Speed, weight, ballast, and horsepower

[smokeysevin]

I have an 04 Mobius LS with the 310 Indmar Assault 310 Carb motor and it seems really sensitive to the weight and position of weight in the boat.


When we first got the boat the center ballast bag in the ski locker kept filling up which REALLY slowed the boat down.

Full throttle was only about 2800 RPM and 18-22 MPH. This was only with the center bag full which is a Fly high fat sac with the serial number 120503101970MW. Rather than fix the valve I just bypassed the sac and removed it temporarily which got the boat up and running much better.

This past weekend my dad took the boat out with ~7 people in it and it was running really slow again, when I asked him where everyone was sitting he said in the open bow which led me to think that the boat is probably okay it was just the position of the weight that was causing the issue.

I have filled the rear tank under the seat up with several people sitting on it without it slowing the boat down to the same extent that the front sack did.

My question to you all is, does this sound normal?

Thanks,

Sean

[trayson]

I can get my MPH pretty easily between 25 and 30+ with a full 3000+ pound of ballast on my 08 XLV with the 340 engine and the Acme 537 prop.

my full throttle will rev RPM's well up to 4000 to 5000 RPM's (if I let the RPM's get that high).

If you're getting full throttle at only 2800 RPM's something isn't right.

[smokeysevin]

I can get my MPH pretty easily between 25 and 30+ with a full 3000+ pound of ballast on my 08 XLV with the 340 engine and the Acme 537 prop.

my full throttle will rev RPM's well up to 4000 to 5000 RPM's (if I let the RPM's get that high).

If you're getting full throttle at only 2800 RPM's something isn't right.

That is kind of what I thought, with a lot of weight up front the boat really bogs down. I will have to start doing the engine checkup then.

With the stock prop and full passenger/ballast where should I be rpm wise?

Thanks,

Sean

[brain_rinse]

I would check your prop closely. What are the specs on your stock prop? A compression test might be a good idea.

[brain_rinse]

With the stock prop and full passenger/ballast where should I be rpm wise?

Thanks,

Sean

5000 rpms. Otherwise you are lugging the engine.

[z28ke]

I'd start with spark plugs and a fuel filter and work from there.

[smokeysevin]

I'd start with spark plugs and a fuel filter and work from there.

Already replaced fuel pump, plugs, fuel pressure switch, and all the fuel for a different issue. I am looking for a fuel filter or water separator but am not sure exactly where it is on the Mobius ls.

Sean