ideas to check before we need to take it to the dealer. Might not get the bike back for 2-3 weeks if we have to take it there. The bike currently has 5800 miles on it. Thanks for the help.

AmyLee

Could be a vacuum leak. Check your caps on the carbs or better yet, just replace them.

Check the rubber plugs, like Phil says. Drain the carb bowls and check for water or debris..
Synch your carbs if you have the tooling and set your idle to 1100-1200 rpm.

If that doesn't fix it you have a fuel flow problem. Clogged petcock screen or clogged "secret" filter in the fuel lines.

Also be sure the breather hose has not become pinched or plugged. Test this by removing the gas cap when it dies, if it goes "Whoosh" you are not getting correct air into the tank as needed. If you took the gas tank off recently you may have pinched it under the tank, or check the little valve thingy on the vent hose at the rear of the carbs clipped onto the frame. You should be able to blow through the vent hose easily, if not it's plugged.

Hi Amylee,

Check your air cleaner too. Stock air filter changed every 8 thousand miles. Since you have 5800 miles, you might want to check it, especially if you ride in dusty areas. Hold it up to the sun and you should see some light pass through it. The inside 'fanfolds' will be translucent orange. A dirty filter will pass sunlight through the filter and the 'fan folds' will not be transparent. You can blow it out, from the inside out. And you can tap it to help release some of the dirt. That secret filter. You can inspect/clean this without pulling carbs. Is your idle problem only at idle or is it when you are taking off from idle too?

Hi AmyLee,
I have had the same problem. Also after a ride involving refuel and inadvertently leaving the choke out for a while. At first I thought I had gotten a hose full of regular gas from the single hose unit, causing too low octane. I filled it back up with top grade and rode a while. Still idled rough. I checked the plugs - they were gorgeous. I changed them anyway and it ran fine. I had a friend look at the plugs. He told me no matter how pretty they were, they could have an unseen failure. Maybe it was a coincidence, but plugs are cheap. Please do check for leaks and synchronize your carbs. Another case of rough idle was fixed by sync'ing the carbs. Be sure to follow Dinqua's advice by switching the hoses to carb tuner and double checking.
Ride Safe & Be Blessed,
Dennis

Hi all,
Thanks for the advice. We check the other plug, but it looked ok. We drained the carbs and there was a little bit of sediment that came out of each, but not much. We blew out the air filter, it had a few bugs in it. How they get down in there I don't know. We did a short ride tonight and it idled better. Bob took out the snorkel, so the bike had a bit more pep. I also have all of the original AI junk install. We haven't had it removed and everything capped yet. We will try and get that done asap. Bob's bike had that done before he rode it home from the dealer. We will get a new filter and plugs too. We are going on a nice ride Saturday, so that will test our quick fixes. Will let you know how it runs after the changes.

Thanks again,
AmyLee

Hey Amy, if you guys can remove the seat and filter and tank, doing the AI removal yourself should be a snap! Go for it:) I'm sure someone else suggested it, but if you found some gunk in the carbs, it's probably worth inspecting and cleaning the "T filter" in the fuel line everyone talks about. Ride safe!