Need Help! Gearbox problem 125 Ji Pin engine

[Sanford & Son]

I have bought a 2nd hand 125cc pocket/pit bike for my son for x-mas & don't know much about them. It's been working gr8 until it started to jump out of gear every now & again. Thinking it might have been my son's fault as he is just learning to use gears & clutch, I didn't worry about it until just recently on a ride, it started to jump out lots. after stopping we discovered that we couldn't find neutral easily. After returning home it was almost impossible to find neutral & when you did if you moved the bike forward or back it seemed to engage gears again. It seems to me that it may have a problem with the selector but not knowing these type of bikes I'm a little reluctant to split the case to take a look. Is this a common problem & if so how do I fix? The engine is a 125cc Ji PIn 1down 3up gear pattern. any info on this engine would be gr8. e.g how good are they? is it worth fixing? & can I put another make of engine in it if it's not a good 1? I don't even know what type of bike it is which makes it hard to find parts for it, like the plastics(which we need), So if anyone can help identify the bike that would be a gr8 help also.
It was brought from ebay shop for x-mas 2006 & then sold to me in nov 2007,
the new price was approx. $699. I haven't been able to find 1 like on internet as it is an old model.

Love the website, Excellent that it's Australian!
Thanks for reading.
Regards Brett

 

[cass38a]

I dont know how much you paid for it, but your best bet would be to piss it off and get a better bike. I know that this is not the answer you want but buy the time you sort it you will wish you bought a new bike with a Lifan engine.

 

[nafe]

i had a ji Pan 125 not long ago. i only paid 500 for the bike brand new and never even took the transport oil out, or changed the oil or anything. It ran fine for a year then started having problems. Having experience with these motors i would just get a new motor from eBay or some where cheap, if your not looking at ripping it up just taking it easy grab something cheap. The deeper i delved into this motor the more problems i found and ended up getting rid of it. lol it literally fell apart.

 

[Sanford & Son]

Thanks for the response, still wondering if I can replace it with another make of engine if they all bolt in the same way or are they different how they bolt up? We only paid $300 for it which isn"t much but my son is very disappointd as it hasn't lasted long after xmas & we can't afford to buy a new bike. Is buying 2nd hand o.k or is this asking for trouble?

Regrads Brett

 

[Custom]

The gearbox problem is an easy fix, all the problem is is the roller has sliped off the star cam.