Low power on New F60

Details:
Motor is installed on a 420 Zodiac and propeller is exact same dia. and
pitch as Yamaha performance bulletin. 101/4X14. I have also tested with a
101/2X12. No difference. Symptons are lack of power on plane out and engine
rpm will not exceed 4200 under load. It will rev to 5800-6000 with no load.
I have had the engine to a local franchised dealer, not the selling dealer,
and all items checked out as new, leak down, compression and no error codes
voltages from sensor to fuel pump where at spec, plugs looked good. Dealer only had test tank.
So where might the problem lie? Engine runs smooth but weak.

[Whitedog]

Typical, As aYamaha owner I have found that they don't seem to deliver as advertised. More than one engine and boat combo set up as in the performance bulletin failed to reach the same performance numbers Yamaha reported. One prop guru told me Yamaha must test these boats extremely light with a small child in his underwear as the driver. I have a 90 2 stroke that checks out but will not reach Yamaha's claim no matter how it is set up. I am disappointed to the point of not considering Yamaha at all on repower.

[boats.net]

I don't have any experience with Zodiac boats but with 12 pitch prop I would think it should turn more than 4200 rpm's. The dealer needs to test it on the water to find problem.

Thanks for the guidance. One of my boat yard friends who I whined to helped resolve this issue before my scheduled on the water test. He went through the fuel, air, spark cyle. Looked at my boat which is fitted with a Yamaha supplied engine cover and suggested that I try it without the cover. I tried to blow through the cover which is both tightly woved and coated. A closer look revealed an impression of soiling around the engine air intake. After taking off the cover all things worked pretty much in accordance with expectations top rpm is now only 100 shy of the performance bulliten and I have actual acceleration. Its curious that the dealer didn't seem to know about this aspect of the fabric cover or that Yamaha didn't note it on the package, kind of like don't put a trash bag over one's head. I cut and seamed a air intake hole in the fabric cover.

[robert graham]

just when you think you've heard it all!