I have been (re)assimilated! Zongshen GS250

[SpudRider]

Here are the specs for the Yamaha, TW200 engine: 67.0mm Bore x 55.7mm Stroke

This information is incorrect; I made an error. :oops:
It appears Zongshen kept the TW200 engine bore, and increased the stroke to gain the extra 34cc engine displacement. Therefore, TW200 pistons, and piston rings should work in the 230cc, Zongshen engine. However, the connecting rod, cylinder, and cylinder head might be unique to this motorcycle. Also, the engine might be 5.5mm taller. A taller engine might require slight modification to the upper engine mounting plates if you wished to mount this engine in the 200GY-2, or Yamaha motorcycles.

This is the correct information; therefore, I have edited this post.
It appears the ZS250GS is basically a Yamaha XT200/TW200 engine, with a larger bore. It seems Zongshen enlarged the cylinder bore 5.5mm in diameter to gain the extra 34cc engine displacement. Therefore, Zongshen is using a larger piston, and larger piston rings than the Yamaha motorcycles employing this engine block. Also, Zongshen enlarged the cylinder head, and relocated the exhaust port on the right side, instead of the left side.

Spud

[FastDoc]

Originally Posted by SpudRider

Here are the specs for the Yamaha, TW200 engine: 67.0mm Bore x 55.7mm Stroke

It appears Zongshen kept the TW200 engine bore, and increased the stroke to gain the extra 34cc engine displacement. Therefore, TW200 pistons, and piston rings should work in the 230cc, Zongshen engine. However, the connecting rod, cylinder, and cylinder head might be unique to this motorcycle. Also, the engine might be 5.5mm taller. A taller engine might require slight modification to the upper engine mounting plates if you wished to mount this engine in the 200GY-2, or Yamaha motorcycles.

Spud

What about a Yamazong? Would it drop in?

[SpudRider]

Bill, you might find some useful information reading the threads on the Sportbikes Forum at ZongshenForum.com.

http://zongshenforum.com/forum/index.php?board=5.0

Spud

[SpudRider]

Originally Posted by FastDoc

What about a Yamazong? Would it drop in?

Do you mean the ZS167FML engine in my 200GY-2 motorcycle? My engine has the exhaust port of the left side of the cylinder head, so you would encounter problems with the exhaust header, et cetera, if you tried to mount my 196cc engine in your ZS250GS motorcycle.

Spud

[FastDoc]

Thanks for the link Spud. Looks like lots of good stuff there!

[SpudRider]

Originally Posted by FastDoc

Thanks for the link Spud. Looks like lots of good stuff there!

You're welcome, Doc. Thanks for taking the time to post this thread, and document your work with photos; I am going to enjoy following this project!

I realize you were very busy today. However, when you get time, please try to read all the posts in this thread. I would still love to see photographs of the swingarm and lower shock linkage on your ZS250GS. I am curious to know if your bike employs a progressive, lower shock linkage.

Spud

[FastDoc]

Never too busy for you guys. Here are your pics Spud, let me know what else you want to see.

[SpudRider]

Thank you for the additional photos, Brother Bill. I don't know about anyone else, but I got $200 worth of entertainment value from this bike already! I rotated two more photographs for you.

Here's the left side of a very nice, TK MV30 carburetor.



Here's the lowest part, right side, of the lower, progressive shock linkage.



This bike is worth a lot more than the $200 you spent, Doc. Zongshen makes reliable engines, and good motorcycles. This bike reportedly has a lounge chair for a saddle.

Spud

[humanbeing]

From chinese forum http://motorcycle.sh.cn/t_637419.htm
Kill switch maybe the cause

[SpudRider]

This information is incorrect; I made an error. :oops:
Here's my current, best guess concerning the engine design. Your ZS172FMM engine is basically a Yamaha XT200/TW200 engine. It appears Zongshen lengthened the cylinder 5.5mm to gain the extra 34cc engine displacement. In addition, Zongshen modified the cylinder head so the exhaust port exits the right side, instead of the left side.

This is the correct information; therefore, I have edited this post.
It appears the ZS250GS is basically a Yamaha XT200/TW200 engine, with a larger bore. It seems Zongshen enlarged the cylinder bore 5.5mm in diameter to gain the extra 34cc engine displacement. Therefore, Zongshen is using a larger piston, and larger piston rings than the Yamaha motorcycles employing this engine block. Also, Zongshen enlarged the cylinder head, and relocated the exhaust port on the right side, instead of the left side.

If someone wished to mount this engine in a Yamaha, or Zongshen 200GY-2 frame, he might have success employing a Suzuki DR200SE, or similar, exhaust header.

Spud

[MICRider]

Flame switch... Sounds cool! I'm betting it's something simple but possibly hard to track down. That's how it usually works with electrical gremlins. Somebody should put out the bat signal for Lynn Edwards, bet he could shed some light on the weak spark

Cheers,
Stew

[SpudRider]

I don't have a parts manual for this motorcycle, but I'm pretty sure the stock bike has an airbox, Doc. It appears the previous owner removed the airbox, and installed a pod air filter. In the process he needed to install a small air filter on the crankcase ventilation tube, since it connected into the absent airbox.

Did you get any manuals with this bike? I believe this bike is sold with three manuals: An Owner's Manual, a Parts Manual, and a Maintenance Manual. If you wish, I can check on the availability of these manuals from Zongshen America.

Spud

[FastDoc]

I would think that if the problem was the kill switch there would be no spark, I have a weak one. I don't know. :?:

I tried putting a few cc's of gas in the cylinder and it still did not start so I think this really is a spark issue .

I fixed the broken rear fender and the blinkers at least though. :wink:

[FastDoc]

I could use the manuals, Spud.

The seat is one of the most comfortable I have ever tried. This bike would be great, if it runs!

I'm glad you got $200 worth of fun so far because that's what I'd sell it to you for if I can't get it going! :P

LOL!

[SpudRider]

Someone is parting out a ZS250GS on eBay, Doc. Another vendor is also selling the airbox, if you want to replace it.

http://motors.shop.ebay.com/i.html?_...506.m270.l1313
http://cgi.ebay.com/ebaymotors/06-ZO...item19bb235d64

I'm happy to sell you any new parts you need, but I also want to make you aware of these used parts.

Spud