CM91: Clutch Continued

My box from Beatrice Cycles came today bringing, among other things, a clutch nut tool and clutch basket holder.  So I figured I may as well push forward on the clutch disassembly.

Everything pretty much went by the book.  The screws holding the outer clutch cover were extremely tight, but thankfully not frozen (given that they were countersunk, if the impact driver couldn't get them out, I wouldn't have been able to Dremel them very easily).  The cover itself was also tough to get off and I had to resort to using a screwdriver to wedge it out slowly around the edges.

A few other oddities, as usual.  It seems that the cam plate assembly was damaged and then repaired.  Also, the set spring had no little "arms" on it, meaning it could freely rotate around in a circle. 


Some pictures...

The cam plate (showing a repair at the lower right?)

The outer clutch cover before removal (held by the two screws at the 2 and 7 o'clock spots).

The clutch basket holder tool - absolutely essential!

The clutch nut tool (uses a 3/8" drive).

The back of the clutch itself.

My set spring doesn't have the two little "teeth" that hold it in place.  It didn't really look broken, though, so I'm guessing that someone just swapped in an incorrect part to make it work?

CM91: A Picture of the Sunset

Ok, so this is just a picture of the clutch, but it's like climbing a mountain all day then saying your picture from the summit is "just a sunset".

I knew I'd be dealing with some frozen screws on the clutch cover, and the bike didn't disappointed.  Turns out all nine of them were frozen solid. 

Starting with the one at the 12 o'clock position, I just went around and tried the Lisle impact driver on each one.  I'm starting to get my technique down.  I usually start with a sharp hit to sort of set the bit in the metal.  But I try to make the next two as hard as possible, figuring that that's the point where you'll have the most grip.  If it doesn't work in the first three hard blows, it probably won't work at all, since by that point you're almost surely stripping the screw.

So as I made the circuit, I was able to free five of them just with the Lisle, stripping the other four in the process.  After the first stripped screw, I already knew the Dremel would have to come out to play.

I'd already been through a very tricky Dremel re-slotting when doing the rocker cover screws, and luckily all the stripped screws on the clutch cover were relatively accessible, though I did have to take off the muffler, foot pegs, and loosen the brake pedal so it hung free.

I used the same re-slotting approach I had before: cut a little, check the progress, adjust depth or angle as needed.  It really pays to make sure you're re-slot is wide and deep enough to give the impact driver plenty of grip.  If not, you'll just end up stripping it again, and by that point you'll have lost a lot of material.

Happy to report that the Dremel re-slotting followed by the Lisle's flat head bit freed the other four.  I was a bit nervous on the last screw, which was at the 7 o'clock spot.  Without taking off the brake pedal completely, I could only reach half the screw head with the Dremel cutting wheel.  So I just cut a slot on one side and that seemed to be enough to let the impact driver do its job.


So I couldn't have been more thrilled to gaze upon the fruit of hours worth of work...

 

 

A look at the oil screen...

A look at the screws that had to be Dremel'd...

S90: In Progress

Spent a little time just cleaning the big rust spots on wheels, fender, and muffler.  Nothing like brightwork that is actually bright.

S90: Stop and Go

Decided to take a look at the throttle and brake controls.  The brake lever seemed frozen stiff and the throttle had very limited movement.

First I popped open the clamp that houses the light switch and holds the throttle tube in place.  There's wiring that runs up through the handlebars and into the switch.  Pretty dirty inside, a lot of caked mud mixed with grease.  Had to scrape out big chunks of it with a small screwdriver.  After a thorough cleaning, the light switch had a full range of motion again, but I somehow doubt it'll work without getting into the wiring.

Discovered another modification: looks like the last active owner had setup the front brake lever to actuate both the front and rear brakes simultaneously.  There's a small custom piece that is screwed into the brake lever that operates a cable down to the rear brake (with another modification down there to link everything up).

The mods I've found on this bike so far: toggle switch (battery cut-off?) mounted next to battery compartment, skid plate mounted (of yet unknown origin), knobby tires, plus this brake modification.

 

The throttle cable is gripped by a piece of metal that can travel up and down the length of the handlebar.  The throttle handle itself has an internal thread that mates to the diagonal slot in the metal piece such that twisting the handle back and forth will pull or release the cable.

There didn't seem to be anything mechanically wrong with the assembly, it just seemed very gunked up with either old grease or anti-seize.  After a very thorough cleaning with WD40, it ran very smoothly and with good positive feel.

S90: New Seat!

The old seat was basically just rust held together by more rust.  No salvaging that one; it had to go.  Bought a new one off eBay for $100 delivered and it looks great.  It was a very tight fit against the tank, though.  At first I thought I had a seat from a different year that wouldn't fit at all (and perhaps it is the wrong year), but if you push it hard against the tank you can just barely get the bolts to line up and drop in.  Never take fit for granted on these old bikes!  Bolts and mounting points may look identical in a picture, but you need to confirm measurements to be sure.

I was happy as a clam seeing the new seat mounted, but I quickly realized that it's almost too pretty to leave on the bike right now.  The bike routinely gets sprayed with WD40, there's grease and oil going all over the place, and the seat is still sitting on a very rusty frame.

And so I learn a good lesson about the restoration process.  It makes sense to do things in a certain order sometimes.  As much as I wanted to replace the old tattered seat, mounting the new one on there is probably a bit premature.  It's almost like putting down new carpet while you're still building the house.

But still... I'll be damned if she doesn't look good in her new leathers.

S90: I Hate Spiders

I don't mind grease, mud, oil, rust flakes, carbon build up... but I just hate the dead spiders and egg clusters that are all over these old bikes.  Though I guess I'm lucky in that I haven't come across the mouse corpse (yet).

It was a less-than-glamorous garage session as I scrubbed the bottom of the engine with a steel brush to get all the crud and insect nests off.  I've decided not to put the skid plate back on, so I just re-attached the footpegs using shiny new bolts and washers along with a healthy dose of anti-seize.

S90: Top End

Pulled the cylinder head off the S90 to get a peek at the piston.

The Lisle impact driver took down four more stuck screws: one on the points plate and all three baseplate screws.  That makes it Lisle 10: Stuck Screws 2.

The baseplate was welded onto the cylinder head by the old gasket.  I had to delicately hammer a screwdriver tip all the way around the top until I could gently pry it off.

Managed to take a chunk out of one of the head cover cooling fins with an open end wrench.  Learned a good lesson... two actually.  First, they always tell you to be careful what your hand may hit if the bolt you're trying to loosen suddenly comes free - but same goes for the wrench itself.  Second, the age-old advice: use the right tool for the job.  I should have just used a socket wrench to pop these off instead of the open end wrench.

It only occurred to me later that evening that the S90 shouldn't actually have a skid plate.  I'm not actually sure what model bike this is from, though it's obviously made for a 90cc engine as it even has a cut out for the oil drain.  But the S90 also has some knobby tires, so it looks like the last active owner had turned it into something of a make-shift Scrambler.

Camshaft seems ok.

Some debris on the piston, but what surprised me was how little carbon build up it had, especially compared to the CM91.  Either the last active owner just kept it in tip-top shape, or maybe it never ran that often...

Same deal on the combustion chamber...

CM91: Stymied by Kickstarter

I'd hoped to get a look at the clutch today.  I knew there was a good chance that I'd be dealing with some stuck screws on the engine cover, but I never got past step one of getting the kickstarter off.  The bolt holding it on came off with no problem, but I think the splines are so gummed up on the inside that it's just jammed in there tight.

I'd spray it with WD40, worry it as much as I could, spray, worry, repeat.  Eventually I got it about halfway off but then ran out of time.  Maybe there's a trick to it, but if not, it'll just be more of the same until I can work it free.

This was as far as I could pull it out after 20 minutes of WD40 and wiggling it around on the splines.

S90: Vintage Oil

Is this what happens to oil after it sits for fifteen years?