125 lifan second problem

[Borgfamily41]

Hi all can anyone give me some idea if its worth trying to fix this proboem. I have a lifan 125cc engine. Motor runs great but wont engage second. It grinds away and the only way it will run is if I jump the gear to third. The box is the standard 1 down and 3 up configuration. I pulled the engine down but could not find anything wrong with the teeth, but maybe im missing something I should have looked at. when I put the bike up on a stand it seems to change with out problem, but soon discovered as soon as there is any resistance on the wheel while in second you can feel it grinding again and the wheel stops turning.

Im a mechanic by trade but dont have a great deal of experience with bike engines and would appreciate any help please.

Anthony

 

[rhysieboyy]

sounds like 2nd gear dog clutches are gone?i think thats the right word.

 

[Borgfamily41]

Thanks for replying. Not sure what that is. Please explain.

 

[rhysieboyy]

to be honest i dont know how to explain im yet to learn manual gearbox repairs(1st year diesel mechanic)sean01 would be the guy to speak to or terry aka the gdfp i think is his username,he is a site sponsor so just look for him in there.

 

[Borgfamily41]

thanks anyway mate.

 

[loace]

Pull your clutch cover off and check the shift drum mechanism if all looks good there no bent parts etc u will need to split cases, I'd just buy a whole new gear set and replace the old one , you probably hsve broken dogs or a twisted shaft

 

[Borgfamily41]

I have stripped the engine down twice now. Going to have to have a closer look at the teeth (dogs), but didnt know if you could buy the gear mechanisms complete. Can you get them or is it better to just scrap the motor and start again with a fresh one.

 

[lenny17]

you can buy new gear sets and shifting drums off dhz and other site sponsors mate, if your happy with engine size, power and speed just fix her up but if your not you can flog that off and up grade to something big

 

[Borgfamily41]

thanks mate.

 

[my67xr]

have a look at these
lifan gearbox | eBay

 

[sean01]

depending on the gear drum setup some engines had a drama with selecting gears.. if its the star shape one then you could try grinding out the star a bit..

but it does sound like the gear dogs are f'ed.. gear dogs are the little block looking things on the side of the gears, they lock into another gear with holes in the side. if any of these are stuffed then the gear will just jump back out..

also you say its only a 125 engine.. do your self a favor and buy a new engine. price wise they aren't worth repairing gearbox's as 125's are cheap. plus you get everything new not just a gearbox..