Crank exchange for beginners



The final point of the scooter engine custom will crank,This is the most difficult places in the engine custom.

Crank parts-related exchange and the act to perform a custom,It in japanese say “a waist bottom”.

If to be able to on their own until the under waist is the degree of difficulty of about the scooter may be said to have mastered.

Of course, to do under the waist on your own you will need some of the knowledge and special tools.

Therefore a beginner declines it … I don’t say so.

Anyone is a beginner first. Let’s challenge to do your best.


This is not work to do outdoors


Advanced users would be less than one hour to access to the crank from down engine.

Beginners should not think it to be completed in one day, Let’s have margin of 3 days even at least.

By that, Like the image mentioned above, I bring in an engine indoors.

But there is an engine oil smell for the demolition work. At the time of the interruption of the work it is recommended to cover the garbage bag.

Single-mindedly Remove the parts

The drive system and a cylinder,remove all part. Let’s demonstrate this to the knowledge and experience to the fullest.

Working procedure …

  1. Cylinder head
  2. Cylinder
  3. Piston
  4. Pulley
  5. Cooling fan
  6. Flywheel
  7. Generator coil
  8. Oil pump and gear

First, get rid cylinder, pulley, starter clutch, the air-cooling fan.


Pull out the flywheel

It is work considered that flywheel omission is difficult for a beginner.

To pull out the fly wheel, you need a special tool called a flywheel puller.


Prepare the flywheel puller tailored to the type of vehicle. How to use is simple,It will be the way that remove push.

Set the tip, grasping at monkey wrench, it will come off and screwing in the cross bolt.

It’s incomprehensible by the character, so a reference youtube link to you.

How to use the cross-shaped flywheel puller (for Motorcycles)

Beginners, act to remove strangle the bolts I think scary.

Also breaking sound will occur when removing the flywheel Depending on the model. However, this breakdown sound is a sound that is pulled out pull the flywheel.

You are once remove the flywheel, which is as simple if confirmed the structure, and you can understand.


It is in such a condition when you take off a flywheel, a generator coil.

Further continued Remove the bolt, Remove the oil pump unit.

Since the engine oil leakage at the time of opening the lid, let’s pull out in advance.

Open the crankcase

The words that are romance for the beginner, It is crankcase open.

Let’s Further continued Remove the bolt.

Vehicle in which the center stand is attached is do not forget to remove.

Once you have removed all of the bolt, While hitting lightly with a plastic hammer to split the crank case.


Finally we were able to meet with the crank.

Progress in work up to this point, the crank is not fixed,You only pull out crank afterward.


Let’s check whether the crank is what fits in with a clean image.


It is not complicated structure,However, the work to be in such a state is very difficult.

Let’s also exchange incidentally oil seal.

In addition, the internal crank case might have solidified the engine oil,Such dirt Let’s clean together.

Do not forget the liquid gasket

Let’s be sure to apply a liquid gasket when assembling.

When the assembly without painted a liquid gasket, engine oil leakage will occur,Please think the leak anymore certainty.

Also easy mounting parts also forget the cam chain.

Maybe you could say that you have mastered your scooter if you can by yourself up to here.

Is a skill that you can brag to your friends, You should be able to approximate perceive also the event of a failure.

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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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