yamaha dirt bike problems

I have a 1992 yamaha WR200RD that would not start because of no spark. I performed all the checks in the service manual and found both the pick up coil bad (open) and the ignition coil bad also(open at the secondary) I replaced both coils and now the bike will run, but it won't rev up to full throttle. this bike is kind of bizzare in that it has a power valve that is driven by a servo motor on the left side of the bike unlike the YZ"s in which the valve is driven from the right mechanically from the engine. this bike has one cdi unit that controlls the spark, timing, and servo motor. when the bike runs, it backfires through the carb and through the exhaust. I have checked and cleaned the carb, the reeds and block, I did not remove the cylinder or head but a look into the exhaust and intake ports show everything there to look OK. also the compression is very good. the power valve opperates with the hooking up of a 12 volt battery as per the sevice manual and also moves when the engine is started. .... I was wondering if anyone out there has any experience with this bike. the cdi unit is very expensive. the owners service manual I have does not explain how the cdi system works, and does not list any trouble shooting for the cdi unit. my son just purchased this bike from a friend for a bargain basement price because of it not running. any help would be greatly appreciated!

Yeah there isn't any way in the manual to test a CDI. All bikes are like that. You follow the flow chart and check everything else. If they are all in spec the flow chart ends with "faulty CDI". Most automotive manuals are like that to but they end in "faulty ECM".

Seems to me you already checked everything out that I would have thought of. Did you try a new spark plug yet? Sometimes they won't fire right under load like opening the carb up fast. I didn't see that listed. The only other thing I would try would be some fresh gas. Looks like you covered everything else. It could be a bad crankcase seal or base gasket pulling in air and leaning out your mixture.