125-200cc What Do I Need To Fit A 144 Kit On My Wr125

As part of a rebuild project for a wr125 with a broken cylinder head, my 144 kit will arrive next week, and im seeking advice on the correct way to do it for maximum performance/reliability.
I am new to this, and have a mechanic that will help do the swap itself, my question is
What other parts do i need to replace? Can i run the stock CDi, Carburetor with it? What does jetting practically mean and do i need to adjust it?
Is it even possible to adjust spark timing?
Thanks youre my only hope.

And where is the damn CDi
The parts cat shows one but the bike doesnt. Is it straight coils to plug?

There is no CDI on the older WR's. It is an older analog ignition. Lots of flywheel weight but pretty bullet proof. You can adjust ignition timing with the stator backing plate screws. There will be timing mark on the stator plate and corresponding mark on the cases. Jetting and carburetor will be pretty close for both. The 08 WR comes with the older style TMX that works well for mid to top but can be a bit hard to jet for the bottom end if you have a lot of changing conditions.

Your kit will need to have the head, cylinder, piston kit, and power valves. Everything else will interchange with the 125. The power valves are very different between the newer 144 kit and the older style 125, but all the connecting parts are the same. The new 144 likes to have the power valve adjustment set so there is tension against the power valves keeping them closed. Search the site as there are quite a few threads on this.

Thanks wallybean that cleares it up for me.
From your experience will I need to adjust the timing?

No, I would just set it where the factory mark is at.