Different strokes

kevbo

kevbo

Location
dfw
It has nothing to do with the engine type. Yamaha designed this Superjet as a rec ski using parts at hand. If it was a race ski it would have been at least as good as the Kawasaki is.
 
Aquaholic

Aquaholic

World's Oldest Teenager
Location
San Diego, CA.
faceplant2 said:
Curious: Question to Aquaholic's post .Why would a 4 stroke turn less than a 2 stroke Superjet ? Also: if the turning is soo bad , why doesn't Yamaha install better system during manufacturing ? Safety issue maybe ?
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faceplant2 said:
Curious: Question to Aquaholic's post .Why would a 4 stroke turn less than a 2 stroke Superjet ? Also: if the turning is soo bad , why doesn't Yamaha install better system during manufacturing ? Safety issue maybe ?
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Like Kevbro sez... it's not so much the 4 Stroke motor that makes the new Superjet handle inferior to the Gen 2 Jet, although the substantial increase in weight does factor in. The hull length and shape and pump tunnel config, all make the new Superjet a really poor handling watercraft. Yamaha got the steering all wrong on the 2008+ two stroke, as well. It's almost as if Yamaha sourced out a gazillion short throw steering cables, and they were going to use them up no matter what. And as far as the actual steering system... perhaps RRP paid Yamaha to make it so bad?

Anyway, on to the pump...E7A34ACC-9697-44AE-911F-C60739604AEE.jpeg3248F823-0E00-417A-B87B-FC467ED08904.jpegD53D9927-BF87-43A8-941B-51095E0B1073.jpegC91B35C2-77C3-475C-BF5C-426F447E3E4D.jpeg758E4C8F-37C4-4EFE-B6C5-90BE039092B0.jpeg
 
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kevbo

kevbo

Location
dfw
A large company cannot change its products fast enough to keep up with the whims of customers, especially young ones. Making a standup that a fit and experienced rider wants would leave most of the actual buyers frustrated on the beach.
 
Aquaholic

Aquaholic

World's Oldest Teenager
Location
San Diego, CA.
kevbo said:
A large company cannot change its products fast enough to keep up with the whims of customers, especially young ones. Making a standup that a fit and experienced rider wants would leave most of the actual buyers frustrated on the beach.
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I totally disagree with that. It wouldn't have cost Yamaha anything more to at least use a longer throw cable with a different mounting location. And, things like handle bar, pole spring and grips, are 3 things that wouldn't cost Yamaha anything extra to get right, out of the crate. You know the saying, "The best you've ridden is the best you know"? Most new riders jumping on a new SuperJet, will have no idea how bad the turning is. They will struggle with the learning curve and may even develop bad habits, to boot. Not getting the steering right from the get go, is inexcusable. And, as far as the cavitation problem on this thing...how could the test riders, during development... sign off on something that is only going to frustrate owners, regardless of their skill level.

It's planned obsolescence, really.

Take most modern MX bikes...for the most part they are pretty dialed in, and track ready, right off the showroom floor. You can take them to the track with very few changes made. This has been something that has always left me scratching my head on standups from not only Yamaha, but Kawi , as well.
 
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kevbo

kevbo

Location
dfw
I said the same thing in 1990 as far as low power and poor hookup. I think their goal was to make a ski that anyone could get on and never fall off. And one that floats when someone swamps it. Their big selling points are the gas guage and the little kid power limit. I don't know any experienced rider who wants the big turd. Different skis do different things, a short freestyle ski can't race and an SXR1500 can't flip. Which one is obsolete?? I still have a 650sx that serves its purpose.
 
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Aquaholic

Aquaholic

World's Oldest Teenager
Location
San Diego, CA.
Update on the latest mods to Rodney's 4 Stroke:

1. Reflash of ECU from Riva. Rodney chose the 8600 Pump gas R tune. The OEM rev limit is set to 7500.
2. Solas 12/17 prop. I scuffed up the blades.
3.Mildly blueprinted pump. I spent a couple of hours on pump work. I can go further with it at some point if Rodney requests it. The goal is to address the caviation problem on this ski. Yamaha chose a 144mm pump off of their couches. It's a bad mismatch for this ski. It should have had at least a 150mm.
4. Capped off bidet nozzle on reduction nozzle.
5. Modified steering cable to get 3- 4 additional degrees of throw.

IMG_9252.JPG
The OEM pump has some nasty mismatches where the stator meets the wear ring. It's a pretty substantial step. I knocked that down and blended the transition.

IMG_9253.JPGIMG_9440.JPG

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IMG_9444[1].JPGIMG_9446[1].JPGIMG_9447[1].JPG

Uploading some videos from yesterday, now. All of the mods we've done so far have completely transformed this ski. It's actually capable of making turns now. The pump work definetly helps with the cavitation, but....this platform will always be limited by pump size. Overall gains, Rodney says at least 15% across the board.
 
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kevbo

kevbo

Location
dfw
A larger diameter pump would allow for a lower impeller pitch, that helps mostly at low speeds. The inlet is probably too short for a standup, they need to be longer with a large radius up front. A 1050 four stroke wont make any more torque than a 750 two stroke. Notice how similar the impellers are to what is used on an old Superjet..
 
Aquaholic

Aquaholic

World's Oldest Teenager
Location
San Diego, CA.
fastgtfairlane said:
They used a 144 pump in the new sj? Sheesh
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Ridiculous, eh? Why they paired such an anemic, puny pump on this thing really is a head scratcher. Maybe it was the bean counters at Yamaha mandating to use an existing pump setup off of their couch to keep production costs down? The plastic reduction nozzle ( also off of their couch) still has the reverse bucket tabs.
 
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Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
We had a good conversation about this the other day........ Some different points of view as to why Yamaha Effed this up so bad............ I dont get the pump tunnel and pump size. Hell, My Edge has a better pump tunnel.
 
kevbo

kevbo

Location
dfw
What RPM does it turn? There may be some gains with less pump load.
 
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