Trouble getting rebuild started

Rebuilt my 250r motor, split the case and new bearings, seals etc. Its all back together, except with a 265 ESR powervalve cylinder and cr250 ignition, but I can't get it started. At the bottom of the kickstart it backfires and doesn't start. It would seem like its getting spark due to the backfire. Could it be the jetting in the carb from switching cylinders? It has a keihin PJ carb, not sure which size and the main is 180. Any ideas? I'll try and find some calipers to figure out what size carb it has

check the woodruff key

Woodruff key looks good. I wonder if its because I used a 99 cr250 flywheel, would there be any difference? Its got a 2001 cr250 cdi.

If I remember correctly the 1999 flywheel does have different timing specs.

Sounds like that might be it. Do I have to use the 2001 or would a 2000 or 2002 also work?

This was a few years back but the 2000 flywheel might work but I think the 2002 was a whole different ignition and timing. I have a box of CR ignition stuff, I'll try to see if I have anything.

Do any of honda's other engines use the same flywheel?

edit:
Found out the 2000 and 2001 flywheels are different, but according to this site they are interchangeable. http://www.oem-cycle.com/HONDACR250BIKEID.shtml

For future reference, says the flywheel part numbers are:
2000: DENSO KZ3T 032000-9510 - FITS 00-01 CR250
2001: DENSO KZ3V 032000-9600 - FITS 00-01 CR250