Mech

Those figures are only right for the ignition systems using three cdi windings. All the two winding systems use figures more like what I say. I'd recheck that coil that seems open circuit.. It might only have .085 to .1 of an ohm.. It's possible that a cheap gauge might not register it..

I don't think those resistance figures are right. I've never seen a cdi charge coil that had more than about 1.5 ohms. The trigger coils are often between 80 and about 200 ohms. Those high resistance figures are for a different stator in a different model.. A model that has six cdi wires comimng out of the stator. That system you have there should have one high resistance, which will be the trigger coil, and one very low resistance, which will be the cdi charge coil.

If they are getting torn to pieces then I'd suspect they are hitting/touching the case.. probably only at certain revs when the belt flexes and flaps.. I'd leave the cover off and either sit there revving it watching for excessive belt flapping, or go for a ride and see if the belt survives without the cover on.

Yeah 350 doesn't seem to be well supported.. I dare say some other model will be wired the same way.. but which one .. If the OP lets us know the answer to the questions earlier, I'll post up the diagram options I have..

Bad switch, broken wire, wire shorted to the frame...

That stator has three lots of cdi windings Gw.. It's not the right diagram.

The earliest ones had the number down under the bottom left lower frame tube, near your foot. They faced down and slightly out and were a prick to read and always got rubbed out..

Can't find any manual for a U/B/L model.. Looks like you are going to have to improvise.. Some things to check are.. How many wires the ignition switch has, and how it operates. Some are duel circuit and some are single. The number of wires going into the cdi unit. The number of wires coming out of the stator. How the start button is interconnected with the cdi unit. Some feed a 12 volt signal into the cdi unit when the starter is being operated, and others have 12 volt going into the cdi unit and then coming out and to the start button. If you suss those points it will narrow the likely candidate wiring diagrams down a lot.. If you can answer as many of those points as possible then I, and probably Gw, will have several different wiring diagrams that might suit.. with a few colour changes. Oh.. another little trick they like to play, but which helps find the right diagram, is they change the shape of the plastic plugs the wires go in.. They are too hard to describe, but it's worth checking the bike against the pictures in the diagrams you eventually look at.

Ha.. Danged power tools.. That's why I don't like them. The washer got mangled because it was squished between the gear jambed solid on the case, and the rotating gearbox shaft.. It was never designed for that. Neither the washers or the bush should have any load on them. When it's not being used the gear only rotates very slowly in relation to the gearbox shaft it's on, and once the gear gets engaged, it's locked to the shaft, so not wearing at all, and only has to resist the pressure of the two gears pushing apart as they turn under load. Well done so far.. If you can get the parts at a good price, it looks like being a good buy..

No that is all perfect. There is a one way clutch/ratchet inside the centrifugal clutch to provide engine braking at low engine revs when the revs are so low the centrifugal clutch would have normally have disconnected. When you're pushing it with the engine off, the centrifugal clutch is disconnected and so you can turn all the gearbox shafts, the plate clutch, and the centrifugal drum, with the back wheels, but only in reverse. If you push it forwards the one way clutch tries to apply engine braking. Each higher gear you are in makes it a little easier to turn the engine, which is why it can just be pushed forwards in top, but not in low. Are you getting reverse ? Sounds good.. Don't forget to adjust the clutch after it's together, and do that again after a it's been operated a few times.. a half hour or so of use.. Things will settle in. Hopefully, the electric shift is going to work now..

Yeah they are rather difficult to get a good match with the wiring diagrams and the actual bike quite often.. You need to get the full definition model number.. One way to do that is to use some online parts place like partzilla and look into all the models of 1999 big bear 350.. Here's what they say came out in that year.. https://www.partzilla.com/catalog/yamaha/atv/1999 What you need to do is start looking at specific parts like the carb, or body work or drive line/shafts, and figure which one you have.. UL, or ULC.. If neither though seems to be exactly like your's, then you should look a year earlier and later.... model years vary around the world. In 2000 your options would be M or MC.. You need that specific M, MC, Ul, ULC.... then we might be able to find the right diagram.

It idles so it won't be the idle jet. Does it die as soon as you open the throttle to 1/4, or does it start to rev and then die after a few seconds ? And it does die right out does it ? The engine stops running ? At 1/4 throttle the things controlling the fuel are the main jet, the emulsion/discharge tube, and the slide and needle.. Check the short discharge tube(if it has one), which sits on top of the emulsion tube is there, and the right way up. Check the needle is held in the slide. If it takes a few seconds or more to die out though it could be because the fuel level is going low in the bowl, in which case it could be a blocked filter or float needle jet.

Most manuals would quote per hub.. so that would be for each hub.

Perseverance always wins.. giving up never does.. Good onya.

What's the vin Mitch ?

The spring will have come off because the lip got distorted as you worked it over the shaft. The outer should only need to be wiped clean with a rag and have some sealer on it if it's a metal body, or dry if it's a rubber bodied seal. The sealing lip should have a bit of grease on it. You should be able to tap the seal into where it sits easily with an 8oz hammer. Use a fat engineers punch if it's recessed. It shouldn't take any hard hitting at all..You have to hold it down and tap a very little in on one side, then jump to the opposite side before working your way around tapping it in evenly all the way around in stages, going around about six or ten times before it's right down.. If it gets cocked it will distort the body of the seal, but as long as you can tap on the opposite side and get it moving down on the higher side again is it will come right if you don't let it get more than about a 1/8 inch out of flat. If you have any trouble and end up getting a new seal, I'd recommend the new rubber covered seals.. that are way better.

Ok, and so when it's trying to move off, does it labour for a while and then die, or does it just conk out the moment it starts to stir ? The difference being, if it labours before it dies it might be carb, or weak spark, or something else.. haha.. but if it dies the instant it starts to move at all, before the engine even gets any real load on it, I'd be suspecting a wire moving and touching an earth..

Yup. I agree with these guys.. Use a jumper cable and feed power straight to the starter, and also use one on the earth if it doesn't go. just to check the earth cable or connection. As has been said, the brushes are real prone to wearing or sticking in their holders. I'd also though check the regulator. It could be draining power, but it might also be that it's not regulating, or not charging enough. Also, switches, because we turn them when we park up, have to be a suspect in intermittent cases.. along with breaks in wires making intermittent connection. You might try turning the key on and off a whole lot of times and see if it doesn't sometimes make better or worse contact. You could also leave the bike idling, and then start wriggling all the wiring bit by bit, especially near the steering head, and at the ends where they go into plugs. It may conk out or sound different make dash lights flicker if you make or break a contact.

If the kitchen stone is courser I'd use that cut off saw, which I presume has a diamond blade, to take a four mill slice off the end. Then you can press down real hard on the four mill edge. If you want to move a lot off metal with a stone you need to press hard, and move slowly.. It's a bit like getting a file to start biting in on cold or rusty steel.. Once you get it to start biting in, then it does it really well.. other wise they slide over the surface taking off not much..

That definitely sounds like the fuel isn't getting into the fuel bowl quick enough.. If you pull the fuel hose off the carb and run it into a bottle it should flow petrol out full diameter of the hose, or very close to. As long as there is plenty to there, then the blockage is nearly certain to be the float needle or seat is playing up/maladjusted.. Unless this thing has a fuel pump ?

Ok.. That's good. So.. running for a few minutes and then starting to run lean is not a jetting problem. A jetting problem happens the second the fuel starts trying to flow through that jet.. not after a few minutes running. You need to check the fuel supply is getting to the carb. The best way to do that is to undo the drain screw. That tests the tap, filter, and the float needle are all allowing fuel through. It needs to keep running even after the carb is empty. If t starts slowing it could be a dirty filter in the tank, or a vacuum because the tank vent is blocked. If the tank vent is blocked it will likely take 15 minutes to show a problem, if it's the float needle blocked it will take abut a minute to three depending on how blocked and how you are revving it up and stuff.. Rough figures but you will get the idea.. If you get the fuel supply problem sorted, then the carb(and jets) might not need too much.. we hope.

Yeah a stone being flat will work like a plane and show up and grind the high spots.. while the dremel will go over/follow small discrepancies in a flat plane and eventually magnify them. That cutoff saw you have will probably take a thin slice off your kitchen stone... That's what I do. I've always had a small pocket knife stone, and a bigger block stone in my tool box and workshop. I run them over burrs, heads, anything damaged or that has to be flat..

It doesn't look to me to have any moving parts.. Any chance of a side view ? Or behind.. And if it is a circuit breaker then sure a fuse will do the job. Depending on what it was protecting though, you may need a standard auto fuse, or a slow blow fuse. A standard fuse may keep blowing due to startup current if it was for the fan for instance, but a slow blow fuse will tolerate that two second overload.

So you're saying it can start good, and rev up, as long as it's not in gear, but if you try to rev it up in gear it dies, and the engine stops.. right ? Then.. does it try to move when you give it the throttle ? Or does the engine just stop running straight away before it even tries to move ? And lastly.. does it start up again good after it's died ?

Are you sure that's a circuit breaker ? If it is, circuit breakers are like fuses, except they self reset once the over load has gone away. They are usually used on essential and safety circuits.. like headlights or ignition. I reckon itt might pay to check it with an ohm gauge and see whether it conducts one way but not the other, or, in through a wire and out that metal plate, but not the other way.. It looks to me more like some sort of semi-conductor. Back when that bike was made, circuit breakers were crude electro-mechanical devices, not solid state electronics like that thing you have there..