Interesting pictures
 

So this 69mm piston and cylinder kit was one that humanbeing linked to on Taobao. Learned alot about buying from there. Thanks HB!

You guys might actually find these interesting. The new cylinder is the 250cc cylinder kit, the old is my 200. I'd like to get a hold of a 230 to do some side by side comparisons.

Attachment 7646

Welcome!


You've hit some hot buttons for me. I had an '88 CR125 that I was going to do the same thing with, but a buddy of mine needed it more, so I gave it to him. He bought a Gio dirt bike with a CG230, and we intend to transplant it into his CR. He's around 6'3", so the CR will suit him much better than the Gio (which is a small wheel bike).


Did you have to get creative with lower motor mounts, or could you use the CR mounts on the XR engine? I spotted that you'll need to do something custom on the upper mount. I'll be watching for your solution, and then I'll promptly steal it. :D


Fundamentally, your new cylinder isn't actually a 250 kit, in the same way an SR250 Yamaha is actually around 230. There isn't a 250 combo for a CG motor that I'm aware of, unless you want to go liquid cooled. The three-wheeled trucks from China often use that setup, which gets near 270cc, IIRC.


Is the wristpin diameter the same on your new cylinder as on the XR200? Is it the same as your China motor?

The 200 that was in it was done years ago by a previous owner. The rear lower and mid mounts bolted right up!! :yay:

This motor is advertised with the same bore and stroke as a crf230. Which makes it a 223. (65.5 x 66.2 mm bore x stroke) Would need to measure to confirm.

This cylinder is sleeved at 69mm which should (math be right) make 247cc motor. I *thought* that this was a CB based unit and not a CG based???

Attachment 7650

No. The 200 and 230 use a 15mm wrist pin. This cylinder/piston kit has a 17mm wrist pin.

Not too strange- witness spud riders "yamazong".

How did the sprocket alignment turn out? Do you have rear wheel bushings that can be adjusted (washers,sanding to remove thickness etc,etc)

I don't claim to be a mechanic by any means, but if you start messing with the internals of Chinese engines, it will prove your friends right. These engines are best left to sprockets, exhaust, and carbs...just posting this as a precaution, not to necessarily discourage you, because I am very curious to see how reliable these bikes can be.

Yeah, Spud's yamazong is partly to blame for my confidence in the Zong clone.

Still not sure how to proceed. The sprocket wants to run right on top of the retainer groove. It seems like cutting another retainer groove would weaken the shaft too much.

Considering trying to find some starlock washers that fit the shaft tightly; put one on each side of the sprocket.
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The rear sprocket already rides pretty close to the swingarm, plus it aligns with the chain wear guide in its current position.

Well, I already have a larger exhaust header and a Supertrapp muffler and I started it up with the new carburetor I bought from Honda for my xr200.

The plan is to leave it stock for now, but eventually I'd like to put the 247 cylinder on it and see if a Torker 2.0 camshaft will fit or if I can get one ground by WEB. We enjoy building these little motors as much as riding them. From what I can see there is no reason these cannot be built in similar fashion to a Japanese motor.

The new camshafts available for the 230 and 200 series really wake these little motors up; the 89a cam in my 200 didn't hurt bottom end at all, but gave me a nice boost through the mid-range and much more pleasant over-rev.

i thought the same, you wouldn't catch me tearing into a factory built engine. with my luck (and lack of skills) i would ruin it in no time.

not saying anything about chonda ability. sounds like he is completely confident in the process.

Thanks for this info!

I checked their page, but it says they are out of stock. For $89.95 it must be gooood!

Maybe I can build an offset sprocket using the 428 part that came with the motor, then drilling/machining the center out of a 520 such that the retainer can still bolt up?? I may just try this.

Sorry, I was wrong; it is a CB-based motor. I think I was tired when I wrote CG.

I'm with you on the math, but I have one CB motor that is incorrectly stamped. The only way to know is to measure the stroke yourself (as you say). So cool that you might hit 247!

Wired everything up today and put the "magic" button on the handlebars. Starts right up and runs great! Haven't ridden it yet, just sat on it and imagined some.

I want to change the oil first thing and get the sprocket figured out before I venture too far. This bike is plated and insured so I'm jonesin to get it back on the road.

Also need to figure out a good way to mount the starter solenoid. Will post some pics when its figured out.

Move your rear?
 

Nice crossbreed build. For the sprocket alignment, do you have enough clearance on the right side of the rear tire to move the hub over? Even if not the full 8mm, any shift would be good. If you don't have spare hub spacers laying about to play with, find a nice fat washer to add to the left side and cut/grind the same amount off the right side spacer.

Having said that, considering the distance between sprockets I'm not sure that the misalignment would really be an issue. A bit of wear will occur on the sides of the sprockets until the 3 components wear in to each other, but how long do chains & sprockets last anyway?

Jay (more than slightly off center).

The rear sprocket would actually need to move the other way. I'm not sure it will help to change the whole alignment of the rear tire and brakes, etc.

I'm more than slightly off-center too!! :) :D