2000 R1100RT - Missing at 3,700-3,900RPM

[zbassman]

Hi,

 

New here. Just bought a used 2000 R1100RT. Its got 55,000 miles on it and seems like it was well cared for. I've only had it a week and have put about 400 miles on it so far. I've noticed one little problem with the bike.

 

Periodically if I'm cruising along with the bike turning about 3,700 - 3,900 RPM if I start to roll on some throttle the engine sort of misses, it hiccups. Then it catches and continues to accelerate. This happens in 3rd or 4th gear. I haven't noticed it in 2nd, but I tend to accelerate harder from 2nd to 3rd.

 

My inclination is to think this is a carb issue, but I'm not really very mechanically knowledgable and this is my first BMW.

 

Any help greatly appreciated.

 

-Z

[Ken H.]

Well ignoring the fact for a second that they don't have carbs, it has throttle bodies with fuel injection, tell us more about how the miss feels. Is it a hesitation such as a momentary fuel starvation, or is it a very sharp 'hit' sort of a miss that could be ignition? How strong of a roll on are you talking about? Suddenly whacking it full open, or just a rather normal roll on of some additional power? Can you reproduce it at any other RPM?

[T__]

Hi,

 

New here. Just bought a used 2000 R1100RT. Its got 55,000 miles on it and seems like it was well cared for. I've only had it a week and have put about 400 miles on it so far. I've noticed one little problem with the bike.

 

Periodically if I'm cruising along with the bike turning about 3,700 - 3,900 RPM if I start to roll on some throttle the engine sort of misses, it hiccups. Then it catches and continues to accelerate. This happens in 3rd or 4th gear. I haven't noticed it in 2nd, but I tend to accelerate harder from 2nd to 3rd.

 

My inclination is to think this is a carb issue, but I'm not really very mechanically knowledgable and this is my first BMW.

 

Any help greatly appreciated.

 

-Z

 

Z, if you are not very mechanically inclined then most of what we suggest here will be a chore for you..

 

An engine miss in the RPM ranges you suggested could be about anything as both fuel & spark problems feel about the same at that high of an RPM..

 

I would suggest you start with the easy things like new spark plugs properly gapped. & checking the air filter for being oil soaked or partially plugged off…

 

Look closely at the spark plugs wires for touching the throttle body cams at your RPM/throttle position problem range (especially the R/H plug wire being worn at the TBI throttle cam area).. I have seen a few worn in that area from rubbing on the throttle cable cam on the early oil heads..

 

As you become more familiar with working on your BMW you might do a hot compression test & a good valve lash adjustment (look in the archives here for some good procedures on those)..

 

With your given problem RPM range & engine load parameters your problem could be about anything from low fuel pressure,, to weak or erratic spark,, to poor fuel (or water in fuel),, to a valve problem,, to bad spark plugs, to ????.. About all you can do is work through all the possibilities starting with the easy & the obvious..

 

Twisty

[zbassman]

LOL, no carbs. Told ya I don't know much.

 

Its a gradual roll on of the throttle, usually when I'm coming in to a curve as I lean the bike over I gently roll on the throttle and the engine hiccups like it was momentarily starved for fuel.

 

I guess it could just as easily be a problem with spark. Supposedly the dealer put in new plugs before I picked up the bike.

 

It doesn't happen every time but when it does its usually around that 3,700-3,900 RPM range. Once it gets over 4k it doesn't seem to be a problem.

 

The bike starts fine, idles good though maybe a little low. I took a 200 mile trip Sunday and aside from this little problem it ran great. Cruised at speeds ranging from 60-90MPH and at a constant speed it ran great. It just does this little hiccup when gently accelerating out of that RPM range.

 

I hate taking it to a mechanic because I don't want to be without two-wheels for that long.

 

If it looked like it was something "easy" I might try to work on it myself. I got a repair manual for it. But I've only had the bike a week and haven't even cracked the manual, much less tried anything like taking the gas tank off.

 

But I'll probably end up having to take it to a mechanic and I just want to get an idea of what the problem might be so that I'm less likely to get someone telling me a need a new "fallangy" at $1,200.

[Edgar]

It could be something as simple as your throttle bodies are out of sync. If the throttle cable length is different (slightly) for each throttle body it can cause different air pressure from each cylinder and an uneven engine response. The sync is straight forward, but you’ll need some additional tools. One test to tell if the TB’s are out of sync is to rev the engine from idle to 3,000 RPM or when downshifting blip the throttle from 4,000 to 5,000 RPM. If the engine stumbles then, it's one sign of an out of sync throttle body. It could be a number of other things but until you know that the valves are adjusted and a throttle bodies are in sync, you’re kind of going around in circles.

[1fastjunebug]

Start, as others have suggested, with a neurotic valve adjustment, a more neurotic TB sync., clean oil, clean air filter and new spark plugs. After this is done and the engine is up to operating temp. try a little test. As the bike is sitting on the center stand, try reving the engine up and try holding the rpm's at 3000rpm's with constant throttle. If you have to manipulate the throttle on or off because the rev's drop or gain with constant throttle, then perhaps you are experiencing the dreded "SURGE". Take the bike on the open road and see if you experience the same symptoms as noted in the same situations. If what you did to this point cured the issues-at least to the point that you can live with it, enjoy your ride. If it didn't, the surge issue is a whole nother can of worms. I cured mine with the above in conjunction with a cannisterectomy and a Techlusion box. Now I'm in love.

[zbassman]

Just a follow up:

 

I rode yesterday for a few hours, no problems at all. The only two things that changed: I had a new tank of gas and the weather was much cooler than it has been.

 

I'll see what it runs like this week, if the weather clears enough to ride. 37 degrees and raining in Austin today. Blech.

[OlGeezer]

 

Any help greatly appreciated.

 

-Z

 

My solution requires no tools.

 

Don't let the engine drop below 4k RPM!

 

 

This method also solves the dreaded surge problem.

 

[flat_twin]

Just a follow up:

 

I rode yesterday for a few hours, no problems at all. The only two things that changed: I had a new tank of gas and the weather was much cooler than it has been.

 

I'll see what it runs like this week, if the weather clears enough to ride. 37 degrees and raining in Austin today. Blech.

 

When my RT had a surging problem, I noticed it ran much better in cool weather.

See if warmer temps make your "miss" return.

As others have said, a very careful tune up may cure it completely.