CB 125 - XR 200 head and barrel swap

Looking into doing this swap on my CB 125

What years of XR 200 head and barrel work

Is it a direct swap

What all do i need? (carb, header, anything else?)

Thanks,

Curtis

Its the 80s models. Check the cylinder base gasket part numbers on here: http://www.westhills-honda.com/fiche_select.asp If the cylinder base gaskets numbers match, you should be good.

VonYinzer said:

Its the 80s models. Check the cylinder base gasket part numbers on here: http://www.westhills-honda.com/fiche_select.asp If the cylinder base gaskets numbers match, you should be good.

Click to expand...

Thanks,

Not having road an XR 200, will I notice a huge difference or no?

The difference between an xr200 and a cb125 is night and day.

You have to bore case, cylinder wont just slip in
You'll need to fit 185/ 200 crank as well as there is about 8mm difference in stroke
I haven't done one for a long time (around 1980)
It's much easie rto use a modified CB750 piston which gives you about 145cc or look for a complete 185/200 motor
The ATC motor uses a different cylinder head so don't bother with that.
Major problem will probably be finding an XL/XR as the motor is pretty unkillable if you keep some oil in it
There is a huge difference in stock motors between 125 and 200, about 9.8bhp to 17bhp, up to 22bhp with modifications (overbored XR200)
24bhp is possible, but, it doesn't last very long (maybe 20 mins?)

Not even worth the swap then.

The Lifan 200 is a chinese clone of the Honda 200 OHC engine, they are not very expensive to buy as a crate motor that will bolt straight in and they come with carb and cdi and a starter motor as well as a kick start. Plug and play.
http://www.china-parts.co.uk/acatalog/info_EN001027.html
A lot easier in the long run than trying to squeeze more zip out of your 125.

The LIFAN is a push rod motor, the 'screw' in middle of cylinder is pivot point for rocker arms
It is a cheap alternative and it is 200cc though

Oops, I meant OHV. I know people who've done some quite challenging offroad journeys on bikes fitted with this engine and they can't fault them. Also come in watercooled flavour:

http://www.china-parts.co.uk/acatalog/info_EN001026.html