New Zongshen RX3 (ZS250GY-3) Dual Sport

[SpudRider]

I use high octane fuel in my Honda CRF250X. This is 89 octane in most places, but is only 87 octane at Idaho elevations. Therefore, I am inclined to follow the Zongshen Owner's Manual, and use high octane fuel in my Zongshen RX3. If high octane fuel is not available, I'm confident one can use regular octane fuel when necessary.

[jimjr21]

After some research I have found that the parts used in the carbureted and fuel injection engine are different. So be careful determining parts by the available lists that are linked here.

[jimjr21]

I am happy that the tolerance is smaller with this engine. The newer engines with higher quality parts are going to smaller and smaller valve clearances. This is a great thing to know the overall quality of the materials used in the valves and the seats.

[jimjr21]

I can't wait to get my hands on an engine along with the bike. I will be developing parts for more HP ASAP. Short list would be valves, springs, cams, pistons, rods, and cranks for internal engine parts.

[Weldangrind]

Originally Posted by SpudRider

Indeed, I understand the entire engine expands as the engine heats. However, I still believe the exhaust valves must certainly heat up more than the intake valves. The intake valves are cooled by the incoming fuel/air mixture on every intake stroke, whereas the exhaust valves are always heated by the expelled gas on the exhaust stroke.

Agreed. I also believe that the gap between the rocker and valves decreases when the engine gets hot.

[Weldangrind]

Originally Posted by Wolftrax

That's a very frequent valve clearence check schedule! KLX 250, CRF250L and WR250R are all between 14000 and 24000 miles. So every time you change the oil you will have to adjust the valves. That's going to be a real PITA.

Once a person becomes accustomed to the process, I'll bet that it can be accomplished while the oil is draining.

[Weldangrind]

Originally Posted by Wolftrax

The good news is it has threaded adjusters as opposed to shim and bucket.

Agreed. Sometimes older tech is better.

I'm grateful that all of my bikes and atv's have threaded adjusters.

[Weldangrind]

Originally Posted by SpudRider

The following video demonstrates an oil change for the Zongshen NC250 engine. You can view the three, stainless steel, oil filters during this process.

Thanks for the very interesting video, Spud.

I was surprised to see how messy the process is, and I'm looking forward to seeing the ChinaRider solutions that are developed over time.

It appears to have a brass drain plug with a magnet epoxied in it. I recommend that each RX-3 rider buy a spare drain plug, in case it should become cross-threaded. It would be wise to use a little anti-seize on the threads.

I'm glad to see a sight glass. My Bro-in-law's XT350 has neither a dipstick nor a sight glass. Most annoying.

Did anybody spot the snow track gear at 13:25? I wonder if they've adapted it for use with the bike in the video.

[SpudRider]

Originally Posted by Weldangrind

Agreed. I also believe that the gap between the rocker and valves decreases when the engine gets hot.

Yes, that is why you are always told to adjust the valve lash on a stone cold engine. I always let my bikes sit overnight before I adjust the valve lash.

[SpudRider]

Originally Posted by Weldangrind

Thanks for the very interesting video, Spud.

I was surprised to see how messy the process is, and I'm looking forward to seeing the ChinaRider solutions that are developed over time...

The process didn't get messy until they removed the coarse (small) oil filter on the right side of the engine. Also, if they had not changed the oil on a lift stand, the mess would have been smaller.

I always drain my oil with the bike on the kick stand. I will also be expecting a lot of oil to issue from that coarse oil filter. In addition, I will probably remove the skid plate before changing the oil.

[SpudRider]

Weld,

I had not noticed the snow track gear. You are a keen observer. Perhaps you missed your calling as a detective.

[Mudflap]

Wonder how many people have actually compared the lash measurement on a hot engine vs. cold? Back in the 80s I had a bet going with the mechanics at the motorcycle shop I worked at. We checked several bike engines cold and hot, push rod and OHC. All were looser when hot though the OHC engines showed less difference than the push rod engines.

Originally Posted by SpudRider

Yes, that is why you are always told to adjust the valve lash on a stone cold engine. I always let my bikes sit overnight before I adjust the valve lash.

[thillskier]

I hope that someone at CSC can double check the exhaust valve specs for us at least. That MAY be why the intervals are as short as they are because thats not a lot of leeway for being out of tolerance, and a burnt exhaust valve would be a real possibility with no lash gap when it got hot and expanded.
I'll be a bit "nervous" when I first am riding the bike, especially on the initial ride back home that 2300 miles +...I will probably try to check them (and adjust if necessary) at CSC before leaving. Its not what I want to do enroute from Cali to Bama, for sure!
Love the threaded adjusters though, and the reusable oil filters. They absolutely WILL NOT collapse in very cold weather with thick oil either!
So safer there as well...
This will prove to be a REAL time saver when servicing the bikes, IMHO. They will not need any more adjustment than any other motorcycles, IMHO, as they should all wear a similar amount of time/miles after initial break in and settling.
Does anyone know the suggested oil viscosity or does it have a differing cold and hot recomendation? Oil change suggested intervals (after break in?) I holp I can avoid that as well on the way back....
Also is the chain o ring, or do I need to pack a can of spray chain lube?
If not o ring, thats going to be the first upgrade!! hehe

[SpudRider]

Originally Posted by Mudflap

Wonder how many people have actually compared the lash measurement on a hot engine vs. cold? Back in the 80s I had a bet going with the mechanics at the motorcycle shop I worked at. We checked several bike engines cold and hot, push rod and OHC. All were looser when hot though the OHC engines showed less difference than the push rod engines.

Thanks for posting the interesting information. It would be nice to have data from a larger sample than several engines, but I am surprised any engine would exhibit a looser valve lash when hot. Since the valves are directly exposed to engine combustion, it is counter intuitive to expect them to expand less than the rockers, which are located in the cylinder head. I would be even more surprised to see the valve lash get looser with an overhead cam directly contacting a bucket over the valve stem. How much money did you collect in bets?

[SpudRider]

Originally Posted by thillskier

...Does anyone know the suggested oil viscosity or does it have a differing cold and hot recomendation? Oil change suggested intervals (after break in?) I holp I can avoid that as well on the way back....
Also is the chain o ring, or do I need to pack a can of spray chain lube?
If not o ring, thats going to be the first upgrade!! hehe

I use 15W/40 motor oil in all my motorcycle engines. However, you can check the RX3 Owner's Manual at the following link to search for the recommended oil.

http://www.chinariders.net/files/Zon...ers_manual.pdf

If you check recent posts, you will also find links for the Gas Gas and AJP bikes which employ the Zongshen NC250 engine.

The RX3 specifications state the bike comes with an O-ring drive chain.