QM200GY (XF200) lost 3rd gear, possible causes?

I was riding in forest when suddenly the revs went up and the bike stopped moving. I thought of snapped chain or something, but I was wrong. 1st, 2nd, 4th and 5th gears work fine and there is no 3rd. It just like in neutral, the bike does not move. There was no abnormal noises coming from the engine when it worked, there is no noise now and there wasnt any when I lost the gear. It just went.

I took the engine out of the frame and I'll try to split it as soon as I can. Does anybody have any ideas what might be wrong with my bikes transmission or do I have to let it be a surprise?

I will take pictures when splitting the engine...

http://www.gadgetjq.com/transmission.htm

You likely wore down the dogs, and its no longer able to engage.

There is a shop manual on this site for that model.....not sure were it is though.

Service manual thanks to Andrew.

http://www.jamestowncomputer.com/cli...ial-downloads/

I already have service manual thanks to this forum. :)
I opened the engine, took me about an hour or so. MJH is right, dogs are fractured. I must admit that dogs on these gears didnt look like they are very strong.

So I need a new gear. Broken one is on the driven shaft (shaft which has the sprocket on it) of the transmission. Dont know if local dealers can help but I e-mailed to them about that.

I'll upload pictures of the damage later.

Nice work, Extinction! I admire your confidence and skill with the wrench.

I the gear is not too difficult to find, and that you can share your repair with us through photographs and descriptions!

good luck.

Split crankcase. Almost everything has been taken out:
Attachment 4004
Here's the gear with broken dogs:
Attachment 4002
It came from the driven shaft (I put it next to the shaft with other gears to take a pic):
Attachment 4003
There is some stange marks on some of the gears on the other shaft.
Attachment 4001

I would replace all part that are damaged…I would not keep the damaged gears. You may have had a piece caught between the gears that caused the marks? All this stuff is typically caused by missing gears when shifting.

Also the wearing in on bikes comes into play and also the idiots spreading the hard break in theory, the importance of good oil and regular oil changes as well matter.

Heating cooling expanding and contracting gears that all are meshing….the metal changes characteristics and eventually stabilize and then over time eventually loose strength, Chinese made bikes do not have or use the best metal and have shorter life spans.

Eventually at a certain accumulated mileage the metal looses it strength and the bikes have to be retired. That is all bikes, but you can be sure that the Chinese die sooner.

If you check the service manual you will see that the Qinqqi has a actual scheduled end of life.

Were are you on the time line? If you have very high mileage accumulated then consider that before repairing it because other metal components liked bearing and such can become life threatening. Old is high mileage and high mileage bikes can seize up, the metal only lasts so long.

Holee sheet, Extinction! Those broken teeth were sloshing around in your crankcase?? You're pretty lucky they didn't find their way into the engaged gears or you'd have had a very abrupt cessation.

Sounds like very good advice from MJH to go ahead and replace all five gears, especially if they are showing signs of normal wear or, as you've noted, unusual markings.

This really does put MJH's observations about the qualities of metal into perspective as well. Let's all give our engines a few minutes to warm up before putting them under the heavy strain of normal use!

excellent pix, and I especially like the special daisy patterned towel you've used for displaying the errant gear!

cheers

I found the gearbox original in taobao.
I would like to know how to buy parts for motorcycles in China and receive here in Brazil

http://img01.taobaocdn.com/bao/uploa...sw9_102640.jpg
http://item.taobao.com/item.htm?id=3421440463

Euphonius, yes they were in the crankcase, I found 3 of them, fourth piece must have gone missing.

I'm currently waiting for my local china bike parts dealer to answer my e-mail. They dont have any parts for the QM200GY on their website.

Luis Carlos, I found the whole new gearbox with all gears and both shafts from taobao, too!