Is this a clutch problem?

[Chazmo]

I have a 2006 R1200GS ( about 70,000 miles ) and have had a problem with "hesitation" on acceleration. I put that in quotes because it does not seem like an engine problem to me; however, it also does not totally fit a clutch problem.

 

In 4th, 5th or 6th gears, the bike seems to stumble accelerating through 4000 rpm. The motor does not rev through 4000 rpm with no acceleration of the bike as is typical with a clutch problem. The the bike slowly accelerates herky-gerky through 4000 rpm where it finally catches and runs past. It was suggested that this was an electrical problem; however, pulling in the clutch instantly stops the herky-gerkyness of the motor and it revs fine. Also, the problem does not exhibit in 1st, 2nd, or 3rd gears.

 

It almost feels like the clutch is partially catching, then slipping, and then back and forth, back and forth. At least that is the theory I was running with. That is why the I think the motor was not reving past 4000 rpm.

 

Took apart the bike and found that the clutch is measuring fine in terms of thickness to spec, however, there is some wear on the two pressure plates on both sides. Half of the diameter of the pressure plates is smooth and the other half has swirl marks.

 

So, does anyone have any thoughts? I have successfully changed the clutch on an RT recently ( and will post pics and a walk through in a few weeks ), but just not totally convinced that this is the clutch even though it is the most likely culprit.

 

 

 

[dirtrider]

Afternoon Chazmo

 

Without seeing it or riding the bike it is difficult to give you a definitive answer.

 

From what you have posted it sounds more like an engine runability problem than a clutch problem though.

 

There have been other reported instances of the 1200 hexhead engine falling flat with hesitation & bucking in the 4000 RPM range.(I think a dealer computer programming update also)

 

When did your problem start?

Did it just suddenly appear or start acting up a bit at a time?

Does it do it when accelerating a cold engine?

Better or worse with a hot engine?

 

[Chazmo]

Thanks for the quick reply...

 

There is a little of both. In some ways it seems like a clutch problem and in another like an engine problem. Do you think it could be software? I searched for this hesitation problem at 4000 rpm and found nothing. If it is a motor problem then why does it act that way only in 4th, 5th or 6th gear? And when it is doing the 'hesitation' the motor revs freely once I pull the clutch in.

 

In answer to you questions...

 

- The problem only recently showed.

- Just started as far as I can tell but seems to be getting worse. First showed itself with a passenger on board.

- Not when cold - seems to be all the time. Took it out and was able to get the problem at first drive and after running the bike for a bit. Does not seem to be temperature related.

 

I also looked at the drive shaft and the rubber mount in the middle looks fine ( it was suggested that I look here ). I will try the stick coils next, but, right now, I am wondering whether to put the bike back together or with or without $600 of new clutch parts...

 

Here is the wear on the pressure plate...

[dirtrider]

Evening Chazmo

 

Like I mentioned in the first response it is very difficult to tell the difference between a slipping clutch & an engine runability problem over the internet without riding the bike.

 

It just seem strange your clutch is only slipping at 4k in 5th-6th gear & not at 6-7K in 5th or 3rd. Or not also slipping on a moderate throttle uphill launch with a passenger.

 

You might not find much on the internet on that 4k flat spot. I have only heard of a few & worked on one. You might ask your BMW dealer if they have a service bulletin on that issue.

 

Now that you have it apart you are in a bit of a quandary as you now have no way to verify if the clutch is the issue or the engine is. It is all visual on the clutch parts until you assemble it again.

 

Upper stick coil(s) come to mind as the lowers are phase shifted at higher RPM's so basically phase shift right out of use at higher RPM's. It could be running fine on the lowers until they change their timing at higher RPM's. (try to borrow a couple of KNOWN GOOD upper stick coils & try them)

 

Another thing is the FPC (fuel pump controller)--if the FPC is acting up it might be limiting fuel pressure/volume at higher RPM/loadings. (maybe try a FPC jumper harness if you get it back together).

 

Might be something like a fuel pressure/flow problem, or a coil/spark issue, or fuel injector problem, or maybe you DO have a clutch issue.

 

I'm not sure what to tell you as you have it apart & can't do further ridability diagnostics.

 

If no oil on the clutch parts about all you can do is replace anything in the clutch that looks suspicious then re-assemble it & see if your problem is gone or not.

 

Personally I would find someone with a like bike & swap your coils into it then see if the problem follows the coils. Same with the FPC.

 

[2UPRT]

I had a similar issue with my 2006 RT after a spark plug change. Turns out one of the coil wires had pulled out of the plastic cap and failed to make contact.Bike idled fine but every time I throttled up it stumbled.

[Chazmo]

Ok... so now I feel soooo stupid...

 

Had the bike apart and new clutch in hand. Do I put it in or return it? I did not relish (sp?) putting the bike all back together and then having to take it all back apart. Looking back now, the smart thing to do would have been to leave the original clutch in and return the new clutch ( saving big ??? ), but what if the problem was not easily found? That clutch would have been nagging me during my entire search for a solution. So, reluctantly, I installed the new clutch.

 

Got the bike back together and ran it and the problem persisted. Luckily I have an RT that I am trying to sell, so I started swapping coils ( and spark plugs too! ) back and forth. At first I thought it may have been the secondary coils because it wasn't like an entire cylinder was out, just weak. But that wasn't it. So I swapped the main coil, and sure enough, that was it.

 

So I spent alot of money and three days of work to find that I needed a coil! But thanks to dirtrider here for pointing me in the right direction to the coils. I really appreciate the help!

[dirtrider]

Morning Chazmo

 

Glad you have your problem sorted out. Too bad about the new clutch but once you had it apart & new clutch in hand then installing the new one was probably the correct thing to do.

 

You can always list your old clutch in the classifieds to recover some of your investment.

 

By the way I forgot to-- welcome you to the board here.

 

[Chazmo]

Thanks for the welcome...

 

Yes, it was quite a difficult decision. I had recently replaced the clutch on an RT and that was the correct diagnosis, so I think I had 'clutch' on the brain...

 

I have pictures of both. I'll write it up soon and post it...

 

BTW, I compared the thickness of the old clutch to the new. The new, out of the box was 6.33 mm thick total. The old was 5.95mm ( the worn one on the RT was 4.4mm for the sake of comparison ). So this clutch probably has much of it's life left in it. Anyone want to buy a slightly used clutch and associated pressure plates?