onesojourner
I use a thumb throttle.
- Location
- springfield, mo
Can some one explain how the bpipe screws control water?
How do bpipe water screws work?
- Thread starter onesojourner
- Start date
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
when you close a screw it cuts off the water going through the pilot hole. as you open the screw you are controlling the flow of water into the head pipe. There are 3 screws. The top one controls the bottom end, the middle screw controls the midrange and the lower screw controls the top end. Depending on what you want you would open up the screws to find the optimal setting to give you the power delivery you want.
As far as the effect of water entering the exhaust stream it helps to tune the sonic wave.
As far as the effect of water entering the exhaust stream it helps to tune the sonic wave.
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
High Performance 2-Stroke Exhaust 101
The purpose of an "expansion chamber" is to return to the exhaust port a negative sound wave then a positive sound wave at precisely the right time. If the pressure wave returns too late, you lose some of the fresh fuel charge in the combustion chamber and performance. If the wave returns too soon, it pushes hot exhaust gas back into the combustion chamber contaminating the fresh charge and creating hot spots on the piston.
The challenge to the pipe designer is to arrive at the proper exhaust tuning that will return the sonic waves at the correct time. This challenge is made all the harder by many impeller/nozzle combinations, engine configurations, riding conditions and rider preferences.
Traditionally, if you wanted low RPM torque and high RPM horsepower, it required several pipes. A few of our competitors cast rings into their pipes to achieve pipe tuning by "cut and try". In 1992 Factory Pipe introduced the first truly tunable pipe using our variable water injection system.
This system allows you to modify where and how much water injects into the exhaust by the turn of a set screw. Where our competition had you change the length of the pipe, the Factory Pipe allows you to vary the exhaust gas temperature which in turn changes the sonic wave speed within the pipe. Changing the sonic wave speed within the pipe has the same tuning affect as changing the length of the pipe.
Tuning Your Exhaust System
Note - The following information pertains to Factory Pipe systems that use our "A" or "B" headpipe with three (3) water injection screws. Some systems such as the SeaDoo 580/650/720 and Kawasaki 750SS/XI have only one injection screw. On pipes equipped with ECWI use only the bottom injection screw.
Most Factory Pipe systems have our exclusive "tunable" headpipe which allows you to custom tune the pipe to your riding style. The following information gives a general overview of how this system works and how each adjustment will affect the performance of your watercraft.
Double check all hoses, bolts and clamps from your installation. For the first "on-water" test of your new Factory Pipe we recommend closing the top and middle adjustment screws and opening the bottom screw 3/4 turn out from closed. This setting will be more water than is required but will provide a good starting point to test the pipe.
Ride the watercraft for several minutes while varying the throttle position. Put the boat through a long series of slalom turns keeping the engine loaded. Hit the kill switch or pull the lanyard and let the boat come to a stop. Open the engine cover as quick as possible and check the pipe temperature by splashing water on the chamber body directly after the headpipe coupler. The water should lightly sizzle for the first few inches on the chamber body. If the water does not sizzle, close the bottom adjustment screw 1/8 turn and retest. If the water sizzles rapidly, open the bottom screw 1/4 turn and retest.
This set up will provide the best top end performance for your watercraft. With the pipe adjusted as stated above, open the top screw 1/4 turn. This will cool the exhaust in the headpipe and provide better bottom end performance at the expense of some top-end. This would be an ideal setting for running slalom or a tight buoy course. If you want a change that is somewhere in the middle of the two settings, close the top screw and open the middle screw 1/4 turn or add another 1/8 turn to the bottom screw. Some engines may react differently from the above. For example, while testing the 650 Super Jet we found that we gained top end performance by running the top screw open and the others closed. You may use any combination of the three screws to achieve the desired performance. However, AT LEAST ONE SCREW MUST REMAIN OPEN AT ALL TIMES TO PREVENT DAMAGE TO THE PIPE.
This is from Factory Pipes website
The purpose of an "expansion chamber" is to return to the exhaust port a negative sound wave then a positive sound wave at precisely the right time. If the pressure wave returns too late, you lose some of the fresh fuel charge in the combustion chamber and performance. If the wave returns too soon, it pushes hot exhaust gas back into the combustion chamber contaminating the fresh charge and creating hot spots on the piston.
The challenge to the pipe designer is to arrive at the proper exhaust tuning that will return the sonic waves at the correct time. This challenge is made all the harder by many impeller/nozzle combinations, engine configurations, riding conditions and rider preferences.
Traditionally, if you wanted low RPM torque and high RPM horsepower, it required several pipes. A few of our competitors cast rings into their pipes to achieve pipe tuning by "cut and try". In 1992 Factory Pipe introduced the first truly tunable pipe using our variable water injection system.
This system allows you to modify where and how much water injects into the exhaust by the turn of a set screw. Where our competition had you change the length of the pipe, the Factory Pipe allows you to vary the exhaust gas temperature which in turn changes the sonic wave speed within the pipe. Changing the sonic wave speed within the pipe has the same tuning affect as changing the length of the pipe.
Tuning Your Exhaust System
Note - The following information pertains to Factory Pipe systems that use our "A" or "B" headpipe with three (3) water injection screws. Some systems such as the SeaDoo 580/650/720 and Kawasaki 750SS/XI have only one injection screw. On pipes equipped with ECWI use only the bottom injection screw.
Most Factory Pipe systems have our exclusive "tunable" headpipe which allows you to custom tune the pipe to your riding style. The following information gives a general overview of how this system works and how each adjustment will affect the performance of your watercraft.
Double check all hoses, bolts and clamps from your installation. For the first "on-water" test of your new Factory Pipe we recommend closing the top and middle adjustment screws and opening the bottom screw 3/4 turn out from closed. This setting will be more water than is required but will provide a good starting point to test the pipe.
Ride the watercraft for several minutes while varying the throttle position. Put the boat through a long series of slalom turns keeping the engine loaded. Hit the kill switch or pull the lanyard and let the boat come to a stop. Open the engine cover as quick as possible and check the pipe temperature by splashing water on the chamber body directly after the headpipe coupler. The water should lightly sizzle for the first few inches on the chamber body. If the water does not sizzle, close the bottom adjustment screw 1/8 turn and retest. If the water sizzles rapidly, open the bottom screw 1/4 turn and retest.
This set up will provide the best top end performance for your watercraft. With the pipe adjusted as stated above, open the top screw 1/4 turn. This will cool the exhaust in the headpipe and provide better bottom end performance at the expense of some top-end. This would be an ideal setting for running slalom or a tight buoy course. If you want a change that is somewhere in the middle of the two settings, close the top screw and open the middle screw 1/4 turn or add another 1/8 turn to the bottom screw. Some engines may react differently from the above. For example, while testing the 650 Super Jet we found that we gained top end performance by running the top screw open and the others closed. You may use any combination of the three screws to achieve the desired performance. However, AT LEAST ONE SCREW MUST REMAIN OPEN AT ALL TIMES TO PREVENT DAMAGE TO THE PIPE.
This is from Factory Pipes website
onesojourner
I use a thumb throttle.
- Location
- springfield, mo
so does the tip of the screw control the water?
Mark44
Katie's Boss
- Location
- 100% one place
i
Yes that is why it is damn near impossible to drill for a new screw and match the seats up properly.
Mark44
Yes that is why it is damn near impossible to drill for a new screw and match the seats up properly.
Mark44
NVJAY775
My home away from home.
- Location
- Gardnerville, Nevada, United States
I'm not trying to thread jack that much. But don't most of you experienced freestyle b-pipe tuners run the top out 1/2 to 3/4 ish and the middle and bottom closed? Bottom end set-up basically.
jetski9010
Team RTYD
- Location
- Lancaster PA
I just tune my bottom screw so that I get proper sizzle on the pipe first then end up opening the top screw about 3/4. Not sure how the other guys are doing it.
so you guys that have your pipe dialed in for freestyle (the low end hit) does your pipe sizzle anymore, or is it pretty cool. I noticed when i tuned my bottom for a sizzle and then opend my top 1/4, my pipe no longer boils water, and i can touch it without burning myself
Philip Clemmons
Owner, P&P Performance
- Location
- Richmond, Va
Thats the big debate..................many say adding water gives better low end by slowing the wave, yet others say you still want the pipe to sizzle, but you adjust different screws to get the desired bottom or top performance, while still keeping it hot.
I guess in the end its like all the other stuff............test test test! Each combo may be different based on plumbing, water pressure, etc................
I guess in the end its like all the other stuff............test test test! Each combo may be different based on plumbing, water pressure, etc................
vjhardcore
Ride It Like Ya Stole IT!
- Location
- Toronto, Canada
Interesting thread. i bought my 07SJ with impeller/Bpipe/jets already installed and apparantly 'dialed' in. It runs awesome with no problems. I'd be apprehensive to change anything - but interested in whether or not an adjustment would do anything noticeable to the low end?
Mouthfulloflake
ISJWTA member #2
- Location
- NW Arkansas
one of the screws on my wife's boat headpipe is stuck, I tried the torch, no luck, I tried welding a ball to it, it turned 1/16 turn and snapped again.
I think Im going to rough up the area inside the headpipe, smear some jbweld on it, and plug it there.
Its the bottom screw I dont run it open on my other pipe setup anyway.
I think Im going to rough up the area inside the headpipe, smear some jbweld on it, and plug it there.
Its the bottom screw I dont run it open on my other pipe setup anyway.
masterblaster
X-H2
dont open the bottom or the mid,you want the pipe dry as possible when you start adding water from the top if you are just looking for better low end and not concerned on rpms at top end.this drastically increases low end throttle response in larger motors
Mouthfulloflake
ISJWTA member #2
- Location
- NW Arkansas
yep, exactly what I found out. just enough water via the top screw to NOT melt the coupler, and thats as brappy as I could get it, after LOTS of tinkering.
oxnard111
Creative RE Purchasing
- Location
- so Cali, Ventura/Oxnard area
When you say drill for a new scre are you referring to drilling for an oversized screw, such as a screw that Pardaddy sells?
masterblaster
X-H2
This is the case with 701s cause its harder to feel the diff but with larger motors,big bores or strokers Ive found adding way more water to the top screw gets way better low end response and immediate hit off the pipe.pipe doesnt even have to be really hot at all,it being hot is further changing the wave length for more top end,pipe temp has zero effect on low end from my testing with 800cc or so motors
Mouthfulloflake
ISJWTA member #2
- Location
- NW Arkansas
701 is as large as I have tuned so far, got wife's 760 on the bench, so Ill tinker with it next..