As requested above, when asking for info/help on an engine the year, model, and serial number information should accompany the HP info when posting a thread.
You would need to know the reputation of the shop well enough to know if they tend to be parts changers instead of diagnostic technicians regarding your $1,700 bill already.
If you are going to contest the bill above, I would ask for what steps (in some detail) was used to determine all those parts were at fault. You could at least get that information regardless and post it here to know if you need to the change service shop you go to.
The middle one appears lean, I would request a compression test on the cylinders (ask for the numbers), and if they are all good then go ahead with rebuild the carbs or if you're mechanically inclined enough, do it yourself with the service manual and the needed tools easily available.
Carb rebuilds are money makers indeed. Legitimate but expensive, the parts aren't too bad but the labor charged piles on.
Compression for two stroke should be between 110 to 130 and each cylinder should be no more than 10% difference than the highest number. example: 125, 115, 120
Four stroke should be much higher: At least 120 up to 180 depending on the engine. Again, no more than 10% difference than the highest number.
Any cylinder that reads below the listed ranges or is more than 10% difference in compression means possibly very expensive repair/replacement expense.
