Change Log

A while back, I bought one of my kids an SSR SR70C dirt bike. I was so impressed with the little bike that later, when I was looking for a used 250 to ride with my kids, I decided to take a chance on SSR's larger machine, the SR250S.

Picture of the SSR SR250S

Information about these bikes is somewhat hard to come by; despite their low price, and although the SSR pit bikes seem to sell pretty well, I've only spoken to a couple of other SR250S owners.

I expect to get a lot details wrong on this page and I count on readers who know more than I do to set me straight. Please, if you have corrections or additional information for the page, email it to me at .


The NC250 is manufactured by Shandong Asiawing Motors Co.,Ltd. (their website appears to be down at the moment I am writing this). It is distributed to other countries around the world by other importers. In the United States, the bike is imported by SSR Motorsports and is known as the SR250S.

In Europe, Borossi distributes the bikes, now under the Asiawing brand.

In Australia, the bike is distributed by Crossfire as the XZ250RR.

The SR250S is patterned on the 2007 model year CRF250X. In most cases, parts for that bike will fit the SR250S.

VIN Decoding

A very helpful contributor sent me this the (CARB letter)[valuegroup_ofmc_un2150003_250-449.pdf] on the SR250 and SR450, which has some information about the VIN scheme for the bikes.

The VIN Prefix is:


The tenth digit decodes the model year

E = 14
F = 15
G = 16

Presumably this works for earlier model years, but we only have 2014 and 2015 bikes for reference, so have not been able to confirm this yet.

Crossfire Parts Compatibility

I have removed the Crossfire XZ250R(R) Parts Compatibility table, since the exhaust compatibility information there was definitely wrong, and another contributor reports that after looking more closely at the Crossfire bikes that they had several important differences with the NC250.

I have archived that table here for reference.


The NC250/SR250S engine is a Zongshen ZS177MM, manufactured by Chongqing Zongshen Power Machinery Company (宗申).

This engine is also used in a number of other Chinese motorcycles and scooters, perhaps most notably the Zongshen RX-3 adventure-touring bike, which is distributed in the United States by the California Scooter Company

The ZS177M is definitely not a clone of the CRF250 engine, at least not when it comes to service parts like filters.

ZS177MM Parts

When searching online for SR250S parts, it is helpful to use "NC250" rather than "SR250S", since the bike is called NC250 everywhere except the US.

Crossfire published this parts diagram for the ZS177MM.

Parts for this motor are plentiful and relatively cheap if you don't mind having them shipped from abroad.

Another option is to purchase parts from CSC for the RX-3:

Oil Filter

The ZS177MM does not use the same oil filter type as the CRF250.

The oil filter included with the bike is a serviceable screen-type filter, not a pleated paper filter. When changing the engine oil, you can remove the filter, slide the core out of the screen, and use a solvent and bristle brush to clean the screen. I used compressed air to blow out any bits from the screen.

Although I neglected to get a photo of it, I gave the bike an initial oil change after about 6-8 hours of riding, since many forum trolls had claimed the filter would be full of shavings as the engine inevitably destroyed itself after a few hours of use. I found virtually nothing, a few very fine bits (which I think might've been from the filter screen itself), and a little bit of ferrous gunk on the oil drain plug magnet, about what I've seen on any brand new motorcycle.

I'm going to stick with the serviceable filter for now, although I think that CSC RX-3 pleated paper filters will fit this motor. I will be interested to hear if anyone tries it.

By the way, my oil drain plug was sealed with gray hi-temp RTV rather than a crush washer, although I used a crush washer instead of more RTV when I made the first oil change.


The 2015 SR250S carburetor is manufactured by Sunworld Moto. Mine has the marking SWR H34AS4-1514 PHB E34.

Picture of SWR H34AS4-1514 PHB E34 Carburetor

The carb is pretty similar to a Keihin PWK, which has a flat slide and a venting arrangement similar to the Keihin QuadVent carbs.

A contributor reports that the 2014 model shipped with a Dellorto carb (Thanks David R!), possibly a PHBE34.

Idle Adjustment

The pilot circuit on this carb uses an airscrew rather than a fuel screw. From the dealer, the factory setting for the air screw was 2.5 turns.

The effect of adjusting the air screw is not instantaneous, in my experience I need to work in quarter-turn increments and give the system about ten to twelve seconds to catch up with the change in air.


Picture of SWR H34AS4-1514 PHB E34 N68E Needle

The needle is marked N68E and appears to be a standard PWK type. The clip is in position 2 from the factory.

The easiest way to remove the needle is to unbolt the petcock, remove the carb fuel line, remove the tank, and then unscrew the plate where the throttle cable enters the carb body. I think a patient person could probably do it without removing the tank, but the tank is so simple to remove that I don't think it's worth it.

Picture of SWR H34AS4-1514 PHB E34 with slide cover off

The needle can be removed from the slide once the cable is unhooked. The SWR has a clever window in the slide that makes hooking the ball-end easier.

Picture of SWR H34AS4-1514 PHB E34 slide

Main and Pilot Jets

The main jet is marked 140, and looks to me like Honda Part no 99101-357-1400, which a Keihin main jet.

Picture of SWR H34AS4-1514 PHB E34 Main Jet

The pilot jet is marked 45, and appears to be a standard Keihin PWK/CVK/PE style.

Picture of SWR H34AS4-1514 PHB E34 Pilot Jet

The main jet can be removed with a 6mm driver through the portal on the bottom of the float bowl after unscrewing the plug.

To get the at the main and pilot jets:

The main jet is the smaller 6mm brass hex bit, which is screwed into the emulsion tube. On my carb, the emulsion tube was torqued slightly less than the jet, so the tube and jet came out together, no big whoop.

The pilot jet is situated alongside the main jet, but I couldn't get to it through the portal, and had to remove the bowl.

Picture of SWR H34AS4-1514 PHB E34 floats

A word of warning, there's a small breather tube pressed into the bowl at an angle, which will catch the left float if you pull the bowl straight down when removing it, which can bend the float. I suggest removing the small vinyl hose from the rear left corner of the bowl first, then jiggle it to make the tube clear the float.

The first hour or two that I rode the bike, I had some trouble keeping it running and then even mor trouble hot starting it. I'm kind of clueless when it comes to carburetors, but it seemed like it was running rich, so I tried to lean it with what I thought was a fuel screw. I didn't realize at the time that the SWR carb has an air screw rather than a fuel screw, so when I thought I was leaning the mix, I was enriching it. I thought maybe the dealer had filled the tank with 87 octane gas (sorry CycleMax, I should never have doubted you :) ), so I drained it and refilled it, then reset the "fuel" screw to two turns and everything seemed fine.

Since then, I've experimented with the slow jetting a little. I tried replacing the #45 pilot jet with both a #48 and #42. On my bike, the stock #45 gives a little bit of black smoke on opening the throttle, it should have been obvious that a #48 was going to be way too rich (it is). With the #42, I don't get any smoke if I blip the throttle with the engine warm, and it starts a little more easily than with the #45.

I've also experimented with the needle clip in both positions 2 and 3, although it was when I was trying the #45 and #48 pilots. My next test is going to be with the #42 pilot and the #3 clip.

The main jet on my bike seems fine, although I ride like an old lady and have not spent much time at full throttle.

Needles and jets (both main and pilot) are readily available and inexpensive on Ebay. I got a pack of 10 pilot jets for 8 or 10 bucks, and there are packs of 10 needles for 15-20$.

I don't think there would be any value in buying a CRF250X jet kit. The needles and main jets in those kits might fit, but I don't know (and most of the kits I looked at don't tell you) specifically what size jets and needles are included, and neither the engine nor the carb in the SR250S are not similar to the CRF.


The Zongshen and Asiawing manuals recommend 91 or higher octane fuel. I've been using 93 so far.


The stock exhaust on the NC250 has the appearance of an aftermarket pipe, is fairly light (4.8lb/2.2kg), but lacks an internal spark arrestor.

I ordered a Lexx Slip-on Exhaust, but I can confirm that it is not compatible with the SR250S. In addition to being the wrong diameter pipe, the mid-pipe is the wrong length, has the wrong bend, and the mounting bolt carrier is in the wrong location.

Another contributor to the site installed a FMF PowerCore 4 Universal, reusing the factory header the welded-in factory mid-pipe. He used a local exhaust shop to fabricate a working pipe:

FMF PowerCore 4 Universal

FMF PowerCore 4 Universal, exposed

(Thanks Brian C!)


According to Borossi, rear suspension is "rear pergressive FastAce Performance mono shock absorber with spring preload and rebound and compression damping" (sic).

My shock doesn't have a manufacturer's mark that I can find; I'm not sure whether the FastAce shock is a Borossi-specific upgrade. AsiaWing of France reports in their Chassis Parts Diagram (Thanks, David R.) that the rear shocks are either of FastAce or Zhenglin manufacture. On the SSR bike at least, the shock appears to be patterned on a KYB.

I took my rear shock to my local RaceTech dealer, MRP Motorsports, and had the factory spring rated. The stock spring is 270mm in length, with 58mm and 60mm ID on the top and bottom ends, respectively. The rate is 6.1kg/mm, which differs considerably from 2007 CRF250X rate of 4.8kg/mm according to Racetech.

At 250lb, I've resprung mine with a 66 N/mm Öhlins spring (06310-17), which Öhlins lists as a KYB replacement spring. More Spring Rates.

Also according to Borossi, the front suspension is an 47mm Upside-Down FastAce Performance fork; rebound and compression adjustable.

The rear shock fairly easily using this method, which involves removing the pipe and unbolting the subframe, without having to remove the airbox. I recommend loosening the pipe clamp by the carb outlet, and have some (I used zip ties) to support the subframe while the shock is out.

Handlebars and Risers

Picture of SSR SR250S triple clamp

The stock handle bar tapers from 1.125" to 0.875" (1 1/8 to 7/8)

I'm tall with a long torso so I like bar risers if I'm standing on the pegs a lot. I tried adding a set of 2" Rox Risers, but using them would require lengthening the throttle cable. Also it is virtually impossible to tighten both handlebar bolts while the Rox Risers are installed. A ball-end hex wrench may be able to do the job, but since the throttle cable is too short anyway, I'm not going to bother.

Aftermarket Electronics

I fitted a small battery-powered tachometer and hour meter from Metertech to my bike.

Picture of the Metertech Tachometer

To install this type of meter, you just stick it to something, route the thin coaxial cable down to the engine, and coil the end around the spark plug wire.

A contributor to the site installed a much nicer Trailtech Vapor computer to his bike, which measures speed, RPM, temperature, time, and distance

Picture of the Trailtech Vapor

The Vapor includes application-specific sensors


Picture of SSR SR250S shifter

The shifter is of the folding design, similar to the CRF250X pattern, but I haven't compared them.

Length is about 5" from the front edge to the center line of the shifter shaft, which I measured as 0.425" (10.8mm?). I crudely measured this without detaching the shifter. If you are looking for this measurement let me know, I'll take it off and get a more accurate measure.


I haven't determined whether the SR250S plastics are a match with the CRF, but I've got a couple of photos that might prove useful:

Picture of the SSR SR250S Front Fender

Picture of the SSR SR250S Side Tank Plastic

These brake plastics are reported to fit (Thanks David R!)

Wiring Diagram

Available here

Chain and Sprockets

(Thanks David R. for most of this section!)

A contributor reports that the [Acerbis Chain Slider Honda CR-125/250 CRF250 CRF450-R/X] ( . He also reports that his front sprocket had been flipped when installed, after correcting the orientation the chain slider wore unevenly and needed to be replaced. He also reports that MSR's Chain guide for CRF450X 2007 is a fit.

He also reports that JT Sprockets JTR210.51 51T Steel Rear Sprocket was a fit after the center section of the stock two-piece rear sprocket separated from the ring at some point.

I am not aware of an aftermarket front sprocket that fits; a call to your SSR dealer is the best bet for now.

Wheels and Sprockets

A contributor to the site reports that after breaking several stock spokes in the rear wheel, he used the Tusk Motorcycle Spoke Kit (Rear 18" Silver - Silver 18" for 2007 HONDA CRF450X). (Thanks David R!)

Other Parts

TBolt USA carries levers and misc parts. They're helpful on the forums so I plan to buy from them when I can.

Useful Links