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Jeremy R.
Jeremy R., MarineTechnician
Category: Boat
Satisfied Customers: 9020
Experience:  Multiple factory certifications 20+ years of experience.
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Can I test the WOT of my 90 HP 2 Stroke Yamaha outboard while

Customer Question

Can I test the WOT of my 90 HP 2 Stroke Yamaha outboard while the boat is on the trailer and the motor in the water or do I need to launch the boat and run it to use the momentum of the boat and the prop going through the waterto acheive full throttle ( 5000 + ) RPM ??? because with it on the trailer I can only get it up to 2500 RPM
Submitted: 6 years ago.
Category: Boat
Expert:  Jeremy R. replied 6 years ago.
Hi, and thank you for letting me try and assist you with your problem.

never run a boat on trailer over 1500 RPM
you need to get it in the water and get back to us
either you have a bad fuel pump
bad fuel lines and primer
low compression
missing spark on cylinders
or gummed up carbs

i would do a spark check and compression check first
Customer: replied 6 years ago.

Ok thank you for your advice but let me explain what I have done so you have a correct idea of things. I have complety disassembled the carbs and cleaned them, compression test @ 105 PSI on all three using Two test guages on three different tests. sync the carbs and set all linkages to factory spec. Used dial indicator to get #1 TDC and set timming pointer, set idle speed @ 800 Rpm with timming @ 8 degrees ATDC, aligned markes on CDI with Idle stopper and the WOT stopper, New NGK plugs set @ .035 and spark test @ full throttle position using a 7/16 gap results very good Blue spark. New fuel pump, All lines from new fuel tank and all new lines on motor with new clamps at all terminations.. So knowing all of this what am I missing to try or do other than to actually run the thing on the water and should I expect to get different results than on the trailer??

Expert:  Jeremy R. replied 6 years ago.
try running it on water