95XP Pump Loading

[JeremyD615]

So as the boating season is coming into full effect here and the lakes are getting busier, we’re seeing more and more chop while out on the water. My 95XP is running like a champ, but I believe the pump extension is making it difficult to keep the pump loaded in the not so smooth water.

I’ve been considering either picking up a solas grate, or swapping the R&D that I’ve got on my 96 over to throw a bit more water in the pump, but since the 720 ski is a bit underpowered to begin with, I don’t really want to scrub off any more top end than I have to. That’s got me thinking, would I be better served by going to a swirl or Concorde style impeller and leaving the stock grate, or swapping the grate and leaving the impeller alone?

I really have no complaints about this ski other than it’s tendency to unload the pump and take a noticeable amount of time to build pressure back up, and I generally ride the other ski and leave this one for guests, but it would be nice to get a little more grunt out of this one in rough water. Any thought?

 

[mikidymac]

The only way to hook up better in the chop is to feed the pump more water and suck the hull down. To do that you need a deep scoop grate but you will sacrifice some top end.

 

[JeremyD615]

That was my first inclination, but I have heard quite a few singing the praises of the swirl impellers and their rough water hookup ability, so I figured I’d ask before I threw a grate on it. Any opinions on which grate matches up best with the extended pumps on the 95? I’d assume that almost all of them were designed and flow tested for smaller pump volume of every other X-4 hull...

 

[mikidymac]

@Matt Braley will be able to give you that information.

 

[Matt Braley]

I like Jet Dynamics(#6 and #17) and Inventioneering but both are hard to find these days. Any of them would help and so would sponsons and/or extended trim tabs. They help keep the ski flat over the chop and that helps the pump stay fed as well. These parts might take off a mph or two on flat/calm water but your actually gaining lots of speed on rough water because it makes the darn thing rideable out there.

 

[JeremyD615]

I appreciate the insight! I’ll keep an eye out for a grate and some extended tabs then. I’m avoiding sponsons, as I have novice riders on this ski fairly regularly, and it’s a super clean hull that I’m hesitant to modify... Its gotten so rare to see stock ones in good shape that I kinda want to keep this one as a survivor.

 

[JeremyD615]

Matt, do you think it’s worth attempting to shim the stock tabs, or should I just track down some aftermarket ones?

 

[Matt Braley]

Yes it works. I know a racer that put nickels between the hull and tabs toward the rear of the tabs. It held the nose down just fine. I have also seen different plastic wedges that were bolted in between, a more civilized way of doing it.

 

[JeremyD615]

I may experiment a bit then. We will see if I can come up with a DIY setup that doesn’t look like a complete hack job...

 

[racerxxx]

These are what you're looking for as Matt mentioned. Sorry, these are for me. Inventioneering are very hard to come by. The Jets pop up now and again ad on the front mount on the hull side the number is cast into it.

 

[JeremyD615]

That Inventioneering grate is an interesting design for sure! I’ll have to keep an eye out for something to pop up. In the meantime, I may try the R&D grate that I have on the 96 and throw the factory grate back on that one. Between that and shimming the trim tabs I should be able to get the 720 ski to hook up a bit better... Thanks for the help guys!

 

[racerxxx]

I'm sure any grate will help, does your VTS work? If so stuff the bow into the water, if you're trimmed up to keep the bow out of the water you're gonna bounce all day long, if you're in the middle and it's choppy you're gonna bounce.. It's the nature of the X4 hull. It rides ON the water not THRU the water.. All the "add ons" will make it hook up but all at a price. Literally speed, better handling (sponsons) and in your wallet. Stretch it out and step up to a 96 GSX. You'll get the 787 and a little longer hull which is better in the chop. Or go balls out and get an HX or a 98 XPL (noticed I skipped the under powered 97 XP). When I ride my HX and a buddy is on my 96 XP I will pull away from him in the chop cause the HX will cut thru it. But if you share your toys the HX is not the one for you.

 

[mikidymac]

Jet Dynamics is still in business and making rideplates and intake grates. Give him a call, just spoke with him last week but his website sucks.

The Inventioneering was made by one of the guys at Hot Products. Wish I still had one, they are awesome on the 97+ XP hulls.

 

[JeremyD615]

I know what you’re saying. Unfortunately I’m out of room for any more toys! Plus I’m already pulling two trailers out for my lake trips... My issue isn’t so much the porpoising, it’s that funky three inch pump extension taking too long to load back up after it gets out of the water. I can trim it down and keep it from unloading, but as soon as you trim up to play you’ve got to wait for the pump to load every time it hops. I originally thought it was cavitation, but the impeller and wear ring are in good shape and it hooks up fine from a dead stop or after a spin. It’s only when the grate comes out of the water that it’s got a noticeable delay between when the power comes on and when the pump produces thrust.

 

[JeremyD615]

Well to update an old thread, I finally got around to playing with the grate on my 95XP with the 717. I pulled the stock grate off and replaced it with a Solas SD-IG-B, and it did make quite a noticeable difference! I’m sure it scrubbed 1-2mph off of the top end, but the pump is loading much better than it did previously, and the ski feels much more planted! Since this is a second ski for me that really only gets ridden by guests, I hadn’t fooled with it since last summer, until I jumped on it last week to let my brother have a go on the 96. I noticed it was really hard to set up for jumps, since the pump would unload right as you crested one wave and wanted to get into the throttle for the next one. After the swap, that’s almost completely gone... I also noticed that in slides I have to intentionally shift my weight or really goose the throttle to get the tail to come around. Overall it was a pretty good upgrade for a ski with the extra pump volume from that extension...