02 YZ250 Kickstart assy. mod (Step 1)

Great news, I have machined the parts with a friend of mine. We actually figured out a different way to complete the setup as we didn't have the equipment to perform machining of the splines. Plus, average costs are about 60$ CND or more an hour to get these splines machined. Average was a 3-4 hour job needed for the splines.

Machining was done at : http://www.usinage5axes.com/

We did it a bit differently for those who would be interrested anyways.

- Machined the interior of the kickstand lever to remove splines
- Machined the Kickstart shaft to "Pressfit" the kickstand lever
- Machined the 2002 crankcase cover to accept the new shaft dimention (not even 2mm)
- Dealer has the 2001 oil seal in stock (will check if it fits nicely)
- Final design will be a "Spring pin" that will run across both parts (kickstart lever and shaft)

* Note : Of course resplining the shaft would of been the best solution. I've decided to take another route because of budget constraints and many other factors. If anything breaks and I need to access the clutch of any other bottom end parts, the removal of the "Spring pin" shouldn't be that bad. I'll give you updates went it's completed and fully mounted on the bike.

02 YZ250 Kickstart assy. mod (R & D).

I've decided to start a little blog to help owners of 2002-up Yamaha YZ250 Dirt bikes. This was inspired by multiple ideas coming from a great ATV, Dirt Bike forum, ThumperTalk. This is the first picture of the bike I bought for a small amount of money, it will be modified and new pictures will appear during winter and as I go.





Short Story:
I bought a 2002 YZ250 dirt bike with the kickstart assembly shaft snapped inside the case, leaving a portion of the shaft remaing and huge cracks in my crankcase cover. I decided to browse the web for similar issues and found a great thread on the Thumpertalk website. Many members had the same problem and one member got me thinking while he mentionned using pre-02 parts ...

Reasearch :
I've pushed that idea a bit more and decided to give the idea a try. From the micros, I searched for parts and figured they could probably fit with minimal modifications. I ordered a 2002 Yamaha YZ250 Crankcase Cover and a 1999 Yamaha YZ250 Kickstart assembly from the popular ebay motors.



Comparing parts :

Identical specifications are (Go!)

• Starter Gear is the same size, same # of teeth


• White plastic is identical


• Spring is identical


• Lenght is identical


• 2002 Kickstart lever bolt fits in the 1999 shaft (shown in picture)

Picture :

• Left part is the 1999 Yamaha YZ250 starter assembly kit


• Left part has the 2002 kickstart lever bolt to prove it fits perfectly


• Both parts are the same lenght

Parts that will need some modification :

• 1999 shaft is 2mm bigger. Splines will need to fit the 2002 kickstart lever


• The hole in the casing will need ajustment (2mm bigger so 1999 shaft can fit)


• External Rubber bushing will need to be fit (might need to buy a 1999 rubber bushing)

Next Steps :

• Talk to my contact that has a machine shop


• Have them do the modifications


• Add comments and pictures to this blog