Adjust power valves and noticed that servo motor twiches with RPM below 900 and then back upto 1,800. Tried it with all 3 cables loose and same thing. Is this normal? I thought it is suppose to open and close smoothly or is that only after 6,000 RPM?
Devilin AblueDress!
New member
Below 900 twitch is cables to tight...above 900 
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Devilin AblueDress! said:Below 900 twitch is cables to tight...above 900
I loosened cables all the way still twitched opening and closing cables. They are not tight.
Devilin AblueDress!
New member
SRX_700 said:
Above 900
. I would suspect some sort of short or power supply issue.srx steve
New member
Check for a wire rub through under the moter.
bluemonster1
LIFE MEMBER ONLY ONCE!!!
wouldn't you not get a light on the dash is servo is acting up???
No light comes on the except for when I start it and I get 3 blinks indicating everything is okay. Does not blink when the valves open up over 6,000 RPM. Could it be a faulty servo motor?
did you ever have the harness rub thru under the engine on this machine?
Not since I haved own it. Have never looked. Can I test it first before I pull all the wires out to inspect for a rub thru? Everything else electrical runs flawless.
only reason i ask is because I had a srx here once that had me pulling my hair out and here, the harness had rubbed thru previously about a month earlier and then after repairing that the guy brought the sled back complaining it didnt have the power it used to. So after countless hours of problem searching and finding nothing, changed out servo motor, no differance.SRX_700 said:
So looking thru the spare parts bin, I had a spare cdi, threw it on and presto perfecto.... before this, i adjusted the cables 2 times, tried all kinds of stuff and to no avail. it would open and slightly close the valves even at 7500+ rpm, would not open them and hold them open, jittery and jerky.just a thought, you always remember the ones that gave ya a few extra gray hairs....LOL
The servo motor, with RPM turned down below 900, opens up, but stalls for a split second half way thru the turn. It will stay open as long as RPM is under 900. When I turn idle back up, it closes, but stalls for a split second half way around turn, and then continues. I do not have the parts to swap out so how should I trouble shoot this?
780srxgeorge
Member
I had something like this happen to me.as longe i was on the lake it was ok but when i hit the trails.pop-pu-pu-pop it realy suck!.my budy said the servo runs of the lighting coil so replaced the stater & everthing aok now.this just my experience & my 2 cents.
servo is operated off the cdi box, all of the srx and vipers are like this.
780srxgeorge
Member
how dose the cdi box get the info?were dose it come from? 
780srxgeorge said:how dose the cdi box get the info?were dose it come from?
its all rpm activated, off of the tach wire. The signal comes out of the cdi to the servo motor to open it and close it. With the 98-99 sleds its all off the tach pulse, on the 2000-02 its still off the tach pulse but with the 3d system, the flywheel keeps it all in line as it tells the cdi where each cylinder is and it doesnt waste the spark on all 3 coils at 1 time like the 98-99 do. regardless though, the cdi still operates the servo on all of them ,viper included. yamaha was pretty crafty on its deign for sure!
780srxgeorge
Member
thanks mrviper good info .
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