Replace watercooled nc250 with zong 230cc aircooled

[b44]

Long time no post here, but was going to try something a little different,
Ive got a zongshen xtr/cfr crossfire nc250 watercooled mx bike, got 2 engines both watercooled,found out they both have catastrophic gearbox failures,not even worth rebuilding,
Was getting angry at the amount of time required to rebuild these engines water jacket etc, was thinking how good would it be if a 230cc would bolt straight in,
So i tried and the it bolts straight in, even header pipe fits.
The engine i tested the fit in is a dud, so may look at getting a used one and try that, has anyone tried this?
That 230cc is awesome to work on,simple small & robust
Only drama i can see is the chasis (stamped.steel honda crf250 copy ) is pretty heavy so power might be down a bit,
I like the theory of it,as the chasis build quality is pretty decent, better than the last zong i had, great engine, crap frame
Any thoughts will be appreciated

[Merlin]

i would go for the 230cc. Look on TaoBao you might be able to afford a new one.

[crackerjac]

I'm actually in the process of using an extra air cooled ZS230 in a CRF450 frame cause why not if you have the extra parts, lol. Being all aluminum I don't see any issues but with an all steel frame you have it's hard to say if the little air cooled 230cc 12~15hp motor would like it. They are really cheap to buy and work on though, and I find them pretty reliable.

[pete]

theres something to be said for the old school air cooled motors..
My TTR is carbed ,air cooled never gives a moments trouble..
no radiators hanging out the side of the tank to bend... i bent
2 radiators on My GasGas & I could boil it on real slow gnarly terrain.
being air cooled it's down on power a bit but still more than enough
to put yer on yer ass... I think the TE125 Husaburg has more Hp , which
still looks new... I ride the TTR all the time... I really should sell the Burg...




.

[b44]

All done, found a cheap used loncin 230cc,for $50 , gave it new piston rings, valves, regrind & stems, everything bolted up perfect was very simple straight forward swap, rings are stil being bedded in, but very happy with result, chasis is a bit bigger & stiffer , but also can take alot more hard knocks, left the honda stickers on for bit of a laugh,running 13front sprocket 51 rear, gearing is spot on for the tight trails here, not bad for a $350 bike

[Weldangrind]

Looks great! Is the swingarm steel?

[Rangerscott]

I'd take those engines off you hands. Dang oceans in the way. Lol

[b44]

Yes steel swingarm, & to be honest id be hard pressed to rebuild the watercooled ones, the bottom ends are identical to 167-169fmm, but jug & piston are a true 250cc, im betting why so many gearbox issues with the 171fmm, higher reving /bigger piston on a bottom end from a effectively a 150cc, im glad i went with the simple aircooled 230cc, engines are so plentiful here in oz, its almost not worth the rebuild in some cases, but such a good simple engine to work on, i might just rebuild a spare just because

[Weldangrind]

I'm wondering if the CRF250 swingarm would be a bolt-on deal.


I bet you could rebuild the bottom end of the water cooled motor with XR200R parts, giving you Honda reliability and an extra gear.

[Rangerscott]

Youre lucky having easy access to engines. I dont know of any place in the US that sells engines. Usually its just a person selling chinese bikes on the side.

[b44]

According to xtr-crf compatibility chart the swingarms are 1:1 match, that'll be a nice diet,
Ranger , unfortunately there is next to no interest in 2nd hand watercooled & aircooled engines, im resigned to the fact ill just have to use as a ornament or throw em, eg i got both engines for almost nothing, good grunty little things but found bottom ends to unreliable, people are practically giving them away

[crackerjac]

Did you fab up your kick start lever or is that a stock piece? I'm going to have to make something or buy something like you have for clearance on my conversion if I have to ever use the kick start as the foot peg and rear brake lever are in the way.

[b44]

Originally Posted by crackerjac

Did you fab up your kick start lever or is that a stock piece? I'm going to have to make something or buy something like you have for clearance on my conversion if I have to ever use the kick start as the foot peg and rear brake lever are in the way.

Crack
stock piece mate, lever has L bend, it, :clears it perfectly

[crackerjac]

Stock piece? Refresh my memory what bike is this from? I need to buy something similar.

[b44]

Originally Posted by crackerjac

Stock piece? Refresh my memory what bike is this from? I need to buy something similar.

Xtr250/xz250rr /chasis is crf250r copy
Ebay has great selection of all these kickstarts, $16-$20 delivered