Hey All,

 

I am having some problem maximizing my horsepower.  I run a 20' 1997 Javelin 400TE with a Johnson 225 Venom.  I am getting 46-48 mph when from what I've read I should be between mid-60s to low 70s.  I have a manual jackplate and have been reading that Javelins need to be set up lower than other boats on the jackplate.  Can anybody confirm this?  I can't imagine that a wrong jackplate set up would cost me this much mph.  Is there something specific in the motor I should be looking at?  The motor smokes due to a fouled plug so I am changing them and the wires this weekend.  Is there anything else I should or could look at?  

 

Thanks in advance,

Andrew

What rpms are you seeing?  What is your p2p? What prop do you have? What octane gasoline do you use?

From your post it sounds like the used boat and engine are new to you?

Way2Slow is an expert on your engine and follow his advice when offered.

When you change the plugs look at them, they should be light brown color not black or light grey. Check the compression in each cyclinder and write it down.

Lots of things can affect boat performance from contaminated fuel supply, filters, power packs, wiring and powerhead damage. 

The boat may be set up with unbalanced weight distribution, water logged insulation, planning surface uneven and the engine set too high or too low, wrong prop etc. Standard engine height is 3 1/2" centerline of prop shaft to plane pad with engine level or paralell to the plane surface.

What rpm's do you have at top speed? What is the prop pitch?

Tom