Electrical problem?? At wits end!

Skidooslayer687

Skidooslayer687

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Joined
Dec 17, 2006
Messages
711
Age
38
Location
Almonte Ontario Canada
Okay so heres the problem:

On cold days when I first start the machine, it only wants to run on 2 cylinders, sometimes though, it does not occur every time. It seems to be the middle cylinder. Once the machine is warmed up (for like 10 or 15 min) suddenly will kick onto all 3 cylinders and run perfectly fine for the rest of the day, even after shutting down to have a break/ lunch or whatever. I've put a set of used coils on it and the problem has still persisted after changing these. Ive measured the resistance values for the stator with an ohmmeter and it comes out within the spec the service manual says. Ive inspected the wiring harness very carefully and have found nothing, no rub throughs, not even a mark on the outside of the harness.

My question is where do I go next? Could the problem be in the stator even though it tested within spec? What else is there that controls the coils? My machine does have dcs on it and it has acted up in the past, but i cured that last year with a new sensor (old sensor had a tiny crack in the epoxy which i think was letting moisture in).

Im just at my wits end with this, I dont want to invest the money in a new stator if I dont have to, but Im not sure where else to look?

Any help would be MUCH appreciated

Thanks guys
 

1. check the carb for that cylinder.. pilot jet and main
2. maybe try a new spark plug.. I had one with cracked porc.

3.also what kind of compression you getting on that cylinder compared to the other 2? major difference would indicate a problem

Its an 02 which means it has to be something dumb...
 
Last edited:
Thanks for the quick response guys!

Okay, sorry forgot to mention a few other details, this thing has got my head spinning... I have checked the carbs thoroughly, cleaned and everything, no dirt at all, im absolutely sure of this as ive had them apart twice now. I tried moving the plug but the problem stays on that cylinder, then I put a new set of plugs in, same problem. I borrowed buddies compression tester, got basically equal readings (within 5 psi across all 3)

This is why its got me at wits end, i know its something dumb, but i dont know what it is, and its gonna be one of those things that when i find it im gonna be mad at myself for not checking that.
 
did you have the carbs off earlier this fall? something may also be out of adjustment. how do the plugs look on that cylinder when you do get it running?

check the grounds and connections

also, check your air box and pipes for mice!!!
 
It may be a stretch but remove your pipes and run your hand along wiring harness under the case,you are checking for a compressed section that has worn through and inter grounds out causing an inter misfire/dead cylinder have had similar experiences as you have described and this was the corrective action...good luck n keep us posted.
 
interesting this is a problem for you because I have the same problem happening on my Maxim700.Start up cold and cyl 3 does not fire.I had major backfire's this morning.Once I pull plug wire off and slowly put it back..it starts to fire.If I start it later in ther day it is fine.But my plug is looking really black in color,what color is yours? Oh yeah,I have tried switching plugs ..no go.This is driving me nuts also as I want to sell the bike.I feel your pain here
slayer...Maybe our issues are the same and can be worked out together here....
 
try a new plug cap? my harness was pinched where it runs down by the recoil and along one of the coolant hoses. i had simalar problems.
 
on newer ignitions, the cdi controls each individual coil, not firing all three three times a revolution. they fire each one once for each revolution. If it is only effecting the center one and you have changed out coils and plugs, if it is ignition, I would try the cdi first, stator second. Tell someone you know you want to wash there sled because they are such a good friend, swap out the boxes while its there, if it works, tell your friend you don't know what happend to his sled but you think it might be his Cdi box.
 
I agree with BTV, if you have already swapped the coils and plug wires/caps. Check your CDI (easiest way is to swap one), and your stator closely (use a multimeter).

Yes, check your harness carefully.

On another thought, did you check your reeds and compression at some point? Also your compression (cold versus hot)?
 
had a Trigger that went bad. caused a similar issue. Tested good but was intermittent and drove me nuts! Pruchased an aftermarket trigger and that did not work for some reason, did the same type of thing. Stator was changed and the problem was still there. It was fixed with a used replacement yamaha Trigger. Change the trigger with another one if you can find one, to troubleshoot. Just an idea.
 
I've replaced the caps last year, and Im 100% sure this problem is not in the carbs, since this problem has occured ive had the carbs on and off at least 4 times, i've been through them with a fine tooth comb and cant find anything that is adjusted or out of spec compared with the other ones. When the machine runs on all 3, all 3 plugs are the same colour and it runs really strong, doesnt hesitate or anything runs like a top so to speak. Compression is basically all the same cold, havnt had a chance to test when hot yet though. I will check the wiring harness again, ive checked it already but to be certain I will go through it again. Its just weird as its only when its first started usually on a very cold morning so that kind of leads me away from a harness issue, to me if it was that it would be more intermittent then it is.

I have the stator off now, Im going to test it and post results with what i find. Now when you guys say cdi your referring to the box on the left side of the machine above the belt guard correct? Im also going to pull my reeds and inspect them with a fine tooth comb and will post results when i've done this.

Thanks for the help guys, its much appreciated!
 
The very first thing that I would do is start it up cold and check for spark on the middle wire. Have a good plug in the cyl and another hooked up to the wire and ground it to see if you have spark. If you do, I would guess you have a reed problem, if you don't then I would guess CDI.
 
Okay, finally located the specs in a post on here for the stator... heres what i found:

When the stator is at room temperature, i measure the pickup coil, found a reading of 206 ohms, and 0.7 ohms when testing the source coils. When I measure to see if there was a short to ground I got 7.8 Mega ohms. So this to me is within the spec the stator is supposed to be. I then took the stator off, put it in the freezer at home for 6 hours, then pulled it out and measure it, got 178 ohms on the pickup coil, and 0.4-0.5 ohms on the source coil when going in between the 3 wires.

To me this rules out the stator, I will check the wire harness tonight when i get home, Im also going to pull reeds as a longshot but im nearly 100% sure there going to come up okay as well. All that is left is the cdi box itself correct?
 
Yea, I think that is what I would be disecting next. You need to really take BTV advice. If you don't have any friends see if you can locate a "friend" close by on here to try a CDI box before you actually spend money on one.
 
Okay, got some time to work on the sled finally heres what I found....

I checked the wiring harness again, thoroughly, found nothing, no pinching, cuts, nothing... checked the harness that plugs into the cdi box, also found nothing, no damaged pins/pushed out pins.

I also pulled the reeds, just for the heck of it as a longshot... also found nothing, all reeds are in great shape.

I think Im going to follow the cdi route first as its really the only thing i cant test, definately would like to find a used one if I can.

Now I did some research on it, found the 2001 and 2002 cdi boxes are the same, earlier model years were different part numbers. I guess the next question is are those the only 2 years that are compatible? A viper cdi with the dcs would not be compatible would it?

And another question would be if I do end up buying a new cdi, is there any aftermarket performance ones available or is it best to stick with the stock yammy part?

Thanks again guys, hopefully I can put an end to this nightmare of a problem soon enough! :)
 
2001 and 2002 CDI boxes are the same

Last year, I was in the opposite place that you are in today. I thought it was the CDI box and not the stator. Turned out that it was the stator, which was testing fine at room temperature, but when the garage heat was shut off and it was retested the next morning before it warmed back up - it proved to be a bad stator.

However in the mean time, I bought one used CDI box, which as I mentioned did not solve the problem. So, we thought, hey someone sold me a bad CDI box and so I bought another, swapped it in, and still the same problem. That is when the stator was retested and it was found to be bad at cold temps.

In going through this exercise, I learned that the 1998 and 1999 CDI boxes are the same, the 2001 and 2002 CDI boxes are the same, and the 2000 is just for that one year alone. The number of terminals are different between the years. Can't tell you anything about being interchangeable with Viper CDIs.

By the way, I now have 2 spare CDI boxes for the 2000 model if anyone is intersted in one.
 
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