Stx 1100 di running at 41mph

[Kawachris]

Hey guys, I have a 2000 kawi stx 1100 di. When I got the ski it had 145 hours and didn't run. Fixed a few things, she now runs and has 178 hours. (Got it running April 2020)

When I first got the ski running it was running like a bat out of hell, running a consistent 52 mph choppy or smooth water. Now every time I get on it, it seems to get slower every ride.

I just got in from a ride on a calm lake and by GPS I could only get up to 41mph. The rpms reach up to one bar past 7k, no warnings on the dash. Starts right up Everytime and no issues other than what was described.

The work I have done was a new stator, new to me engine with 112 psi on all three cylinders, oil pump drive bearings, New spark plugs, and fixed a few ground connections.

It does smoke a little extra after idling for a a few minutes, could be because I mixed oil/gas for a break in period. Oil pump works great.

If anyone has experience with this and could steer me in the right direction, it would be much appreciated.

[steve45]

First I would check the spark plugs to make sure you don't have a lean cylinder, as indicated by a white plug insulator.

Next, I would pull the jet pump off and check the bearings, impeller clearance, etc.

[Kawachris]

So I pulled the plugs, they look like they're ok a little dark but seem good. The ski is still in the water so I will be setting up the trailer soon.

I have never messed around with a jet pump or impeller, what should I be looking for? How do I take it apart and rebuild if needed? I have 2002 di parts ski which actually ran faster than the 2000 with the same exact engine. If it's in better condition could I just swap for the season I til I make it correct?

I plan on getting to it today. Here are the plugs I am running.
Poor picture quality

[steve45]

Disconnect the cables, remove the 4 nuts that hold the pump on, pull. Be careful, it can break loose suddenly and hurt you.

Get a service manual.

[GlenT]

Hey guys, I have a 2000 kawi stx 1100 di. When I got the ski it had 145 hours and didn't run. Fixed a few things, she now runs and has 178 hours. (Got it running April 2020)

When I first got the ski running it was running like a bat out of hell, running a consistent 52 mph choppy or smooth water. Now every time I get on it, it seems to get slower every ride.

I just got in from a ride on a calm lake and by GPS I could only get up to 41mph. The rpms reach up to one bar past 7k, no warnings on the dash. Starts right up Everytime and no issues other than what was described.

The work I have done was a new stator, new to me engine with 112 psi on all three cylinders, oil pump drive bearings, New spark plugs, and fixed a few ground connections.

It does smoke a little extra after idling for a a few minutes, could be because I mixed oil/gas for a break in period. Oil pump works great.

If anyone has experience with this and could steer me in the right direction, it would be much appreciated.

My $ is on the jet pump. That's a lot of hours without a rebuild.

[GlenT]

That black soot plug color is normal for a DI engine. These are lean burn engines. The injectors fire directly on the plug tip.

So I pulled the plugs, they look like they're ok a little dark but seem good. The ski is still in the water so I will be setting up the trailer soon.

I have never messed around with a jet pump or impeller, what should I be looking for? How do I take it apart and rebuild if needed? I have 2002 di parts ski which actually ran faster than the 2000 with the same exact engine. If it's in better condition could I just swap for the season I til I make it correct?

I plan on getting to it today. Here are the plugs I am running.
Poor picture quality

[Kawachris]

It makes sense that the jet pump is warn, since it has full rpms but doesn't go full speed. I haven't gotten to it yet probably have time Monday after work.

If it is warn and is in need of a rebuild, how would I go about doing it? I saw a jet pump rebuild kit on amazon with some bearings, bushings and a few clips. I don't mind spending extra on better parts, I am planning on keeping this ski for a while. Thanks I'll keep this project posted

[steve45]

You can get a service manual and read the procedure and decide if you want to tackle it. You will need a few special tools, but they're not expensive. A hydraulic press is nice, but you can use a large vise and some sockets.

SBT has a pump rebuilding service, too.

[turboman412]

Your better off sending to impros then sbt...

[Kawachris]

I will check it out asap. Has anyone done the ride plate mod? I just read about it on groupk. I guess it is a plate you put above the jet pump somewhere and it is supposed to lift the front of the boat. With a full tank of gas and going slow, the trim on the front of the hull is under water.