Gwbarm

Looks like 20mm nut 51 ft ads torque, with a note probably saying left hand threads.

I had crank threads buggered up on a Yamaha DT 400 I was building, I measured with mm ruler, of course your tap and die set never has the one you need, but was handy measuring the thread pitch. I then ordered the one I needed to straighten the threads up, it worked, of course machine shop would be better but I didn't want to haul the bike there to get it done. If you have calipers you could definitely measure it with that, I did that also, but mine were not really expensive ones so I double checked with mm ruler. Will your nut start back on there at all. You might get away with just buying a new nut, get two, get it started and let it straighten out the threads.

I’m thinking it’s 21 but I’m going from memory from the looks of it fine thread pitch probably .75 you can measure it with a ruler and come close if you have a tap and die set they have thread pitch guide with them for measuring the pitch

That showing the same for stop/start switch b/w to CDI and b to ground.

I was also thinking faulty tensioner, plus the rubber piece wears and causes it to not be as effective.

This is the ignition system diagram

May be a common problem with the 300 engine

Inspect your gears really closely for damage, I generally like to put on a new cam gear when I replace the chain. Im a little concerned as to why it came off, they can be noisy for a while and not come off, just inspect everything down there really closely when you get it apart

Big Bear must be different because I have B/W and B at the start/ stop switch, just checked the Diagram I also have red from stator to CDI and from start/stop switch I have B/W going to CDI and black going to ground(earth). I have R/W and Bl in my aftermarket starter button, that connects to L/B and B in the original wiring harness .

You have voltage and when you turn it to off it goes to ground contacting the black wire, I think your CDI is different from mine, not sure of that, but I do have a B/W and B going into CDI from stop switch , I haven't got mine to spark yet and everything else is working, im suspecting my CDI is bad, but I have been chasing electrical problems for a while. I was just reading your other post do you know what the trim letters mean, I did a vin search on mine and it came back YFM400F/YFM400FH. I have a post 2000 Big Bear it was in bad shape and im documenting everything I find as i go along. So far it been interesting.

Well, that was fun, it seems like every simple thing I go to do on this Yamaha turns into an adventure, went to change the oil filter, which by the way is more trouble than it should be, housing came off in two pieces, that explains the massive oil leak, that's OK I wanted to flush out the oil cooler anyway.I think I will temporarily put it back together with JB weld while im waiting on the new part.

I am working on 2000 big bear wiring and my start stop switch has black/white and black, I only mentioned that because you said your red was hooked to black/white I ran into problems with aftermarket switches put on and the color codes didn't match the harness, yours may be different I see you have r/b and r/w going from switch on your diagram I don't show that in my manual and I think it also covers the Kodiak I just assumed they were wired the same.

Just reading all the posts since you found the chain, no a whole lot to add except also curious why it came off , is the tensioner in tact. From what I remember you can get the chain back on like mech said by taking the gear off getting it back on the gear and manipulating it into place, hoping you have enough fingers to hold it in place hold the bolt, start the bolt at the same time, I would probably do that first just to see what's going on . I think to put a new chain on that engine you have to pull the clutch and the oil pump to get it on the crank.

Did you take the top cover off where you can see the cam gear chain and valves or is that what's stuck.

Idle speed could also cause this is it normal or a little high.

I haven't used either of those, I use the Berryman 1 oz per gallon , but as new as your machine is I would probably stick with Polaris Products, they are made for that machine, and see if they have a fuel injector cleaner. As new as your machine is carbon is probably not causing a problem.

If you are having trouble getting the head off maybe the chain just jumped off the cam gear.

Try using premium gas with a little fuel injector cleaner added to gas and see if it helps. Certainly won't hurt anything.

Got the new cutout relay today installed it and no more jumper wire it actually worked, no spark as of yet, I feel very strongly that its the CDI , everything else seems to have the correct voltages and resistances except for the coil waiting on a new coil.

I just assumed from your last post about replacing the chain it was off, I would say if the valves aren't moving when you roll over the engine it is either off or broken, did you pull the inspection cover to see if it was there.

Did you try manualslib.com

Not too bad, you have to pull the head to be able to fish the broken chain out of the crankcase

I was just watching a video on that, and Marvel Mystery oil beat Seafood on carbon removal, put into carb while running, another one I like to use is Berryman Chemtool. Never used the Polaris.

Increase tightens the clutch, when you feel resistance toward increase, back off counter clockwise about 1/8 to 1/4 inch

Thanks for the update, you got it sparking, downhill from here.