Super Jet Need advice to improve handling on SN SJ

[shockwave538]

Hello all. I broke into the standup world with a '91 SJ with a '95 701 engine. I have been out multiple times and am trying to improve handling and reduce porpoising. I know many will say more tray time will help. I have reduced it, but even with my weight fully over the pole (while dug into my gut) and many variations of footing and such, I still have issues getting over 1/2 throttle because of the bounce. Have even tried to power through it and see if it'll steady out with more speed, but no luck with multiple approaches. Don't think there's a big waterlogging concern, as the tray sits up well when in the water.

I also really have to work hard to find a balance between the tail sliding and laying it over in faster turns, and I'm not even trying very fast/tight turns most of the time. I know SJ's aren't built to carve turns as well as maybe an SXR, but some improvement would be nice as I would like to do some speed work as well as learn some freestyle. I also read that SJ's use more steering in turns, while Kawis use more leaning, so I'm trying to find a balance but I think my current setup doesn't give me much margin to work with.Trying to do what I can without spending $200-300 on tubbies.

I am 6'3", 220 lb. Prior owner was close to same size and put on a lighter pole (fiberglass, unknown of length vs stock), an R&D scoop intake, and a Worx Dominator plate, which he shimmed to reduce the bouncing, though he admitted it never fully went away and he was very experienced. Is the cutout in the plate the "D cut" I keep reading about? Am I right in thinking this is a scoop intake? Don't think this is hurting me any, but throwing it out there as a possibility.

Was reading several others with similar issues and thought maybe a good finned plate would help with both the bounce and the loose turns. Also something a little shorter might help me sub and do other stuff easier, but not too short that the high speed turns will be a problem. Could it be possible the plate is so long, and being shimmed, that it's pushing the nose down too much and causing a bounce? What are some good ride plates that would fit the bill? Also, he put some sort of sealant between the plate and body. Don't think this is common from what I've read elsewhere. Why would one do this if there's no leak concern?

To recap since I threw a lot out there:
Ride plate recommendations?
Intake - fine or change it? What kind is it?
Ride plate sealant - yes or no?
To shim or not to shim? (plate, not pump)
What to do if I leave everything as is, except maybe shims?

There more things I can get help with, the better. I hear the X is the place for SJ info. Thanks a bunch.

 

[Vumad]

I had a finned ride plate on my 650sx and hated it. It had too much hook up. Ifyou ever broke that fin free, such as in a rough corner, it would have too much leverage on the boat when it hooked back up, and roll it.

Rear sponsons on my rn superjet however, i like very much. They took the yaw out of the rear end. I got launched a few times when coming out of a corner at first, but quickly learned to dealwith it. i made a set for my rn superjet. You can buy them for about $150, but i made my own. I used glass, but you can buy a cutting board from the dollar store and use that. Rear sponsons hang about 1.25" down and areabout 21" long. Cut it so you can use any existing holes in the bond rail and bolt them on.

As for your porposing, i think you could have bad technique still. My rn i stand forward in the tray at low speeds, but start moving back as i get on the throttle. Im prety far back after 1/2, and by wot im hanging as far back as possible. At low speeds, forward weight holds down the nose, but at high speeds it preeloads the nose and makes the back end loose.

Always keep your elbows up like doing a bench press. Chest into the bars on hard acceleration, but once the ski is on plane, get back and pull on those bars, weight on the plate.

I have the works dominator on my superjet too. It helps with porpose but not with yaw. Im actually running astock ride plate unless i am specifically racing. I think the jet dynamics plate had more potential for racing, but i didntget to use it much. It was on someone elses ski. All that lomg crap is only useful for racing though.

 

[Vumad]

Is your motor stock?

Do you have foot holds or straps or wedges or nothing.

 

[shockwave538]

Is your motor stock?

Do you have foot holds or straps or wedges or nothing.

All (known) mods are Blowsion 0 degree bars (snapped the stock ones) intake, plate, impeller, pole, primer, and the 701 upgrade which is stock from what I can tell. Also plan on putting in a bilge pump. Down the road I might do a shorter pole (I hear a RN pole is good without paying for an AM one), wells or straps, and then new paint and turf.

 

[Vumad]

I am 30 lbs lighter than you and had a very hard time in rouh conditions on my stocker. The prop helped but i lost tons of speed anytime the chopped picked up. Id come out of the water, then bash into the next wave. The pipe and head, installed at the same time, made a huge difference. The ski didnt care if something was infront of it, it just kept pulling. Power is one of the best handling upgrades you can get.

You will need a hazard bracket to upgrade your pole.

 

[smoofers]

Looking at your ski and mods, I'd say 80% of the porpoising is the rider. That ride plate is SUPER long and intended to keep the nose down for racing. The little D hole in the ride plate is meant to add some downforce to the back of the ski and also give more braking when off the throttle. With your height, I would recommend going to a shorter pole. I'm 6'2" and run a round nose pole cut 4.5" and that makes a huge difference for a taller guy.

Also forgot to add that the sealant between the ride plate and hull is to prevent air from getting sucked into the pump tunnel and causing cavitation. It is definitely a good practice.

 

[King Kang]

Get a hooker 9/15. It'll virtually eliminate the cavitation that might be causing you to porpoise. I'm 6'4 and 190 and I love how my SN handles. I have an R&D intake, Rend finned ride plate, Pro Watercraft Racing front sponsons, cold fusion turn plate, hooker 9/15, and 4 degree Blowsuon Kommander bars.

 

[BruceSki]

Get rid of that intake grate. It's made for wide open racing and is VERY aggressive(super large scoop). If you are not riding that Wide open everywhere that grate will hurt your learning curve.

Also more tray time and a shorter pole may help you.

 

[shockwave538]

Thanks for the positioning tips vumad, hard to find specifics on how people handle it at different points.

So maybe my intake is part of my other handling issues? Any good recommendations otherwise? I know even less about them than plates. And I'm getting mixed feedback on my plate. Some say the downforce should be helping me, others say it's too big. I understand the size is less nimble for non-racing uses. So besides stock, what are some other plates that would be good?

 

[King Kang]

I bought my plate from Wizard Powersports off this forum and it is an old school one designed for the SN. I was pretty cheap too.

 

[Vortex]

Stock bushing steering is not helping you they get sloppy over the years. go after market. Blowsion etc. Rn pole, rad dudes bracket and the steering upgrade would be significant.

The worx plate is a good plate for handling and keeping it hooked up. D cut is not really what you want for high speed handling.

Sponsons. Worth every penny.

 

[cmlangdale]

https://www.prowatercraftracing.com...amaha/superjet-90-95/hull-handling-products-5

PW has a great price on sponsons. If I still rode a square I would buying these for sure. This should be one of the first handling mods you do.

I agree with the others about the ride plate. It's for racing and will help keep the nose down.

Rider position and a shorter pole will make a big difference on how everything feels.

Go ride a 550 or 750 and you will appreciate the SN more lol

 

[SXIPro]

I'd be ditching that long ride plate, and tossing on a stock plate and just getting in more ride time. If you are going to be messing around hard you are gonna 'find' that long ride plate with various body parts, and that ain't no fun. I think the key is a shorter pole. A trick I learned when I rode my SXIPro which porpoised like crazy was to ride with a slight turn in my handlebars. If I rode with them perfectly straight it was like a bucking bronco. If I turned them just the slightest bit, it leveled out. Not sure if that will translate to a SN, but it's worth a shot.

 

[alwaystandingup]

Prowatercrafracing.com urethane sponsons will be a huge improvement everywhere for your square. Better drive through chop, less bounce, more stability, and much better turning.
best handling mod you could do for that ski

 

[shockwave538]

Prowatercrafracing.com urethane sponsons will be a huge improvement everywhere for your square. Better drive through chop, less bounce, more stability, and much better turning.
best handling mod you could do for that ski

Nice. Wasn't really considering these due to the $300+ cost, but might consider the urethane ones. Would rear sponsons help much, at least for turning? Know how I can get some on at low cost. What are their disadvantages?

I'd be ditching that long ride plate, and tossing on a stock plate and just getting in more ride time. If you are going to be messing around hard you are gonna 'find' that long ride plate with various body parts, and that ain't no fun.

Found out how comforting that extended plate is to a shin my first week on it. Learned some good positioning lessons. Trying to decide what plate to get. Have no idea how a stock plate is set up (but haven't looked yet either). Saw a Rend plate, but it has something similar to a D-cut that may raise the nose more, which I don't need. Also looking at a finned intake, or something less aggressive than the scoop I have. Think I can feel where it might be affecting me (though I could be completely wrong). Pole might also be sooner than I planned after being out some more recently.

I think the key is a shorter pole. A trick I learned when I rode my SXIPro which porpoised like crazy was to ride with a slight turn in my handlebars. If I rode with them perfectly straight it was like a bucking bronco. If I turned them just the slightest bit, it leveled out. Not sure if that will translate to a SN, but it's worth a shot.

Noticed that last time out. Was throttling repeatedly and trying different stances and such with the usual results, or worse. Turned a little to correct a wobble, and noticed the bounce went WAY down. Got it up to full speed finally for the first time! Just need to keep a slight lean or turn, and even then any weight shift back at all sends it bouncing with a vengeance. Also can't get much weight back at lower speeds to setup for a sub or anything else without getting instant big bounces. Don't know if all this is typical for a SN and I'm just figuring it out, or if my pole, intake, or plate is the biggest contributor and should be tackled first.

 

[Vortex]

You have to spend some money to get these things to really handle...

Rear sponsons don't do as much on the old sj hull as the O8+

If you still have the stock prop that is what's holding you back. And it's safe to say your steering bushing is worn and the cable alignment is off.

Leave the worx plate and the intake grate there for now.

-hooker prop
-pwr urethane sponsons
-blowsion -1 steering

 

[550headache]

tom21 tubbies. best money spent on the old square! think they were under $200 shipped

 

[Dlt174]

X2 on the Tom 21's. $220 well spent. For porposing we put a couple of flat washers under the plate at the rear bolts. You can add or remove to get the ride you want. Really cheap cure for porposing. With sponsons you will want to take the washers out.

 

[superjet119]

Hey man I am on lake Anna, we are all superjet guys. If you want to ride with us we can give you some pointers. I'm currently building up one of my old sn right now. Back when I raced a sn, I had your intake grate, riva groovy ride plate and a -1.5 pole like yours.

 

[shockwave538]

So what are the differences between the PWR and Tom21 front sponsons? I am not wanting to get into glass work at this time.