Honda xr125 engine swap

[Chrisc54]

Evening all been helping out a mate with his 2005 xr125
Due to low oil the engine is totally shagged and eaten half the piston and conrod so needs a new one

Hes on a budget and the bikes only worth about £500
Only decent engines ive found on ebay are around £450 so was wondering if theres any other engines that would pretty much bolt right in like a cg or xl lump?

Cheers chris

[Teflon-Mike]

Most of the small honda 4T singles share common frame mount bolt patern, so both a CG or an XL engine will bolt in the frame; in fact XR uses the CG pushrod engine; so any of the Chinky pushrod CG copy engines should drop in a treat.

Anomolies come in the ancilliaries; matching carb to airbox and generator to electrics and didderent plugs. BUT you have the oroginal engine, so just swap the generator and anything else off that on to donor motor.

Chinky copies are cheap and MOT fails especially' I'd likely go for a whole bike as easier cheaper tham trying to source just an engine.

BuT, genuine XR aught command more than £400, so if its really a knacker to start with.... there is likely more needs sorting than just the motor to worry about.

CG lump itself is pretty easy to work on though, and a barrel & piston kit is daftly cheap, like £50... might be worth stripping the motor and seeing just how beyond redemption it is; a rebuild might be cheapest as well as most reliable option. You never know how much 'better' motor frome a take-out may be.
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[Chrisc54]

The engine is not worth trying to rebuild in my opinion
This is whats left of the piston that was floating in the barrel
The con rod an gudgen pin ect have disintegrated an smashed up the bottom end
https://flic.kr/p/28y9hV9

The bike was mechanically ok just very tatty an had been stood for a year before we got it up and running

Will have a look an see if i can find a cg engine from a similar year
Only ones ive see so far are very old ones that look to have a different valve setup