Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
could always trim some of the scoop on the WCOT grate to lessen the grab!!!!!!!!!
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Different strokes
- Thread starter Aquaholic
- Start date
Aquaholic
World's Oldest Teenager
- Location
- San Diego, CA.
I have to admit, the more time I spend on this thing, the more I like it! I absolutely hate these things in stock form. It's unrideable. But, really, the same thing could be said about a stock 2 stroke SuperJet , as well. Bobby has chosen wisely in his modifications, and the order in which he's done them. I'm just along to help spend his money. I too, didn't really care for the WCOT grate. It's designed for rough water riding and chasing bouys. On glass..it sucks. Bobby and I grew up on 2 strokes, and engine induced braking when you let off the throttle is something that bugs us. So, the combination of pump and handling bits alleviates that, as much as possible.
I still don't ever see owning a ski like this, but when Bobby throws me the lanyard... I don't hesitate to take it for a rip. The motor [now] is truly badass! I do like making right hand turns, though.
I still don't ever see owning a ski like this, but when Bobby throws me the lanyard... I don't hesitate to take it for a rip. The motor [now] is truly badass! I do like making right hand turns, though.
Aquaholic
World's Oldest Teenager
- Location
- San Diego, CA.
Wait, what???? I thought you are the guy who knows everything?
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
With certain plate grate combo's when you let off the throttle the pump gets loaded to hard giving the ski a "Braking effect"...
As I said, " This is just what Steve and I came up with, this doesn't mean this will work for everybody out there. But we're having fun seeing what the 4 stroke SJ will do."
You're right BK, Steve brought that up to me. But then I thought if I didn't like it I could never sell it. So to compare I tried the Kommander first and liked it a lot and then sold the wcot.
These dam jet skis get expensive trying different parts to see what works for you. Part of the game lol.
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
Was at the races 2 weekends ago, we were talking about the new SJ. There is alot of buy trial and error with this ski. I have ridden 4 different ones. All set up for racing. None handled the same. Back when I had my SXR 800, Combo's out there worked for most. TBM Plate & Grate, TBM Grate with Stock Plate. R&D Grate & Plate........ You just bout could not go wrong just straight up buying one option over another. But the SJ is way different!!!!!! Lots of R&D Time to find correct combo.
I will say on my Stocker, I ran the TBM Grate wither either TBM Plate or Stock Plate (depending on race course), I did borrow a friends Mild Limited SXR with TBM Plate and grate that combo was way different from on a stocker. The Plate did not let the ski slow down coming into turns, you had to really rail the turns hard!!!!! It was the next year people were starting to cut the windows into the plate to help the handling with more powered ski's!
Agree, I only have knowledge about 2t superjets, but depending on the course like you said, there is sometimes reason to run the WCOT, jet dynamics, or worx 205 all serving different purposes, not to mention static nozzle tilt and rideplate combo, it is all part of the game, especially in lites. WCOT and R&D 'limited' grates always had massive braking effects, less top end, but overall great hookup in race conditions which are normally a washing machine.
What I noticed from day one with my bone stock SJ4 is that if you chop the throttle on a high speed run the ski had much more braking than my 2 stroke 898 Edge, 550, SJ or FX1. On my very first fast run when I chopped the throttle I kinda felt like I was going forward into the pole. My own opinion here is the 4 strokes just have more of an engine braking effect at high speeds. Add an aggressive intake grate and it doubles or triples that. But an aggressive grate has its positive points too, just pick your poison lol.
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Aquaholic
World's Oldest Teenager
- Location
- San Diego, CA.
Part of what you can feel , as far as braking effect when you chop the throttle, can be attributed to the hull shape and design (which has more surface area than it's smaller 2 stroke cousins), as well as pump tunnel volume, and intake grate design.
But, the engine braking from the 4 stroke also contributes to this in a substantial way.
Simply put, 4 Stroke motors have more internal moving parts and friction generated than a 2 stroke.
The four stroke engine, with its valves, when not firing or being on overrun, acts like a pump; trying to suck air in through the inlet and out through the exhaust but this is hampered by the throttle valve being shut.
The two stroke engine attempts to do the same thing... but since everything takes place in 360° rather than the four stroke’s 720°, relies on the resonance of the exhaust, inlet and crankcase to control the motion of the gases through the engine. When the engine is on over run it is either not firing or only at decreased rpms; so there are no resonant pulses, so it is unable to act as an effective air pump, so it provides very little engine braking.
This is waaay more pronounced on a motorcycle where the wheel is in contact with the ground. But, the same thing happens with our jet pumps, but to a lesser degree.
Rodney, you could really feel this in effect, even with the stock intake grate, on your SJ4. It takes some recalibration when you first transition from a 2stroke to 4. And that alone, is something that doesn't jive with my riding style.
As far as the WCOT intake grate...I tried it on the MonsterSX for awhile. It definetly sucked the back end down and provided more grip. It made the boat handle better and more predictably in rough water. But, it killed top end by about 2 mph and also decreased RPMs. Beacause of that...I tossed it after 2 rides.
But, the engine braking from the 4 stroke also contributes to this in a substantial way.
Simply put, 4 Stroke motors have more internal moving parts and friction generated than a 2 stroke.
The four stroke engine, with its valves, when not firing or being on overrun, acts like a pump; trying to suck air in through the inlet and out through the exhaust but this is hampered by the throttle valve being shut.
The two stroke engine attempts to do the same thing... but since everything takes place in 360° rather than the four stroke’s 720°, relies on the resonance of the exhaust, inlet and crankcase to control the motion of the gases through the engine. When the engine is on over run it is either not firing or only at decreased rpms; so there are no resonant pulses, so it is unable to act as an effective air pump, so it provides very little engine braking.
This is waaay more pronounced on a motorcycle where the wheel is in contact with the ground. But, the same thing happens with our jet pumps, but to a lesser degree.
Rodney, you could really feel this in effect, even with the stock intake grate, on your SJ4. It takes some recalibration when you first transition from a 2stroke to 4. And that alone, is something that doesn't jive with my riding style.
As far as the WCOT intake grate...I tried it on the MonsterSX for awhile. It definetly sucked the back end down and provided more grip. It made the boat handle better and more predictably in rough water. But, it killed top end by about 2 mph and also decreased RPMs. Beacause of that...I tossed it after 2 rides.
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- Location
- Southern Indiana
I’m new to modding and I’ll be putting on OVP steering next weekend. How did you remove the nub?
- Location
- near beautiful bobcaygeon
I removed nub similar to @Aquaholic.
The plate is cast aluminum, so fairly soft. I roughly cut the nub off with a hacksaw, rounded it up with a small angle grinder / zip cutter, did final sanding and shaping with a dremel (one of the courser sanding cylinders), and painted it with black semigloss tremclad. My tremclad was in a spray can so I just sprayed a wee bit into a little plastic dish and painted it on with a small hobby brush.
In my case I was installing the RRP “AST” pad and that nub needed to be removed so that the pad could move with the handlebars / pivot plate without interference or rubbing the back of the pad on end of the pole.
- Location
- near beautiful bobcaygeon
Some pics:
Attachments
- Location
- Central Ohio
Does it still slide with the sponsons if you keep it flat? Trying to get the best of both world... rails when i lean and buttery when i just shift my hips!Good thread! Curious... How come you send the ECU to Riva for a re tune instead of using the MaptunerX with the different download maps?
Or is that what you're using, but just having Riva load it for you?
Are these the new prowatercraft sponsons here?
Yamaha SuperJet 2021+ Wedge Rear Sponsons - Pro Watercraft
Rear sponsons for the 2021 fourstroke Yamaha Super Jet.prowatercraftracing.com
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
Rode a nicely setup 4S This past weekend at Southern Fried Freeride. It had the Prowatercraft Rear Sponsons, OVP or close to OVP Steering. Tune, and as I got on the gas hard then let off......... Yup WCOT Grate. The tracking and hookup was very nice. But you can really tell the Braking effect, Rode 2 other SJ's with different mods and they were nice as well, Different feel to them with more of a modified stock steering setup.
- Location
- meadow lake
chopping the throttles coming into the bouys on 4 stroke does massively break but your always prepared i ran out of fuel this summer on gp1 full wick lake cruising let me tell you it was 78mph to zero in like 45 feet when that engine stops turning that machine plants itself.
Aquaholic
World's Oldest Teenager
- Location
- San Diego, CA.
Last weekend.
![IMG_E3798[1].JPG](https://www.x-h2o.com/data/attachments/360/360580-4a821364d6bf9df01f39f0400ad1ea93.jpg "IMG_E3798[1].JPG")
![IMG_E3797[1].JPG](https://www.x-h2o.com/data/attachments/360/360581-b94d0e73b9e9655beb83607906f91963.jpg "IMG_E3797[1].JPG")
![IMG_E3796[1].JPG](https://www.x-h2o.com/data/attachments/360/360582-c58609803a59d5dcbdbe320312b064c9.jpg "IMG_E3796[1].JPG")