• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

85 K100 w 168,000 miles: Putting new Starter Sprag Clutch in Early March 2015

075038

New member
85 K100 w 168,000 miles: Completed new Starter Sprag Clutch in Early March 2015

I have "the parts." Waiting for my garage to warm up a bit (Phila: we've had a lot of nights in single digits F recently). Did the rear main seal at 114k and was almost there. This time a new clutch disk is in my pile of new parts with center o-ring, nut etc. A set of parts is also on hand to replace the Rear Drive Pinion seals, using heat etc as posted.
.
I've read the posts about the sprag clutch, even came across a great set of pics for doing the job.

I've tried the Rislone, CD-2 and Rotella T and tired of bump starting it on and off since about 125K, esp. two up with camping gear or camping on grass, like at Daytona last spring when the rear tire slips too much to start in 2nd gear. It's embarrassing to need some guys to help me push start a motorcycle that I am so proud of and happy with in every other way.

The new parts include the bearings that the alternator enters in case they are worn. I have some idle noises I don't like during the first 10 minutes after starting, raising my idle to 1000 RPM helped these. A new cam chain tensioner and chain rubbing rails did not help. I would describe the noise as "every 5 -20 seconds during a cold motor idle, it sounds like the motor tries to run backwards all of a sudden for a 1/4 of a second." I had thought a loose cam chain might allow this waiting for the tensioner to pump up. It might be related to heavy battery recharging loads related to my upgraded 50 amp alternator.

Some dealer K bike mechanics have spoken with me to help complete the list of "ought to" do this while I'm there stuff. I looked at the 6 rivets a year or two ago, they are fine. It needed a new radiator fan on a trip a couple years ago. It gets Mich PR 3 tires (wide rear rim upgrade) and spline lubes regularly.

Does anyone know about the extra case hole "upgrade" that allows engine oil to wash the varnish build up on the sprag clutch more than the stock '85? Is there a tech bulletin that shows the size of internal hole, the location and the angle?

Followup posts of wide variety are welcome. Thank you ahead of time. Completed Info posted about 6 replies down.
 
Last edited:
Sombody can correct me if I missed a detail, but I thought the extra hole(s) were in the perimeter of the sprag clutch allowing the oil to sling out as it spins. If I remember correctly, and if you bought a new clutch, I think that takes care of the hole issue.
 
85 K100 Sprag: New part has holes as Paul Glaves suggested

Dear Paul,
OP Here:

You and Voni are K bike treasures, thank you.

The new sprag clutch Free Wheel Cage has 3 radial holes at 120 deg. as you thought that don't appear on the microfiche dwg. for this part 11 26 146 097 was 11 26 146 1570. I bet my 85 doesn't have them. Will confirm when job is done. Interesting feature: one radial hole is in center of cage, one is left of and the third is right of center when spun and viewed from the 1/2" wide outside diameter.
 
85 K100RS 168,000 miles: Original Poster (OP) here: I had been trying Rislone etc. since 125,000 miles (Pic)

Job Complete (except new battery this week): New Sprag Clutch Parts, New Clutch friction disk, New Rear Drive Seals and fluid, Heli-Coils for two battery hold downs into Swing Arm, New Alternator Cush Drive ( Monkey )Nuts, Topping up battery water didn’t save old battery, New Battery

Since I once replaced the rear main seal beneath the clutch years ago, I dug in. When I removed the alternator cush drive, some melting of the monkey nuts was evident on the engine side of the 3 blade “spinner.” When I opened the intermediate housing there was brown varnish, esp. on the 6 screws that hold the sprag to the adjacent gear (Pic). Getting this far into the bike took from 9am until 2 pm despite skipping: engine oil draining, gas tank and fairing removal, coolant draining, trans draining, clutch and center shaft fussing and rear brake fluid disconnection. Had to tap gear out of Int. Hsg. (Pic) Had to unstick clutch alignment posts, best place to pry (Pic). Used extra deep extension to stop rotation to loosen center bolt on Alt. 3 blade spinner (Pic) and again to tighten.

The biggest surprise was a hard and soon to be cracked o-ring beneath the monkey nut “cush” spinner. This was shown on Clymer page 126, photo/figure 172, but not shown on any 2 Valve microfiche, so I didn’t preorder this and wanted a new one to put it back together (could do it after clutch and swing arm is on). Overnighted with 3 monkey nuts, a new starter o-ring, and 3 new rubber isolators underneath the battery, 3 were stripped out of the swingarm which I Heli-coiled two (6mm x1). The clutch friction disk was down to .187” (wear limit .177”) and the pre-bought new one is .217” It went in with a new o-ring, 30mm Nut and 6 screws which I tighten without a clutch center tool. I use my fingers to feel for concentric outside surfaces every place I can feel the friction disk outside and sneak up on the six bolts.

I pre-bought a trans. input seal but forgot it and put the trans back in as it was. The exhaust needed one clamp bolt, luckily I had a suitable bolt. The overnight shipment arrived without the starter o-ring and with the wrong alternator o-ring, so the old ones went back in. All back together and the battery, now topped up would not get it going, so bump start a few times, go 90 highway miles twice, still needs a battery.

Tools(Pic of all tools used): Used 6 & 8 metric hex (Allen) drive 3/8 sockets and a T-30 Torx ¼ drive that did not strip the bolts coming out. A 30 mm socket for clutch nut, a dental pick. Driving Helicoils (1/4” square post and smaller square post) took some cobbled up rigs.


Misc. Tips: Sweep under bike, raise rear tire on one lengthwise 2x6 then center stand on another across and rear tire comes out under fender easily. Keep Shop vac handy, box of latex gloves, full can of WD-40, roll of paper towels, spray bottle of kerosene, some clean rags, camera, White Out and center punch clutch parts, Pre buy some I beam clamps from electrical supply house, they supported two cam lock straps to the frame (Pic). The motor rested on a board on a floor jack. I also have a wooden front wheel holder that gets ratchet strapped to the front fork (brace). Add three good lights, some cardboard, some stools, a pair of sawhorses with a sheet of plywood and two or more numbered 18 hole egg crates(Pic). Had two flat washers left over, probably the bolts that hold the footrests. Lost a seat “e-ring” replaced it with a spare but found it later. After 180 miles, the rear dripped a little at bottom plug, found it could have been much tighter. Engine felt good as did the whole bike after almost no riding in Jan. and Feb.

Side Note: Wanted to drill access hole in intermediate case to “squirt sticking sprags” next time but the proper place for an access hole is 100% under the air box, there is no other place that would reach the sprag (Pic). This seems to go against a post suggesting such a hole in an easy access portion of int. hsg.
 

Attachments

  • IMG_1868small.jpg
    IMG_1868small.jpg
    93.8 KB · Views: 151
  • IMG_1872small.jpg
    IMG_1872small.jpg
    89.9 KB · Views: 150
  • IMG_1875small.jpg
    IMG_1875small.jpg
    100.4 KB · Views: 150
Last edited:
OP Here: Second set of 3 pics
 

Attachments

  • IMG_1876small.jpg
    IMG_1876small.jpg
    90.6 KB · Views: 151
  • IMG_1879small.jpg
    IMG_1879small.jpg
    110 KB · Views: 151
  • IMG_1880small.jpg
    IMG_1880small.jpg
    82.9 KB · Views: 149
OP here: last, third set of 3 pics
 

Attachments

  • IMG_1882small.jpg
    IMG_1882small.jpg
    108.5 KB · Views: 149
  • IMG_1888small.jpg
    IMG_1888small.jpg
    109.9 KB · Views: 151
  • IMG_1893small.jpg
    IMG_1893small.jpg
    92 KB · Views: 150
IMG_1873small.jpg10th and 11th pic

Note deep socket keeping spinner from rotating when loosening the center bolt and some melted monkey nut residue on spinner.

New Sprag Ring w same 3 radial holes as old 85 one, New Sprag finger part, Reused Sprag gear, old sprag ring and finger part w varnish and conical washer still in, 6 bolt hole stamping.
 

Attachments

  • IMG_1886small.jpg
    IMG_1886small.jpg
    98.1 KB · Views: 147
Last edited:
Now to amuse yourself and prepare for the next 170,000 mile service, soak the old sprag fingers piece in some carb cleaner to dissolve the varnish and gums. You will wind up with a fully servicable part ready to go in the next time you want to have some fun.
 
Original Poster Here: It's been so nice that every start button push results in the motor running. 20-40 times in a row so far. I park now without regard to how I'm going to roll it to bump start it.

The next and last thing that needs some attention is the trip odometer, I need to wind it around 2-6 times to get back to zero at gas fill ups. Of course I've found a webpage that explains what to do in fine detail, maybe I'll get to it this year, need an old one first for parts.
 
I've unstuck my K1200LT by removing the crankcase cover & using carb cleaner & soaking it with Marvel Mystery Oil. It has 200,000 miles & still works fine.
 
85K100RS Sprag Clutch Fixed/Not Fixed/Fixed

Original Poster Here
After 12,000 miles on new sprag parts it started slipping. This was just after having a week of "flooding" starting trouble, complete with puddles of gas coming out my exhaust to muffler joints. The flooding was due to the vacuum hose, with a spring surrounding, that leaves the rearmost throttle body and goes to the fuel pressure regulator. Back to the Sprag Clutch. After clipping 1/4" off the hose and putting it back on I was test riding it. What a bad sound when the sprag slipped, slipped some more, I then coast started it in 2nd gear. The next start the sprag slipped. This time I bump started it to warm it up on the highway 20 minutes to drain the oil (hot).

I am convinced that enough flooding gas and 10% alcohol got past my rings to pollute my Golden Spectro 4 oil that was only 2,000 miles old. The "bad oil" caused the sprag clutch to whirl (slip).

Now a new filter and 3.5 qts of Rotella-T 15W40 and it should be fine, if it isn't out comes that gallon and in goes a second one before I change the oil to go back to Golden Spectro. Bike now has 184,000 miles.

I will followup if and when it starts to slip again.
 
Last edited:
Original Poster Here
After 12,000 miles on new sprag parts it started slipping. This was just after having a week of "flooding" starting trouble, complete with puddles of gas coming out my exhaust to muffler joints. The flooding was due to the vacuum hose, with a spring surrounding, that leaves the rearmost throttle body and goes to the fuel pressure regulator. Back to the Sprag Clutch. After clipping 1/4" off the hose and putting it back on I was test riding it. What a bad sound when the sprag slipped, slipped some more, I then coast started it in 2nd gear. The next start the sprag slipped. This time I bump started it to warm it upon the highway 20 minutes to drain the oil (hot).

I am convinced that enough flooding gas and 10% alcohol got past my rings to pollute my Golden Spectro 4 oil that was only 2,000 miles old. The "bad oil" caused the sprag clutch to whirl (slip).

Now a new filter and 3.5 qts of Rotella-T 15W40 and it should be fine, if it isn't out comes that gallon and in goes a second one before I change the oil to go back to Golden Spectro. Bike now has 184,000 miles.

I will followup if and when it starts to slip again.

OK, it is just starting - so this is the perfect time for a dose of CD2 or Valve Medic in the fresh oil.
 
85K100RS Sprag Clutch Fixed/Not Fixed/Fixed /Not Fixed/Fixed

OP here: Paul just above suggested CD-2 or Valve Medic. Well after 3 good starts after the new Rotella, I got the whirr for a couple bump starts. To the Parts Store, bought a bottle of CD-2 Power Back Engine Restorer and Lubricant, added 1/3 bottle, bump started it, 10 miles later and several other stops, starter works as it should, btw it turned 184,000 just now. I'll lower the overall oil level to the window center real soon. Had hoped the new sprag parts wouldn't whirr for 100,000 miles but CD-2 doesn't cost that much. Maybe 1/3 bottle of Rislone Engine Treatment Concentrate 500 miles before my next oil change too.

Thank you again Paul.
 
Back
Top