By changing the clutch meet timing, start accelerating UP


CVT driving system

Clutch of the Scooter is structured to connect the clutch by centrifugal force.

Parts that control the centrifugal force is the clutch spring.

In addition, in the case of the novice many people have the wrong applications and names of the clutch spring and the center spring, I think that some people setting of the drive system can not be determined.

Let’s disassemble a clutch into this opportunity.

If you Removing the clutch do not know, see here


Automatic centrifugal clutch is a simple structure

Automatic centrifuging…  so,This is the structure of only have to adjust the centrifugal force in a simple spring force.

So, it is possible to change freely timing that leads the clutch just to replace the spring (clutch spring).


This is a disassembly clutch unit of KOSO,

KOSO, Inc., a custom parts manufacturer of the classic in the field of custom scooters, is a Taiwanese company.

Remove the E-ring

I’m pulling out the E ring with pliers, It is all right if you can pull out the E ring in any way.


E type retaining ring is a lock ring similar to the shape of “E”

The clutch spring will be able to exchange

pulled out the E ring, you take off the clasp.

With such a state,Clutch spring can be easily replaced.

Clutch spring unplug while pulling,Special tool is not required.


White spring of the above image is the clutch spring.

In accordance with the engine power, need to select the clutch spring

I think I’d like change in the clutch spring according to the engine power basically.

For example, if you want to connect the clutch at low-rpm will change to those weak the clutch spring.

If you clutch meet a high-rpm is strong clutch spring.

Custom parts that stick of strengthening the clutch spring and the name is A part which means high-rpm clutch meet.

But the fact that the clutch meet at a high-rpm,The engine power of the low-speed range, it will be wasted by the centrifugal force.

If the vehicle is going up the engine power,For example, to enable tuning to change the “soon to clutch meet”.

Specifically, is 1800rpm at idling; a clutch meet in the case of 2500rpm, You feel how the acceleration from there? It is.

In such a situation,
When You feel even if more clutch meet is done in the low-rpm area, no problem, I think that is better to change to those weak the clutch spring.

When strengthening the clutch spring, acceleration doesn’t become good.

Clutch spring is setting parts.

Clutch meet timing would slip clutch in high-rpm by Strengthening clutch spring, Low rotational speed range might not be used effectively…   You will only have lost engine power in this situation.

For example when you want like to improve a start,

Clutch spring is changed to weak,The weight roller to lightweight, Low gear state by long pulley boss, This is the effect that you can experience.

But if you overdo the setting as described above, There is when you start, the front tire would up also likely to be (wheelie) state, It might become difficult to ride scooter.

If you want to buy a weak clutch spring,You may want to try in the clutch spring for the small exhaust amount scooter.

weight roller is here
long pulley boss is here

Cleaning of the clutch

By washing the clutch, the state of the drive system will be good.


The clutch shoe is only pull out.

Washed with parts cleaner and brush, back to the original.

Confirmation of the clutch shoe

Let’s ensure the decrease of the clutch shoe.


There is no problem as long as such a state.

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原付二種ライダーの市具 成夫(シグ夫)です。

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CVT driving system