Lifan 125cc jumped out of second gear?

[Pitsterpits]

As the title of this Thread states, my lifan 125 engine jumped out of second gear by itself yesterday when I was riding trails. I hit a bump and it got in neutral and revved up...

My clutch IS adjusted correctly, so it must be something inside the gearbox thats gone bad suddenly? I got 20 Hours on this, and have changed oil VERY often!

Is this a common problem on the 125 lifan engines? it is the 1 down 3 up..

Thanks for answers!

 

[my67xr]

check the bolt that is behind the rubber bung above the front sprocket to see if it's tight
that holds the shift drum in place.
otherwise it may be the bolt on the other end of the shift drum has come loose
you need to take the kickstart lever off, and then the whole clutch cover off to see it

you can then clean your oil filter/strainer too while it is apart, it sits at the front bottom of the clutch in the r/h engine case (directly above the oil drain bolt)

 

[Pitsterpits]

Thank you very much!

 

[my67xr]

in the picture below, you can just see at 11 o'clock behind the big gear, a smaller star.
when you have the cover off you will see the 10mm headed bolt that holds the shift star to the shift drum, this is the other bolt that could be loose
the guys thumb sort of points towards the shift star bolt, diagonally down to the left of the yellow top engine mount bolt/nut

 

[Pitsterpits]

Highly appreciated! I will take it apart tomorrow to take a look, and let ya know what caused it

 

[my67xr]

just be careful taking the side cover off, that you don't break the gasket,
it sometimes sticks to both sides and can tear as you try to separate the cover from the engine

 

[Pitsterpits]

I will try to be careful

 

[Pitsterpits]

I checked the bolt behind the rubber bung, it seemed fine.
Took the entire clutch side cover off, to check the other one, didnt damage the gasket luckely!
I found out that one of the 4 screws on the clutch had been damaged from factory, so I will be struggling a loooot if I ever need to take it off...
Everything else in there seemed in very nice condition, I got to tighten the 10mm that holds the drum maybe by 1/5 of a turn. So Im not really sure if there ever was a problem with them not being tight enough.
Checked the oil strainer/filter as well, and it had NO metal particles or debries in it, That may be due to the Magnetic Oil drain plug, wich I HIGHLY recommend !!!! That will save your engine.

Anyways, fired it up afterwards, took it for a long and nice run in the trails, shifted smooth, everything was normal. I might think a branch or something nocked the gear shifter down a bit or something, so it hit neutral....you never know do you

But another problem I have, it that when I fire it up, let it warm up it can stand on the support tilted in neutral just fine. But when hot, it will make a grinding noise and pop into 1st/2nd gear sometimes... So always after a run I have to keep it standing up before turning it off..
There is something in there thats not right though, but it has NEVER affected riding/ gear shifting. Common problem with the 1 down 3 up?