300/440/550 JS550 pump size? any possible swaps for low end pull?

[b.lee]

What is the stock mm size of a JS550 Pump?

Is there any good pumps that would fit easily into a JS550 hull? and provide more low end thrust?

I'm looking for more get up and go out of the hole.
The engine runs very strong, but it doesnt seem to move enough water to get my fatass out of the water easily. It does, but not like a superjet or what not. Obviously a superjet is a way better ski, but is there anything I can do to get that low end pull from 0 to 20 mph?

The reason im asking is sometimes I'll be messing around jumping and whatnot, then almost fall off, when I go to pin the throttle, It pulls me back up to straight but not easily. I have to balance perfectly for a few seconds and wait till the jet ski gains some more speed before it really starts to rip.

 

[ger87410]

What prop?

U sure it's not cavitating?

EDIT: I read your post again. It sounds like cavitation to me.

 

[b.lee]

"Cavitation is the jet pump pushing out water faster than it can come in. You will know this happens because generally you will rev up fairly high and not move"

Its not cavitating.
Not sure on the prop.

I bought this ski knowing nothing about it, other than someone dumped a few dollars in it previously.
$100 and it needed an engine rebuild.

 

[ger87410]

What grate and ride plate? That makes a difference as well.

You'll probably have to pull your pump to get the prop size. Also look for any damage to the leading edge of the prop as this will effect the performance. While you have it out, take a good look all over your pump and make sure nothing is broken or chipped.

What's your height/weight?

 

[b.lee]

im little over 6ft
250 lbs

 

[ger87410]

im little over 6ft
250 lbs

That won't help.

Post a pic of your pump. :smile:

 

[Wilke]

im little over 6ft
250 lbs

Your problem isn't the pump. You need more power and youre just not going to get the performance you want out of a 550 without serious mods, regaurdless of the pump.

 

[b.lee]

That won't help.

Post a pic of your pump. :smile:

im working on losing some weight, but beer is just sooooo goooood.

 

[b.lee]

Your problem isn't the pump. You need more power and youre just not going to get the performance you want out of a 550 without serious mods, regaurdless of the pump.

Wouldnt a bigger pump push more water from the get go?
I'm thinking of buying a rn superjet and flatdecking this js550 and a pump swap...

 

[Wilke]

A pump will help, yes. But your not at a point powerwise that a new pump will make the kind of difference you're looking for. Money would be better spent modding the 550, or better yet on a 650 conversion, than it would be on a pump swap at this point. If you plan on flat decking it and really building it up, you'll definatly benifit from a pump swap from a 650, but not untill you get some more power to push the pump, and the pump swap is a lot of work.

If you want a little bit for the time being find out what size prop you have now and try to step down a bit, but unless you're running a stock prop or one thats way over pitched you're not going to see a huge improvement.

 

[jetskifreak]

i put a 440 pump in a 550 reed motor and it pulled harder but i dont no if a 440 pump would help or not