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jaydougempire
Guest
Ok so i bought this 2002 viper. Got it home and the first thing I did was pull the pipes, manifolds and powervalves. Wanted to have a quick look inside. Everything checked out except my PTO powervalve cable was broken right where it goes into the guillotine. I bought a used one in good shape. Going to re-install these bad boys and I am concerned about the location of the servo motor. I had to pull all the cables to get the PTO cable out unfortunately. I did not mark the servo location before it moved on me. I have re-installed the P.V.s and heres what i did since i had the pipes out... i hooked the cables back up at full slack. i turned the servo by hand counterclockwise as far as i could until there was no play in it. i then reached my hand into the exhaust port and snugged each cable until i could feel each guillotine was perfectly flush with the top of the exhaust port. Should i be worried that the servo is not in exactly the same location as it was before? is there anyway to check this without running the sled? any tips would be much obliged. BTW i am brand new to this site so forgive me if im posting about something that has been covered before. i tried researching and wasnt able to find an exact answer. Thanks!
staggs65
Moderator
Yeah you cant do it that way. You're going to have to put the pipe on, fire the sled up, and idle the sled down below 800-900 rpms and the servo will open. Then you mark the servo position and do you're adjusting.
Devilin AblueDress!
New member
Unless its a factory E start then just turn the key on. Or if your brave and want to rig up the battery leads, I have read this can burn up a CDI if done wrong......I have always done it the ways Staggs described.
staggs65
Moderator
Also if you do a search there are tons of threads with the adjusting procedure. There needs to be some free play in those cables in the open position so you don't get pull thru-s. You'll find some posts where you use 2 2.5mm allen wrenches to set the gap. Also if that cable cut where it goes into the powervalve it could very well have the stainless steel head repair done and the slot needs to be chamfered better or it's going to cut the cable again. I went through this 2 years ago with a set of repaired valves.
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jaydougempire
Guest
Ok awesome. Yeah I did manage to find those other threads with the directions using the 2.5 mm Allen wrench. Seems easy enough. Thanks again guys. This is my first yamaha sled so I've never had to worry about adjusting these valves. They must be a lot more accurate than traditional valves and better on fuel provided they are properly adjusted. I'll let you know how I make out.
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jaydougempire
Guest
I thought that when the motor was at idle then the powervalve would be closed...does it just open at low idle for service purposes? At what rpm does it close again? Thanks
staggs65
Moderator
Yes at normal idle the servo will be closed, it opens under 800 or so rpm. it will close again after the rpms go any higher than that.
Devilin AblueDress!
New member
Something I don't believe is in any of the how to write ups (have seen it in a few threads though) If your servo doesn't "park"(meaning instead its twitching/moving) once you have the idle down your cables are already adjusted to tight, loosen them up so servo will "park".
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jaydougempire
Guest
Ok great thanks again fellas. I will double check the chamfering and adjust them once I get the beast back together.
Mac
Member
Jay -- One more option would be to purchase a servo test harness. You plug the harness in an access port. Then connect to a 12 volt battery or use a battery charger. Turn the key and the servo activates. This allows for adjustment when the engine is apart. ---mac---
I can't speak to the Viper specifically, but my '01 SRX has a white, triangular shaped three wire test connector near the servo that has a red and black wire leading to it (the third hole isn't used). After loosening the cables, apply 12 volts to it (red=positive, black=negitive), then mark the servo wheel. Make your adjustments, then re-apply the 12 volts and recheck.
As Devil suggested - if your servo twitches and doesn't park when opening, one or more cable needs to be loosened before the servo wheel can be set.
I believe the tester in the shop manual uses a 9 volt battery in place of a 12 volt source but the servo sees 14 volts when it's running. I suppose if you reverse the polarity you could cause problems but the wires at the connector should be clearly colored red and black.
I made a fused two wire test lead with two blade terminals that plug into the test connector on one end and with banana jacks on the other that plug into leads that go to my tractor battery. I personally like using this since I adjust the PVs with the pipes off during pre-season maintanence.
If you deside to adjust the valve flush with the port as opposed to the 2.5mm measurment at the PV cable housing, make sure after your adjustment that you can still push the valve into the port a bit indicating you have some slack and aren't hard against the cable.