Centrifugal clutch blues

GoldenMotor.com
silverbear

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
8,325
670
113
northeastern Minnesota
locutus_1 said:
the sleve you put on covers the keyhole there is no cut in it like the stock manual gear.... it uses friction and the bolt... thats what mine is
Click to expand...
You're right as I recall. I had two of these HT girls. First one was a dream for a year until it started slipping. Before that started happening I had ordered a second one. Was still working on the first one, trying to create a slot for a woodruff key when the second one came... installed it on a second bike and it was crap from day one... went fifteen feet and the clutch no longer worked. I lost both engines in a fire a week later, so never resolved the issues. All I can report on the positive side is that first year with the first engine... just a real nice experience and no 'wobble'. Sounds like a bum motor to me. Much as I liked that first one I'm done on HT automatics, having moved on to four stroke automatics with pull start... oh yes.
SB
 
L

locutus_1

New Member
Oct 31, 2010
196
0
0
california
usflgi think ill just use the engine till it falls apart... then switch over to the 4 stroke one.. or even then i can fab my own stuff...

these engines are just crap.. learned my lesson..:) but since i already spent the money and dont have anything else for now might as well enjoy it...wee.
 
rohmell

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
Guys, Guys, Guys, don't give up.

I just got my centrifugal clutch in the mail, and like everyone else, there is no keyway machined into the clutch itself.

I will machine a keyway into the clutch, but it will not be a tight fit.
There will be a tiny, wee dab of clearance so that the clutch can slide onto the crankshaft without hitting the Woodruff key.
On startup, if there is any slippage between the clutch and crankshaft, the clutch will rotate a little bit , like a micron, until it hits the Woodruff key and then it will jam and stop.
The key will not be able to come out of its slot due to its oval shape, as it comes out, it tends to rise, and will hit the keyway in the clutch and stop coming out.

I have a spare crankshaft, so I can test fit everything and see what the deal is with these Woodruff keys coming out after usage.

So don't give up, keep at it.

By the way, my centrifugal clutch kit came with a 'puller', it engages the threads that are in the hole where the fastening bolt goes, and the end of the 'puller' pushes against the crankshaft, and you turn the 'puller' and the clutch comes off.
 
Last edited:
rohmell

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
UPDATE: 50 miles on the centrifugal clutch so far, and it works great.

I test-fit everything with my spare crankshaft, and when I tried to install the clutch on my regular MB, the taper was different and the clutch did not go deep enough on the crankshaft so it was hitting the outer cover when I put that on.

I machined away most of the taper in the centrifugal clutch and cut the keyway all the way to the shoulder that is on the inside of the mounting bolt hole. It slid on easy until it hit the taper portion and tightening the bolt homed the clutch all the way in, so no more rubbing on the outer cover.

The Woodruff key is contained fully inside of the clutch, so no way it can rise up and out of position.

I don't think it is a good idea to rely on the taper to hold things together and keep things from going wrong.

I think all of my future China Girl MBs will have a centrifugal clutch installed.
 
Last edited:
silverbear

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
8,325
670
113
northeastern Minnesota
Nice going. Sounds like you have a sound good to the problem. While mine worked I really liked it. I didn't like it so much when it slipped and I went nowhere.
SB
 
rohmell

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
Sorry SIlverbear, no photos.

I do have a digital camera, but the closeups are always fuzzy and out of focus, no matter what the settings are, macro, micro, wide, tight low res hi res, etc., you get the idea.

I have seen some excellent, excellent closeup shots of gears and carburetors, etc. on this forum, if only I knew what kind of camera(s) was being used, I would buy one immediately!
 
industrialphreak

industrialphreak

Member
Sep 7, 2008
188
3
18
Omaha,NE
silverbear said:
I got the bike out to remove the clutch cover and noticed something. There appears to be a bolt missing as shown in the first photo. The second photo shows my other automatic with a bolt in the same spot. Could this be the problem? What is it for? Anyone know? I hesitate to just remove the one from the new engine without knowing what's up, but if there are no responses I guess that's what I'll do, make a trip to the hardware for another and see if that was the problem. Thanks in advance.
SB
Click to expand...
Yeah i would make sure that was fully in their otherwise you could have a catastrophic failure like i did. see the photo link. https://picasaweb.google.com/lh/photo/v3konhretSS8lbLo-e5e2A?feat=directlink
 
V

vincent713

New Member
Jun 2, 2010
287
0
0
Dallas
GearNut said:
There really are no adjustments on the cenrtrifugal clutches other than changing out the springs to affect engagement rpms.
I agree with AaronF, check to be sure that the woodruff key is still where it should be and that the nut is tight.
Click to expand...
I thought you're suppose to take out the woodruff key to install the centrifugal clutch?
 
rohmell

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
vincent713 said:
I thought you're suppose to take out the woodruff key to install the centrifugal clutch?
Click to expand...
Yes, the centrifugal clutch uses the crankshaft's taper for a friction fit, and the Woodruff key is not used. Some members machine a keyway into the centrifugal clutch so that the Woodruff key can be used with it.
 
V

vincent713

New Member
Jun 2, 2010
287
0
0
Dallas
rohmell said:
Yes, the centrifugal clutch uses the crankshaft's taper for a friction fit, and the Woodruff key is not used. Some members machine a keyway into the centrifugal clutch so that the Woodruff key can be used with it.
Click to expand...
I have a dremel tool, which bit can I use for this mod?
 
You must log in or register to reply here.
Top Bottom