Hey Gang, I recently picked up an old but decent condition '83 PW50 for my youngest son. The Zinger runs but won't come off idle. And it's not the Stop-Run-Start switch. Appreciate any ideas. Here's what it has and has been done: - good compression (120psi)... engine turns over smoothly - new Miniky (clone Mikuni) PW50 carb. It has the right jets in it ~#67.5 main and #40 pilot (jets measured). - mixture screw changes making no difference - reed valve good, new gaskets - new NGK plug - new aftermarket coil... lots of strong blue spark when cranking with plug out and grounded. - coils in magneto ohm tested in spec - exhaust de-carbon'ed (burned out)... clean and free flowing. I've even tried running engine w/o exhaust on... no difference (other than louder). No restrictor washer. I ohm-tested the Stop-Run-Start (SRS) switch... tests fine per wiring diagram. Bike starts and idles in both Run and Start position... but won't rev any higher. I can see the slide/needle in the carb (airbox off) lifting up... but engine won't rev. Sounds like it's being held back like a rev-limiter. I've disconnected the SRS switch and the bike will still start, but not rev. I've even removed the entire ES Control module (the Start mode rev limiter, right?) and the bike will start and idle, but not rev. I'm stumped. I'm down to the stock CDI being possibly bad... or the stock ES Control module... or the magneto (which tested in spec)... or possible wire short?? (Anyone know which wire could be shorting that would cause this?) Appreciate any ideas!