jet size in the stinger of a dry pipe

blaster801 · 12-31-2009, 12:31 PM

Hi Bill,
Can you please explain me what happens to the engine output if I increase or decrease the size of the stinger jet in a dry pipe?
I think that if I increase the jet I can pick up some top end power attending that with the bigger jet I should have more backpressure at high RPM but if I decrease the jet the only effect that I could imagine is a overheating of the stinger coupler and of the waterbox.
What do you think?
I wish you a happy new year!!
Thank you Michele

link · 01-01-2010, 03:19 AM

Take the jet out & use a flow control valve, best of both worlds..

Mr. Bill · 01-04-2010, 04:38 PM

The amount of water entering the stinger will effect the way the chamber works to a very limited extent. Yes flooding it with more water may help with rpm as long as it is a limited amount of water over what is necessary to keep the hoses from melting on the exhaust system. They chamber will interpert more water to having a smaller diameter stinger opening, but you are splitting hairs here, don't expect too much from it. A flow valve will dry out the waterbox at low rpm, then add water as rpm increases and the water pressures overcome the sping in the valve, much the same as a Sea Doo water regulator will, but add water instead of reduce water. These flow valves work well too.

Keep in mind that any kind of restricor you decide to use will need regular cleaning as once clogged up, the repairs can be expensive, especially if the boat swamps from overheated exhaust couplers and you suck water into the intake and engine.

rando22 · 06-19-2010, 03:25 PM

I installed a Flow Control Valve on my 2002 XLT from Island Racing and it doesn't feel like it make a difference. Can any body PLEASE help me?? The way the instruction say to install is, install a plate off the side of jet pump running a hose from plate threw the hull then tap flow valve control valve in line and to the top of the exhaust pipe where is separates. Then tap a fitting on bottom of exhaust pipe (directly under the top fitting) the this line will discharge out the back of the ski. Now, does this make sense????
Can any body shed some light????

rando22 · 06-19-2010, 03:26 PM

I installed a Flow Control Valve on my 2002 XLT from Island Racing and it doesn't feel like it make a difference. Can any body PLEASE help me?? The way the instruction say to install is, install a plate off the side of jet pump running a hose from plate threw the hull then tap flow valve control valve in line and to the top of the exhaust pipe where is separates. Then tap a fitting on bottom of exhaust pipe (directly under the top fitting) the this line will discharge out the back of the ski. Now, does this make sense????
Can any body shed some light????

Mr. Bill · 06-20-2010, 04:48 PM

I think you are confusing a water jacket drain hose fitting with a newly drilled and taped hole that does not penetrate into the waterjacket but does go directly into the exhaust stream of the inner pipe, and that water line you added will now become the source of water travelling into your exhaust pipe's stinger.
If you bought the valve from Jetworks, did it come with instructions specific to YOUR model of Yamaha ?

I also suggest that you talk to Art at Jetworks for concerns about his products as he is the one who has the knowledge to give you the answers you desire.

Bill O'Neal
WCM