Did that flywheel come off that trike ?. I see a lot of Goki kits that already have the gear pressed on the flywheel, meaning that flywheel may be for the wrong year. The 85 and 86 have a different size taper.
If YOU took that flywheel off and pressed the gear on the only thing I can think of right now would be an issue with the key and the key slot not fitting right, either buggered up or not lining up. The flywheel should just slide on and the bolt only used to keep it there. It's a tapered fit there should be no resistance until it's all the way home.
YAMAHA 450 HYBRID
85 350X- RED
85 350x -BLACK
86 350x-WHITE (with Goki)
85 250r
83 atc 70
84 atc 70
84 atc 110
09 yfz 450
2006 Arctic Cat Prowler
RZR XP 900