You will need a rich mixture running thru the bike. Maybe choke it after it is warm.
And spark plugs in the end of the exhaust with a coil and wiring to fire the plugs.
That is how we did it in the old days.
Warning no warranty on this advise as to damage to anything.

I guess today you could plumb in bottled gas and igniters in the exhaust.
Have fun and do not blow yourself up.