Curtis Underwood

You both are correct. Here is something you might consider. They make a charger that will recover a AGM that has been completely discharged and set up for a while. These chargers have a battery reconditioner in them. What this does is to put out a low frequency pulse that takes about 48 hrs to break up the solidification that happens when these batteries set up and completely drain. But I have found on a good battery they will tend to try to recondition them if the battery voltage is below 11.8 volts and it will not charge it until the battery recovers to above 12 volts.. If you use your lights and say your winch it will drain the battery below this point. So I have about 4 chargers lol one I use to recharge a low battery, couple I use for as a maintainer and this reconditioner that will recover some of the batteries but not all of them. It has recovered 3 out 4 I have used it on. The fourth one I think may have had a dead cell(meaning the plates were worn out from use) and it was 5 years old and the others were like 3 years old and less.

That MV reading do you have the reading in both electric start and while pull starting? If not in pull start then this is going to be a sensitivity problem in the CDI. But this make it sound like you have a bad ground somewhere. The only thing in common is the grounds. If a ground is loose near the CDI and you start the engine with electric starter it could put a load on the ground wires causing the ground which is natural low to go higher and interfere with the CDI. This is the only thing I can think of that could be causing the problem. Here is what I would do. With everything hooked back up as it was when you started. Ohm the black wire on at the CDI unit and make sure it ohms is 0 ohms to negative at the battery and not some high number(you can do this by stripping back a little of the insulation then later you can tape it back when your have the ATV fixed). Then I would run a temporary ground from battery negative to the black wire where you stripped it. If it starts you have a bad ground connection somewhere. If it does not start then I would have to have the unit in front of me to see what is going on. I am a senior electronics technician and would have to run some tests that require specialized equipment. If it does not start grounding that black wire at the CDI then it will most likely be the CDI has become sensitive to electrical interference. Some CDIs have a micro chip in it that control the firing, this microchip can become sensitive. Electric motors will generate electrical interference. The only things in common between electric start and pull start is the B/W kill wire and the grounds. A bad ground or one with a higher resistance could allow it to start with pull start and during electric start open up and not give a ground to the CDI.

Yes Scott if you cut the B/W wire on that kill circuit and it runs and starts under electric start it would confirm that the switch assembly is bad causing the problem. The way you described this problem it has to be in the wiring or possibly a cross feed during electric start. The Main Switch has two functions one is to supply 12+ power to the system when the switch is on and the other is to ground the kill circuit when the switch is off. The way this starting circuit works is the when the Main switch is turned on it opens the the connection to the kill circuit and send 12+ to the Brown wire which supplies power to the relays and lights. All three control relays Start circuit, Neutral safety, and Reverse relay have 12+ applied to one side of their relay coils as long as the main switch is on. This is a European style electrical system and uses a ground to control the on/off of the relays. The Start circuit cut off relay has 12+ supplied to it's coil as long as the main switch is on then when the start push button is pressed it connects the ground to the other side of the relay coil which energizes the relay and the contact in the start cut off relay closes sending 12+ to the starter relay which has ground to one side of the relay coil (just the opposite of what is used on the control relays). They did this so that there is no +12 Volt on the handle bar and I think this was a safety issue. Since ground is used as the control it causes a lot of places where the kill circuit could be grounded. From What I have been able to find this 1988 diagram is the same as the 1993 using 3 relays. The blue relay (Reverse Relay)is a Normally close forced open where the two other relays(Neutral safety and start cut off) is normally open forced closed.

To start with sounds like you have either a issue with a switch or wiring. The CDI unit is powered by the CDI magneto (it has no battery power running to it). So if it is running correctly from pull start and not from electric start then you could have a bad start relay, bad neutral relay, bad wiring, bad switch, Bad connection in a connector or Lose ground wire could also cause this. If you have a voltage meter hook red lead to positive on battery and hook black lead to B/W wire coming from kill switch. If at any time this shows 12 volts then the ignition circuit is killed. If it shows 12 volts during electric start then that means the kill circuit is grounded. This test will tell you when the kill circuit is not allowing it to fire.` Look at the neutral light. Does it stay on when you mash the starter Pushbutton? This sends a ground to the CDU unit that has to be grounded for the start circuit to energize, if the neutral light is going out the your losing ground to the CDI. I had this problem and it was a bad relay, contacts in the relay were made all the time allowing the starter to turn over in any gear but it would not fire unless it was in neutral. The kill switch is bad about being intermittent and the contacts when closed kill the machine (this handle bar switch cause more problems then most of the other wiring put together). Disconnecting this to take that out of the circuit(either cut the b/w lead or use a tool to remove the lead from the plug, you will have to hook this back up after troubleshooting). It should start and run with it disconnected if it is this switch causing the problem. Your start pushbutton and kill switch is in the same assembly on the handle bar, pushing the button could be causing the kill contacts to make and not allowing the machine to fire.. The issue sounds like the cdi is grounding on its kill circuit when the starting circuit is engaged. Most all the wiring diagrams are about the same except for a few things, like reversing relay 1988 has it but most don't, this one is for a 1988 Yamaha Big bear. Highlighted in yellow is the black wire which is ground. Red is the R/W wire witch is comes from brown 12+volt. The green highlighted wire B/W is the kill circuit, if this is grounded at any time, then the machine will not fire.

Here is a wiring diagram it should be for your machine if not it will be close. There is only 4 wires going to the switch. The red dashed on print I believe will be a red white striped wire which is positive 12 volt (terminal Batt). The red wire is the kill wire(terminal HO). Green dashed or green white goes to ground(terminal E) Then the black wire is the ignition wire(terminal IG). With switch on position contact is closed for the terminal Batt and terminal IG giving power to the CDI unit. The terminal E and HO is open. With switch in Off position the terminal Batt and IG is open and the terminals E and HO is closed turning the CDI off.

Get a clear piece of hose the size of the carburetor bowl drain tube. Put it on the bowl drain and run the tube up beside the carburetor. Open the drain and let fuel run into the tube if the fuel goes up to the lip of the bowl where it connects to the carb float is correct but if it is below that then the float is not allowing the bowl to fill up and stay filled during high RPM.

Oh just got through rebuilding a Differential. It cost about 350$ in parts. The problem was the ring gear/axel was stripped out. Had to have all new bearings, seals, axle, and ring gear in differential. Since you have to tear it all down you might as wheel replace the wheel bearings. If you do tear into it make sure you take all spacers that space ring gear , pinion gear and mark the from witch side they came off. It make a big difference when you go back together these have to be back where they came from.

This appears to be about a 2000 big bear. The big bear and kodiac are very similar. I looked up some pics of big bear atv and seen one looks like it but different color and it was 2000 model.

I have had this on several machines I have worked on and every time it has turned out to be one of the following. The air filter not on machine, cracks in the intake adapter, float not adjusted right, carb air fuel mixture not set correctly, or intake/exhaust valves not set correctly. I would start by first making sure the air filter is on the machine these ATVs will not run good without the air filter in place. The second thing I check is to make sure there is no cracks in the intake adapter and to make sure it has a good seal(this will give it to much air and cause this type problem). Next check the float level in the carb to ensure it has plenty of fuel in the bowl. I do this with carb on machine by taking a clear hose and putting on the drain tube of the bowl opening the drain with the tube running up the side the carb. If fuel level shows where the top of bowl lip meets the carb then float is set correctly if not carb will starve for fuel when you push the throttle. Another problem that can cause this is the valve setting. If the valves are to tight or to lose they will cause this type problem. On one occasion I had a coil bad that when engine was running at high rpm it would start cutting out and miss firing. But it would rev up just would not go down the road at higher then 1/3 throttle. From your description I do not think this is timing or ignition problem.