Zongshen RX3: Suspension System

[SpudRider]

Fork Disassembly and Inspection

Upper Fork Tube Disassembly

To disassemble the forks, begin by loosening the cap of the fork with a 19 mm wrench. Lower the upper fork tube to reveal the fork spring. Insert a 14 mm cone wrench, or another thin wrench, between the fork coils, and grab the lock nut below the fork cap. While holding the lock nut, remove the fork cap and washer with a 19 mm wrench.





Remove the fork spring, and drain the fork oil.



Remove the upper fork tube following the instructions in the CSC Fork Maintenance Tutorial at the following link.

http://www.cscmotorcycles.com/Articles.asp?ID=263

[SpudRider]

Lower Fork Tube Disassembly

Disassemble the fork base by removing the bolt (A) with a 2.5 mm Allen wrench.

Secure the fork base (A) in a vice. Insert a thin rod through the holes of the fork (B), and remove the inner fork tube from the base by twisting the tube in a counter clockwise direction.



Push the damper rod down the lower fork tube to remove the base plug (A), and disassemble the lower fork tube.

[SpudRider]

Fork Spring Inspection

Measure the length of the fork spring. Replace the spring if it is shorter than the minimum length.

[SpudRider]

Shock Absorber Adjustment

Cylinder Gas Pressure

The standard gas pressure in the cylinder is 44 psi. The gas pressure influences the compression damping of the shock.

[SpudRider]

Spring Preload

Loosen the Allen head bolt, and turn the locking collar (A) to adjust the spring preload. The spring preload should be set to the proper race sag for best performance. Directions for adjusting the spring preload are contained in the following thread.

http://www.chinariders.net/showthread.php?t=14677

[SpudRider]

Rebound Damping

Rebound damping affects the speed at which the shock extends while recovering from compression. The shock absorber has 15 settings for rebound damping. Turning the screw clockwise slows the rebound damping. Turning the screw counter-clockwise accelerates the rebound damping.

[SpudRider]

Today I removed the valve cap on the stock shock absorber. Underneath I found a standard schrader valve. I measured the pressure in the shock with my tire gauge, and it read 67.5 psi. The specified press is 44 psi. Perhaps the high pressure contributed to the harsh ride I experienced with this shock absorber.

I lowered the pressure to the standard setting of 44 psi. If the shock is not performing properly for you, you might want to check the air pressure. However, the shock cartridge contains very little air, so it might not make much of a difference.

[Danimal]

Man Spud, you're good.

Always got something cookin

[SpudRider]

[RedHawk47]

Originally Posted by SpudRider

Today I removed the valve cap on the stock shock absorber. Underneath I found a standard schrader valve. I measured the pressure in the shock with my tire gauge, and it read 67.5 psi. The specified press is 44 psi. Perhaps the high pressure contributed to the harsh ride I experienced with this shock absorber.

I lowered the pressure to the standard setting of 44 psi. If the shock is not performing properly for you, you might want to check the air pressure. However, the shock cartridge contains very little air, so it might not make much of a difference.

I would assume that you would want to check it with the wheel off the ground, or does it matter?

How do you access the valve? Do I have to take everything apart? My valve faces the rear. I'm thinking of removing the shock and reinstalling it with the valve facing the front. Will it fit? Will I be able to access it then?

Rebound adjustment and preload: What is a good starting setting? I am a lightweight, 160 lbs w/o gear.

[SpudRider]

Originally Posted by RedHawk47

I would assume that you would want to check it with the wheel off the ground, or does it matter?

How do you access the valve? Do I have to take everything apart? My valve faces the rear. I'm thinking of removing the shock and reinstalling it with the valve facing the front. Will it fit? Will I be able to access it then?

Rebound adjustment and preload: What is a good starting setting? I am a lightweight, 160 lbs w/o gear.

The following thread describes how you set the shock spring preload.

http://www.chinariders.net/showthread.php?t=14677

You might be able to check the air pressure from the top. I can't guarantee a minor difference in air pressure will make any difference in shock performance, but it can't hurt to try. However, adjusting the spring preload will certainly improve the performance of the shock.

The schrader valve of the stock shock absorber is located in the same position as the pressure valve on the Progressive shock absorber.



You must remove the saddle, fuel tank, and a small emissions canister to see the valve from the top.



Remove the valve cap, and you might be able to get a small pressure gauge onto the valve, if you have small hands. Lift the rear wheel to get the weight off the shock before you measure the pressure.

If you cannot access the pressure valve from the top, I wouldn't worry about it. I'm beginning to doubt a small difference in air pressure will have much effect on the performance of the stock shock absorber.

[3banger]

With my understanding of suspension wich is some what limited but with a good ME guess; I don't think chages in air pressure will make any noticeable pre-load difference. These are not air spring shocks like in many mountain bikes. The air pressure is there to minamaize oil foaming while working the shock hard. So the pressure is in the oil damping circuit and thus acts equally on the top and bottom of the internal piston and valving.

[SpudRider]

Originally Posted by 3banger

With my understanding of suspension wich is some what limited but with a good ME guess; I don't think chages in air pressure will make any noticeable pre-load difference. These are not air spring shocks like in many mountain bikes. The air pressure is there to minamaize oil foaming while working the shock hard. So the pressure is in the oil damping circuit and thus acts equally on the top and bottom of the internal piston and valving.

I'm sure you are correct. There is very little air in the cartridge.

[AZRider]

Spud, would it be possible to attach a flexible extension on the valve and then zip tie it to an accessible location?

[SpudRider]

Yes, that might be possible, George.