Re: Trials offroad motor bike??
I could see that. use a 50t sprocket and pull steep grades. I would ask Jim of creative engineering what sprocket would be best. Then maybe a custom muffler like a scooter muffler to cut the sound down to a whisper. With the low gearing it would work. you will lose a bit of the rpm but the sound would be worth it.
Always do a pre-ride check. Make it a habit, and ride safe.