Im building a project with a YZ125 engine that im stuffing into a pocket bike i have. i need to get kinda like a brochure to see the specs on power, fuel mixture etc.... also i need to figure out what kinda rear sprocket to run (number of teeth). the motor has a 13t spocket on there and the rear tire is 9 inches tall so im jus tryin to figure what size rear sprocket im goin to need. my goal is (and may sound crazy) is to be able to tag about 100-120mph. i plan on strechin the frame and racing it at the track.

 

first off i think ur crazy. i strongly suggest putting a wheelybar just in case in addition to strethcing the frame. my bike likes to run on 20:1 with no smoke after its warmed up. the compression ratio is 8.4-10.5:1. also the correct spark plug is a br9egv just in case you were wondering. i would think a 25-30 tooth sproket would be the area to start around maybe smaller if its not fast enough. hope this helps.



-mike

 

your crazy going 100mph 2inches off the ground...