Hi I know I have been a huge nuisance with this whole motor bike thing, but I have the easiest layout and more decided yet. I am going to buy this awesome engine the predator from harbor freight (link below). It will be mounted on my 26" bicycle and by using a jackshaft system I will use the gears already on my 18 speed mountain bike (except for the ones on the pedals) and use them as a transmission. I will remove the pedals completley and put the jackshaft through the whole wher the pedals went. The jackshaft will have two spokes on it- a big ine and a small one. I will route the chain from the clutch on the engineto the big sprocket on the jackshaft. Then I will take the second chain and put it on the small sprocket to the gears in the back. This will create a transmission for the motor. I will get hydrolic disc brakes when finished for easy stopping. I want the bike to go as fast as possible like 60 mph. sounds crazy but its going to work. I just need your opnion on what size gears I should use on my compound gear system. I know it will be a compound gear ratio, I just don't know how to set it. Thanks for reading.
Predator 212 cc OHV Horizontal Shaft Gas Engine - Certified for All States Except California (http://www.harborfreight.com/predator-212-cc-ohv-horizontal-shaft-gas-engine-certified-for-all-states-except-california-68120.html)

Sorry l don't want to be a party to your injury or death. Be reasonable- and 60mph is not, for the setup you are considering. I already gave you a $179 setup that will be safer and within reason.

Its going to be a racing bike. I am dirt bike rider and a speed demon. I am making the nessessary modifications. Nobodies opinion is held responsible for my injury or death. This bike has shocks, will have hydrolic disc brakes and it will not be ridden on the road after these modifications with the engine upgrade.

Hi,
You have the sprocets on the wrong sides.
Peace,
Clarke