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Discussion Starter #1
I have a flat spot between 4K and 5K rpm

It seems like it is running too lean and was wondering if the dealer might have a new map to load on the bike to smooth it out?

It normally isn't a problem unless you are accelerating from 3k to 7K on the freeway in 5th gear.

could it be a 02 sensor that is not reading correctly ( I get 42 mpg average)

is this something easy for a dealer to resolve? I just did plugs, fluids and all looked normal. The bike has had this issue since I bought it.

Is this problem a little mor epronounced on my bike and all LT's have it based on passing emmissions?

your help with my bald I mean flat spot would be much appreciated.

Ian
 

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Wrong gear...

Perhaps a perspective you don't care to hear, but, here it is:

I would not be in 5th gear, on an expressway at 3,000 RPMs. :eek: 5th is an overdrive. I only get into that range when I am cruising at 70-80+ with no interruptions.

You are asking too much of the engine in that gear.
 

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Discussion Starter #3
I am away for a week but thats my problem 70 to 80 is the 4k range (I think) it should be my sweet spot. the 4K to 5K is the rough spot and that is .... mph?

Having a rough spot on the upper or lower end is much easier to deal with not the center of the power band. Typically I don't slowly accelerate but now I avoid this range and I would prefer to be in it.

It is the worst when I slowly accelerate through it obviosuly when pushing the bike it fly's through it with no problem.

Ian
 

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coug66 said:
I am away for a week but thats my problem 70 to 80 is the 4k range (I think) it should be my sweet spot. the 4K to 5K is the rough spot and that is .... mph?

Having a rough spot on the upper or lower end is much easier to deal with not the center of the power band. Typically I don't slowly accelerate but now I avoid this range and I would prefer to be in it.

It is the worst when I slowly accelerate through it obviosuly when pushing the bike it fly's through it with no problem.

Ian
Okay, now I get it! Before, in your 1st post you said "Flat" spot, now you are saying "Rough" spot.

The LT is known to have a 'Spot' around 4200-4500 RPM that is rough and exhibits some varying degree of vibration. It is generally thought to come up from the center exhaust hanger. Some find it unnerving, others use it as a shift point.

Me, I removed the center hanger. Buzz, vibration, roughness gone.

Others have gone to Remus or other aftermarket exhausts to cure the 'vibes'. In any event, I would suggest you ride slower or faster ;) and not ride at the buzz zone! The LT's sweet spot is just starting at 5K anyway... :bmw:

Good Riding!
 

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Ian, are you talking about the “buzz” or rather a RMP range with poor acceleration? By the way, how many mile on the clock? 42 mpg average isn’t all that bad, probably close to what I get on my ’00. Mileage depends on so may things, riding style, altitude, temperature, wind, type or windscreen, and on and on. The O2 sensor could be a problem, or maybe the fuel injectors?
 

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If it's in 5th at 4K rpm, drop it into 4th and go. If it's in 4th at 4K, drop it into 3rd. Forget about the mph (er, well, one does need to keep the speed limit in mind, I suppose), to accelerate you want to tap torque. By dropping it one (or if you really want to jump, two) gears you'll jump over most of the buzz range and be at the low end of the power band, which doesn't flatten out until about 7K.
 

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Discussion Starter #7
Sorry for abandoning my own thread, I have been on a bike trip ( VTX)for the past couple of days and the internet connection is not always possible.

Unfortunatly it has not been on the BMW but I wanted to drive something a little better than the Harley riders I am with.

The buzzing center exhaust hanger sounds and feels like a potential candidate.

I have 33K on the clock and it is engine speed not bike speed related.

I will look into the buzzing hanger but the comment regarding a rough spot relates to my real question is this a common issue with these bikes ( not really fixable) or is it something wrong with my bike?

I am not unhappy with 42 MPG and I do weigh in at 350lbs so if I gave up a few meals maybee the BMW would give me a few more mile?

Ian


Ian
 

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If it is a felt vibration that starts around 3500 rpm and ends around 4500 rpm in every gear, it's the "K bike buzz." It happens on many, many, many K bikes. I've read lots of causation theories (the center stand bracket is a new one to me; I'm partial to the "asyncronous overlapping resonances put out by the crankshaft in this rpm range, which are translated to vibration at the engine casing wall and transferred to the frame" theory. I don't know what it means, but I'm partial to it.) The recommendation that I have found most useful is to consider it the gateway to torque and acceleration. Get above that gateway when you want to accelerate, and all will be well. You can run the bike through the gateway (i.e., accelerate through it in a particular gear), or you can pop over the gateway by downshifting and then accelerating. The latter is lots more fun.
 
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