Bard,

On an ‘84 so much would have to be swapped out that it would be simpler to swap for an e-start engine and swap your kick start into that engine. You’d want a ‘97 to ‘07 engine if you could get it. If you could only get an ‘85 (or perhaps it was ‘86 that saw the e-start; on the road now and can’t remember. @pdwestman will know) to ‘96 that would work, too, but the later engines are much improved.

Someone asked this question on my YouTube video 5 days ago. Scroll through the comments to see the answer.

 

Forum member "Ian H" from the UK knows even more than I about the 600 - 650 compatability. I think I remember he has installed a 650 into a 600 frame.

Left Click on this, Kawasaki KLR 650 Forum - Members List

Then left click on his name.

I wouldn't hesitate to use a 1987-1995 KLR650 engine for this project. They all could use some improvements!