21 inch pitch,dam that sounds like a big pitch to me,I have a 150 black max and my prop is 15 x17 and that's perfect ,maybe I'm missing something.

What is a tracker valve ? You have a sweet looking boat there bud

The prop came with the motor, thought it would be too much but not so. Dropped my crusin rpm by 600 and increased speed 3 mph. No problem at all getting on plane. I dont think its 15 diameter though. Will check and let you know.

Thanks. I havent looked up exact location but its a strainer in front of the fuel rails. Typical symptoms were sneezing at idle, hard start, and wont reach high rpm.

the tracker valve is located on the fuel/air rail, it maintains a preset pressure bias of 10 psi between the fuel side and the air side, they are known for leaking and will cause a rich condition or no start scenario.If it wont run, or runs rough, check for fuel on the air side schrader valve, if you get fuel out of there, its most likely a failed tracker valve. They are not hard to install

Prop is a 14.75 diameter Mirage Plus. My guess would be the Opti has more torque in the lower rpm range than the carburated Black Max is the reason it can power a 21 Pitch.

I run mostly in the ocean and have not run it at WOT so I don't know what top rpm is but will let you know when i do. Whatever it is, I doubt it would make me change props.

Thanks Spareparts, found it in the manual. Attached pic if anyone wants to know location.

re 21 pitch
 

Steplift20, you are correct, could only get about 4500 rpm out of 21 pitch. Tried 15 x 17 this weekend. Lots better, 5300 or 5400 top end now and of course better holeshot. Running cooler too.

thks