That will be pretty easy actually now that there’s a CAD file.

The key should only be an alignment reference. If the taper is done accurately and the nut is tight there should be zero stress on the keyway. Trials bikes also have much bigger flywheels than this.

@@ChuckfromTrueTech Really like your videos mate. I have a CR500 that I had converted to a 250 ignition and flywheel, I loved the free and snappy engine response. I then installed an electric start unit, it has the heavy CRF450 flywheel. Man I hated that flywheel, it really dulled the power response and made the front end push through the corners worse. I then went about removing weight from any other spinning items I could. Aluminium clutch plates instead of steels, Titanium clutch bolts, Ti front sprocket bolt, Ti rear sprocket bolts, Ti rear disk bolts, changed the steel rear sprocket to aluminium, tubeless rear tyre system and a low drag chain. All these combined really did help to get the engine snappier, although I'm used to it now I still believe it has a negative affect on cornering. My point to this is, if it affected a 500cc engine so much I would guess it would really impact a 250. The aluminium clutch plates and the aluminium rear sprocket made the biggest changes. But because the clutch spins backwards, reducing it's weight cancels out less of the cranks enertia, thus keeping the front push.

I’ve seen clutch weights wiggle loose too many times. Can’t trust them. I’m not sure why people think a bigger flywheel will stress the bearing & seal. The weight is machined very accurately, so it shouldn’t have a balance issue anywhere near the inconsistency of the piston & crank on a non-counter-balanced engine. Not to mention that counter-balancers don’t wear out bearings prematurely. I have no worries. I would consider hiding clutch weights inside the inner hub or on the back of the basket somewhere if they could be mounted securely, but since the clutch spins slower than the engine the flywheel is my first choice.

No, does not change the overall power just the responsiveness.

Lol. Well technically it was a turning operation. 🤣

Since the final one was done via CNC I can provide them for anyone that wants one. The X is the same. Tested this on a stock one last summer.

@@ChuckfromTrueTech Sending a friend your direction. He has a steel framed YZ setup for PNW woods and it works well.

I have actually purchased one recently. My kids are learning to use CAD. I’m getting them to design stuff for me.

I tested with different motor setups. Massively different feel. Can’t spoil the surprise though. I’ll report soon.

Can't put it on a lathe and turn it down to be heavier. It's better to start heavy and work back than have to make a whole new part.