Let me start by saying this forum has proven more knowledge base than any of the dealers have proven. I do ride a 01 1200 XLcustom as my bike. But I am also a motorofficer and get to ride at work. The problem is our bikes are downed and no one is allowed to ride because of a wobble that we can not fix....

I hate to do this to you guys. I ride a BMW 650 at work, it is set up with the police package. The BMW has been to the dealer several times to check for a tank slapping wobble. They can't fix it and don't know whats causing it. While riding the bike at 40mph and decelerating using the engine. If you have a light grip on the bars they start flapping back and forth and try to jump out of your hands. They will do this at slower speeds if there is an uneven pressure on the grips for instance putting on the turn signal while decelerating. The thing that is strange is we have two of these bikes and both experience the same thing. I have searched the net for similar problems reported and came up nothing. No recalls, No warnings... I convinced the LT. yesterday to ride them and he is now of the opinion they are too dangerous to ride and downed them for repair. I know that there is not a motorcycle manufacture out there that would want these on the road nor is the bike designed with the wobble in the geometry. THey are set up with hard bags and a trunk bag but there is nothing in them (empty) in attempt to remove the weight to elmininate one more possible solution. The Wheels have been balanced, the neck bearing have been checked...I put the bikes on the center stand and weighted the back of the bike to lift the front tire. The triple trees seem good the neck doesn't have any slop. The only thing that I have noticed is that they may be too tight. With the front wheel off the ground the bars have to be turned lightly to get them to full lock. They are not loose enough to swing around on their own weight.

Any Ideas? At this point we are going back to BMW manufacture to go for Lemon law.

Thank you for your understanding in that this is not an XL specific question but I trust you guys more than the BMW...

Gadget54

what's the mileage on the bikes? front springs may be to soft or worn and compresses too much at deceleration.

what's the mileage on the bikes? front springs may be to soft or worn and compresses too much at deceleration.



That was my thought, as well. Have any mods been done that might change the geometry of the bike in terms of rake/trail?

Check the head bearings for wear and proper pre-load.

Have they tried replacing the front tire ?

On a Harley, when decellerating through about 40 mph with your hands off the bars, when they do this, it's almost always the steering head bearing adjustment. On decelleration, you are loading the front end more, so it's going to be something in the front. Could be the tire (defective, not out of balance) could be fork oil or fork spring issues, or my guess is that it's in the steering head bearing adjustment. You said the bearings were checked, but I still think there might be a problem with the adjustment, typically it's too loose.

Also, how many miles on the bikes and what other mods?

--Chris

It sounds like the bike is squatting too much in the rear.

Instead of using engine braking, try using just the rear brakes, just the front brakes, and then use both front and rear.

If the bike wobbels with just the rear brake, and not with both, or just the front, take a look at the rear suspension.

These bikes may be "tail heavy" due to the added police equipment. If the suspension is not setup properly, any weight transfer to the rear end may be unloading the front end which would change rake and trail.

The change in rake and trail may be causing the front end to loose traction.

I did a google search and found this:
http://w6rec.com/duane/bmw/wobbles.htm

Check out the Wikipedia link at the bottom of the page.

That's a shame, because those are very nice bikes. No mainstream factory would EVER release bikes with dangerous wobble. The resulting lawsuits from crashes and damage to reputation would cripple any company. It's almost certain it has to be the manner in which the suspension and/or load is setup.
However, if the issue is not solved and the bikes have to be returned, push hard to fight for the BMW R1200RT with police package. It is THE GOLD STANDARD for police bikes, globally.

Lot's of good responses...Mileage is less than 3000 miles. The Dealers have balanced the tires, so they say...Tire is a good idea but both bikes wobble. It would be hard to imagine they both got bad tires, but then again...

The Fork oil was also one my thoughts after the head Bearings and rake. I am pretty sure it's not in the Geometry, we haven't done anything to change that. The bags are hard side from the factory setup and they don't have anything in them. On the Jiffy stand I lifted on the rear of the bike. The rear shocks lift no more than an inch so they are not overweighted in the back. We have a range of rider that have expeienced it from 185-240lbs. When I drop down on it it seems to squat equally front to back.

Google 'BMW 650 police package' and the top hit will be on policeone.com. On the right side are the PDF fliers for the 1200 and the 650. The 650 is the one we have and is the pic of our same setup. (sorry it forum woun't let me post a link until I have more posts)

On a side note: We have two Harley Dyna's specd out and are waiting for the Seizure money to be released to purchase them. In the mean time these are what we have to work with and have to make due.

Gadget54

From all the info supplied so far it sounds like head bearings or front tyre design, I would re-adjust the bearings first, then try a different brand of tyre.

Lot's of good responses...Mileage is less than 3000 miles. The Dealers have balanced the tires, so they say...Tire is a good idea but both bikes wobble. It would be hard to imagine they both got bad tires, but then again...

The Fork oil was also one my thoughts after the head Bearings and rake. I am pretty sure it's not in the Geometry, we haven't done anything to change that. The bags are hard side from the factory setup and they don't have anything in them. On the Jiffy stand I lifted on the rear of the bike. The rear shocks lift no more than an inch so they are not overweighted in the back. We have a range of rider that have expeienced it from 185-240lbs. When I drop down on it it seems to squat equally front to back.

Google 'BMW 650 police package' and the top hit will be on policeone.com. On the right side are the PDF fliers for the 1200 and the 650. The 650 is the one we have and is the pic of our same setup. (sorry it forum woun't let me post a link until I have more posts)

On a side note: We have two Harley Dyna's specd out and are waiting for the Seizure money to be released to purchase them. In the mean time these are what we have to work with and have to make due.

Gadget54

I think you nailed it in the first post, the fork should "fall off" to the stop under its own weight from centered with just a nudge.
Matt

Let me start by saying this forum has proven more knowledge base than any of the dealers have proven. I do ride a 01 1200 XLcustom as my bike. But I am also a motorofficer and get to ride at work. The problem is our bikes are downed and no one is allowed to ride because of a wobble that we can not fix....

I hate to do this to you guys. I ride a BMW 650 at work, it is set up with the police package. The BMW has been to the dealer several times to check for a tank slapping wobble. They can't fix it and don't know whats causing it. While riding the bike at 40mph and decelerating using the engine. If you have a light grip on the bars they start flapping back and forth and try to jump out of your hands. They will do this at slower speeds if there is an uneven pressure on the grips for instance putting on the turn signal while decelerating. The thing that is strange is we have two of these bikes and both experience the same thing. I have searched the net for similar problems reported and came up nothing. No recalls, No warnings... I convinced the LT. yesterday to ride them and he is now of the opinion they are too dangerous to ride and downed them for repair. I know that there is not a motorcycle manufacture out there that would want these on the road nor is the bike designed with the wobble in the geometry. THey are set up with hard bags and a trunk bag but there is nothing in them (empty) in attempt to remove the weight to immininate one more possible solution. The Wheels have been balanced, the neck bearing have been checked...I put the bikes on the center stand and weighted the back of the bike to lift the front tire. The triple trees seem good the neck doesn't have any slop. The only thing that I have noticed is that they may be too tight. With the front wheel off the ground the bars have to be turned lightly to get them to full lock. They are not loose enough to swing around on their own weight.

Any Ideas? At this point we are going back to BMW manufacture to go for Lemon law.

Thank you for your understanding in that this is not an XL specific question but I trust you guys more than the BMW...

Gadget54

Tank slapping wobble is caused by any one, or more of several things....(typically more than one)

The only way to truly cure it, is to do a chassis job....

I don't know BMW's for nothin, but on a BT, this means swingarm pivot bearings and races, head bearings and races, front fork fluid/air checks...., Rear Shock checks (or monoshock, in your case?!?) Wheel bearings and alignments, including run-out specs of the wheels themselves......nevermind the possibility of a bad batch of rubber from the plant?!!....

If after all of this, there is STILL a wobble problem, I would be stumped... :dunno

That gives me a lot to go on. At least at this point the Command staff are aware of the problem and will 'down' the bikes until they are fixed.

Thank you for all the replies and Thanks for the forgiveness of posting BMW issues.

Gadget54

Follow Up. We got a definitive answer from the Dealership. It appears they got a notice about this quite some time ago but ignored it. A bunch of these bikes apparently had the same problems on the west coast being used by Police.

The Solution is to change the springs in the forks and there is an adjustment in the Steering head that requires a special tool. We were told that they were flying a Mechanic out to show them how to make the adjustments and we should be riding soon.

Thanks for all the help.
Gadget54

Any update on this?

well sounds like the BMW mechanics/dealers can be just as annoying to put up with as Harley :P

We got one of the bikes back finaly! It doesn't seem to be having any problems. This one needed the steering head bearing replaced along with the "fix" of new springs and adjustment. I guess they overtightened the head in attempt to fix it, damaging the bearings. The guys are back on the bikes. I have since been promoted and no longer on the unit. (bitter sweet) I will only be riding for special events and extra duty when they need it covered. I got a great leather patrol jacket though.

Gadget54