Zongshen 200GY-2: Carburetor Jet Information

[SpudRider]

The Zongshen 200GY-2 motorcycle employs a Teikei MV28, constant velocity carburetor. This same carburetor is also employed in the latest Yamaha TW200 motorcycles. In stock form, the Zongshen carburetor comes equipped with a size 132, Teikei main jet.

If you wish to change jets on your TK MV28 carburetor, you have several choices. Teikei carburetor main jets are sold at MotorcycleCarbs.com, but they are fairly expensive at a current price of $7.95 per jet. :(

http://www.motorcyclecarbs.com/Teike...n_Jet_C825.cfm

Many members of the Yamaha TW200 forum prefer to use Mikuni series N102/221, small, round main jets. The thread on these Mikuni jets is a little different from the Teikei jets, but they still fit pretty well. The Mikuni jets are more widely available than the Teikei jets, and are much less expensive. The current price for N102/221, Mikuni, main jets from Rocky Mountain ATV is $2.99 per jet. I personally use the Mikuni N102/221 main jets, and I like them.

http://www.rockymountainatvmc.com/al...FamilyId=25085

Mikuni carburetor jets employ a different sizing system from other manufacturers. However, through a process of trial and error, Yamaha TW220 owners have discovered that a size 132, Teikei, main jet is roughly equivalent to a size 130, Mikuni, main jet.

Operating at sea level, a Zongshen 200GY-2 with the stock muffler seems to run pretty well with the stock, size 132, Teikei main jet; however, several Zong owners have reported better performance after raising the jet needle one notch. At higher elevations, the stock, size 132, Teikei main jet is too rich.

The stock Zongshen 200GY-2 muffler is very heavy, and highly restrictive. Therefore, I strongly encourage Zong owners to install an FMF Turbine Core 2 silencer/spark arrestor. The FMF Turbine Core 2 is much lighter than the stock muffler, and it definitely increases the motorcycle’s performance. However, once you convert to the FMF silencer, you will probably need to rejet your Teikei carburetor.

Based upon the experience of several Zong owners, I can suggest you begin your experiments with the following main jet sizes.

Zongshen 200GY-2 With Stock Muffler:

If you are using the stock muffler at sea level, the stock, size 132, Teikei main jet is probably pretty close to ideal. Begin your experiments by raising or lowering the jet needle. If the jet needle adjustments are not adequate, I suggest you experiment with the N102/221 Mikuni main jets. The stock Teikei main jet is roughly equivalent to a size 130, Mikuni main jet. Therefore, to lean out your mixture, start your experiments with a size 127.5, Mikuni main jet. To enrich your mixture, begin experimenting with a size 132.5, Mikuni main jet.

Zongshen 200GY-2 With FMF Turbine Core 2 Silencer/Spark Arrestor:

If you have installed an FMF Turbine Core 2 silencer on your Zong, and you are operating at sea level, you will probably need a slightly larger main jet. Therefore, begin your experiments with a size 132.5, Mikuni main jet.

I am personally running an FMF Turbine Core 2 silencer at 4,500 feet above sea level, and my fuel mixture is running rich. I started experimenting with a size 127.5, Mikuni, main jet; however, my mixture is still too rich. Therefore, I will next try a size 125, Mikuni, main jet. I think this jet will probably be the correct size.

If you are running an FMF Turbine Core 2 silencer at 9,000 feet above sea level, begin your experiments with a size 122.5, Mikuni main jet.

I hope this information helps you as you begin experimenting with the jetting on your Teikei MV28 carburetor. If you have experimented with your Teikei MV28 carburetor jetting, please share your experience with us. Also, if I have made any errors, please let me know; I will appreciate your help.

Spud

[Weldangrind]

That's excellent information Spud. I'm keeping a close eye on Zong tech, because I'll import one into Canada if I get the chance.

[davidsonsgccc]

nice post. you give great info.

[SpudRider]

Gentlemen, you are welcome.

Spud

[fishman10]

OK now ,I'm bummed,rejetted the zong cause with the stock 132 jet and the clip in the middle needle position the plug was showing lean.So I put in a 137.5 and moved the clip down one notch.Now it runs worse it breaks up at the higher rpms and pops a little out the pipe on deceleration, so now what ,???? which has more effect on these problems .Should I put the stock jet back in with the clip moved down , OR leave the bigger jet in and put the clip back up one notch were it was.It ran better with the stock setup ,but the fmf silencer was causing the plug to be whitish.Also there was no Idle mixture screw on the bottom of the carb ,nor could I find a plug to drill out to get to one ,like I've found on other bikes.Help please.

[Weldangrind]

Perhaps before changing to a 137.5 it would be a good idea to move the clip to the bottom position with the 132. If that's still too lean (according to the plug), you could switch to the 137.5 with the clip at the top and slowly work your way down. You'll eventually find a balance between plug colour and smooth acceleration.

Is there a 135 available? Maybe a jump from 132 to 137.5 is too much at your specific elevation.

[fishman10]

Any one who has found the magic combination , for under 2000 ft. elev. I would appreciate it .BIke is new and stock except the fmf turbinecore2 silencer.

[fishman10]

W&G thats worth a shot ,but it is a pain in the $%^,,, getting the carb in and out so would like to reduce the amount of times I do it.

[SpudRider]

Originally Posted by fishman10

OK now ,I'm bummed,rejetted the zong cause with the stock 132 jet and the clip in the middle needle position the plug was showing lean.So I put in a 137.5 and moved the clip down one notch.Now it runs worse it breaks up at the higher rpms and pops a little out the pipe on deceleration, so now what ,????...

I assume you are using the small, round, Mikuni main jets. A size 130, Mikuni main jet is equivalent to a size 132, Teikei main jet. Therefore, I suggest you try a size 132.5, Mikuni main jet, instead of the much larger, size 137.5, main jet you are now using. I think even a size 135, Mikuni main jet will run too rich for you at your elevations.

Originally Posted by fishman10

…Also there was no Idle mixture screw on the bottom of the carb ,nor could I find a plug to drill out to get to one ,like I've found on other bikes.Help please.

Below is a photo of your TK MV28 carburetor. Unlike the Teikei carburetor employed by the Yamaha TW200, the pilot mixture screw on the Zong’s carb is readily accessible. In the photograph below, the idle adjusting screw is located inside the orange oval. The pilot mixture screw is located inside the yellow circle.



Spud

[SpudRider]

Originally Posted by Weldangrind

…Is there a 135 available? Maybe a jump from 132 to 137.5 is too much at your specific elevation.

Indeed, a size 135, Mikuni main jet is available. However, I think Fishman will discover a size 132.5, Mikuni main jet will give the best results. As usual, you are correct, WG. A jump from a size 132, Teikei main jet, to a size 137.5, Mikuni main jet, was too much.

Spud

[SpudRider]

Originally Posted by fishman10

W&G thats worth a shot ,but it is a pain in the $%^,,, getting the carb in and out so would like to reduce the amount of times I do it.

It is unnecessary to completely remove the Zong’s carburetor for either jet changes, or jet needle adjustments. Of course, you do still need to remove the saddle, fuel tank, and side plastic to gain access to the carburetor.

If you wish to adjust the jet needle position, simply loosen the clamps at the carburetor’s air box, and intake manifold. Then rotate the top of the carburetor toward you. You will have a lot of space to remove the top of the carburetor, and adjust the jet needle position.

If you wish to change the carburetor’s main jet, first drain the float bowl, then unhook the throttle cable. Next, as described above, loosen the two carburetor clamps. Then, rotate the top of the carburetor away from you, exposing the bottom of the carb. Remove the four bolts securing the float bowl, and you will have easy access to the carburetor jets.

If you replace the four, Phillips head bolts that secure the float bowl with Allen head bolts, it might even be unnecessary to rotate the carburetor to change the main jets.

Spud

[FastDoc]

If you replace the four bolts that secure the float bowl with Allen head bolts, it won’t even be necessary to rotate the carburetor to change the main jets.

That's a really good tip that applies to most any single cylinder! I'd not thought about that!

[Weldangrind]

Great tip Spud! I hadn't thought about socket head cap screws on a carb bowl.

[FastDoc]

Typical Spudification.

Make a significant positive change for free or for pennies.

Use nothing more technologically advanced than what can be found at the feed store.

Share the benefits of his research with others for free.

Well done! :P

[SpudRider]

Originally Posted by Weldangrind

Great tip Spud! I hadn't thought about socket head cap screws on a carb bowl.

Thank you, WG.

Originally Posted by FastDoc

Typical Spudification...Well done! :P

Thank you for the kind words, Doc. I must admit, I got this tip from reading a post over at the TW200 forum.

I live, and ride, at elevations of 4,500 feet above sea level, and higher. I have also replaced my stock, Zong muffler with an FMF Turbine Core 2 silencer/spark arrestor. When the weather gets nicer, I need to jet down my carburetor from a size 127.5, Mikuni main jet, to a size 125, Mikuni main jet. At that time, I am definitely going to replace the float bowl screws, and see if this tip will work for the Zong. If someone experiments sooner, please tell us if the replacement bolts make the job easier!

Spud