RGS

Just an update. I returned from my trip and finished putting everything back together and it is working good. Still have a couple of small issues but they will just take some time. I want to thank you again for all your help. If I have any more issues with the ignition I now know what to look for as far as what signals to expect.

Sorry for lack of response but have had little internet the last few days. I do want to thank you for all your help with this as I had a big learning curve. Not having good schematics didn't help either. It has started to work. I hate problems that just go away on their own. The fact that the pit bike CDI worked from the start leads me to believe that it is most likely one of the interlock inputs. I suspect that one of the interlock switches was flaky and when I checked it without any movement it would show good and when the motor was rotating it would come and go. If not that then a bad connection that when disconnected and reconnected. The fact that the pit bike CDI worked from the start leads me to believe that it is most likely one of the interlocks. I have not tested it by riding it as I want to go through the brakes and make sure they work good before I do as it has set so long. Stopping is always a good thing. Luckly this ATV will mostly be used on my property in Idaho and not on trails so when (not if) this problem appears again I won't be in some remote location. I also plan to take the older CDI that I purchased and that didn't work and cut the connectors off and wire up the pit bike one to have as an emergency spare. This will disable all the interlocks but should allow me to get it back to the garage easily.

When I said the gray wire was missing it is the one on the stator. The one on the CDI is still there.

Will try and confirm the VIN on the frame but the title says JY43HPW05KC000565. The wire colors on the ATV side of the CDI match the 1990. The wire colors on the stator side of the CDI match the 1988 except that the 4 pin connector is missing the grey wire.

When I check my main switch in the off position the ground pair is shorted together and the power pair is open. When in the on position the ground pair is open and the power pair is shorted. Not like in the schematic for the 88 but like the one for the 90. The main switch is original. In fact the only thing that I have changed out is the coil and that is because the secondary was open on the original. This Quad has been in the family since the late 90's and had very little use when purchased. My father used it to get around our property and plow some snow in the winter so has not had rough use and has need very little other than routine maintenance sinch we have had it. Almost done with the carburetor just waiting on Amazon and then will try to get back to the electrical. We will be traveling in a couple of days so it might have to wait until I get back.

Interesting. I have the original CDI unit along with the original stator. This is something that I will keep in mind if I have to start swapping in parts. I did buy a CDI from amazon for the 87-88 and that did not work and if I put that back in will try swapping wires around. Also, there are 2 different pickup coils on it although they have changed the wiring on the stator so that the second one is not hooked up. On the 87-88 schematics there are 4 wires going to the stator connector and on the 89 there is only 3. On the 90 stator they deleted the second pickup coil and placed the source wiring in the 4 pin connector instead of on bullet connectors. OK I am beginning to understand all the imputs and outputs of the CDI on my ATV. On the ATV side of the ATV you have 2 3 pin connectors and one bullet connector. On my 1989 ATV and on the schematic for 1990 and later ones Bullet connector is the input to the coil. 5 This is ground 6 Kill switch. This is ground provide by either the "main switch in off postion" or the "handle bar rear brake switch in the on position". 7 No wire on the 1989 and later ones. 8 This is a output to provide a ground to the Starting circuit cut-off relay. Not sure of its function but assume that when the ATV is running that it turns off the relay disabling the starter. 9 Front stop switch for the rear brakes. 10 Neutral switch. Same lead that powers the neutral light. On the Stator side of the CDI. On my 1989 2 bullet connectors which are the source coil. 1 Pickup coil #1 2 Pickup coil #2 ? 3 Pickup coil #1 4 No wire On the schematic for the 1987 and 1988 there are 2 pairs of contacts. One pair going to ground and the other going to power. It shows both being enabled in the on position. On the schematic for the 1990 and later same 2 pairs of contacts. One pair going to ground and the other going to power. It shows the ground pair being enabled in the off position and the power being enabled in the on position. On my 1989 it works the same as the 1990 ones. In the online parts places and on Amazon it shows that there is only one part # for all the years so I am assuming that the 1988 and older schematics are wrong.

Thanks for the schematics. They are the same as the ones in the manual that I have. It is weird that my 1989 more closely relates to the 1990 model. They do not have upgraded schematic in the supplement that I have for the W or 89 model and as you mentioned I expected it would be represented in the prior year instead of the later year. I think that the next step for me is to open the stator housing and look in there. I had thought about some rust as you mentioned but as it was in oil I was kind of ruling that out. I was getting ready to clean the carb so will finish that before going further.

The bike has been in a garage for the last 7 years or so and for most of its life was stored inside. This bike was my fathers until he passed several years ago and he used it to get around the property as well as plowing snow in the winter. I did check the outputs from the stator and had 92VAC on the source coil. The trigger coil had just mV and I was using a Fluke digital meter. It has a bar graph on the bottom of the display but I will have to remember where I put my analog meter but haven't used it for awhile.

On my unit as well as the schematics for both the 1988 and 1990 the brake switch input just goes to the CDI and not the brake light. I wish that I had the schematics for the 1989 but have been unable to find them. I do not have access to the downloads yet so am unable to see if what you uploaded is for a 1989. I assumed that it was a interlock to prevent it from starting without the brake on but a rev limit also makes sense.

OK I made some progress. I purchased a pit bike CDI and put it in the circuit. This is something that I would not want to run with but for the price it was OK for checking some things. When I put that in I now have spark and it will attempt to start. I do know that I need to go through the carburetor still but this is a start. This is what I know now. With this CDI I am getting spark and it is attempting to fire. That tells me that the stator inputs are good. So this brings me back to either bad input signals to the CDI or a bad CDI. Unfortunately, the CDI for this unit is not available.

1989 Moto 4 YFM350ERW intermittent spark. Quad has set for about 7 years and was running when parked. When I replaced the battery and attempted to start it had no spark. What I have done. Followed troubleshooting in the manual. 1. Coil failed the resistance check so I replaced it. Still no spark. 2. I performed resistance checks on the stator and they all pass. 3. Found a bad rear brake stop switch and unplugged it and connected the wires in order to disable. Now I have intermittent spark. I believe that the issue is with either the stator or CDI and not sure which. 1989 seems to be a transition year for electrical. I can get new aftermarket CDI units for 87-88 and 90-94. I cannot get ones for a 89. I can get new stators for 87-89 and 90-95. Looking at the schematics the wiring on my moto is closer to the 90 ones on the ATV side of the CDI and closer to the 87-88 on the stator side of the CDI. Looking at part supply sources the stator housing is the same part # for all the years and looking at some of the stators on Amazon that have the dimensions on them both of the stators are the same size. What I am thinking of doing is to replace the stator and CDI with a 90-95 one as these parts are all readily available. Does anyone know if this has been tried before and if there are any issues with doing this. As a side note I also have a 1993 Moto 4 YFM350ER that has been sitting longer but it is located about 400 miles from me at this time. By doing this change in addition to being able to get parts I will also have 2 ATV’s that are the same electrically.