Zongshen RX3 carbureted version mods & repairs

[FTEY]

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.

[SpudRider]

Originally Posted by FTEY

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.



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.

[Adventore]

Originally Posted by FTEY

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.

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]

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.

[Weldangrind]

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

[Adventore]

Originally Posted by Weldangrind

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

What can I say. I'm a mechanical engineer. Doing research is my daily job. This is also my hobby. When things are getting in your way, you just have to find how to work around the problem until it's permanently solved.

[Weldangrind]

Originally Posted by Adventore

What can I say. I'm a mechanical engineer. Doing research is my daily job. This is also my hobby. When things are getting in your way, you just have to find how to work around the problem until it's permanently solved.

That is exactly what I'd be doing, if I could start again.

[SpudRider]

I agree.

[FTEY]

Great remedy.. Worked except the shifting to N. Sometimes still cant get it. So i shift down from 2nd gear when i cant get it.

[Adventore]

Originally Posted by FTEY

Great remedy.. Worked except the shifting to N. Sometimes still cant get it. So i shift down from 2nd gear when i cant get it.

You know? I hate revving the engine at the stop light. Especially when there are young bikers. They will think that you are trying to invite them for a race. But as the matter of fact, I'm just trying to get to my neutral gear.

[Adventore]

FTEY and I went for adjustment today. The mechanic uses a short screw driver bit attaching to a socket of ratchet to adjust the PMS. The tuning of our carb is slightly rich. The spark plug is a bit dark. But the adjustment still doesn't solve our problem. We have to send our bike back for him to readjust the carb. Sounds like he will open up the carb and change the pin.

After the adjustment, we put the bike to test by riding over 200km. Although it's not at its best condition, but the ride seems smoother than before. Especially when we ride on a countryside. Slow speed with high gear seems to be very relaxing.

As for the hard to get neutral problem, the mechanic told us that he will change the pin on the clutch. by doing that, shifting to neutral shoul be much easier. But we will have to leave our bike for a day.

[SpudRider]

I'm glad you are making progress. It is important to adjust the PMS first, before changing the carburetor jets. If the PMS needs to be tightened too much, you need a smaller pilot jet. Conversely, if the PMS needs to be loosened too much, you need a larger pilot jet.

[Adventore]

Originally Posted by SpudRider

I'm glad you are making progress. It is important to adjust the PMS first, before changing the carburetor jets. If the PMS needs to be tightened too much, you need a smaller pilot jet. Conversely, if the PMS needs to be loosened too much, you need a larger pilot jet.

Thank you, Spud. I've learnt something from you today.

[SpudRider]

You're welcome. Different carburetors might have different values, but the correct setting of the PMS should be about 2-1/2 to 3-1/2 turns out from the lightly seated position. If you need to adjust the PMS much farther in either direction, you a need a different pilot jet.

[FTEY]

Yup. Was a great ride with Adventore. Gonna send my bike in for the tunes this comig weekend. Will keep all posted of the outcome, and probably go on another ride with Adventore after he did his.