Generator belt numbering

I hope that the community can shed some light for me:

Last summer I bought a 2005 R1200ST with 48000 kms on it. I am trying to change the generator belt with one from Beemer Boneyard, but using Jim Von Baden's technique of cranking the rear tire in 6th is not working for me. I even had a friend work the wheel so that I could focus up front and it would not go on. My friend and I then compared the new to the old and found that the old one was about a quarter of an inch longer, and I didn't think that a belt so small would stretch that much. I thought that the belt must be the wrong size (It was a Contitech 4PK 611(592) and the original was a Contitech 4PK 592) so I went and bought a new OEM belt at the dealership (expensive).

I was surprised to find that the new OEM one was the same length as the Boneyard one: considerably shorter than the one coming off. I want to try using a wrench to turn the lower pulley (as I have seen on youtube) to see if that will give me the leverage I need to get it onto the lower pulley. Before I do that, however, I have one niggling question (because that was a lot of stretch and if I somehow manage to get a too short belt over the pulleys, I worry for the life expectancy of the spindles).

As you can see in the attached photo, the first 4 digits in the part number are different on the OEM belts. The old one starts with 11.28 and the new one starts with 12.31. Everything else is exactly the same. Does anybody know what these numbers are?

I hope that the community can shed some light for me:

 

Last summer I bought a 2005 R1200ST with 48000 kms on it. I am trying to change the generator belt with one from Beemer Boneyard, but using Jim Von Baden's technique of cranking the rear tire in 6th is not working for me. I even had a friend work the wheel so that I could focus up front and it would not go on. My friend and I then compared the new to the old and found that the old one was about a quarter of an inch longer, and I didn't think that a belt so small would stretch that much. I thought that the belt must be the wrong size (It was a Contitech 4PK 611(592) and the original was a Contitech PK4 592) so I went and bought a new OEM belt at the dealership (expensive).

 

I was surprised to find that the new OEM one was the same length as the Boneyard one: considerably shorter than the one coming off. I want to try using a wrench to turn the lower pulley (as I have seen on youtube) to see if that will give me the leverage I need to get it onto the lower pulley. Before I do that, however, I have one niggling question (because that was a lot of stretch and if I somehow manage to get a too short belt over the pulleys, I worry for the life expectancy of the spindles).

 

As you can see in the attached photo, the first 4 digits in the part number are different on the OEM belts. The old one starts with 11.28 and the new one starts with 12.31. Everything else is exactly the same. Does anybody know what these numbers are?

Evening Sound Guy

BMW had problems with the early 1200 bike elastomer belts squealing so went to a slightly shorter belt.

It sounds & looks like you have the correct belt (they do stretch a LOT after installing so are difficult to get on)

If you have an asphalt driveway put the new belt out in the sun on the driveway for while (that can make installation easier).

Using the front pulley nut usually helps. On real stubborn belts I have unplugged the fuel pump (so it won't start) then cranked the starter to run the belt on (they are REAL TIGHT so can put up quite a fight).

Please forgive what may be a silly question, but you did remove a plug from each cylinder, right?

I found the belt swap to be very easy. A quick rotation and it slipped right on.

Not a silly question at all aggieenginer, that is something that I might have done a few years ago, but unfortunately, the main plugs are out.

Thanks dirtrider for the info, I'm going to try the wrench method and see if that works.

So, I tried with a pair of wide-head pliers that I borrowed from a friend... no dice. The belt was too tight against the nut to allow the pliers in and the funny thing was that the belt kept coming off from the top pulley which adds to my suspicion that it might actually be too short. I'm using the Beemer Boneyard belt in hopes that I can return the OEM one to the dealer. I just went and bought another set of wide pliers with a more needle-nosed shape so that there is not so much contact.

Going to the garage now. Please wish me luck.

Did you try using this method?

I looked at the Max BMW parts fiche specifically at the R1200ST. There was a note:

4 PK 592 = 4 ribs, 592mm. In some rare cases, this belt does not apply to early production dual spark models. We recommend you look at your old belt for the model (4 PK 592) or PN prior to ordering.

Perhaps there was something unique to the ST model. You might give them a call at the New Hampshire location. Drew Batson has been most helpful to me on occasion. Is it possible that the belt you removed wasn't the original?

Also, when trying to get the belt over the lower pulley, is it seated in its normal position on the upper pulley?

I looked at the Max BMW parts fiche specifically at the R1200ST. There was a note:

 

4 PK 592 = 4 ribs, 592mm. In some rare cases, this belt does not apply to early production dual spark models. We recommend you look at your old belt for the model (4 PK 592) or PN prior to ordering.

Perhaps there was something unique to the ST model. You might give them a call at the New Hampshire location. Drew Batson has been most helpful to me on occasion. Is it possible that the belt you removed wasn't the original?

Also, when trying to get the belt over the lower pulley, is it seated in its normal position on the upper pulley?

Evening aggieengineer

BMW says that for all (or most of anyhow) the early 1200 hexhead bikes, some of early bikes had slightly larger belts that squealed when wet.

I doesn't seem to apply to the OP's bike as he stated he removed a Contitech 4PK 592 from that bike.

Thanks for all of the advice,

Dann, I did try using the wrench method, but I could not keep the upper pulley part of the belt aligned (I said "pliers" in my post above, but I misspoke. it was a wide-head wrench). The tighter it got on the bottom pulley, the more the belt was pulled over the front side of the top pulley. I even tried threading the top pulley with the belt misaligned towards the back. I thought that if half of the belt was overhanging the back of the top pulley, then the forward pressure from tightening the lower one would pull it into place. I was wrong, it still came off of the front. If I removed my exhaust, this might me easier, because they get in the way, but that's not on my priority list right now.

I am now trying to find someone locally who owns the BMW tool. Anyone in Ottawa, Canada here?

Thanks for all of the advice,

 

Dann, I did try using the wrench method, but I could not keep the upper pulley part of the belt aligned (I said "pliers" in my post above, but I misspoke. it was a wide-head wrench). The tighter it got on the bottom pulley, the more the belt was pulled over the front side of the top pulley. I even tried threading the top pulley with the belt misaligned towards the back. I thought that if half of the belt was overhanging the back of the top pulley, then the forward pressure from tightening the lower one would pull it into place. I was wrong, it still came off of the front. If I removed my exhaust, this might me easier, because they get in the way, but that's not on my priority list right now.

 

I am now trying to find someone locally who owns the BMW tool. Anyone in Ottawa, Canada here?

 

Morning Sound Guy

I haven't ever had much of a problem installing those elastomer belts on the 1200 bikes & I don't use any special tools.

Is your belt real cold & stiff????? If so try warming it up first.

Maybe a second set of hands from a friend or neighbor can guide the top & keep in tracking on the upper pulley as you work the bottom on the lower pulley.

I have been heating it up in a dryer because it is freezing up here.

My guess is that I will wind up doing exactly as you suggest, with lots of help.

Success!! The belt was in the house all night and so it started the dryer treatment warm, which probably made it more elastic.

The belt over the top pulley still dislodged forward, but once the lower pulley was properly mounted, all I had to do was re-do the plastic strip trick over the top pulley and it popped right into place.

Thanks again to everyone who took the time to help me out and offer advice.

Great to hear. I know you are relieved. So are we!

I personally don't mind the bit of squealing... I worry more about the wear on the alternator with a too tight belt. Is there any way to order one of the old ones??? What's the correct one to get?

2006 R1200RT

I personally don't mind the bit of squealing... I worry more about the wear on the alternator with a too tight belt. Is there any way to order one of the old ones??? What's the correct one to get?

 

2006 R1200RT

 

Afternoon RedMac

You won't find any premature failed alternator bearings as there just isn't much difference in the belts. As far as I know the part number & size on belt is the same, just a very slightly smaller belt after run-in for less squeal. If you can find an early 1200 bike with an original belt you might find something identifiable in the sub numbers but I haven't ever compared the belts to see if there are any specific identifiers.