Does anyone know what is the max rpms I can run safely on a 90hp 2003 Yamaha 4-stroke? I can get 6200…I can’t believe it should be that high.. I usually run it at 5400. Does that seem more reasonable? Hope some one can help.
check your owners manual and call a yamaha dealer. i have a 115 yamaha 4-stroke that runs at 6100 “ish”. that should be around normal. your prop/pitch may also change the desired rpm.
Thanks for your help…I don’t have the manual but I just got a call from a friend saying 5500 to 6000 is what it should run. 
I used to have a 115 yammie. 5600-5800 was optimal according to the wrench(mechanic) where I bought it. He helped me switch from Aluminum to Stainless prop letting me try different pitches until I ended up with the right pitch to get 5600-5800 rpm at WOT. This rpm/pitch combo will be different for each boat/motor combo but I think you wanna stay under 6000 if you want the motor to last.
You can view the manual on the Yammi web site. pdf file I think.
I have a 2005 yamaha 90hp 4 stroke and the maximum rpms on it is 6000.
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