150 2stroke

i recently purchased a 17'6" hydrasport bass boat with a 150 merc 2stroke on it and i have one definite issue and one possible issues which could both be linked. First of all the boat will not plane off unless someone sits up front and second it dosnt run as fast as what ive read it should. approximately 5200 to 5300 rpm at 48 mph (gps). i will list the set up and how it ran. any suggestions would be appreciated.

trophy plus 21 pitch prop
10" offset from transom
hydraulic jack plate
3 batteries
1/2 tank of fuel (10 - 12 gal)

Re: 150 2stroke

Some may tell you that the prop has just a bit too much pitch. while that IS a possibility, before spending ANY money on a prop, first check your set-up, and tune your motor to ensure it is running at its best.

Start with the simple things.

Test compression on every cyl to ensure they are near the same.

Test spark using an adjustable gap spark tester set to 7/16 inch.

DVA test the stator to ensure it generates sufficient voltage for the high speed operation of the ignition.

Verify WOT ignition timing is set to factory specs.

Once all the above is checked and proven good, find out from the prior owner when the carbs were last cleaned, if more than a couple of years ago you may want to order carb kits and clean then.

Take a close look at the motors mounting height on the boat, you want to see the A/V plate immediately above the prop is level/even with the 'pad' or up to 1 inch higher than the pad, any lower leaves too much gearcase in the water, causing un-necessary drag, wasting HP.

Check all the above and repost your findings.

Re: 150 2stroke

Charlie pretty much covered it..that is a perfect post. nice job