50 amp alternator swap for a 1992 K75

[lefthander]

 Hello,
 Can anyone tell me if a 50amp alternator from other BMW bikes such as an 1150R will fit my 1992 K75 bike? Can you direct me to what parts I need to do this? Planning going across the USA and adding auxilary lights. I've ordered the Eastern Beaver relay package. I've added heated grips, gps and radar detector. I am boosting my headlight to a brighter bulb. Any input would be appreciated.  Thanks

[The Mighty Gryphon]

I have bikes with both alternators.  If you use LED driving lights, I would guess that the 34 Amp alternator would be okay. 

If you really want to switch to a 50 Amp alternator, getting one from another K100, K1100, or K75 should be a direct bolt up.  As far as I can tell from the parts fiche is that the clutch is a different part from the 34 to the 50 Amp.  If you get an alternator with the clutch you will probably be all set.

[Laitch]

According to Max BMW's parts fiche, the R1150R alternator body is the same as the 50A Brick alternator but you'll need a different clutch housing. The drive dog from your current set up should work. Install new drive cushions for best performance. You should install a larger diameter cable to the battery, too.

Learn how to use BMW's parts fiche to compare part numbers and verify what works after some random geezer on the Web tells you it will. If part numbers are the same, a swap should be good. I use MaxBMW's parts fiche.  Many members use realoem.

[mw074]

50 amp.

[rbm]

From this page:  http://www.motoelekt.com/Alt.htm  : it appears that it might be possible.  You'll have to adapt the drive dog from the K100 alternator to the shaft of the 1150R alternator.  That might be tricky.  The frame of the 1150R alternator might not be specifically correct for the K100 and might position the drive dog either too close or too far from the drive.  You'll have to make careful measurements.

[kioolt]

The alternator will work fine.  What you will need to do is remove the pulley from the R bike alternator and replace it with a drive coupling from a K1100 or late K 75 (I believe they had 50 amp alternators as stock).  All BMW parts.  I did this on my 91 K100LT which originally had a 33 amp alternator.  The drive coupling from the 33 amp alternator will  not work because of a different shaft size.

[mobydick]

Can you rewind the stator windings and add beffier diode packs to increase the amp output?  I picked up an extra (low output) alternator for my K bike and will go to my local alternator shop for ideas.  My heater suit and lights need more amperage so it'll be a welcome change. 

Not to thread jack but....I use home sewn neoprene hippo hands that are awesome in the cold and rain and save on amperage.  My home made electric jacket sucks up the current but saved my bacon in snow and cold rain storms in my Cross Canada 2017 150 yr Anniversary trip.
thanks
Mobydick

[Laitch]

 

[kioolt]

Can you rewind the stator windings and add beffier diode packs to increase the amp output?  I picked up an extra (low output) alternator for my K bike and will go to my local alternator shop for ideas.  My heater suit and lights need more amperage so it'll be a welcome change. 

I don't know if it's possible or not but it would probably be cheaper to buy a used 50 amp alternator  than to have someone try to up the amps on a 33 amp alternator.  If you need more than 50 amps you could try a 60 amp R1150RTP alternator.  I've seen some posting somewhere about how to make that work.  The 60 amp will not bolt right up.  There is a mechanical clearance problem that can be overcome by following the directions in the post that I referred to.

[volador]

EME K-bike upgrade cable kit

MOE builds a 60A

[RobP]

http://www.kbikeparts.com/50a_alt/50a_alt.htm