I have a 2002 Yamaha SX Viper with some electrical issues.
Current symptoms:
-If speedo and lights are both plugged in it wont rev above idle and speedo goes out
-HighBeam change, brakes, and warmers make the lights go out
-check engine light it on
History:
When I first bought it (1400mi), it ran fine but the speedo turn off randomly and always when you changed to high beams or turned on the warmers. A mechanic I was working with told me to change the voltage regulator. After the new regulator was in it was presenting the same symptoms and added a new one. This was that once it was running higher than 4k rpm it wouldn't come back down to a regular idle of 1.5-2k.
Then the big problem happened (1650mi). I was putting in through some fast lake runs and after it just bogged out and wouldn't rev above idle anymore. I had to tow it home and a mechanic suggested that I get a CDI for it. I then bought a cdi and put that in and it still does the same thing.
I read on here someone had a similar issue and they unplugged the speedo and lights and it ran fine. This works also for mine and I can also run one of the two but running them together does not work. It goes back to only idling. When you hit the throttle it goes up for less than a second and then just goes back to idle. I would like to get the headlight and speedo functions back. Any suggestions would be appreciated.
Current symptoms:
-If speedo and lights are both plugged in it wont rev above idle and speedo goes out
-HighBeam change, brakes, and warmers make the lights go out
-check engine light it on
History:
When I first bought it (1400mi), it ran fine but the speedo turn off randomly and always when you changed to high beams or turned on the warmers. A mechanic I was working with told me to change the voltage regulator. After the new regulator was in it was presenting the same symptoms and added a new one. This was that once it was running higher than 4k rpm it wouldn't come back down to a regular idle of 1.5-2k.
Then the big problem happened (1650mi). I was putting in through some fast lake runs and after it just bogged out and wouldn't rev above idle anymore. I had to tow it home and a mechanic suggested that I get a CDI for it. I then bought a cdi and put that in and it still does the same thing.
I read on here someone had a similar issue and they unplugged the speedo and lights and it ran fine. This works also for mine and I can also run one of the two but running them together does not work. It goes back to only idling. When you hit the throttle it goes up for less than a second and then just goes back to idle. I would like to get the headlight and speedo functions back. Any suggestions would be appreciated.
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First check for any rub throughs on your harness if you didn't already they were a problem for yamaha triples, they run under the engine seem and to wear the wires bad, it could cause all sorts of electrical gremlins
mod-it
Member
Your stator is going out it sounds like. I had this same issue.
When hitting the brake or changing from high/low beam, the tach would reset. It also developed a bad mid-range bog if the hand warmers were on, Mrviper said this was from the low voltage affecting the cdi. When you unplug the headlights it is lowering the voltage draw, so then it works okay again.
If you meant the stator when you said you changed the voltage regulator, then Modsrx is correct and you need to go through your wire harness. Since this is a common issue, it would be a good idea to check this anyway. It only costs you your own time and a few dollars for tape and wire lume. Do a search, there are tons of posts about it since it is such a common issue. There are lots of instructions on how to check the harness and cure the issue. The most commons spots are under the motor, around the cdi, handle bar area, and under the tank and seat.
When hitting the brake or changing from high/low beam, the tach would reset. It also developed a bad mid-range bog if the hand warmers were on, Mrviper said this was from the low voltage affecting the cdi. When you unplug the headlights it is lowering the voltage draw, so then it works okay again.
If you meant the stator when you said you changed the voltage regulator, then Modsrx is correct and you need to go through your wire harness. Since this is a common issue, it would be a good idea to check this anyway. It only costs you your own time and a few dollars for tape and wire lume. Do a search, there are tons of posts about it since it is such a common issue. There are lots of instructions on how to check the harness and cure the issue. The most commons spots are under the motor, around the cdi, handle bar area, and under the tank and seat.
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Jesse Peterson
New member
I had similiar issues and it was the stator.
axapowell
New member
What about the Mag Rotor? I am in the process of changing the stator, but no one seems to be replacing the mag rotor?
Mine has some marks on the inside shiny surface. Will it be ok? The outside was real rusty, cleaned the whole thing with brake clean. Anybody? The rotor is VERY pricey, hope it will be ok.
Sorry for the hijack, but I think we all need to know.
Dave
Mine has some marks on the inside shiny surface. Will it be ok? The outside was real rusty, cleaned the whole thing with brake clean. Anybody? The rotor is VERY pricey, hope it will be ok.
Sorry for the hijack, but I think we all need to know.
Dave
Jesse Peterson
New member
axapowell said:
Taking the stator out isn't that big of a job you just need a fly wheel puller which most dealers will let you borrow, and some of the screws have loc tite on them so I heated them up good and they came right off, but don't strip them. Also there's a really thin plate that holds the stator wires back, be sure to keep the heat away from that I burned mine up like a dry leaf. Take the stator out and have it tested or test it yourself.
Final Repair
Thanks for all the responses. I rode the rest of the season with the electrical issues but recently ohm tested the stator now that I have the sled off the trailer and in the garage. One of the terminals tested at about 26 ohms at room temp and the other didn't read at all. I took it apart and the wire that wasn't reading was completely stripped and in contact with other parts of the stator. I haven't put a new stator in yet but I think its pretty obvious that it was the problem. I also checked all the wires for rub through and found nothing.
Thanks again.
Thanks for all the responses. I rode the rest of the season with the electrical issues but recently ohm tested the stator now that I have the sled off the trailer and in the garage. One of the terminals tested at about 26 ohms at room temp and the other didn't read at all. I took it apart and the wire that wasn't reading was completely stripped and in contact with other parts of the stator. I haven't put a new stator in yet but I think its pretty obvious that it was the problem. I also checked all the wires for rub through and found nothing.
Thanks again.
09nytro
New member
Well i'm glad you found it 
Check Engine Light
I put in the new stator today and ran the engine. The electrical symptoms are all gone but the check engine light is still on. Could this be caused by an old code from when the stator was bad or is there something else going on? If it is an old code is there a way to reset it?
Also I did some soldering on the old stator and now it tests perfectly. Around 26 ohm at 70F from both pins. Is this worth anything. My new one was 165 from cycle parts warehouse and I see used ones selling for 140-150 on ebay.
Anyways. Thanks for the help so far and hopefully I can figure out this engine light.
I put in the new stator today and ran the engine. The electrical symptoms are all gone but the check engine light is still on. Could this be caused by an old code from when the stator was bad or is there something else going on? If it is an old code is there a way to reset it?
Also I did some soldering on the old stator and now it tests perfectly. Around 26 ohm at 70F from both pins. Is this worth anything. My new one was 165 from cycle parts warehouse and I see used ones selling for 140-150 on ebay.
Anyways. Thanks for the help so far and hopefully I can figure out this engine light.