Hi all, I am looking into getting the larger alternator, i.e. 50 amp. My K75 is a '90 with a 33amp alternator. Well actually think I may have several extras of those around. But are there any negatives to upgrading? And which part number or bike should one come off. I figure to get it used.

K1100LT and K1100RT police spec. You can spot them on ebay as the fan that is exposed on the 33amp version is now internal but monkey nuts cup is still there. Beware of any without the cup on as the K1200 60amp alternator visibly looks the same but it's a few mm wider and won't fit. The 50amp alternator is a drop fit but you will need to make one change: the 50amp alternator power feed is via an 8mm stud (8mm id ring terminal) and the control (blue) wire is fitted with a 6.3mm (1/4" inch) female terminal. The regulator is the same. Here you go:

https://www.ebay.com/itm/204258874150
https://www.ebay.com/itm/363766264792
https://www.ebay.com/itm/174401391464

The last two deserve a quick click at that price. You'll need to supply your own drive cup for the middle one.

I have a 50 amp alternator that has been taking up space on my work bench.  You can have it for the cost of shipping. 

I don't know what model bike it came off of, but it has the 306 020 part number that says it's for a K75RT.

If you are interested PM me with your address and I will get a number for the shipping via the Postal Service.

Won't hurt anything but might not really be necessary these days. Many people went with the 50A in order to run a pair of 55W aux lights. LED aux lights generally need half of that or less. You can also run an LED headlight which also sucks about half as many watts as a halogen H4.

Amps are still nice for heated gear, for the parts of your body that don't get heated by the engine

Tranberg wrote:Amps are still nice for heated gear, for the parts of your body that don't get heated by the engine

+10. I used to think that a heated vest was good (they are) until I got a jacket liner that does the arms too.