Can't get up on plane

cqa0007

Have 96 Rinker Fiesta Vee 266 w/5.7lx and bravo 2. I've read where my boat should run 30mph...my GPS shows 18/I've replaced plugs/distributor cap/carburetor. Supposedly the boat came with a 17.75x21 from factory and it looks like it currently has a 18.75x17. HELP capt Steve

JC290

What is your wide open throttle rpm? Is the hub spun on the prop? 

Weber

Rpm will tell you a lot, no alarms?

If you can't get over 2,500 rpms, no alarms, and no other signs, I would replace your anti-siphon valve in your fuel tank.

212rowboat

just a bit on an aside:  when re-propping, I've read and proven in practice that 'when increasing diameter, pitch must be dropped', so.... it would appear whoever re-propped your rig did it right... but you gotta ask yourself, 'why did they drop pitch?'

for low speed, there ain't no substitute for diameter, but, you'll pay for it on top end... I doubt very seriously you're being restrained from planing speeds because of that prop.  I don't know what you could expect to see north of 25mph or so, but you should at least sit up on plane, I'm thinking... but be advised, that prop set up is devised more for displacement cruising. 

you replaced the carburetor?  Or, did you clean it or rebuild it?  Jets could be an issue...

did you replace the fuel filter/separator?  it could be limiting fuel delivery as well, as could a bad adjustment on the carb... riddle me this: what is your operational temperature on your dash gauge?  These rigs are provisioned with 160* thermostats- which means they should be wide open at 160*, not just starting to open- though, the 160* is a bit of a misnomer because none of them are precision devices... but... if you are holding a steady engine speed of, say, 2k RPM, which is a position the boat should be pushing a bit of wake a but not attempting to rise on plane and the temperature is north of 175*, it could be indicating a lean running condition as lean engines run hotter.  If so, we gotta figure out why fuel isn't delivering.  dirty jets lead that charge, followed by clogged filters and then bad anti-siphon valves which are mounted within inches of your fuel tank lead.

What kind of condition is your spark arrestor/air filter in?

LaRea

If you store the boat in the water, check the condition of the bottom paint.

cqa0007

Thanks everyone!  I will forward this on to my mechanic and see what he says.  Work in progress.

MarkB

What is your peak rpm?  This is important, will tell us a lot.

rinker312

Yes. If you have been in the water a long time. Don't rule out fouling.  I can tell the difference in my boat when the algae starts to accumulate just after a few months of being on the water.