Powervalve operation

[Half flip95]

What techniques do you guys use to verify powervalve operation?

Do you rev the ski on the trailer and watch for operation?

Do you pump up the cylinder similar to a leak down test and record a certain psi?

Are different weight springs available?

The valves on my Dasa appear to operate much more freely than those on my xscream I suspect the valves on the xscream may not be opening correctly.

Il what is the exact intended function of the bleeder passages in the cylinder/power valve?

 

[Jr.]

On Freestyle type PV motors, The Bellows operate via cyl pressure. As rpm increase, valves blow open
so, best viable test is to simply run and rev motor. When I build, or rebuild motors, bench testing is done via pressure testing motor.
The correct way to pressure test motor is negative pressure for leak down. But for finding leaks, positive pressure is preferred. This will also test PV operation. But be very careful you don't damage crank seals using too much pressure. Pressure testing cooling is also advisable, but a differant subject for another time.
As part of my performance tuning for rider specifics, Yes, I adjust PV spring tension. Basically, stronger springs hold blades down longer for better off idle response. Soft springs allow blades to open quickly, getting into upper powerband sooner.
There is significant differances between DASA and XS motors. And PV operation reflects that.
one greatly overlooked part of a PV motor is blade maintaince. Cleaning is critical for PV operation. I suggest Synthetic oils for all PV motors.
In most cases, it burns much cleaner, and has minimal residue gumming up PV operation. PV blades are operating in the thermally hottest point in the motor. Natural oils flash off quickly and leave a heavy residue, restricting blade operation. Depending on ride times, blades should be removed and cleaned via solvent and scothbrite pads. Pressure port also needs to be cleaned. Note valve locations, as most builders fit blades to specific slides. Lastly is the bellows. Its common to see aftermarket bellows on these motors. The bellows from Bombardier is made of a softer material and provides smoother valve operation. Due to the heat the PV operate under, its advisable to change bellows at specific maintaince intervals..

P

 

[mikesx]

On Freestyle type PV motors, The Bellows operate via cyl pressure. As rpm increase, valves blow open
so, best viable test is to simply run and rev motor. When I build, or rebuild motors, bench testing is done via pressure testing motor.
The correct way to pressure test motor is negative pressure for leak down. But for finding leaks, positive pressure is preferred. This will also test PV operation. But be very careful you don't damage crank seals using too much pressure. Pressure testing cooling is also advisable, but a differant subject for another time.
As part of my performance tuning for rider specifics, Yes, I adjust PV spring tension. Basically, stronger springs hold blades down longer for better off idle response. Soft springs allow blades to open quickly, getting into upper powerband sooner.
There is significant differances between DASA and XS motors. And PV operation reflects that.
one greatly overlooked part of a PV motor is blade maintaince. Cleaning is critical for PV operation. I suggest Synthetic oils for all PV motors.
In most cases, it burns much cleaner, and has minimal residue gumming up PV operation. PV blades are operating in the thermally hottest point in the motor. Natural oils flash off quickly and leave a heavy residue, restricting blade operation. Depending on ride times, blades should be removed and cleaned via solvent and scothbrite pads. Pressure port also needs to be cleaned. Note valve locations, as most builders fit blades to specific slides. Lastly is the bellows. Its common to see aftermarket bellows on these motors. The bellows from Bombardier is made of a softer material and provides smoother valve operation. Due to the heat the PV operate under, its advisable to change bellows at specific maintaince intervals..

P

X2 on Vacuum test AND pressure test ! Always give the motor a Push/Pull test !

 

[WFO Speedracer]

I have to second Pauls synthetic oil recommendation , without synthetic oil the power valves will gum up in short order and cease to operate.

I work mostly on sitdowns , the Seadoo setup which is what all the aftermarket systems are based off of is very easy to clean and maintain , The Yamaha setups on the other hand require massive amounts of disassembly to take apart clean and replace .

If you don't keep them cleaned and maintained they simply gum up and stop working correctly or sometimes they stick closed and don't work at all .