Please encourage me to buy this bike!

[Barrieb]

Guys,
misleading title, but after a few years of being disappointed, with a number of different bikes including 1 Funduro and a K75 with major spline issues,  I have an opportunity to buy a 1987 K100LT, in amazing condition and alleged 22K miles (I can only trace millage back to 2004) and it reflects the condition.
I have the bike in my garage as i'm changing the Hall sensors for a mate, and if that solves the ignition problem i can if i wish have the bike.  Here is the list of concerns:

1. Minor oil/fluid leak around the water/oil pump - assuming worst case of shaft corrosion, are the £200 kits with shaft and seals any good and will they fix most leaks
2. After the horror of the K75 splines - can i get a good indication of the overall splines by removing rear beval and checking status of those?

i'm in a unique position of being able to give the bike a thorough going over before i decide to buy - tank will be coming off

I'm quite familiar with the K series having done clutch, oil/water pump change, cylinder head gasket and most other rennovation jobs

Any advice gratefully received otherwise i'm gonna end up with a Yam 900/600 diversion (Seca in the US of A)!

Thanks

Barrie

[Laitch]

Remove the rear drive. Look at the spines on the pinion gear shaft of the rear drive and the spines in the socket of the driveshaft that couples to it. Take some photos slightly elevated from straight-on in good lighting and post them here if you want opinions. The splines on the output shaft of the transmission and the u-joint splines to which it couples r are held together by a clip so don't wear from sliding against each other.

You've replaced a clutch so you understand that the clutch hub splines and the transmission input shaft splines are subject to wear. If the 22K mileage is accurate, you should not encounter significant wear on any of those parts or the rear drive parts either.

[milq]

Buy it, you know you want to. All the cool kids are doing it. 

[The Mighty Gryphon]

Crap splines happen.  If you can't handle it, you should probably get a chain drive bike. 

[sebas2357]

1. Minor oil/fluid leak around the water/oil pump - assuming worst case of shaft corrosion, are the £200 kits with shaft and seals any good and will they fix most leaks

The oil/water pump rebuild kit will resolve the faulty seals that occur with age. If you end up buy the bike, make sure that if your shaft is corroded, that you buy the one with correct number of teeth. There are two variants, when (or if) you take apart the waterpump, you'll see what I mean. Make sure you buy a rebuild kit from a reputable shop, I'm assuming you're in Europe, I recommend motoworks. The kits are BMW OEM, they will solve all leaks if done properly. The real kicker is seating the water seal without breaking it. DAMHIK  .

I rebuilt my water pump last year during my 1st month of ownership of a 85' K100, and while I had some issues (documented here on the forums), it is very DIY friendly, but patience is key. I haven't had any leaks since my rebuild last May; I've rode about 7000 miles since then.

[Barrieb]

Guys
all great advice, think i know which way this is going to go :-).   

Motorworks do a waterpunp seal seating tool, very basic, but looks like it would really help pull the shaft through the seal, which appears to be when the damage happens to the seal on assembly

Will read all the posts on this

I joined this forum in 2015 and with a lot of help managed to save a K100RS from being scrapped!
Its great to be back!

Barrie

[Barrieb]

Crap splines happen.  If you can't handle it, you should probably get a chain drive bike.

Ouch!

Crap splines do happen on chain drive bikes, BMW F650: primary drive sprocket is held on with a circlip, with an o ring behind to keep it tight.  If the o ring is not maintained and splines are not lubed, the Output shaft splines wear and if your lucky the sprocket does not come off.
When I found that on a bike I had foolishly bought, only fix was to strip engine and replace shaft.  Lesson learnt

[Barrieb]

Well, I changed the Hall Sensor and found the tank breather pipe connected with a one way (but working neither way) valve then connected to the little stub around the top of the camchain cover - not seen this on other models i have owned

The bike has come back to life and i'm certain with fresh fuel/fuel filter new plugs air filter and full service will be spot on

Condition is amazing, for the past 25 years its been kept in a heated garage and rolled out once a year for its MOT

i'm sure you have guessed i bought it!  Very happy to be owning a properly engineered bike again

Now where did i put my spline lube from 2 years ago?