Complete Rebuild - EC250

[RockefellerGG]

Remove the two bolts holding on the shaft block and remove the assembly:




Lift out the centrifugal mechanism:


Lift the kick start return spring out of the hole and release the tension:


Remove the starter pinion circlip:


Lift out the inner starter pinion and spacer washer:


Lift out the Starter pinion assembly:


Remove the gear selector spring:


Lift the gear selector unit straight out of the case. Mine didn't come out too easily. It got tighter the further out i pulled it. There is a small white plastic bushing under it. Don't forget to grab it.


Remove the spring from the hole and remove the bolt that holds in the gear lock:

[RockefellerGG]

Time to remove the crankshaft flywheel nut. This is opposite thread. YOU NEED TO TURN THIS CLOCKWISE TO REMOVE IT.


Lift of the washer, crankshaft gear, and flywheel:


Don't forget the drive pin:


Remove the reed block:


Remove the ignition cover:




Remove the ignition flywheel nut:


Remove the flywheel using a flywheel puller:

[RockefellerGG]

I marked the timing position to help reassembly:


Remove the ignition: It looks like there should have been three bolts holding it on, but this one only used two:


Remove the c-clip and front sprocket:


Fragments are everywhere!


Remove all the cap head bolts from this side. Notice that there are three lengths of bolts. Keep track of what goes where:


I used my Tusk case splitter. I know this can be done with other techniques, but using the right tool for the job makes this a snap. It came right apart with no drama. It happened so easily, that I forgot to snap a pic of it all mounted up.





All the sub assemblies are removed and put into labeled bags:

[shultzy]

Awesome post! Thank you for taking the time and effort to document the tear down. I appreciate the detailed informative pictures.

[Zrt1200]

Originally Posted by shultzy

Awesome post! Thank you for taking the time and effort to document the tear down. I appreciate the detailed informative pictures.

X2. I will be watching this thread as I am new to GG bikes. Thank you for sharing it with us.

[Moto7man]

Nice post, thanks for sharing!

[gasgasman]

+1

I stickied this thread so it will serve as a quick reference for those that need it.

[shang]

I just did a full rebuild. Where was this post then!?!?

Hahah!! Good work! Rad post!

[RockefellerGG]

Glad you guys like it. More to come soon. Sending parts out and I hope to document the case mating and cylinder stacking in a couple weeks.

For now, I leave you with the removal of the inner bearing ring from the crank:

Installed the bearing splitter and tightened the base under the ring:


Tighten down and the magic just happens:

[RockefellerGG]

Ok, to send off the cylinder for repair, I needed to remove the power valve and bearings from the cylinder:

On the left-side, start by removing the bolt and washer that retain the two bearings:


The bearings were frozen in there pretty good. I used a small torch to heat up the aluminum around the bearing and using a small L-shaped pick, they popped right out:


There should also be a small washer behind the two bearings, but it might be adhered to the exhaust valve.

I pulled the pin and the exhaust valve came with it. Notice on this one, the washer is basically baked up against the little valve. They all separated with very little force.


I slid my long 4mm allen wrench through the hole of the shaft that was just removed and lined it up with the hole on the right side. With a little pressure, the right side valve assembly came right out:


I inserted the 4mm wrench again into the small hole and drove out the other pin that acts as a hinge pin for the power valve. Push the pin out the right side and fish the power valve flap out of the cylinder: