I talked to Skat Trak today

[Green Hulk]

I had a very interesting chat with Glen at Skat today. Basically i wanted to know about the new pumps they have available for the RXP and the different vane configurations and diameters and so forth. I told him that i mainly wanted a set back pump for better hookup. We all know that the hookup on our pumps suck! Well, he told me that what they do is take our impellers and cut them down thus moving it further toward the vanes in the pump.
This in effect turns our stock pumps into a set back type pump giving better hookup. The cost to cut the impeller down is $30. They also do a double bearing mod WITH a stainless steel wear ring for $400'ish.
So basically for under $500 you can turn your pump into a much better magnum setback pump(double bearing)

I should be getting my head back from Mark for the weekend and once i get it back on and running i'm going to pull my pump off and send to Glen at Skat to have these modifications done. I'll keep everyone posted on how it turns out.

[Jrsrxp]

So the set back pump is going to add better hook up in chops. What about on not so choppy condition, and glass??? I am trying to get a visual on if they cut off some of the impeller which I would be from the front of the back. di dyou say a bering is used to fill the gap that is left??

[Green Hulk]

They actually move the impeller closer to the vanes. As it stands now the impeller is about 3/4" away.

No, they don't put a bearing in to fill the gap. The RXP pump only has 1 pump shaft bearing. They machine the pump and add a bearing. It's a much stronger setup.

[nitro rxp]

I very interested in this so I have a few ?s.
Do you still use the stock drive shaft?
Is this mod for stock skis also without hurting performance?
Any performance gains besides better hookup?

[11]

On their Kawasaki set backs they make the hub of the impeller longer so it reaches the stock shaft.

Try to consider a Magnum pump like a set of slick tires on a sportscar, it won't make it any faster (and sometimes slower) but handling will be A LEAP better, a skat pump makes the chop feel like glass.

I have had them on 6 or 7 skis and 3 of the 4 I own right now have a MP.

If you're moding a stock ski you might prefer a smaller diameter and fewer veins because a stock motor might just not spin it (like puting 265/30/19 from an M3 on a 325).

Besides once you got a skat pump with 12 or 14 veins, you CANNOT be reckless as far as the depth of the water, swallowing rocks or debris because a 12 vein setup is TIGHT, the space between the veins is VERY small and the smallest rock with TRASH pump, stator and impeller pretty bad.

A 6 veins setup MIGHT let the rock go through it but it doesn't mean you can ride like a pig.
11

[Green Hulk]

nitro, yes you still use the stock driveshaft. It will not improve speed, but will improve hookup thru chop which in turn allows you to build more speed over chop.

[Vern]

This mod has been used for years on other skis - we have done that with Nu-Jet props on the GPRs in particular. The Nu-Jet props have great midrange and top end due to their different design, but would cavitate more. By machining the back of the prop and getting it closer to the vanes, the cavitation was reduced, and hookup was improved. It sometimes reduces rpms (but not speed), behaving as if you added a little pitch to your prop. Riva also sells setback Solas props for the GPRs.

[Green Hulk]

Cool! Thats good info Vern. I'm going to go ahead with this mod and see what happens.

[nitro rxp]

I was going to get the steel wear ring for $300 but this sounds even better for little more money. How do I find more info and going about getting this done to my pump?

[Green Hulk]

909-795-2505 and ask for Glen