Fast(ish) swapped 550 skating around at speed

Myself

Myself

manic mechanic
Location
Twin Lakes AR
OK,......how do we keep the 550 hull from skating around like it's on ice once we get into the mid 40's? I know there's lots of fast conversion skis around so what's the dealio? If I don't let off the throttle from the skating around my whole ski starts to barrel roll to the right.
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
True the bottom of the hull. 4 inch pv wrapped in 80 grit sandpaper. Run back and forth up the length of the chines to true them up. Also where the hull.caps are. I removed them on my old 550 and the ski handled much better and turned quicker. Both of these modifications will help high speed stability a lot. The other weak point on the 550 is the pump. They just won't stay hooked up in choppy water once you start increasing power.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
All of that may not make any difference , I got to ride a Dave Gordon world finals ski one time, it pretty much had every bell and whistle, the damn thing was almost unrideable, as you said it torqued heavily to the right from what I remember and I could adjust my stance enough to ride it but if you let off the gas quickly it was like you let a spring loose and it would torque hard and spit you off. I am pretty sure that one had a trued hull.

Everything I have ever read about those old race skis said they were like riding a marble.
 
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Myself

Myself

manic mechanic
Location
Twin Lakes AR
Don't get me wrong, I have a great time TRYING to control it, but I'd like to really crank it past 2/3 throttle just to see what it's capable of. I don't ride in a lot of chop and I blueprinted the pump, I feel like it stays hooked allright.

fastgtfairlane, you're saying REMOVING the stock hull end caps will HELP with high speed stability?
 
hornedogg79

hornedogg79

dodgin' bass boats
Do you have front sponsons? With the added weight your gonna need more lift up front. Could also trim the nozzle up. Angled pump wedge may help.
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
Myself said:
Don't get me wrong, I have a great time TRYING to control it, but I'd like to really crank it past 2/3 throttle just to see what it's capable of. I don't ride in a lot of chop and I blueprinted the pump, I feel like it stays hooked allright.

fastgtfairlane, you're saying REMOVING the stock hull end caps will HELP with high speed stability?
Click to expand...
Yes if the bottom edge is hanging below the bottom of the hull, it will cause all kinds of strange issues. Truing the hull will also fix this potential issue. If one of the edges is hanging lower than the hull bottom, it'll act like a brake at speed and cause random pitches off one side or the other
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Also sometimes those rear caps are not sealed properly and they get water inside them, but yes removing the rear caps and putting them back on correctly is one of the first hull mods they used to do on race boats.
 
E350

E350

Site Supporter
Location
Sacramento Delta
Ok, since you are on the subject and the posters here know what they are talking about, I have been considering putting these on my 550sx. What do they do good or bad for performance?

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E350

E350

Site Supporter
Location
Sacramento Delta
Well then, think about it. You have an extended ride plate which is planing in the center, but you don't have the hull (i.e., the sides) extended so planing at speed is like walking on a fence top, any little lean or deflection and you are going to fall to the side.

Putting on hull extensions, especially with an extended ride plate should, in my speculation, increase the base of support of the ski at the rear (where your body weight is) and make the ski less tippy (i.e., "roll") at speed.

And notice that the ProWatercraft extensions are not a box and, thus, cannot take on water.

@Myself, I love you brother, but your weight (as does mine) exceeds the original design of the 550. It is ok, but you need to increase the hull design i.e., extend the hull. Right now it is like you are doing a wheely on a bicycle at 45 mph. I have experienced what you have experienced on my 550sx and I have decided to add front sponsons, extend the hull with Prowatercraft hull extensions and add Wax's rear sponsons for cornering. See @Aquaholic Minimonster thread here. He is a little guy. Me at 200 lbs and you at 240 are not little guys. The ski will be fine, but you need to increase the hull length to be stable at speed IMHO.

Just thinking out loud here until others with actual experience comment, like @Aquaholic @waxhead @fastgtfairlane et al.

Custom/Hybrid - Mini Monster

This one's not for sale. However, I'd be glad to build you one with this motor! You game? that is super cool! yeah, PM me with prices I still have a minivan to sell to help cover cost. Also, can you remove the aquaholic stuff and replace with engraved Mikesee instead? Last question for now...
www.x-h2o.com

P.S. And don't think a FX-1 will solve all of your 550 problems. Don't get me wrong. I love my FX-1. But the FX-1 is an entirely different beast with the quirks of the 550 and then some more of its own . . .

There is a reason that @Quinc says "Buy a Super Jet"
 
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hornedogg79

hornedogg79

dodgin' bass boats
Wow you are a large dude on a 550!
I would ask some of these guys in this video. Get some current knowledge from people who still ride 550's. Sadly they don't get much love here on xh2o.
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
I did a lot to my 550 hull to get it to handle halfway decent. Widened the tray 3 inches, deepened the strakes by 1/4 inch with wooden dowels and fiberglass, added tubbies and removed the rear caps. Another thing I believe helped was a shredmaster ride plate and intake grate combo. Eliminated any proposing and possibly gained a mph or so with it. I was running a dual carb sp750 with a modified Westcoast pipe. My ski was right at 50mph on top speed with that setup.
 
E350

E350

Site Supporter
Location
Sacramento Delta
@fastgtfairlane We talked somewhat ~2015 IIRC about what you did to your 550 (way before you moved on to SJ?) but I cannot remember how much you weigh.

@Sparkplug be nice! @Myself is a great wrench on jet skis. He is a professional jet ski mechanic and helps allot of people over at PWCtoday. We will bring him along a little at a time to stand ups here.

You know more than most people who post on this forum, be direct even be rude, but be helpful to his journey. We need more stand ups and @Myself wants to be one of them.
 
Myself

Myself

manic mechanic
Location
Twin Lakes AR
Thanks guys. I've lingered a bit here for years and also ridden standups for many years. Check out the Superjet I'm almost finished building for my wife-->https://www.x-h2o.com/threads/wifeys-sn-superjet-custom-paint.207292/

Leverage.....YEP, took a long time learning to turn decent at all because of that.

Here I am on this 550 I swapped. At about 1:55 I throttled down on it pretty hard for a few seconds, you can see it takes off pretty good with my gigantic ass on board.

 
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