Well, I think my motor is RIP'd.

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Mozenrath

New Member
Jan 13, 2011
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California
I'm very angry.

I finally got my centrifugal clutch working, and I just rode my bike a few hours ago.

I come back to ride it again, and it doesn't start. Instead, I hear a grinding sort of noise, and when I open up the head, I found that the piston only moves maybe 1/8 of the time and only one of the wheels on the inside seems to move.

ARRRRRRGGGGGG
:-||
So am I SOL?

EDIT: Here's a video where I explain my problem.
View My Video

EDIT 2: I've pretty much concluded that the clutch side of the crankshaft is slipping somehow. It may still cause piston movement, but any sort of pressure on the piston causes that side of the crankshaft to slip. I really hope I won't have to rip open my entire engine. :(
 
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Mozenrath

New Member
Jan 13, 2011
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California
Anyone? I've posted a video so I can show you guys my problem.

View My Video

I apologize for the crappy lighting. Like my bike engine, my garage lighting system has failed.

What I've also discovered is that this problem does not occur when I turn the motor backwards. When I turn the crankshaft forwards, it seems to "skip" 1 out of 8 piston cycles.

Could the centrifugal clutch being a little wobbly have caused this?
 
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Mozenrath

New Member
Jan 13, 2011
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California
Thanks for responding!

It has nothing to do with the woodruff key. At least the one used on the small gear. Not only is it not sheared, but I've moved the shaft without the gear even attached to make sure it's moving.

From what I can tell, the piston arm is somehow partially disconnected from the fly wheel closest to the clutch. Does this even happen, though? I'm not sure how that's even possible.
 
Ibedayank

Ibedayank

New Member
Oct 29, 2011
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Columbia Tennessee
Mozenrath said:
Thanks for responding!

It has nothing to do with the woodruff key. At least the one used on the small gear. Not only is it not sheared, but I've moved the shaft without the gear even attached to make sure it's moving.

From what I can tell, the piston arm is somehow partially disconnected from the fly wheel closest to the clutch. Does this even happen, though? I'm not sure how that's even possible.
Click to expand...
each shaft has a woodruff key on each side of the shaft thats 4 woodruff keys in all
 
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Mozenrath

New Member
Jan 13, 2011
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California
I'm guessing that said woodruff keys are inaccessible without cracking open the engine?

Still, looking at it that way, a sheared woodruff key would be better than something more serious. I still really don't want to tear my engine apart, but if the problem isn't serious, I may get a chance to balance my crank. :D
 
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Mozenrath

New Member
Jan 13, 2011
340
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California
Wait, I'm a little confused.

Which gears are we talking about? Let's eliminate the larger clutch gear, because I have turned the crankshaft without it being connected, so it's irrelevant.

Are there other gears that I am not aware of? The small gear on the clutch side didn't have a sheared key, and I have physically moved the gear shaft with my hand and I could see it turning. The problem occurred. That side of the crank has little effect on the piston arm; if I apply any pressure, that side seems to slip. The flywheel on the other side of the crank seems to still be connected to the piston arm and it has complete influence.

Which I think means there is either something wrong between the flywheel and the piston, or there is something wrong between the crank shaft(the shaft that the small gear connects to) and the clutch-side flywheel.

Are there woodruff keys between either of those areas? I'll take some more video and pictures soon because maybe I'm not being entirely clear.
 
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Wally

New Member
Dec 25, 2011
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South Africa
Go and have a look at pictures of the engine they are on this site. You don't know what you are talking about and neither do I. See the chain that drives your back wheel is attached to a small gear on the left hand side of the engine. A shaft goes through to the right hand side of the engine where it is attached to the clutch, a big gear the clutch is part of. The clutch gear runs on a small gear to which the crankshaft is attached.
 
POPS

POPS

Member
Sep 8, 2008
310
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16
Vancouver Island BC .Canada
Did you read the post about the C clutch.

If you did not read it than the problem is

in your clutch. Did you make a new spring

for the center of your clutch to hold it over

to the right or did you just put it on without

a spring. You put it on without a spring...Right!!!

There is your problem!!! Read the clutch thread!!!

POP'S
 
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Mozenrath

New Member
Jan 13, 2011
340
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0
California
No, I know what I am talking about.

The problem is NOT in the clutch! The clutch is completely disconnected, and the problem still exists.

Just to clear things up, what I am referring to as the "small gear" is the one that drives the clutch, not the small sprocket that drives the sprocket on the rear wheel.

Again, this problem happens whether or not I have the clutch attached or not. I have completely removed my centrifugal clutch, and all I am doing is turning the small gear by hand. In fact, I took off the small gear and I am simply rotating the shaft by hand. I'm pretty sure that the clutch-side flywheel should not be slipping on the arm, am I correct? If that is true, then it shouldn't have anything to do with the clutch.

As far as my cent clutch is concerned, I doubt it had anything to do with the spring(though I could be wrong). I lost my spring a while ago, but it still only freewheels in the correct direction without it. I rode around with the cent clutch just fine and it seemed to function normally. I didn't begin to have my problem until I tried riding my bike again. I couldn't even start it.
 
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Greg58

Greg58

Well-Known Member
May 1, 2011
5,353
2,575
113
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Newnan,Georgia
Try this, turn the magnet end of the crankshaft while holding the small gear end. There shouldn't be any flex or movement, if you turn the magnet the small gear should turn the same. Some members report crankshafts that bolt together.
 
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Mozenrath

New Member
Jan 13, 2011
340
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California
Here's another video.

Again, forgive me if I get my terminology wrong. But I think this is going to mean having to crack the whole thing open. If the piston arm is not properly connected to the flywheel, I don't see how I can reconnect it without ripping the whole thing apart.

View My Video
 
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Mozenrath

New Member
Jan 13, 2011
340
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0
California
Okay, I think I found the problem

It appears as if the two flywheels actually severed from each other. :(

Am I right about this? Also, is there any way to fix this without buying a whole new flywheel? How the **** did this happen? I'd think if there was extreme pressure, any of the woodruff keys would have sheared.

The place it sheared off is uneven, so that explains why sometimes it would work and sometimes not.
 

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bigbutterbean

Active Member
Jan 31, 2011
2,417
3
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Lebanon, PA
might as well buy a whole new engine. the centrifugal clutches for these engines usually wont work right unless you do things to make them better. I had a cent clutch fail after 3 or 4 rides. I went back to manual clutch and never looked back. you can still pull start an engine with a manual clutch as long as you start it with the clutch in.
 
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Mozenrath

New Member
Jan 13, 2011
340
0
0
California
Why do I need buy a whole new engine? Can't I get a new bottom crank? Gasbike.net sells one for $18.

http://www.gasbike.net/Bottom-End-Crank-Assembly.html

That seems to be the only part that's broken on my bike. Would this crank from gasbike work with my 66cc engine?

Also, does anyone have any idea why this would happen? I still can't imagine why the cent clutch would cause this, and why the woodruff keys didn't sheer if there was too much torque.
 
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