Help wanted! Big bore kit for my Zongshen 250cc CB replica or XR250R engine?

[Chineeske]

Dear all,

I am thinking of upgrading my Orion 250cc bike as this aircooled Honda CB clone seriously lacks of power in the dirt...


I read somewhere on this forum that there are some bigbore (300cc) kits out there but not everyone is truly convinced about the power increase these things give.

I have a XR250R engine with loom laying around in my shed, but as a Honda 250R doens't have a battery, it would mean that my Orion bike would need a full strip and a lot of rewiring to keep it streetlegal in terms of lights and turnsignals.

My question is, if someone could me so kind to give me some advice;
Dropping the Honda XR250R engine in the Orion or would a bigbore kit with a nice carb also forfill my needs so I can keep the Orion wiring as it is? And where can I buy such a bigbore kit for my Zongshen engine as to me, all the Chinese cilinders looks equal....

[JerryHawk250]

As far as I know there are no big bore kits for the air cooled CB250. There is some gain by porting and decking the head to increase the compression ratio. One thing you can do with the OHV engine is get a custom ground cam from Hot Cams. I ran one on my 200x back in the day. It really woke it up.

[NzBrakelathes]

You might be better if with the latest style engine
It’s an 15Kw 18nm and 249cc
What’s the cost of that motor in the pic? 223cc yeah?

No big bore kits for 223cc or 232.6cc or 249.9cc
All 3 differ greatly but loosely based on each other

[Megadan]

Does the Orion have an AC or DC Stator? Some of these bikes are already wired up with an AC stator with a regulator/Rectifier for battery charging and an AC CDI. Our Hawk 250's would be one example. If the Orion is setup the same way, then wiring in the XR250 engine would actually be quite easy. Even if it isn't, the conversion wouldn't be that complicated.

Cost wise, if power is your goal, the XR engine will win hands down. An XR250R engine makes stock what a Chinese CB250 engine could only dream of after head work, a cam, and wishful thinking.

[Landsvw]

I was gonna say, the XR250R might be able to have its stator changed out with an XR250L, and/or if the stator current can be changed to DC, then should be fine with the bikes wiring. All things being equal, is it an easy bolt in? And/or what other modification tasks need to be done like exhaust etc? If all mechanical things were reasonable I’d go with the XR250 and then figure out the wiring. But then I’m the guy with an XR100 engine in a Suzuki TC90 frame, so I might be a bit off...

[Megadan]

Originally Posted by Landsvw

I was gonna say, the XR250R might be able to have its stator changed out with an XR250L, and/or if the stator current can be changed to DC, then should be fine with the bikes wiring. All things being equal, is it an easy bolt in? And/or what other modification tasks need to be done like exhaust etc? If all mechanical things were reasonable I’d go with the XR250 and then figure out the wiring. But then I’m the guy with an XR100 engine in a Suzuki TC90 frame, so I might be a bit off...

Stator might need to be changed anyway as earlier XR's had a 6 volt lighting circuilt (blue wire stator). Even if the XR engine bolted in, it wouldn't be super cheap if you had to buy a bunch of charging system stuff to make it compatible.

Still, if power is the primary goal, it would likely still be easier to use the XR engine as long as getting it to bolt in doesn't require extensive fabrication. The CB250 would need a lot of work to make the 25hp that the XR250 engine makes completely stock.

[Landsvw]

I also wanted to say, I really enjoy the camaraderie on this China Riders site. Always good discussion with friendly people!

[Chineeske]

Originally Posted by NzBrakelathes

You might be better if with the latest style engine
It’s an 15Kw 18nm and 249cc
What’s the cost of that motor in the pic? 223cc yeah?

No big bore kits for 223cc or 232.6cc or 249.9cc
All 3 differ greatly but loosely based on each other

Well, guess that answers my question!

But what is the latest style engine, do you have a link please?

[Chineeske]

Originally Posted by Megadan

Stator might need to be changed anyway as earlier XR's had a 6 volt lighting circuilt (blue wire stator). Even if the XR engine bolted in, it wouldn't be super cheap if you had to buy a bunch of charging system stuff to make it compatible.

Still, if power is the primary goal, it would likely still be easier to use the XR engine as long as getting it to bolt in doesn't require extensive fabrication. The CB250 would need a lot of work to make the 25hp that the XR250 engine makes completely stock.

Fabricating things is what I like, my biggest issue would be the electrical.
Too bad that a bigbore kit isn't available for this engine...

Guess it will be an (H)Orion XR250R then!

[NzBrakelathes]

Originally Posted by Chineeske

Well, guess that answers my question!

But what is the latest style engine, do you have a link please?

Sorry no link as I would need to order it in etc.
Be something like $850 with DHL from China to your door

[ChipToothy]

I wonder about just getting bigger motors. It's not much more than all the mods we all already do. If there is one that works with our bikes that is..

https://www.alibaba.com/product-deta...4c0165866Qgumx

[NzBrakelathes]

Originally Posted by ChipToothy

I wonder about just getting bigger motors. It's not much more than all the mods we all already do. If there is one that works with our bikes that is..

https://www.alibaba.com/product-deta...4c0165866Qgumx

Alibaba is full of mistakes
It might be called a 300cc and something near 280 real cc and it’s a trike engine not got 2 wheeled frames.
Forget buying it to your door for $350

[Chineeske]

Could resleeving the cilinder together with an oversized piston be an option?

Or is the cilinder wall of these engines too thin?

[Chineeske]

I have made up my mind
http://www.chinariders.net/showthrea...t=21224&page=2

[ChipToothy]

Cool hog