I pulled the radiator to fix the fan and I found a nipple on top of the block towards the front. Can anyone tell me what it's for or what it does?

Thought it was an emissions nipple for the tank breather to go into the sump and avoid fuel vapour entering the air. Californiae invention perhaps.

Looks like a wiring connector to a coolant sensor that's not used.

K75cster wrote:Thought it was an emissions nipple for the tank breather to go into the sump and avoid fuel vapour entering the air. Californiae invention perhaps.

For a K100 yes and for a K1100 it is connected to the cyclonic oil separator.
Good idea is to put the model and year in the signature section that way you can tell all without typing it each time.

The bike is s 1988 k75s.

It will be the tank breather that was put on to keep the numpties in California happy.

RicK G wrote:It will be the tank breather that was put on to keep the numpties in California happy.

It was connected by a hose to the rear pipe of a pair of stub pipes descending from the rear underside of the tank. It was a flawed idea but apparently satisfied governmental Californicators, as Rick G has indicated. Slip a short piece of vent hose onto it, fold the hose then clamp it to the pipe. If you don't block that pipe, you'll need to put a sticker near it warning people that the crankcase contents is poisonous and they should not suck on the pipe.

Is there a hose on either of those pipes at the rear of the tank?

Thanks for the info. Sure sounds like something the commierades would do in this state . I'll just run a piece of hose to nowhere.

One of my bikes had a golf tee hammered into the stub on the front of the block.  Seems to work.

What I've seen on a lot of Ks (and am guessing was done by dealers) is that the factory hose coming off it was snipped, folder over and zip-tied.

andy442 wrote:The bike is s 1988 k75s.

It's easy to do, and makes sense too, go to Signature in your Profile. Add the bike's year and model,  so everyone can see what's being asked about - no guesses.