Recent content by kevbo

All good pipes will make the power either on or off. If you raise the popoff you will also need to use a larger pilot to have the same 1/4 throttle mixture. Your ski may be a little over propped with your high rpm pipe.

The coffmans Yamaha 650 pipe is shorter than their Kawasaki pipe in order to make any rpm with the Yamaha 650s 172 degree exhaust port. The longer Kawasaki version will rev up to 6500 rpm with a 180 degree port. The Yamaha version will rev to 6700 with the same 180 degree port. The stpck...

I have wrapped a WC cone with wetted 2” fiberglass tape until it was 5”. It worked perfectly for years on my 650 coffmans pipe. I called coffmans in 2002 and the lady said they had one 650 pipe kit left but no more cones. She sold me that new kit minus a cone for $160. It’s still on that 650.

The stock F/A isn’t restrictive. Tune the top screw to find peak rpm then open it a little.

To answer your question, as long as the stinger was restricted, a bypass is not necessarily needed in that line. It could be at the head and work just as well.

The actual pipe needs to get hot in order to make power. The rest of the exhaust needs to be cooler so it doesn’t heat up the engine bay too much. You want more pressure in the head pipe than downstream. I like to T a pisser in the stinger line and install a restriction at the stinger. This way...

Flow control valves became a thing long after skis became fast. Everyone, overnight, decided they had to have one. Shutting off the water always makes the exhaust louder, which riders always perceive as faster. I recommend placing a .100” orifice in the stinger, or whatever size it takes to keep...

The gauge can be checked against any known gauge.. Its the schrader valve thats the wild card with every compression gauge. Thats why they're only good for comparisons between cylinders.

I have burned pistons with “pump gas” compression. Make sure your ignition timing isn’t too advanced and the carbs are set rich of peak rpm.

A sheet metal gasket will prevent bolts from loosening since they don’t collapse. Someone on eBay is selling new OEM style exhaust gaskets for Kawasaki’s.

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...