New Zongshen RX3 (ZS250GY-3) Dual Sport

[jimjr21]

Source asked to remain unknown at this time.

Yes. Own a race engine machine shop so lots of fun toys.

[detours]

I'll be watching everyone's mods with interest, but I have to say the pipes look great as is ... mandrel bends, short pipes, pretty constant diameter (at least on the outside), stainless steel, good location for the O2 sensor.

Now the old pipe didn't impress, with the long bend, the big dip to the bottom of the engine and the weird O2 location.

We'll see about the muffler, but I've had more bad luck than good modifying my vehicles over the years. Every change is expensive and requires adjusting 3 other things to make it work. And if I get more power on the top end, I lose it on the bottom. Or it runs worse.

Not knocking power mods, just my experience. YMMV

[SpudRider]

Originally Posted by Wolftrax

It does look like a clean flow from the header through the midpipe. I'm betting the cat is in the muffler right where the midpipe inlet is. Both the CRF250l and TR650 had cats in the muffler just as I described. The Husky was easy to knock out the cats with an air hammer. The Honda is more complicated involving opening the can up and re-welding. That muffler looks like it weighs a ton!!

We might be pleasantly surprised with the weight of the muffler, or we might not. The Honda XR650L muffler looks very heavy, but it is only 2 pounds heavier than an FMF aftermarket muffler. Nevertheless, the Chinese are not noted for their concern regarding weight reduction, so the stock muffler might be as heavy as it looks.

If a catalytic converter and/or weight becomes a problem, I don't think it would be very difficult to cut the midpipe from the muffler, and substitute an FMF Universal Spark Arrestor for the stock muffler.

[SpudRider]

Originally Posted by Wolftrax

I hope you do Spud. Dobeck's little black box has been the best and most versatile performance mod I've ever put on a bike.

Monday afternoon I called Dobeck Performance, and talked to the secretary. They owner and the tech guy were not in the office, so I hope they will contact me in the next few days.

[SpudRider]

Originally Posted by Weldangrind

It could. I can't figure out why else there would be a weld bead at that specific point. There is no need for welding during the bending process. Also, it looks like the diameter might change at the bead.

One won't know until a wire is pushed down the pipe.

I hope a catalytic converter isn't located in the exhaust header.

[SpudRider]

Originally Posted by Weldangrind

I don't see any indications in the midpipe, but the muffler could definitely be hiding a cat. I'd be shocked if there was no cat with this bike, due to emissions regs.

If the cat isn't in the header, I'd be swapping that muffler out. It's probably really heavy anyway.

BTW, the large outlet might be for appearances only. I've certainly seen that before.

Originally Posted by Weldangrind

Spud, you may remember this old thread about Pastor Jim's scooter, where I found a cat in the muffler: http://www.chinariders.net/showthread.php?t=9421

Yes, I certainly do remember your excellent thread. I think you are probably correct, and a catalytic converter is hiding somewhere in the exhaust system. I certainly hope the RX3 muffler is not designed similarly to the scooter muffler you dissected.

[Weldangrind]

Originally Posted by SpudRider

I hope a catalytic converter isn't located in the exhaust header.

If it is, I bet that your buddy could cut, gut and weld the header for you. If he can't, I will.

[SpudRider]

Originally Posted by Weldangrind

If it is, I bet that your buddy could cut, gut and weld the header for you. If he can't, I will.

Thank you for the kind offer, Weld.

[Wolftrax]

Originally Posted by SpudRider

We might be pleasantly surprised with the weight of the muffler, or we might not. The Honda XR650L muffler looks very heavy, but it is only 2 pounds heavier than an FMF aftermarket muffler. Nevertheless, the Chinese are not noted for their concern regarding weight reduction, so the stock muffler might be as heavy as it looks.

If a catalytic converter and/or weight becomes a problem, I don't think it would be very difficult to cut the midpipe from the muffler, and substitute an FMF Universal Spark Arrestor for the stock muffler.

How noisy is that FMF can. I have a Powercore on my Honda with a quiet core insert and it's loud but tolerable. Heck I always wear ear plugs regardless how loud or quiet the exhaust.

[Wolftrax]

Spud. How often do you get asked what model KTM is that?

[SpudRider]

Originally Posted by Wolftrax

How noisy is that FMF can. I have a Powercore on my Honda with a quiet core insert and it's loud but tolerable. Heck I always wear ear plugs regardless how loud or quiet the exhaust.

That FMF silencer is not loud at all. It is U.S.F.S. approved for noise levels as well as spark suppression. It is easy to mount, easy to repack, very rugged, and inexpensive. I love it.

[SpudRider]

Originally Posted by Wolftrax

Spud. How often do you get asked what model KTM is that?

I've lost count; I still get asked all the time how much I like my KTM.

[SpudRider]

I'm proud of my Zongsen Sierra (ZS200GY-2), and I always correct people when they mistake it for a KTM. I could easily rebadge the Zong as a KTM, but I proudly keep the Zongshen markings on the right crankcase cover, and the saddle.

One could put BMW stickers on the Zongshen RX3, and it would easily pass for a Beemer. However, I am happy to ride Zongshen motorcycles, and I will continue to correct anyone who mistakes my RX3 for a BMW, or any other make of motorcycle.

[thillskier]

I really like the way the Ace 125 retro cafe bike looks and is set up. I was looking into them (dreaming) and there was a section removing the cat from the header due to extreme breathing restriction of the engine. It was at the header muffler interface.
If we have a similar set up, I will remove mine, cut, remove, and reweld the exhaust, after I drill out the mid baffles if the RX-3 has them. This should make the tone a bit deeper, and allow some better breathing, especially removing the restrictive cat in exhaust can or header.

The large exhaust hole can be then exploited best, especially after opening up any airbox restriction(s)! The ejk should get 10% or so more hp, close to AJP output or maybe better. I want to look into a helmholtz design using header and exhaust. They REALLY help my 350 Z when I had one a few yrs ago. For info see motordyne engineering. HUGE gains, for an exhaust and tune vs all other exhaust. Power bomb headers have something good happening with their headers, I've read as well.

[Wolftrax]

Originally Posted by SpudRider

That FMF silencer is not loud at all. It is U.S.F.S. approved for noise levels as well as spark suppression. It is easy to mount, easy to repack, very rugged, and inexpensive. I love it.

Did I read somewhere that it only weighs 2.2 lbs. Does that sound about right?