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Its not a very relevant question here. I expect that it will be a good bolt on part that will make its owners happy. Im just curious about how much the narrow bore spacing and case passages affect bmep at higher rpms compared to an engine designed for more displacement from the start.

Open exhaust bmep@7000 rpm???

The leading edges look very steep, this will cause vibration when you open the throttle at low speeds. Any protrusions or air leaks in front of the impeller will also cause vibration.

GroupK did illustrate problems with most large carbs on 785 race boats. They were simply too big for the application and needed a restrictive lame arrestor to act as a choke. One reason why they work so well on freestyle boats is in tank location and acceleration. When the pipe hits you almost...

I mean carbs with no venturi above the throttle plate.

A 900 should be able to pull enough air for all available carbs on the market. If you want to run clean at part throttle then they will need to be on the small side. Novi has started leaving the venturi ring in place on some of their 48s so those will be most adaptable and easiest to tune. True...

And make sure it is turning enough rpm. A Popwerfactor and RPM make a lot of power.

Old impellers with stock grates dont do much in white water. At minimum you need a good grate and a pitched down Concord or Skat 12/17. A hooker 9-15 is even better in white water.

Dont shorten the vanes, the jetstream already swirls with a smooth nozzle installed. If anything grit blast and fill between the vanes with epoxy and use a big hub impeller. This will remove that airspace for faster priming.

I have found that very rich mixtures make pistons clean and plugs dirty. Hot mixtures do the opposite.

Aero-veil is scrim cloth, same stuff that cheap home A/C filters and drier sheets are made from. It helps hide fiber print. Strengthening an X2 for hard side landings is a lot of work and still difficult to achieve. Strengthening one for hard upright landings is much easier since they tend to...

Open the rear to match the front and install new plugs. Check them after every ride for comparison. Freestyle tunes tend to be rich at part throttle and most of the riding is done in this range. This means plugs get darker than they would in something that gets more full throttle time. This also...

Get that impeller, it is very good out of the box and will work with anything up to low port big bores. A good grate is also needed, make sure the grate bolts arent punched through the shoe or it will always vibrate.

Assuming the mid shaft is in, tighten the front bolts and shim the rear as necessary. If the rear tabs hit first then try removing the dowel pins from the nozzle and loosening the thru-bolts so it can float into position.

Nozzles were never a very popular modification so there is not many choices. Solas nozzle is a stock copy. Stock nozzles start at 81MM and can usually go to 84MM. Old Protec nozzles are thick enough for 88MM. Sato made a nice one but are difficult to find. For freestyle use a 62T nozzle bored to...

Make sure to carefully center the exhaust manifold if it was cut for a 62T cyl. Other than that its all tuning, carbs will run richer at part throttle and the rpm range will be lower. It will be a huge improvement if its over propped, with a low pitched prop you will just have better response...

Laugh-in.

I moved mine to just in front of the bulkhead under the rail. The only time smoke is in my face is when idling out with the wind blowing the wrong way. Rear outlet was nicer for general riding but tail stands are impossible. Just as you reach the tipping point the thrust goes away, engine revs...

The 144 is not much better than a Kawasaki conversion with a stock inlet.

Any aluminum part can be anodized. It is commonly performed as a surface prep for bonding.