200 Yamaha Question?

I have 1997 2 stroke 200 hp. Yamaha. My problem is you can be ideling on the water and the tachometer will just drop to zero but the engine continues to run. If you try to throttle up you have very little power. But it will kick back in and go to normal at its own will. When you are running down the lake the syptoms are much like bad or water in the gas. But it will run fine part of the time then back to the same problems. I took it to a mechanic a month ago and he check the comprsion and it was fine. He replaced the CDI box. and said it was good to go. I dorve 100 miles to the lake only to find is was running worse than before. So it has been back in the shop for a week this time. And still no answers on what the problem is or timing on getting it back. Any suggestion or ideas would be greatly appricated.


Thanks
Kevin

Usually if you have a problem with the tach. it points to rectifier issues. These usually don't effect the running of the motor, but all the timing of the engine is done by timing everything to the flywheel ad the rectifier is under the flywheel if I remember right. Something may have got burned or melted if you had a rectifier short out throwing off the timing. Just a thought. Is the motor charging going down the lake, or you just getting 12 V out of the battery. If it's not charging, I would check the rectifier ( voltage regulator) and see if it shorted out. This is common on small 2 stroke Mercs. My 50 HP merc. did it on ly 2 months old. Good luck with it! i can get you a # of a good mechanic in NC you can talk to about it if you can't come up with anything.

Could be stator problem...