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Help Im at my wits end! poor runing and vibration problem remains.


R1100RSpurist

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R1100RSpurist

Hello, I have had posts before and thought that by replacing the intake manifolds, as suggested and recomended by others I could fix my R1100RS however it still has its off idle stumble and 3500 to redline RPM vibration and buzz. So before I go to BMW and pay dearly for perhaps nothing or something I can fix, I made up a log of all my attempted fixes and maybe someone out there knows whats going on. here is the log:

 

1995 BMW R1100RS with 82072 Miles

 

 

The Problem: At idle the bike will sometimes “balk” right off idle and will demonstrate poor throttle response from ~1050 to1150 RPM. Smooth running in any gear from ~1500 to ~3500 RPM; however, in any gear, from ~3500 to 4200 RPM there is a very heavy vibration and buzz that becomes higher in frequency as the revs go to redline. Engine is generally not smooth and throttle response poor. Stalls (hiccups) temporarily (and sometimes completely if below full operating temperature) if throttle is cracked open from Idle.

 

Engine Problem Attempted Fixes:

 

1.BMW Fuel Injection Cleaner

2.Throttle body and Idle synchronization with Twin Max (Multiple times)

3.Cleaning of the Idle screws and Throttle bodies(carbon buildup)

4.Valves adjusted (81200 miles)

5.New spark plugs (81300 miles)

6.Left and Right Intake manifolds replaced (11 61 1 340 769, and 11 61 1 340 770, respectively) and Throttle body O-rings replaced. (82072 miles)

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Have you verified your TwinMax accuracy? (Zero meter, attach both sides via a tee to a vacuum source and verify needle stays centered.)

Twinmax units have a drift issue if the meter light is still connected and also have been known to ship with leaky hose fittings.

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Hello, I have had posts before and thought that by replacing the intake manifolds, as suggested and recomended by others I could fix my R1100RS however it still has its off idle stumble and 3500 to redline RPM vibration and buzz. So before I go to BMW and pay dearly for perhaps nothing or something I can fix, I made up a log of all my attempted fixes and maybe someone out there knows whats going on. here is the log:

 

1995 BMW R1100RS with 82072 Miles

 

 

The Problem: At idle the bike will sometimes “balk” right off idle and will demonstrate poor throttle response from ~1050 to1150 RPM. Smooth running in any gear from ~1500 to ~3500 RPM; however, in any gear, from ~3500 to 4200 RPM there is a very heavy vibration and buzz that becomes higher in frequency as the revs go to redline. Engine is generally not smooth and throttle response poor. Stalls (hiccups) temporarily (and sometimes completely if below full operating temperature) if throttle is cracked open from Idle.

 

Engine Problem Attempted Fixes:

 

1.BMW Fuel Injection Cleaner

2.Throttle body and Idle synchronization with Twin Max (Multiple times)

3.Cleaning of the Idle screws and Throttle bodies(carbon buildup)

4.Valves adjusted (81200 miles)

5.New spark plugs (81300 miles)

6.Left and Right Intake manifolds replaced (11 61 1 340 769, and 11 61 1 340 770, respectively) and Throttle body O-rings replaced. (82072 miles)

 

When an engine operates erratically at different RPM's, the first thing I think of is some sort of vacuum/air leak. I'd start with the injectors. There are three "O" rings, plus the butterfly shaft that can leak on each throttle body. Test them at idle with WD-40 or an unlit propane torch.

 

If everything on the intake side looks tight, the next thing I'd check are the cables. If they are hanging up or stretched, or the bowden box is worn, your throttle sync may change at different RPM's. If they haven't been replaced in 80K+ miles, you should probably do it.

 

When you R&R the throttle cables, it's time to do a zero-zero TBS and throttlebody sync (at least I did).

 

At that point, you've eliminated the most likely causes. If you still have an idle and tuning problem, I might do a leak down test to verify that there's not a leak in the heads or engine. I'd also check the plugs to see if the problem is focused on one cylinder or the other.

 

Good luck ... Scott

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Another possibility is that your Throttle Position sensor is

giving inconsistant readings.

 

When you did the Sync. on your carbs, were you getting consistent ohmeter readings at the TPS at idle position,

or did it vary whenever the throttle was opened and released back to idle?

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You've gotten some good suggestions already. I agree that you should verify your sync with some other instrument than the Twinmax, just to be sure it's OK. You can build a manometer cheaply. Being way out of sync might cause the symptoms you describe. In tandem check your TPS, both for a correct reading at idle and a smooth resistance change as you run from closed to full open. I've attached the data sheet for the Bosch TPS sensor.

882035-boschtps.zip

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Yeeha! Stephen

How many times have you synced the throttles. Have you been chasing a good sync each time?

 

The off idle stumble sure sounds like throttles that aren't opening at the same time. And the higher rpm buzz sounds like throttles going out of sync the farther you twist the grip.

 

How new are the cables? Checked for stretch and/or fraying? Are they too tight? At 80k and multiple syncs, all the slack is gone? Butterflys bouncing off the stops? Check the throttle cable pulleys on the throttle bodies... dirty? Got any grit in them. Or maybe a small pebble? How about your idle speed? Too low? Too high?

 

I had some stumbling probs a while back until I got really anal about setting those cables. I could yank the throttle open and would get a moments hesitaiton and the wham! I got really anal about setting everything just perfect. Not just setting them in the right spot, but backing everything off and re-setting everything like new assembly.

 

Now everything is just fine. Sweet idle. Sweet off-idle. Sweetly smooth all the way up to the 4000 range. Got a little bit of buzz in the high 5k range but my riding spot is 4000 to 4500 and it's really nice there now.

 

I suggest starting over and make sure everything is clean down there.

 

Hope you get it solved! thumbsup.gif

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R1100RSpurist

Thanks I appreciate all your tips. In response however, the throttle cable was replaces 10,000 miles ago, so I believe its still good. The plugs are nice and tan and look good, on both sides. not sure where I can get a certifiable vacuum source though to test out the Twin Max. And while syncing with the twin max things DO seem to move around from time to time. But i cant pin this down on any cause, as it runs the same(bad) each time. I dont know how to read the TPS or fault find it.

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You do not need a certifiable vacuum source. The twin max is a differential device, measuring the difference in vacuum between each side.

With both sides attached to a tee fitting then connected to any vacuum source, the Twinmax meter (after setting 0) needle should read zero when vacuum is applied. If the Twinmax is leaking, the meter will display non-zero results.

On my TwinMax, each side had a rubber hose, a coupling, then a nylon hose.

My unit leaked at the coupling and at the nylon hose interface to the throttlebody. I replaced the couplers and reduced the size of the nylon hose. Fixed!

Also, disconnecting the meter lamp of the Twinmax will virtually eliminate meter drift.

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Owen, maybe we could help you more if we had a little more history on when your problem started?. If it has gotten worse over time?. Had you worked on or added anything just prior to the problem appearing?.

 

Did the problem occur slowly or did it just appear one day?. (if it suddenly appeared was anything done to bike just before that time)?.

 

There are only a few connections between an off-idle stumble & high RPM buzz so my feeling is they are not related (that is UNLESS they both appeared at the exact same time) –Did They?.

 

Does the bike still have good power in the mid range & on top end?. A plugging or plugged catalytic converter could cause both problems but that usually kills power in the mid range & top end..

 

Without knowing more specifics of when the problem started,, if anything was done to the bike about the time it started.. I would have to say the off idle sag is fuel or spark related & the high RPM vibration is normal for the 1100 non-counterbalanced engine..

 

Maybe run a fuel pressure test (low fuel pressure can & will effect tip in & top end power..

 

As mentioned above track your TPS output (pins 1 & 4 ) from idle to about ½ throttle..

 

Make sure the closed throttle idle TPS voltage is below .395v & higher than .340v..

 

Measure the primary & secondary ign coil resistance (you will have to look the data up on that)..

 

Look for obvious throttle plate tracking issues (check balance at BOTH idle & part throttle then open the throttle slowly & make sure the balance tracks fairly even as the throttle is slowly opened.. If you can rig it up try tracking the balance while riding the bike..

 

If your bike still has the original vapor recovery tank make darn sure it is not plugged, the vacuum lines are hooked up correctly & it is correctly operational (if not, just plug it off (plug purge lines going to the manifolds) then vent the fuel tank to atmosphere below the bike..

 

Run a HOT compression test on the engine..

 

Verify both cams are timed correctly..

 

There are marks on the flywheel so make sure the ign timing is on the marks (maybe someone has installed a new HES at one time & screwed the ign timing up..

 

On the vibration problem.. Check ALL the engine & trans attachment bolts for being tight.. Make sure the alternator belt is in good shape & the alternator is tight (a loose alternator will really vibrate at high RPM).. Make sure the exhaust system isn’t grounding out on the frame or center stand..

 

Twisty

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R1100RSpurist
Owen, maybe we could help you more if we had a little more history on when your problem started?. If it has gotten worse over time?. Had you worked on or added anything just prior to the problem appearing?.

 

Did the problem occur slowly or did it just appear one day?. (if it suddenly appeared was anything done to bike just before that time)?.

 

There are only a few connections between an off-idle stumble & high RPM buzz so my feeling is they are not related (that is UNLESS they both appeared at the exact same time) –Did They?.

 

Does the bike still have good power in the mid range & on top end?. A plugging or plugged catalytic converter could cause both problems but that usually kills power in the mid range & top end..

 

Without knowing more specifics of when the problem started,, if anything was done to the bike about the time it started.. I would have to say the off idle sag is fuel or spark related & the high RPM vibration is normal for the 1100 non-counterbalanced engine..

 

Maybe run a fuel pressure test (low fuel pressure can & will effect tip in & top end power..

 

As mentioned above track your TPS output (pins 1 & 4 ) from idle to about ½ throttle..

 

Make sure the closed throttle idle TPS voltage is below .395v & higher than .340v..

 

Measure the primary & secondary ign coil resistance (you will have to look the data up on that)..

 

Look for obvious throttle plate tracking issues (check balance at BOTH idle & part throttle then open the throttle slowly & make sure the balance tracks fairly even as the throttle is slowly opened.. If you can rig it up try tracking the balance while riding the bike..

 

If your bike still has the original vapor recovery tank make darn sure it is not plugged, the vacuum lines are hooked up correctly & it is correctly operational (if not, just plug it off (plug purge lines going to the manifolds) then vent the fuel tank to atmosphere below the bike..

 

Run a HOT compression test on the engine..

 

Verify both cams are timed correctly..

 

There are marks on the flywheel so make sure the ign timing is on the marks (maybe someone has installed a new HES at one time & screwed the ign timing up..

 

On the vibration problem.. Check ALL the engine & trans attachment bolts for being tight.. Make sure the alternator belt is in good shape & the alternator is tight (a loose alternator will really vibrate at high RPM).. Make sure the exhaust system isn’t grounding out on the frame or center stand..

 

Twisty

 

The Story is that I had just been learning to ride this bike, and did not really take it up in the higher RPM range or push it very hard. When I got new tires and more experience, and started riding harder, I noticed the vibration and annoying off idle stumble. So i guess they have both been there for a while somewhat simultaneously. For the power, It still has the power its just not very accessible because of the vibes. The vibration however is not high RPM as its starts at 3500 RPM and just continues from there, but is lessened after 4200 or at least the frequency of it becomes more buzzy. I have no carbon/emissions can so that wont be a problem, and the HES is original. I however will look into the compression issue, and check the bolts. Thank you for your help.

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tom collins

in regard to the vibes, the dealer may clean them up a little, but if you are expecting 4 cylinder smoothness, you will be disappointed. i had a 97 version of that bike and the sweet spot was right around 3500 and 70 mph. beyond that, it would vibe more until about 100 mph where it would again smooth out. it was not a debilitating vibe, but it definitely made its presence felt. another thought is that the bars are rubber mounted and the bushings may be worn after that many miles. ask them to check while it is in.

good luck. my 97 was a fine machine.

 

tom collins

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