Zongshen 200GY-2: Teikei MV28 Carburetor Tips

[SpudRider]

Zong owners are very fortunate that the Sierra 200GY-2 is such a close copy of the currently produced, Yamaha TW200 motorcycle. Since the TW200 has been in continuous production since 1986, we will never need to worry about securing replacement parts for our Zongshen 167FML engines. In addition, we also have access to the excellent TW200 Service Manual available for repairing, and maintaining our motorcycles. We are also very fortunate to have access to the superb information available from Yamaha owners who contribute to the TW200 forum.

http://tw200forum.com/forums/

The TK MV28 carburetors installed on our Zongshen motorcycles are slightly different from the TK MV28 carburetors installed on the Yamaha TW200. However, most of these minor differences work in our favor!

The Yamaha carburetor employs two throttle cables, located on the right side of the carburetor; the Zongshen carburetor employs one throttle cable, and a return spring, located on the left side of the carburetor.

The Yamaha carburetor jet needle is not notched for height adjustment; the Zongshen carburetor jet needle is notched.

The Yamaha carburetor has a choke knob located on the carburetor body; the Zongshen carburetor has a remote choke adjustment, located on the left handlebar.

The TW200 pilot mixture screw is hidden under a brass cap, on the bottom of the carburetor; the Zongshen pilot mixture screw is easily accessible on the left side of the carburetor.

Despite these minor differences, the two TK MV28 carburetors are essentially the same. Therefore, I have provided a few links to TK MV28 carburetor threads located on the Yamaha TW200 forum. The first link, authored by Centerline, provides excellent photographs, and a detailed description of adjusting the TK MV28 carburetor jet needle, and main fuel jet.

http://tw200forum.com/forums/1/28976...ost.aspx#28976

The next link provides a lot of good, general information concerning TK MV28 carburetor removal, rotation, and cleaning.

http://tw200forum.com/forums/71353/ShowPost.aspx

Also, if you are interested in TK MV28 carburetor jet information regarding the Zongshen Sierra 200GY-2, you might enjoy reading the following thread, posted here, at China Riders.

http://chinariders.net/modules.php?n...ewtopic&t=9165

Spud

[fishman10]

eureka!! so following spuds advice, I took the top of the carb without removing it and put the clip back up one notch were it was ,,,but i left the 137.5 jet in cause the others haven't come in yet.It is amazing that one small adjustment has made it run good again,granted it may still be rich ,I'll have to do a plug check but it ran well, no breaking up at higher rpms and very very little pop on deceleration.

[Weldangrind]

Good news! Can the clip be moved up one more notch?

[fishman10]

yes it is in the middle, right were itwas from stock.I could probably move it up one more nothc and leave the 137.5 jet in there,Its running pretty good the way it is .Gotta get ready for work now ,so Tomorrow will try and do a plug check.

[SpudRider]

Originally Posted by fishman10

eureka!! so following spuds advice, I took the top of the carb without removing it and put the clip back up one notch were it was ,,,but i left the 137.5 jet in cause the others haven't come in yet.It is amazing that one small adjustment has made it run good again,granted it may still be rich ,I'll have to do a plug check but it ran well, no breaking up at higher rpms and very very little pop on deceleration.

That is excellent news, Fishman!

As a general warning to all Zong owners, be careful when you replace the slide diaphragm after adjusting the jet needle position. Frequently the outer lip of the diaphragm will not seat properly into the small groove on top of the carburetor body.



Carefully inspect the diaphragm to insure it is seated properly, as shown below, before you replace the top cap on the carburetor body.



I wish to thank Centerline for these excellent photographs he originally posted on the TW200 forum.

Spud

[fishman10]

i should probably recheck that spud ,I was in a hurry and its kinda dark where i was working.

[SpudRider]

Originally Posted by Weldangrind

Good news! Can the clip be moved up one more notch?

I might be wrong, WG, but I think Fishman is still two jet sizes too large for his main jet. Therefore, I would leave the jet needle in the middle position, and begin testing anew with a size 132.5, Mikuni main jet. Or I would reinstall the stock, size 132, Teikei main jet, and move the jet needle clip down one, or two notches.

Spud

[fishman10]

i ordered a 132.5 and 135 from rocky mtn. thanks again for the link spud, ,,,Going to wait till they come in ,,then try again, see ya ,,gotta go to work!

[SpudRider]

Originally Posted by fishman10

i should probably recheck that spud ,I was in a hurry and its kinda dark where i was working.

That is probably a good idea, Fish. If you are going to open up the carb again, you could move the jet needle clip down one, or two slots. Then, if you remove the throttle cable, you could rotate the carb bottom toward you, and reinstall the stock, size 132, Teikei main jet.

Unlike the Yamaha TW200 motorcycles, which are jetted very lean for EPA purposes, I think the stock, Zong jetting is pretty close to ideal. You might be surprised at how well the bike runs with the stock main jet, and the jet needle raised two notches. If the bike is still too lean, I would then test the size 132.5, Mikuni main jet, with the jet needle placed in the middle position.

Spud

[SpudRider]

Originally Posted by fishman10

i ordered a 132.5 and 135 from rocky mtn. thanks again for the link spud, ,,,Going to wait till they come in ,,then try again, see ya ,,gotta go to work!

You are welcome, Fish. I am pretty confident the size 132.5, Mikuni, and size 135, Minkuni main jets will easily meet all your riding needs, down to sea level. In combination with the stock, size 132, Teikei main jet, you should have all the main jets you need for Mid-Atlantic riding.

Spud

[Wild_Alaskan]

the needle and main jet should be adjusted independently, the main jet controls 3/4 to full throttle only. unless it is excessively small or clogged.
the needle jet effects 1/4 to 3/4 throttle when the main jet becomes the main restriction.

if you want to know way too much about jetting this is a great guide

http://www.mikuni.com/pdf/vmmanual.pdf

[450-WheelieBoyz]

Originally Posted by Wild_Alaskan

the needle and main jet should be adjusted independently, the main jet controls 3/4 to full throttle only. unless it is excessively small or clogged.
the needle jet effects 1/4 to 3/4 throttle when the main jet becomes the main restriction.

if you want to know way too much about jetting this is a great guide

http://www.mikuni.com/pdf/vmmanual.pdf

thanks bro ive been asking people and searching for something like this ! thanks man!

[oviking99]

Wow! It has been many many moons! My Zong has sat for years now. I had some unpleasant experiences with tailgaters inches off my Zong twice. I quit riding obviously. Time to get her running. Pulled the carb after loosening the airbox/battery holder. Not as bad as I thought. Opened the float bowl. Melted plastic or fuel line from years of gas. The float was frozen. Usually the pin just falls out, but not the case. Must be pressed in. At any rate I am taking a chance on this carb. It looks like the exact original. I looked at the the TW200 carbs with manual choke, but I like the handle bar choke control. I'll let y'all know how it works!
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

[NzBrakelathes]

Originally Posted by oviking99

Wow! It has been many many moons! My Zong has sat for years now. I had some unpleasant experiences with tailgaters inches off my Zong twice. I quit riding obviously. Time to get her running. Pulled the carb after loosening the airbox/battery holder. Not as bad as I thought. Opened the float bowl. Melted plastic or fuel line from years of gas. The float was frozen. Usually the pin just falls out, but not the case. Must be pressed in. At any rate I am taking a chance on this carb. It looks like the exact original. I looked at the the TW200 carbs with manual choke, but I like the handle bar choke control. I'll let y'all know how it works!
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

I have this bike and tuning the carb - so far I have a 35 pilot jet.

I don't like the cable choke due to cables getting stuck so I have a manual choke

[oviking99]

Originally Posted by NzBrakelathes

I have this bike and tuning the carb - so far I have a 35 pilot jet.

I don't like the cable choke due to cables getting stuck so I have a manual choke

My Zong was running great almost 6 years ago. Unfortunately the fuel seems to have corroded everything and melted the pickup tube as well as the rubber/silicon fittings. Easier for me just to replace it.