I have a 1999 Yamaha Big Bear 350. I have no fire. Sometimes if i hold the starter on and pull the cord at the same time it will start but most times not. Tried new coil; had pickup and stater tested and both tested fine. Also tried CDI box....still no go. Anyone have any ideas??

 

i don't know if those have solenoids or not, but if they do you might want to try that, or you've got a bad connection in a wire, or possibly even your switch for the key. these could all be possible problems, check them out and see if it is.

later

 

The way you are making it start is a common thing. Symptom of a bad electrical component, connection etc. A strange thing about stator/pulse coils and CDI boxes is this. Not all CDI boxes and stator/pulse coils are equal even when new. CDI boxes have a thingy inside called a thyristor. It is the switch that turns on to send voltage to the ignition coil when it recieves from 2 to 5 volts from the pulse coil. Don't trust the fact that Yamaha said they tested them. This is such a touchy area. Now we've occasionally had two bikes that wouldn't start. Take a the CDI boxes from both of them and swap them and they both fire right up. Some CDI boxes need a stronger pulse coil output signal then others to make the switching action happen. Some pulse coils put out a smaller voltage than others. You can do something yourself that the Yamaha guys probably don't know. You will be a step ahead of them. THis is a test to see if the stator is definitely good. You need 3 things. A battery(already in your bike), a headlight, (your bikes headlight is ok but a loose headlight is easier to work with) and 3 test leads. 1 test lead has to have two alligator clamps, the other two test leads will have a clamp at one end and a pointy end at the other. Now take one lead with the two clamps and hook it to either battery terminal and the other end to either headlight terminal. Hook one of the two remaining leads from the remaining battery terminal and the other end to any of the 3 white stator wires in the stator connector just under the gas tank on the left side of the bike usually. Take the remaining lead and hook one end into either of the two remaining white stator leads in the connector and connect the other end of the test lead to the remaining headlight terminal. Now you are running at least 5 amps thru the stators windings. The stator has 3 windings. They are all connected together at one end internally and the 3 white wires you see are the other end of each winding. Imagine a letter "Y". Each leg is a winding. Now the headlight should shine brightly. ELectricity is flowing the the 1st 2 winding you connected to. From a leg thru the center of the "Y" and out other leg and thru the headlight and back to the battery completing a circuit. Move one of the leads at the stator to the remaining unused stator lead. SHould have the same result. A headlight that lights. Now here is a test the shop could easily miss. Take one of the test leads from the stator connector and remove it from the connector and touch it to ground. If the light lights you have found a short inthe stator. The stator windings are supposed to be completely isolated from the engine metal. Just connected to each other. Leave the test lead end on the engine ground and plug the other end (still in a stator lead connector terminal) into the other two remaining stator terminals checking all three wires for a short. The reason or concept behind all of this is.........a multimeter and Yamahas test meter do not push enough amperage through the stators windings to see if there is arcing of electricity thru the clear resin like insulation (or cracks there in) and onto the engines metal at a running amperage. Voltmeters usually only have double A's or a 9 volt battery (zilch amperage) and simply cannot test the stator for shorts under a real life load. Typically the hard starting is very possibly the pulse coil. Now a rare thing is to have a bad flywheel. The magnets can go bad. It is undetectable to you or I but they can lose just enough magnetism to weaken the stator coil output. The pulse coil has its own magnet and fires when a metal tab on the flywheel passes by it. U should also disconnect your kill swith. It may be starting to short out enough at low load levels. Also as a last test, put a jumper across the ignition switch terminals that feeds the ignition system. Refer to a wiring diagram. A jumper wire across these terminals will bypass the switch in case it is reducing the voltage to the CDI. The stator and the pulse coil make voltage all on their own. Not from the battery whatsover. The battery just turns the engine over therefore turning the flywheel over. The battery does send power to the CDI though to make it work. Feel free to ask anything. I know this is a lot.

 

I have researched and tested the pick-up coils, main coil, and beleive that I have come down to testing the CDI box. With the ignition on and I test the voltage on the orange wire to the coil it has no voltage. When I crank the engine the voltage fluctuates but is always around .1 to .3 tenths of a volt. I beleive that the orange wire to the coil needs to have 12 volts most of the time and when the CDI opens the orange wire causing the coil to spark.

Can anyone confirm if the orange wire should have 12 volts. Am I missing something and should be looking in a different area?

 

Hello Wildstang,

I have a similar problem to Your's.

I have what I think is a 1996 YFM 350 Big Bear/Moto4.
It is refusing to start, although there is a spark to the Spark Plug.

Subject: Yamaha Big Bear 350 Moto 4 Quad ?

I have a 350cc Quad ATV, It is not starting, I would very much Appreciate some Help to get it back up and Running.

It is urgently needed back in working order, to get firewood for My Mother's House, to keep Her warm this coming winter.

Yamaha Big Bear 350 Moto 4 Quad bike
1996 Yamaha Big Bear YFM 350 Moto 4 ?
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Details from CDI Module Serial no.
3HN-30
F8T30576
6404

Description to go with attached Photos:
7" Connector: 2 Wire : 1 Black : 1 Black/White Stripe.
7" Connector: 3 Wire : 1 Green/Yellow Stripe : 1 Yellow/Black Stripe : 1 White/Black Stripe.
14" Black Ground Wire with eye.

14" Connector : 4 Wire : 1 Green : 1 Red : 1 White : 1 Brown.
14" Single Orange Wire with Bullet connector.
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Details from Engine:
1UY03 348cm³
bottom Nearside of Cylinder

2400cm³
Offside of Crankcase

Frame/Chassis number very indistinguishable, I think starts with 3HN-244, ends with 1996.
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Hello renegade888
Would the description of what to do which You gave to Wildstang, do in My case?
Have uploaded 2 jpg's of Our CDI Unit.


ATVConnection.com ATV Enthusiast Community - Cunnoquhie_Ron_Hutchison's Album: Cunnoquhie_Ron_Hutchison_1996_Big_Bear_YFM350_Moto _4

Have e-mailed Carmo.nl, They say they can test/repair the CDI Unit.

Any Help would be very much Appreciated.

Regards,
Ronald.