Re: No acceleration
Crank her up on the muffs, routzohn. Do not rev her, that can cause a thermal runaway that usually ends in an explosion.
Spray/squirt some fuel mix in each carb throat. If the idle increases that carb is starving its cylinder.
A multi cylinder 2 stroke can idle and run under no load with no apparent problem when one cylinder is not making power. That may be your problem.
Disable each spark plug, one at a time. If the idle fails to drop that cylinder is not making power. If you have tested the carbs it probably has no spark.
Even if the engine passes both of the above dynamic tests at idle you may have a carb that idles well but has a plugged up mid range or high speed circuit. If you can repeat the carb test with the engine under load with power on that should find any carb trouble.
Finally, the best tests are done on a dynamometer or at least under power in a test tank.
Wrenches at dealerships are sometimes under great pressure to "find" an expensive part that needs replacing. The above simple tests can verify or disprove a shop diagnosis.
Good luck.
