I have been (re)assimilated! Zongshen GS250

[Oengus]

Originally Posted by SpudRider

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.

Is 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

The bore is the cylinder they bored it out to 72mm a bigger cylinder into a bigger opening, the stroke is the length of travel and it seems to have remained constant. The head is not the same on the engines but marry to the same crank or it seems.

I would check the stator remove the cover and look at it, it may be or have corroded? The CDI has to be energized, the battery should do that it builds a jolt and puts it out for that first crank. Then takes it off the stator for the subsequent sparks and it times them....if it had a different stroke it would not share timing with an engine that did not have the same stroke.

The battery, the CDI and the plug all connection... need to be good and then it should start, then, the stator needs to be read it should be generating volts and if not and reads closed its bad. I agree in that a bad stator should not prevent a start, it would affect firing though while running.

[Oengus]

A wiring diagram would be my first request, then just trace it all out something is not doing its part… it could be the kill switch or any circuit for that matter could be a rectifier… I would check everything because one thing can often be associated with another thing. People find one thing and then get all excited and then find that one thing went because of another thing was not working correctly.

How many miles on it…..I doubt the carburetor was re-jetted if the muffler is stock…but if you assume the previous owner was not that smart anything is possible.

Spud can you get documents on the bike…what exactly gets you the part dealer moniker?

I always liked the GS250 but not the support of it….seems like every owner I came across online was just a kid that new nothing….so now that changes with the good doctor having one and you being able to support him…the bike now take the cult a step further, makes me think about picking up a V-Twin Storm, not really but who knows, they may be coming around for cheap soon and they are kind of interesting. We know those are a 249cc Yamaha.

[SpudRider]

Originally Posted by Oengus

The bore is the cylinder they bored it out to 72mm a bigger cylinder into a bigger opening, the stroke is the length of travel and it seems to have remained constant. The head is not the same on the engines but marry to the same crank or it seems...

Indeed, I made an error. :oops: Thank you for letting me know, so I could correct the misinformation.

Zonshen ZS250GS Engine Specifications: Bore 72.5mm, Stroke 55.7mm
Yamaha TW200 Engine Specifications: Bore 67.0mm, Stroke 55.7mm
Yamaha TT-R230 Engine Specifications: Bore 70.0mm, Stroke 58.0mm

Therefore, 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.

I have corrected my original post, in the event someone might read it, and not catch my mistake.

Spud

[SpudRider]

Originally Posted by Oengus

...I would check the stator remove the cover and look at it, it may be or have corroded? The CDI has to be energized, the battery should do that it builds a jolt and puts it out for that first crank. Then takes it off the stator for the subsequent sparks and it times them....if it had a different stroke it would not share timing with an engine that did not have the same stroke.

The battery, the CDI and the plug all connection... need to be good and then it should start, then, the stator needs to be read it should be generating volts and if not and reads closed its bad. I agree in that a bad stator should not prevent a start, it would affect firing though while running.

I don't wish to be argumentative, but I must disagree. My Zongshen 200GY-2 employs an AC-CDI unit, and this ZS250GS CDI unit appears to be similar. If the stator goes bad, the Zongshen engine will not start. The Zongshen, AC-CDI unit does not receive any input from the battery; it receives all its input from the stator. The battery does not charge the capacitor in the Zongshen CDI unit. If the stator does not deliver sufficient voltage to the AC-CDI unit, the AC-CDI unit cannot send sufficient voltage to the ignition coil.

Spud

[SpudRider]

Originally Posted by Oengus

...Spud can you get documents on the bike…what exactly gets you the part dealer moniker?...

I am an authorized, Zongshen parts dealer. Therefore, I can get any parts stocked by Zongshen America. If Zongshen America stocks the ZS250GS manuals, I can obtain them for FastDoc.

Originally Posted by Oengus

...I always liked the GS250 but not the support of it….seems like every owner I came across online was just a kid that new nothing….so now that changes with the good doctor having one and you being able to support him…the bike now take the cult a step further, makes me think about picking up a V-Twin Storm, not really but who knows, they may be coming around for cheap soon and they are kind of interesting. We know those are a 249cc Yamaha.

Indeed, Billcutus of Zong has returned to The Collective! As with you, I too am confident FastDoc can further enrich the status of The Cult of The Zong. You are wise to consider the Zongshen, Storm V250, Oengus. Resistance is futile. You will be assimilated. 8)



Spud

[SpudRider]

Originally Posted by 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 agree, Doc. I think you have either a bad stator, or a bad AC-CDI unit, or both. I will contact Zongshen America on Monday to check for manuals, and parts availability.

Spud

[SpudRider]

Perhaps the Zongshen, ZS250GS CDI unit is different from my Zongshen, 200GY-2 CDI unit. :roll: I just found the following wiring diagram at ZongshenForum.com.

http://zongshenforum.com/forum/index.php?topic=89.0



I will gladly defer to those forum members more knowledgeable than I on this matter.

Spud

[Oengus]

The CDI capacitor stores energy then releases it, I could be wrong but the initial spark should be off the battery as power source and then the subsequent spark come of the generator as the power source? All the sparks come off the CDI but the source of the voltage for that may change, that being the first spark is generated from the battery and then subsequent voltage off the generator. I would say the starter relay is or has the circuit that manages that flow. There is no power supply from the battery to the generator is there? The generator is the supply to the battery and only when running, it should start with a bad stator but simply not maintain the battery charge and also not provide enough to energize the CDI for higher RPM sparks, as the rpm increase so does the rate the CDI energizes and discharges. If the stator is bad then it will not happen. It is also possible the a bad stator would prevent starting if it has a circuit that is required that is not longer functioning. I am not sure….I would have to have a manual, then follow it, then know for sure.

[Reveeen]

At the CDI it would appear: (unplugging CDI and checking at connector bike side)
With a 12V test light:
Green is -12V
Black/yellow fires the coil, and feeds the tach (check it is not grounded once you temporarily disconnect the coil)
Black/red is +12V (with the key on)

Ohm meter:
Blue/yellow, green/white: (pick up coil) check for continuity with ohm meter, guess? 700+ ohms, cranking, another guess .8 volts ac

You need a battery to start this!

[BillR]

Doc,
Good score for $200, even if it gives you fits.
Hope you can get it running.
No new suggestions, eveybody has hit what I would try.
Bill R

[FastDoc]

Thank you Spud, I did see that auction. He does not have the parts I need like the clutch lever, windshield, coil and CDI.

My plan for today is to hook it up to a car battery with large gauge jumper cables to see if the 14 gauge wire I have now (to hook it to another motorcycle battery) is too restrictive and that's the reason for the weak spark, i.e. low voltage.

[FastDoc]

No joy on the car battery and jumper cables. The problem is not inadequate voltage.

[Weldangrind]

Do you have a coil that you can try?

[FastDoc]

I have the XR's coil.

I just don't know. I've never seen a coil fail, but I would think if a CDI went out it would not spark at all. I thought, on a battery equipped bike, the battery energizes the ignition coil not the stator. The stator charges the battery. If I'm right, and I don't know, then a bad stator would not cause my issue and that leaves me with the CDI and the coil.

I think I'll have Spud get me a CDI and coil. I will then find out which of the two new parts, if either, or both fix my problem.

I don't like diagnosing by replacement but I don't see another way at this point.

I might ask my frined Andy the mechanic but I don't like bothering him with this stuff. On the other hand he asks me medical stuff, and that's what friends are for...

[FastDoc]

Spud said:

I don't wish to be argumentative, but I must disagree. My Zongshen 200GY-2 employs an AC-CDI unit, and this ZS250GS CDI unit appears to be similar. If the stator goes bad, the Zongshen engine will not start. The Zongshen, AC-CDI unit does not receive any input from the battery; it receives all its input from the stator. The battery does not charge the capacitor in the Zongshen CDI unit. If the stator does not deliver sufficient voltage to the AC-CDI unit, the AC-CDI unit cannot send sufficient voltage to the ignition coil

If that's the case my theroy this is not the stator may be wrong. I wonder if I should order a gasket and a stator too. Do I need a special puller, or does it simply screw into the cover? Is it a plug and play deal?