Clutch Clutch works Motor Runs No Motion.

[Creative Engineering]

The only keys I can get locally are the SAE standard ones.

They have to be worked a bit to fit.

Jim

 

[AussieSteve]

I just did a search and it looks like most people do that. On my dirt bikes I used to use a piece cut off the right-sized washer.

I'll check with one or two suppliers for ready-made ones, first. Not sure of the dimensions without pulling my engine down. My MBc search results give varying sizes: 3/16", 1/8", 2mm x 10mm.
(This is assuming that it is a sheared key. Symptoms are odd.)

Ha, my failing memory..... I forgot that I had a spare countershaft sprocket and woodruff key sitting here, (and my vernier).

Dimensions: 2.4mm x 8.9mm x 3.6mm

 

[AussieSteve]

Woodruff Key Suppliers

In the US, woodruff keys can be had from GasBike.net, for $3 each, here, (mid-page, RHS).

I just emailed ZBox in Oz to see if Steve will sell them separately.
Yep, same price - $3 each plus $6 delivery - got four ordered as spares.

 

[will_start]

will_start,

Describe exactly...what happens after you start it?

Jim

Start motor as normal, hold clutch in warm engine up.
peddle, release clutch all the way out and rev engine.
nothing happens. Its like the clutch is still in.

IE bike don't move unless I peddle.

need i say more.

I made a vid of installing the woodruff key on small clutch cog.
about 16 years ago on this motor.

I'll post Utube link if I find/search it and MB.com link,
but don't hold ya breath.

FOUND LINKS
page 2 of the below.
http://www.motoredbikes.com/showthread.php?t=8422
http://www.youtube.com/watch?v=_CqUZ0EtGiA

That vid has had 3,300 views...goes to show how much
the woodruff key sucks !!!

 

[AussieSteve]

Was that really 16 years ago and same motor?
That's one sweet HT engine.

On a serious note, your description is exactly how I pictured it. I can't imagine it being anything but a sheared woodruff key, to cause that freewheel effect.

 

[will_start]

Was that really 16 years ago and same motor?
That's one sweet HT engine.
On a serious note, your description is exactly how I pictured it. I can't imagine it being anything but a sheared woodruff key, to cause that freewheel effect.

It feels like 16 years ago (jan 08). I use that timeline description, to affect whats happened to me in that time-frame...3 girl-friends, too many dates to mention, 1 job redundancy, 1 divorce, 3 house moves...you do the maths.

If the Woodruff Key I show in the vid is sheared, then the motor will not start.
So, where are these other mysetrious wood-ruffs A & B, and I need a diagram.
There was an exploded diagram of the motor on this site somewhere...

 

[AussieSteve]

If the Woodruff Key I show in the vid is sheared, then the motor will not start.

Quite true, usually, but at times after shearing they grip at times and slip at other times.
Very possibly, one of yours has sheared and is doing that.

This is a very unusual problem, as Jim and I said earlier, and it's hard to find an explanation for the symptoms.

I don't need to watch the video, (PC is faster but I'm still on dial-up for now), the woodruff key that you replaced is the one on the crankshaft.
It drives the larger cog on the clutch. When the clutch is fully disassembled, there's a nut holding it's base plate-onto the countershaft. When the nut is undone and, using a gear puller, the clutch base-plate is removed, there's a woodruff key that's used to locate it on the countershaft.
On the LHS, there's a woodruff key locating the front drive sprocket on the countershaft.
(Also on the LHS, under the front side-cover, is another one used to locate the magneto rotor, as I've mentioned. This couldn't cause the problem that you describe, though.)
These woodruff keys are identical to the one you replaced before.

 

[srdavo]

Bike stopped.

Clutch works to start motor, motor runs.
But I try and engage engine, and get no motion.

I just gotta ask..... are you pedal starting, or do you use a pull/rope starter??

 

[AussieSteve]

Good thinking Dave.

 

[Stan4d]

Real curious question. If you pull the plug and roll the bike forward and backward with the clutch engaged does the motor turn. In both directions? After removing covers you might be able to do this and see where the loss is. (On electric forklift final drives,I have seen woodruff keys snap and only slip when powered one direction.)