YPVS servo

[treppid]

Hi All, just to check. On my 350 F2 when the ignition is switched on the valve rotates from fully open to closed and straight back to fully open, where it stays not matter what revs. This I take it is WRONG? I've checked the cables and set the pulley as per Haynes etc. Would this explain pretty flat power until about 6000 when it all seems to kick in?
Dodgy controller or servo?
Any advice much appreciatated, hoping to have a sprint at Keevil

[daveg]

Yes, fully open position is where you can push an allen key into the notch in the pulley and it sits in the cylinder (for setting up). As soon as you start it the valves should move clockwise to shut the valve. I have had a bad servo motor..... so If you have checked cable tension and the other stuff I would change the motor first before the controller.

DaveG

[bare]

Could be a lot of things. Firstly the OEM valve opening program is best described as lame. as it doesn't open fully until 9500 which is at least 1000 rpms too late.
It could be the servo but if it doesn't 'hunt' about audibly then it's likely fine, besides the controllers die often (like flies actually) while the servos are quite durable.
Best test .. once.. you've checked ALL electrical connections and the state of the PV cables and ease of rotation of the valves themselves (remove valve pulley and try 'em by hand)
is to substitute a known working PV controller.
G'luck.

[treppid]

Hi guys. Thanks, think I've grasped it now. I was a bit confused 'cos I had it in my head the valves tipped backwards away from the exhaust to OPEN. So with the notch in the pulley lined up with the hole at set up the valves are fully OPEN. Ignition on and the pulley rotates clockwise tipping the valves backwards to CLOSED then forward to fully OPEN. When you start the bike the pulley is supposed to rotate clockwise again closing the valves until rising revs make it gradually open. My problem is the initial clean cycle happens at switch on but the valves never close when I start up, just stay fully open all the time. Pretty sure the wiring etc is ok, the cables seem fine, the valves seem pretty free to turn by hand and the servo dosen't 'hunt' so guess a replacement controller next!! Many thanks, sry for the long post, I'll be quiet now honest!
Cheers...

[Deleted]

Thanks for the explanation. think i understand it now.My F2 has similar problem. Was it the controler in the end?