Zongshen RX3 carbureted version mods & repairs
 

Hi, this thread is for all members to discuss about the technical aspects of the carbureted version of the zong rx3. Be it the engine, how the card work, how to meddle with the carb.... And many more. Here are a few photos of the engine from the carburetor version of the bike. Minbe is a KTN RS3(Malaysian version)
Attachment 2347

Attachment 2348

Attachment 2349

Attachment 2350
The lever for spare gas
Attachment 2351

Tried looking for te screw to the pilot jet just but cannot determine which was it..... Any idea from the engine pics

I can't see it. It might be under the carb, similar to a Mikuni or Keihin round slide.

I looked through a few pages at Taobao, but I didn't spot a carb. If you could find one cheap enough, you could experiment with it and leave your stock carb alone.

Can you use a mirror and get a picture of the underside of the carb?

Look under the carburetor for the PMS screw. Is there a brass cap or a screw located inside the red circle shown in the photograph below?

http://i442.photobucket.com/albums/q...pskdjn6ym4.jpg

Check for a brass cap, or a screw at this location.

http://i442.photobucket.com/albums/q...psumecno3n.jpg

Way to go, eagle eye! :D

The carb is a Keima PD36J.
Could this be the cap that we were looking for?
Attachment 2353

Seems to be the same as a replacement carb that's being used on the Yamaha YFM 400. ( I think its some kind of quad bike )

http://www.amazon.com/gp/product/B00...4J2RKK6ZBHA4FT

if this is the same as yours then this exploded carb diagram maybe of use

http://www.yamahapartshouse.com/oemp...9a4/carburetor

:)

I don't think so. I think the PMS is probably located inside the yellow circle.

http://i442.photobucket.com/albums/q...psbhyc1t3u.jpg

Based on your guess and also the blown up diagram from katflap, i think you got it....in a way, it's actually hidden.
So I should be sticking the screwdriver into this hole shown in the yellow arrow.
Attachment 2354

Yes. Turn that out. Maybe a 1/2 turn.

Is the hole covered by a brass cap? If so, you need to remove the cap first. Have you verified there is a screw inside the hole? If so, that screw is very likely the PMS.

You do adjust the PMS with a small screwdriver. You first need to discover the present setting of the PMS. To do so, slowly tighten the PMS, counting the number of quarter turns until it lightly touches bottom. Don't overtighten the PMS. :ohno: You merely want to count the number of turns until it lightly touches bottom. For example, you might need to turn the PMS 2-1/4 turns until it lightly touches bottom.

After you record the number of turns needed, loosen the PMS counter-clockwise until you return it to the initial position. Report back, and I will tell you next step. ;)

I'd like him to count the number of turns first, so he knows the initial setting, Allen. ;)

Have not verified if there's a screw in there.
At work now. Will need to get back then I can take a look at it.

Finding a way to turn that screw (if equipped) is the challenge. I use a tiny hex ratchet with a flat head screwdriver bit.

i guessed so. the space available is close to none.....haha.....went out just now and experienced the same thing again. Was at the traffic light, in 1st gear, clutch fully pressed...engine died while idling and took a few attempts to start it back.

Perhaps you merely need to increase the idle speed. ;) The idle speed adjuster is shown inside the yellow circle in the photograph below. Merely tighten, or loosen the screw to adjust the idle speed of the engine. :)

http://i442.photobucket.com/albums/q...psszkzqrrt.jpg

Hi, I own a KTN RS3 too. I am from Penang, Malaysia. I am having problem for both engine cold start and restart after engine is warmed up. The engine died after engaging the first gear even though the clutch lever is fully pressed. My current RPM setting is around 1.8k to 2k. I think it is too high. and I often smell fuel from the exhaust. I will send my bike back to tuning this Saturday since it is still under warranty.

If you would like to tune the carb by yourself, make sure that you do it after the engine is warmed up.

Cheers

Welcome; we are glad you joined us. :hi:

Your problems also sound as if they might be caused by an improper adjustment of the pilot mixture screw (PMS). Indeed, the PMS should be adjusted when the engine is hot. I emphasize, the engine must be hot, not warm. ;) After your problem is resolved, please let us know how it was fixed. :)

I will make sure my both eyes are glued to my bike when they are tuning my bike. ;)

Welcome! Thanks for signing up. Please show us pics of your bike.

X2. :) If you have time, please post a thread in our Introduce Yourself forum, and include photographs of your KTN RS3. We love to view photos from different parts of our world. :tup:

https://plus.google.com/photos/album...34554099001210

Not sure am I doing this right. I haven't posted in forum for a long long time. Please let me know if you all can view it.

I have changed the top box to bigger box. The rest remain the same as the rest of the world. ;)

How can I find the thread? Please advise.

Thanks. I really hope that they can solve my problem by just adjusting the PMS.

Hello fellow Penangite Adventore.
Where did you get your bike. looks like the idling thing is a common prob for new bikes.
What box did you get? am looking for one also coz the current one is just a bit too small.

FTEY. I got my bike from one of the motorcycle shop at mainland of Penang State. The brand of the box that I changed is Coocase. Model number S48-L Luxury.

I'm sorry; the correct name of the forum is New Member Introductions. ;) If you have time, please post a new thread and introduce yourself to our community at the following link. :)

http://www.chinariders.net/forumdisplay.php?f=112

Confirmed there's a brass screw under that carb and it should be the PMS screw.
Problem now is getting there is a pain. Space is so small. Cant even get the smallest screwdriver in there let alone my hand or fingers. And with the hot engine right in front...... Unless you have an angled screwdriver or the long flexible ones.... Guess i need to send it to the shop to do it.

The PMS is not difficult to rotate. You can probably adjust it with a short screwdriver tip. ;)

http://www.cabletiesandmore.com/imag...illips-top.jpg

If that doesn't work, can you loosen the metal bands on each side of the carburetor, and rotate the carburetor so the bottom faces you? If so, you can adjust the PMS, and then rotate the carburetor back into a vertical position. Just make sure to tighten the metal bands again after you finish. ;)

Can it be reached by the smallest ratchet? The smallest ratchet that I have is just 3 inches long. But I never tried before. Since the bike is still under warranty, I do agree to send it back to the shop. And that's what I'm planning to do this weekend.

Adventore. U goin back to your shop or to the manufacturer in alma.

That is a good idea.

FTEY, I'm going back to the shop. Reason is the shop that I bought my RS3 helped the manufacturer to tune their prototype model when they are still setting up their manufacturing line at Alma. This is also why I went all the way from Penang island to this shop to buy from them. I have asked a lot of shops here but none of them know about KTN RS3 in detail. Only this particular shop answered all my questions. ;)

I keen to learn from them as I might need those skills when I go around peninsula Malaysia one day with my RS3.

You are wise to use your warranty coverage, and let the shop diagnose this problem. :) You are wiser yet to watch, and learn as they fix the problem. ;) Thank you for your willingness to share what you learn. :tup:

I use:
 

A flexible screwdriver Its shaft is "wire" and can bend almost 90 degrees, so turn handle horizontal plane, but tip is vertical (or very close to it:). You can chang to whatever kind of bit you need also, on the driver end. Very handy. They make a flex bit for drills also, you can use if you have one already.

The idea Spud suggested works well also, ie loosen the bands on the manifold, rotate carb, then adjust screw, and rotate carb back to vertical before testing. IT MAY run very rich, if the bowl dumps fuel into intake tract for a minute or so (or be flooded/hard to start for a few minutes).

There is a CHANCE the floats on both carbs are too high, and dumping fuel when starting out and or braking or tilting the bike from side to side at a stop. Try that (tilting the bike) and see if it stalls. Thats the way to find out re floats (one way w/o dissaasembly of carb).

If its floats, I can explain setting them for you as well. (Spud may have this covered already in his thread...)

FTEY. My RS3 has been behaving good today. There are a few thing that I have change during my riding.

1) gear shifting behavior. I shift to higher gear after about 1/2 second after engaging the clutch. When shifting to low gear, I will rev the engine before shifting. I just gave a short rev to around 4000 RPM.
2) when engaging to first gear from neutral at stop light. I rev before engaging first gear.
3) engaging neutral. Short revving the engine, it should be easier to get neutral.
4) starting the engine from cold or hot. Switch off all lights. Turn the accelerator around 5 to 10 mm from its initial position and wait for 2 to 3 seconds then start the engine. I manage to start on 2nd attempt. The free play of the accelerator does not count.

These were what I have discovered so far. But I managed to reach home safely without having a dead engine in the middle of the road.:clap:

It sounds like you're really getting to know your bike. :D

I agree. :tup: