Addressing Jet Pump Cavitation & IMPROVING Pump EFFICIENCY

Cavitation is a huge problem for high performance jetskis! We address what cavitation is, why it is harmful, and how to improve pump efficiency to minimize cavitation.
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[@pete7129]

In for the pump stuffing. Thanks,Greg!

[@bernardmcnamara]

Excellent work. One of the very few that actually explains the physics. Above 8000RPM's is the water's bolling point on the propeller.

[@codyparrish3301]

I've been looking for a video just like this! Thank you so much for the in depth explanation! The drawing was extremely beneficial as well!

[@billy-bo-dilly]

Greg, I always enjoy your videos. They are the best of the PWC subject matter. If you review your series on the 21 RXP and the 21 GP, you will remember that the RXP was the best performer on 5-60 times as well as top speed. Most of the performance difference was based on the cavitation issues on the Yamaha that allowed the Sea Doo to take the hole shot. Why is it that BRP can build a pump that handles 300+ HP without cavitation and Yamaha cannot??? The pump issues have been going on at Yamaha for several years. I could understand it if the issues were only on modified skis, but that is not the case.

[@GreenHulkGarage]

The Sea-Doo pump has more veins, a larger pump cone from the factory, and a larger diameter hub than the Yamaha pump. All of these help with cavitation and holeshot. Even now with my GP running almost 10 mph faster and pulling higher G-forces when accelerating than my RXP, the RXP still out holeshots it. I am doing some pump work to the Yamaha that should fix this! I don’t think Yamaha sees this as an actual issue that needs addressing. The Yamaha pump is an excellent pump and has lots of potential, it just needs some fine tweaking to get the most out of it.

[@gordonlasiter9566]

Love the lucky 13 on my 09 and 16 fz skiis.

[@chrisleach1560]

Throttle control was a good recommendation. I always forget the throttle can do more than just 0% or 100%

[@JoshDK-]

For an everyday ski what would you say the life expectancy of a impeller and wear ring? Should you always change both at the same time. Can you get away with just impeller or just wear ring? Thanks keep up the great work! ✌️

[@GreenHulkGarage]

It depends. Sometimes the wear ring is in good shape but the impeller to wear ring clearance is too big. This would require replacing the impeller. Other times, like in my case, both the impeller and wear ring needed to be replaced. I’m at 115 hours and just switched to my third impeller. The good thing is, you don’t need to buy new impellers. Impros can repair them to save you money.

[@DigitalJazz]

Where’s the build video for the stage 3 and the fueltech

[@GreenHulkGarage]

It’s coming. I have a few more things to do to this ski before getting back in the water. The engine is coming out this weekend for some upgrades. All will be documented on video for you guys.

[@charlestaylor3434]

Great explanation. Bonus points if you actually take your GP1800 to the lake and show us you experimenting with the lucky 13 cone and the results with each washer.

[@GreenHulkGarage]

Absolutely…but first the engine is being taken out of the ski for another video 👍

[@jasonmekush5280]

Yes i bought this exact cone for my 16 fzs. great company---4tecperformance

[@Podchynok]

Is this an option for 2023 Kawi 160lx? If so, what negatives may be at play when using this mode? Thanks in advance.

[@jlc7562]

Hi Greg,,,which solas impeller would be the best option to gain speed in the new Yamaha 1.9 engine??? Regards

[@jimwinn8064]

Thanks for the information/video, question, how difficult was it to remove the OEM wear ring, what is the best way to remove it? Thanks!

[@kyleheiser6622]

What about sealing the intake grate? Is it really necessary? I just took my intake grate off to remove stuck rope and I used 4200 to seal where the bolts enter the hull but didn’t even think about applying anything around the edge of the intake grate like some recommend

[@nyangaming3697]

I have a Honda turbo ski, will not accelerate under full throttle, have to feather it to get it going, can I get a pump cone for it? Or will a seadoo one fit?

[@AdamOpheim]

Would like to know more about which models have to worry about "Stuffing". on an 07 RXT

[@GreenHulkGarage]

You won’t have a stuffing issue with that ski.

[@InTheDirtAgain]

I'm worried about pump stuffing on my Kawasaki TS.....

[@zjw1155]

Need a pump stuffing video. I have a turbo 2007 rxp. Been 90mph on GPS. Never stuffed. Lucky cone no spacers, 161mm pump 15/25 3 blade at 9200rpm. With 2 big PRVS.

[@GreenHulkGarage]

I’ve paid attention to your ski and I’m somewhat familiar with it. 90 is right about the mark where the original RXP hull would start to stuff, you’re definitely playing it safe with the relief valves. The 161 pump is helping you out a lot too. I’ll be doing a video on pump stuffing soon, I just haven’t figured out which of my skis I will do it on. If I don’t jump ship on my RXP-X hull then that’ll be the perfect ski for the video.

[@zjw1155]

@GreenHulkGarage I'm always down for a video. I also log pump tunnel pressure on the fueltech. I think at 90 with that set up I was seeing something like 17-18 psi inlet pressure. Definitely trying to keep it safe because I want my ski to do 95. I'm getting a new sleeved motor from Eastside here soon then we can really turn up the boost. This was also all done on a stock ride plate as well! There was a 3psi tunnel difference between the riva and the stock plate.

[@GreenHulkGarage]

Your tunnel pressure is very safe. I’d put the RIVA plate back on or even try a Jim’s open loop cut stock plate. You should easily get 95+.

[@zjw1155]

@GreenHulkGarage well. I have some data from Raulin. Back in the day he did 104 I think. He said at 25psi of pressure you will go swimming on a 215 hull.

[@GreenHulkGarage]

Interesting, that seems very low pressure to stuff, but I haven’t pushed that hull to those speeds. I have zero experience on that hull over 100 MPH and there are less than a handful of people that have gone that fast on the original RXP hull. I’d hate for anyone to go swimming so play it safe.

[@DigitalJazz]

I would a video about pump stuffing

[@rickohlson3962]

You need a one way valve before the the prop .1 inch diameter some people run two .they dump water out the back of the ski when the pressure increases to much before the prop .

[@tim0e]

Thanks @@rickohlson3962 , I'd love to know more about that. I don't suppose you'd have a link or reference to more info?

[@snoochieboochiess]

Definitely do a pump stuffing vid! I don't think anyone has done one on KZbin, not a good one anyways 👍

[@GreenHulkGarage]

I’ve got the perfect ski for this video! I’ll get working on it

[@snoochieboochiess]

@@GreenHulkGarage awesome!

[@watercraftjournal]

This is all well and good, but what oil should I run? :P

[@GreenHulkGarage]

Peanut oil works well and guarantees a 15 HP gain 😉

[@jeremyjolley9079]

Pump Stuffing! Is going to be the answer for everything from now on! Wife asks me when I’m going to mow PUMP STUFFING! Work asks when are you turning in your paper work AHHH Pump Stuffing!

[@mikehaigler1824]

Hey I have 2 Kawasaki stx 15f Jetskis and I am a new ski owner so I’m new to the ski world, but I have an issue I would like to see if you can help me figure out, Okay on a recent river trip I had the impeller shaft bearing fail, I replaced the bearings,shaft, cone, impeller and used the original jet pump housing. I used kawiperformance upgrade shaft kit and got a solas impeller with stock pitch. Everything went together nicely, and I have rode the ski several times and have noticed a slight vibration? Is the best I can describe the sound, but it only happens when I am at a consistent speed around 34 mph but if I let off the gas or speed up or turn it will stop until I stay at a constant speed. I have since replaced the jet pump housing to see if maybe that was the issue. And it still makes the vibration. It is very slight, and I wouldn’t notice I guess if I didn’t have another of the exact same ski to compare it to, and I also replaced the shaft and bearings in the other ski with the same upgrade kit. The only thing different is the impeller. So I’m wondering if the impeller is the issue and is that something I should worry about ? Thanks in advance for your input or anyone who reads this.

[@LifeBeginsOnTheWater]

Great job Hulk Jr, love it! Truly enjoyed the Jetpump lesson. Please keep the great content coming brother.

[@TheVonMatrices]

I would like a better explanation of how to address cavitation/stuffing issues. My confusion arises in that there are so many parameters of the pump that can be changed - the impeller pitch, the impeller itself, the pump cone size, the pump cone length, the nozzle size, the nozzle length, etc. - that I'm not sure what to do in what order or if all of it needs to be changed.

[@GreenHulkGarage]

What ski do you have and what performance parts do you have installed? I’ll be able to point you in the right direction.

[@jayd1008]

will these ft the new yam 1.9 pumps ?

[@crossmax1084]

Greg, thank you for putting this together. On your ‘21, did you install a bilge pump after you installed the Lucky 13? If so, where did you put the bilge pump outlet? Thanks brother!

[@neilsanson1262]

So much talking

[@GreenHulkGarage]

Maybe go and look at some picture books. If you don't like the information we provide then go troll someone else's videos. Have a good one!

[@john.french]

Awesome explanation! Really great information and analysis. You are a jet ski professor!

[@F1FIDY]

Would the cone and nozzle extension work against each other ?

[@AchikSarih]

Merci beaucoup ❤❤❤❤❤❤