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At slower speeds they are all easy to stay on top of. Once you get over 35-40mph the fx1 and old 750 start feeling narrow. These skis won’t allow you to lose your balance nearly as much as a Superjet will. Little guys have a lot easier time on these. I like my 1994 750 just for the challenge of...

If you are older/heavier, the 750sx is like a slightly larger FX1. Plus you could buy and overhaul the 750 for the price of a POS FX1.

If engine life is important then an expensive test program is required. Riders don’t care about that anyway. All they need to make a purchase decision is enough hype. Then it’s on to something else.

The pump can usually load the engine if you tie the ski to a trailer and sink it up to the hood seal. This is a great way to initially set the main jet/top screw with a tachometer. I have a thrust meter mounted to the front of a trailer. It works up to a certain amount of power then thrust...

Stator vanes can be shorter when more of them are used. You want the least amount of volume between the impeller and nozzle. The easiest way to make a 12 vane pump more efficient is to simply move the shorter vanes aft and modify the driveshaft to "setback" the impeller. Thats where the...

My solution for preventing rust is cheap TCW3 oil and blowing it out until the head gets too hot to hold onto. Then I leave the hood cracked so all water in the hull can dry up. I have a couple of stand ups with 20 seasons and their cranks and cyl walls are spotless.

I know a cheaper way of making propellers is welding blades on the hub. This would probably work for iimpellers as well. Investment casting is cheap enough as long as we have third world labor.

The bed plates you need are easy to spot since they don’t have splash cover mounts on them. A 650-701 is an easy swap and works kind of okay with a stainless impeller in the stock pump. If you are more ambitious, a WR3 pump/ inlet will pick up the 500s mounting bolts and the length is perfect...

Thats a nice one. I think theres more of these around than there are old Superjets. I have one that has been a very successful 701/144 conversion.

That epoxy job would probably be beneficial if smaller carbs were used. You want to make the carbs venturi have the least area. The butterfly needs to be larger diameter because it’s thickness and the shaft take up space and impede flow. Below the carb a very slight taper in the manifold will...

The stock exhaust has no tuning so the main jets will be smaller than an aftermarket pipe would require. Tune the top carb screws just rich of peak rpm. Tune the pilot jets to make it four cycle a little around 1/4 throttle. Lowering the pop off will also make 1/4 throttle richer. If it lags...

Practice on a twostroke leaf blower. They tune very similar to jetskis.

With a single carb you can butcher the seat size and spring all you want. There is no second or third carb to match it up to. I have drilled seats and clipped/stretched springs back when I was exploring the limits of the “new” SBN carbs. The pop off effects mostly below half throttle. For...

The idea is simply to make sure nothing is pulled into a bind when the bolts are tightened. Using shims is one way to fill gaps. Most of my pump change mods get the pump and carrier potted with thick epoxy. Everything fits perfectly after that.

Im not sure Trumps policies are very benevolent since he and Musk are picking winners and losers. I need to see changes that are near and dear to wallets of the wealthy. Balancing a trade deficit or budget is a very easy thing to do, if you want it to happen. It took decades to offshore...

I do.

FWIW Kawasaki hot cylinder is usually the front, Yamaha is usually the rear. Air leaks are a possibility but they have to be more severe on a watercraft since our engines are always under heavy load. They tend to just push air out rather than draw it in. For comparison a bike with a leak goes...

One cylinder will always run hotter on single carb multi cylinder engines. With two strokes, you can never blindly follow others jetting advise. You must open the top screw 3 turns and see if power is reduced at full throttle. If not then install a larger jet. It is very difficult to hurt an...

You are still up against a poor third world guy with some sand paper in his hand. For building boats, high tech hasn’t been able to beat him yet.

As I remember, some engineering student made that twin pump 650. It was in a magazine in 1993.