New Zongshen RX3 (ZS250GY-3) Dual Sport

[Weldangrind]

I tried to translate that page, but I'm still struggling to understand the origin of the engine. I know that it's made by Zong, but is it a Honda copy? CRF perhaps?

[recracer]

Originally Posted by Weldangrind

I tried to translate that page, but I'm still struggling to understand the origin of the engine. I know that it's made by Zong, but is it a Honda copy? CRF perhaps?

That I do not know , in appearance seems to have the CRF mounting locations. different head than a unicam CRF

[SpudRider]

How well did the NC250 engine work for you, Racer? Did you ever have any problems with this engine?

[SpudRider]

Originally Posted by Weldangrind

I tried to translate that page, but I'm still struggling to understand the origin of the engine. I know that it's made by Zong, but is it a Honda copy? CRF perhaps?

I haven't seen evidence to the contrary, so I believe the NC250 engine is a Zongshen design.

The NC250 engine has a single, overhead camshaft. This engine has two intake and two exhaust valves. The centrally located cam actuates the valves via two roller rocker arms.



My CRF250X engine has the camshaft located directly above the intake valves. The Honda engine actuates the exhaust valves via a roller rocker arm.

The Honda engine employs a shim-under-bucket design to adjust the intake valve lash. The CRF engine uses a shim-without-bucket design to adjust the exhaust valve lash. The shims rest directly on top of the valve retainers, and are directly contacted by the rocker arm.

The NC250 engine employs valve tappets to adjust the valve lash.



My Honda CRF engine has a five-speed transmission. The NC250 engine is available with both a five-speed, and a six-speed transmission. The ZS250GY-3 employs the six-speed transmission.

[SpudRider]

My Honda CRF engine has the spark plug located centrally, between the four valves. You must remove the fuel tank to replace the Honda's spark plug. The NC250 engine has the spark plug conveniently located on the right side of the cylinder head.

[recracer]

Originally Posted by SpudRider

How well did the NC250 engine work for you, Racer? Did you ever have any problems with this engine?

No problems with the engine or trans shifting . seemed to be a very solid package . I do hope the gear ratios were changed . First gear seemed a bit high ,even in the megelli . The megelli had no dreams of off road riding.

[SpudRider]

Thanks for the good report, Racer. I forget; did you have the 5-speed, or the 6-speed transmission?

[SpudRider]

The NC250 engine also has a different bore and stroke than the Honda CRF250 engine.

Zongshen NC250 Engine

Bore: 77mm
Stroke: 53.6mm

http://yitonmoto.en.alibaba.com/prod...ine_NC_CB.html

Honda CRF250 Engine

Bore: 78mm
Stroke: 52.2mm

http://www.hondanews.com/channels/po...specifications

The Honda piston has one compression ring, and a very short skirt. The Zongshen piston has two compression rings, and a more conventional, larger piston skirt.

[recracer]

Originally Posted by SpudRider

Thanks for the good report, Racer. I forget; did you have the 5-speed, or the 6-speed transmission?

The megelli was the 6-speed . I'll need to look ,but I am sure the ratios were in the megelli thread . As I had made sprocket changes to it.

[SpudRider]

Later, I am going to read your complete thread for a second time. I see where you posted regarding the 6-speed transmission; thanks for verifying that information once again. I also see you didn't verify a source for the front sprocket. The counter shaft sprocket looks somewhat similar to the C/S sprocket of my CRF250X; I will need to check the compatibility later.

[SpudRider]

I have heard reports Zongshen promotes the RX3 as having a Pro Link, rear suspension. The lower shock linkage doesn't have any grease zerks, so it will need to be disassembled for periodic greasing, inspection, and bearing replacement, as with my Honda CRF250X. I am trying to verify the sizes, and the availabilty of these RX3 bearings.

[SpudRider]

Where is the oil filter located on the Megilli NC250 engine? How did you turn the crankshaft to inspect the valve lash? The bottom end of the NC250 engine is quite different from either my CRF250X engine, or the CRF450X engine. The NC250 engine really looks like a new Zongshen design, and not a copy of another engine.

[recracer]

Originally Posted by SpudRider

The RX3 apparently has a 13T/44T sprocket combination from the factory. Without a bike to inspect, I won't speculate on the compatibility of the rear sprocket.

Where is the oil filter located on the Megilli NC250 engine? How did you turn the crankshaft to inspect the valve lash? The bottom end of the NC250 engine is quite different from either my CRF250X engine, or the CRF450X engine. The NC250 engine really looks like a new Zongshen design, and not a copy of another engine.

I never did verify the front sprocket interchange . I had the megelli for just under 1000 wrist pounding miles (sprung way to stiff) , I never checked the valve lash.

[SpudRider]

Thanks for information.

I see a timing check hole on the stator cover for the NC250 engine, but I don't see a plug covering access to the crankshaft. I'll look more closely, later.

[recracer]

Oil filter lower right side