Rough idle when engine is hot

Marcus · Post by **Marcus** » Mon Aug 29, 2005 9:56 pm

Hey guys,

My 2004 '50R has around 4500 miles on it and something really odd has started to happen: when the bike has been ridden for an hour or more, it starts to idle roughly when I'm stopped at traffic lights. The revs fluctuate between 900 and 1100 rpms. This doesn't happen when the engine is cold.

I've been using Premium 93 octane gas and a service manager at a dealer recommended using an 89 octane fuel instead because it burns faster and leaves less deposits. He thought that I might have a carbon build up issue with the engine.

Any suggestions what could be causing the rough idle and are there any solutions? Thanks.

Marcus

Marcus · Post by **Marcus** » Tue Aug 30, 2005 9:38 pm

Ummm....anyone have an idea what could be wrong with my bike???

Marcus

Post by **NoRRmad** » Tue Aug 30, 2005 10:37 pm

Well, a couple of easy things to try... See if the lower octane fuel helps. Try pulling the Motronic fuse and resetting it (two full throttle pulls after the fuse is back, and ignition on, before starting.) Perhaps the throttle sensor is confused, and that would give it a zero-throttle calibration point. The procedure is in the manual.

My bike idles smoother when hot, and a little faster, but I assume that's due to warmer oil.

Post by **Dauntless** » Wed Aug 31, 2005 8:16 am

Mine sort of does the same thing. When it's really hot out it stumbles when idling and sometimes stalls when I try to pull away. I leave the high idle lever engaged to prevent stalling. I started using Amoco Ultimate and it seems to have improved.

Marcus · Post by **Marcus** » Wed Aug 31, 2005 11:12 am

NoRRmad, Dauntless,

Thanks guys.

Dauntless, what octane gas are you using? I've just put in a tankfull of 89 but I haven't been able to ride yet. I hope after a couple of tankfulls this problem should go away. May use some fuel system cleaner as well.

Marcus

Post by **Dauntless** » Wed Aug 31, 2005 1:19 pm

Marcus wrote:NoRRmad, Dauntless,

Thanks guys.

Dauntless, what octane gas are you using?
Marcus

I think Amoco Ultimate is 93 or 94 octane. Others on this board have also recommended putting Techron in the tank. It's available at Chevron stations or Wal-Mart.

saguaro777 · Post by **saguaro777** » Fri Sep 02, 2005 11:21 am

I ride in some of the hottest temps you'll find this side of the world. The Phoenix valley. I dont encounter any of those problems, maybe the tb's need to be synched. My buddy has an 04 r1150rt he had to re-synch his bike with less than 5k on it for the same type of issues, rough running and prone to stalling. That cleared up his bikes problem. My 02 r1150r had almost 19k on it before I decided to do something about my low idle, 900 rpms, and occasional backfire. I synched the tb's and she's purring like a kitty. I had it out yesterday in 108' temps. It was my first ride in almost a month due to some surgery I had. I put in 89 octane, normally I use 91. The bike ran really smooth and the ride felt so good.

Marcus · Post by **Marcus** » Sun Sep 04, 2005 7:41 pm

I was going through the forum today and noticed the post by chibbert about the bucking ssues he's facing with his bike when he hits the 145 mile mark. I never paid attention to the amount of gas in the tank vis-a-vis the trip meter but I'll be looking into that.

Plus I found another issue with the bike: at times, it's really hard to shift down into some gears, especially from 3rd to 2nd. I'll be posting another topic to see what other riders think.

Marcus

guzzi two · Post by **guzzi two** » Mon Sep 05, 2005 4:38 pm

Adjust the valves

Marcus · Post by **Marcus** » Tue Sep 06, 2005 6:49 am

Thanks for the responses. I plan to do a more detailed observation but I may have a more serious issue at hand with suspected spline issues (see other post). Once that's taken care of, I'll look into the rough idle.

I'm not so sure about BMW reliability now.

Marcus