K1100RS Transmission Woes

[Wescoe]

I was riding in some twisties and on 2-3 upshift, the bike popped out of 3rd gear as soon as I let out the clutch and now I only have 1st and 2nd gear, with no neutral and no 3-5. The bike has 107k miles and has lived its whole life in the Bay Area hills, the last 3 years of its life, based in urban San Francisco. I'm not surprised, I'm just glad I didn't go down when it popped out of gear and locked up.

After reading, it looks like pulling the tranny and replacing with a post 1990 non K75 unit is the best way to go. What if anything should I do to the clutch while I'm in there?

Also, I plan on following the K1100 spline lube guide to do this job and anticipate the tranny swap to be a pull and replace affair? I've never taken the tranny off a K bike.

I've also been thinking the piston rings could use refreshing. Would it be a good time to do that as well? Can someone point me to some more info on that topic?

[Scott_]

As long as you are going to have the transmission off, pull the clutch apart(mark alignment between the pressure plate and rear basket), inspect the friction disk thickness, and replace the clutch nut o-ring.
There is varied opinion if you go so far as to replace the rear output shaft seal, some say leave a sleeping dog lie, some say change it if it is original.
My personal opinion, if it is still original and you are that far into the clutch, spend the $30 and put a new one in there.

As far as piston rings, don't waste your time or money.  If you think that they are in that bad of condition, get yourself a lower mileage used motor instead. These motors are known for 200K+ miles, just keep the oil changed, valve clearances in check, and ride the pi$$ out of it.

[wmax351]

I'd consider just replacing the clutch disk as a matter of course. They're like 30 bucks from motobins, and SF hills burn clutch like none other.

If you plan on replacing the output shaft seal, I have a hardwood driver I made for the task which you could have (It's located at my folk's house in Mill Valley, just north of you), just shoot me a pm. It may need some more soda can slices glued on as spacers to adjust how it leaves the seal protruding. 

Regarding the rings: I think it really depends on the engine. If it runs good, has good compression, and doesn't burn too much oil, I'd leave well enough alone, and do as johhny says: "Ride it till it won't move." Well, you did that once, fix the trans, and do it again. Nikasil bores can be really stable, and likely will still have crosshatching at 100k. Honing them is an SOB, you need a diamond ball hone to actually make any dent in the walls. Otherwise all you can do is deglaze.

When I replaced the engine on my K75 at 100k, it was pretty shot, but I think there was some poor PO maintenance (never buy a BMW from a guy with a Honda PC200), and I also did a 4000 mile tour (with a lot of high speed, high load, high wind riding) with a bad thermostat (discovered later). There was noticeable wear on the cylinder walls and soft ridge formation (feel-able by finger), and the pistons were a fairly loose fit in the bores.

[Wescoe]

WMax, thanks for the advice and kind offer. I remember a while back you were selling a megasquirt setup for k bikes in the Bay Area. Now I see you're in Baltimore, I spent 4 years there myself! I'll probably take you up on your tool offer, are there any decent write-ups of the clutch replacement job? I've never messed with a K bike clutch.

Points taken on the rings. Seems to me it burns a lot of oil, but it's still well within factory specs. My thinking was that if I'm going this deep into it and it's going to be off the road, I should do that job as well. However, other than the burning oil, the engine is very strong and hasn't given me any problems.

Looks like I need to find myself a quality used transmission from a 4v bike and it'll bolt right up and have the proper 5th gear ratio. Any pointers to the clutch portion of this job would be greatly appreciated!

[wmax351]

Glad to help.

For the clutch, the FSM covers it pretty well. The clutch Nut Oring instructions in the library will work as well: just replace the disc while you are in there.

Yeah, K bikes burn oil. The Nikasil usually never fully seats the rings, even after tons of miles, so you get some burn. Especially if they aren't really flogged with non-synth oil for their first 10-20k miles. Just think of it as spark plug lubricant. :P

If you ever need to do the rings (unlikely), they can actually be done with engine in frame. You can also pull the engine out from the front. So not much effort saved by doing it "while you're in there." When I did my rebuild, I had the entire swap done in under a week, with some other tasks as well (re-seal transmission mainly).

[Wescoe]

Awesome, I'm hoping to tear it down this weekend and inspect all the splines. If everything looks good, I'm going to start collecting parts and get her back on the road ASAP.

I took a look at the clutch portion of the FSM, and it seemed pretty complete. I'll take a look at the writeup in the library as well.