How did this happen?
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Allen_Wrench
Resident Mad Scientist
I think Norm or Tom or some of the more experienced builders on here could give you a better answer, but "mechanical or manufacturing defect" is the first thing that came to mind. If one gear had a weak tooth, that'd break some time, then with the aid of momentum the engine would strip the rest off, I imagine. Or if something were to make your rear wheel seize solid and the chain held, you MIGHT get a stripped gear like that.
I think the important question is: would it be cheaper to buy a new China girl? Or is it safe to fix this one?
I think the important question is: would it be cheaper to buy a new China girl? Or is it safe to fix this one?
Maxvision
New Member
Did you look to see if either gear still had it's woodruff key in the keyway? If either gear was ever taken off and put back on, the woodruff key might not have stayed in the keyway and spun out once you got to high speed then lodged between the gears. Only other think I can imagine is a washer or something was left behind in the clutch case and got caught between the gears or one gear tooth broke off and stayed between the gears causing a chain reaction.
Those gears start as powdered metal I believe. Might have been a defect in manufacturing.
Those gears start as powdered metal I believe. Might have been a defect in manufacturing.
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Venice Motor Bikes
Custom Builder / Dealer/Los Angeles
I've never seen that before!!
It's easy to replace the gear for around $15
It's easy to replace the gear for around $15
no it ran smooth since day one, this engine has roughly 150 miles on it, this is my "around the neighborhood" bike. about 2 miles into the ride today, i heard the grinding for the 1st time and quickly turned the engine off. inspected what i could without any tools then tried starting it up again with no luck, it just didnnt engage. i ive never taken the clutch or the crankcase apart so im assuming the woodruff key didnt have a chance at coming out. looks like all i need is this: http://www.bikeberry.com/engine-kit-parts/crankcase/small-bevel-wheel.html to make it run again.
Maxvision
New Member
Hey Yuri, did you check to see if your piston seized? oh wait...if piston seized you wouldn't have spun off the teeth on the small gear...well maybe it could if it seized for a second, broke a tooth then broke the rest in a chain reaction. Will the bike roll with the clutch pulled in?
Can't see from the picture but is the machine screw still in the clutch adjustment nut on the outside of your clutch plate? Is the inside of your clutch cover scored from the adjustment screw grinding on it?
Can't see from the picture but is the machine screw still in the clutch adjustment nut on the outside of your clutch plate? Is the inside of your clutch cover scored from the adjustment screw grinding on it?
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Toadmund
New Member
I was thinking about that same theory, a crack in one tooth, it broke and the gear teeth clashed and broke the rest.
To the OP, were there chunks, bits, or dust on the bottom of your gear case?
nah its not seized, i can manual turn it over.
the machine screw is still in and tight. the bike rolld with or without the clutch pulled in
Maxvision
New Member
Another one of the Universe's mysteries I guess. Kinda like why does a ketchup bottle have a neck so skinny you can't get the ketchup out
Before you send off for a gear see how thick the keyway is. Some motors have thinner keyways. Or bring the gear over, I'm sure I have one that will fit.
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