Sometimes with the hi/lo gearbox lever, you have to rock the trike some back and forth to get the lever to switch gears. Remember, you are dealing with a 35 year old machine that not have always been treated the best. Do a search here on the site for downloadable manuals, they are here. It's alot to type out to explain how to put the cam back in and time it.
Nicholson 500x (Project)
Nicholson 185s
Nicholson 110 (That takes an atc70 tank)
Ascott 500 head/350x (Project)
Homebuilt Racer Chromoly Suspension 110 (Ragin Runt)
PK Racing Suspension 70
A+ Inc Suspension 70
AWS Aluminum 90 frame
Hi Performance ATC Suspension frame rd350
Hi Performance ATC Suspension frame 90