Author Topic: Throttle/Carb problem with an 02 B6s (Read 3320 times)

mimestatic · « **on:** March 03, 2006, 02:31:13 AM »

Okay, so I've posed my problem to a buddy of mine who is going to MMI here in lovely Arizona, and he doesn't know what the problem is, so maybe someone on here can help me.

My bike runs perfectly and idles at the correct rpm's most of the time, but lately it starts to idle at about 2000 after running for about five minutes. It has less than 5000 miles on it, and like I said, it runs great, but I still don't want it idling that high. Adjusting the idle screw wouldn't do any good, because it idles fine on start up and "turning it down" would make it not start. It just had a carb clean and sync about 3K miles ago, and I haven't messed with it since, so I don't know where to start diagnosing. It always tends to stick at around the same rpm's so I really don't think it's a stuck throttle, but what else could make it do that?

Red01 · « **Reply #1 on:** March 03, 2006, 11:50:23 AM »

When you say it idles fine at startup, are you talking a cold motor? If so, it SHOULDN'T be idling fine cold, it should need some choke and be choked to run at ~2000 RPM until it warms up enough to idle smoothly, chokeless, at the specified RPM (~1200 for a B12, I'm guessing the B6 is similar).

mimestatic · « **Reply #2 on:** March 03, 2006, 12:22:06 PM »

Yeah, sorry, I should have phrased that differently. I use the choke to get it started, then take the choke off and let it warm up for a minute or so, and I'm off. The bike runs fine and idles at around 1200 when I'm stopped (at stoplights, etc.) for about five minutes, but past that it starts to idle at 2000.

Red01 · « **Reply #3 on:** March 03, 2006, 12:34:56 PM »

My 1200 needs choke longer than that. B6's are notoriously more cold blooded than the B12. I'm still leaning towards your idle setting - unless you have something going on that's causing you a rich condition, like a dirty air filter or some kind of airbox restriction.

rider123 · « **Reply #4 on:** March 03, 2006, 01:40:12 PM »

I concur with red01 the idle is going to climb as it gets up to operating temperature. I have had bikes that take 5 minutes to idle properly on their own and were perfectly jetted. You must adjust the idle when full hot which means a MINIMUM of 5 mins operating time. Nothing to worry about adjust it when its hot. When its warming up just give it a bit of pressure on the throttle to keep the idle up till it's warm. Also the stock jetting of the B6 and the B12 is quite lean so when it's cold it's going to run like crap untill it warms up.

Put it this way, do you ride more when it's hot or when cold? Always adjust your bike to run best when hot. These bike are carbuerated not Fuel injected so they need a little bit of babying when cold but considering it's only 5 mins of the total time you ride the bike(less in summer) who cares.

Adjust for 1200 rpm when hot.

mimestatic · « **Reply #5 on:** March 03, 2006, 01:49:25 PM »

Thanks gentlemen, I'll try that and let you know how it works out. It HAS been getting a lot hotter during the times that I ride lately. Maybe that'll do the trick.

mimestatic · « **Reply #6 on:** March 03, 2006, 03:20:36 PM »

I let my bike warm up for about 5 minutes as you suggested, then rode it until it got warm and after the rpm's started to climb, I adjusted the idle. It works great now and the rpm's don't fluctuate like they used to. Thanks a lot, guys.

Red01 · « **Reply #7 on:** March 03, 2006, 05:50:28 PM »

Glad it worked out for ya!

Now go tell your MMI friend what it took to fix it, so he can learn from this, too.