Freestyle Pv question

[fast superjet chase]

I have a PV lamey motor that is a 8mm stroker in it running 215psi compression now what's the best way to go about adjusting the PV's. I'm new to them so I need all the know how thanks chase

 

[fast superjet chase]

Should they be tight or loose I have no clue.

 

[yldsix]

Should they be tight or loose I have no clue.

The powervalves I've dealt with have been sea doo one and they are held shut by a spring and when cap is taken of the spring is released which allows the powervalves to be loose you can pull it in and out. Normal function works off exaust pressures and when pressure is obtained pressure in the bellows overcomes the spring and opens the valve. That's about all I know about pv hope it helps but this is with the seadoo setup not superjet. The tighter you make the spring the later the powervalves open the looser you have it the earlier it comes on.

 

[timverhey]

Adjusting spring pressure can make your powerband better when they open to early the timing is high and cut of the botom end when they open too late it is like a lightswitch they keep closed to long and the engine timing is weak and then it opens and get everything.
For my feeling it is a part of your setup.

This are my experiences
Small pitch prop and going fast through the rpm range low spring pressure needed so they open fast also like the engine is going into the rpm's
Large pitch prop and need more time to go in through the rpm range you need longer time low timing for bottom end and with more pressure on the spring they keep closed longer like the engine needs more time to go in the higher rpm's

I test always when i changed my setup and i get a good profit from it results in no weak spots in the engine and goed through the rpm range strong everywhere.

 

[Pablo]

I am for sure not an expert but I found with a bit of trial and error (in an otherwise tuned engine) that you can help compensate for too much prop by decreasing the tension on the PV's and vice versa for a ski with too little prop. There is much more that goes into how and when the PV's "pop" to make their power felt. I don't know for fact but would assume that port timing/duration plays a big role. If you can locate ur engine builder I am certain they can give you a set of complete setup instructions for your driveline. Everything from ignition all the way to pump setup. A phone conversation could save you days of tuning. I say that from experience.

 

[Pablo]

I've also been told that to set them with the red cap flush (seadoo PV's) with the black cap and focus on tuning the engine/carbs. The PV's will do their thing if the engine is tuned correctly.

 

[timverhey]

I've also been told that to set them with the red cap flush (seadoo PV's) with the black cap and focus on tuning the engine/carbs. The PV's will do their thing if the engine is tuned correctly.

i do not agree this as the spring tension does tune the point the timing changes to higher dg op exhaust duration if this is to slow then it will stay in the "bottom end timing" to long.
Is this to fast you come in the "top end timing" to soon.

Just like normall porting a race ported cylinder is lazy on the bottom as the exhaust duration is to long
And a freestyle ported cylinder is good on the bottom but more weak in the top end but will pull way better

The powervalve is closed and this is more like the freestyle porting so it will be strong off the bottom
The powervalve is open and this is more like the race porting so it will be strong in the mid-upper rpm range.

So the moment that they pop open is in my opinion important as it then make the switch from bottom end to mid-top end power (trie to explain it simple)


But also there is the option to do it flush with the caps and tune your pump/impeller combo to these settings.

In the end it is all trial and error and the complete setup is the most important.