SUICIDE SHIFTERS CAN BE QUITE DANGEOURS! BUT i love then!
I made a board track racer a few years ago with a suicide shifter(it was not a shifter it was a hand clutch that looked like a suicide shifter) and worked really well but it was kind of not very safe but it was lots of fun
BUT it didint lasted long, i taken it all apart to paint it and in the same week i had to move house.Now you can guess what happened to all the small ball bearing, bolts and nuts! Never found then anymore
I have started another one and now im doing it right! im not moving house and i will be my new baby(no suicede shifter(clutch) in this one)
So at the conclusion would be:
Suicide shifters can be tricky and messy but they look awsome in almost anything
AND about the engine, i dont thing you will need a suicide shifter in a motored bike because none of the engines used on then have buid in gears to change(you would if you use a sick bike shifter kit) so there ids no point in using one i think because you really dont want to take your hands off the handle bars in the middle of the traffic to change gears or to release the clutch
Good luck with what you thinking in doing
G-Superior