Mech

If a cv had failed it would seem to be out of 4x4... I'd definitely jack it up one side at a time and try turning the wheels to test the axles and diff operation. Then I'd try turning the driveshaft by hand with the diff engaged and the back wheels up.

Have you tried jacking the front up and turning the wheels, and driveshaft if possible, feeling for roughness, clunking, or movement. Try turning it backwards and forwards, and while it's up look for anything that looks like it could have been rubbing..

It could be the sound of a spark jumping. I'd try listening close to the cdi unit and see if the sound seem to come from it. I'd also check the sparkplug's lead and cap, listening for a spark. Other than that it could be a wire coming loose or with a near break in it causing a relay to make a noise intermittently, and at the same time causing the miss. For that I'd leave it idling and carefully wriggle all the wires.

I've read a few cases of the diffs playing up, and diffs are a bit famous for making noises on the over-run. You could check all the trans and diff oils for signs of metal.. Probably just course dust/flakes. Very fine mist of metallic dust is normal, flakes or obvious metal particles.. not so.

If the idle mixture screw doesn't have any effect, then it's because either the idle system has a blocked jet or passage, the fuel jet by the sounds of it, or the throttle is too wide open for the idle system to operate.. You should check the slide is going right up and down, that the slide needle is fixed in place correctly, and that the throttle goes right back if it's a CV carby. The throttle cable may not be attached/sitting correctly. If that stops the high revving then the idle mixture will perhaps adjust. If it still doesn't adjust then it needs the idle jet cleaning again. If you are taking it off again recheck the join to the manifold, an air leak could cause the problems. So could burning oil.. It's not smoking is it ? It would be a good idea to check the valve clearances too.

Some early 250 suzukis had a mod which was to fit a little capsule/filter/valve thing into the vacuum line to the tap. The capsule allowed full vacuum to the tap instantly, but had a restriction in the flow going back the other way, so the tap was slow to close. That might help your new tap...

Standard taps have on-pri-res. The prime being horizontal.. And yeah, reserve normally works the same as on, under the control of vacuum. Might pay to take the rotating part of the tap out, and check the washer behind it is located correctly..

Good one.

It could have an air leak, (either a holed diaphragm or into the inlet manifold), or a blocked jet, or you might have adjusted the idle speed and mixture incorrectly. I'd probably take the carb off and clean it and check the float setting, and then when it's warmed up I'd adjust the idle mixture to it's best running with the idle speed screw wound out as far as possible.

Perhaps the adjustment is not right on the shoes. You could try adjusting the brakes up till the wheels wont turn, then see if you have pressure. Or, put a clamp on each brake hose and that will eliminate brake shoe movement which means any lack of pressure is a hydraulic problem. It could be that you still have air in the system.. Because the hoses run near vertical, bubbles of air can keep rising up and not flush through if the bleeding is done too slowly.. Clamping one hose at a time might help by making all the fluid go to one wheel at a time, meaning it's more likely to carry the bubble down to the wheel cylinder and out. I always bleed brakes by pumping up the pressure, then while still holding the pressure on, release the bleeder as far and as soon as I can.. If we pump up pressure, but then hesitate, bubbles can be rising up the pipes and not get spat out.

Yeah that sounds likely. And they could be 14 or 17 mm hex. Both are common. If you can't find kawa nuts, one of the other jap bikes will have the same size. They are toughened nuts so best to get some genuine rather than common old nuts from the engineering supply shop. If you searched on a jap car wreck you would find nuts with a flange built into them, a part of the nut. Those are toughened too and would do. They would be on the suspension, engine, gearbox.. If they have a separate washer mounted on the nut, but able to turn, those aren't toughened nuts. The tough ones have a flange as part of the nut.

Ok, I did some more reading.. That actuator on the front diff... how many wires does it have going to it ?

Perhaps you could heat and bend the bodywork, or make some brackets which keep it away from the tyres.. or.. last resort, cut the bodywork away so it doesn't touch.

I've had stators rewound before for a good price, and done with better quality wire than the original too..

I'm not sure that we are all talking about the same model of quad here. Apparently kodiaks come in water cooled and air cooled, and some I think have manual gearboxes with five speeds and some are auto/2speed like yours... Your neutral switch might not be on the motor, but either on the gear shift lever or the transmission.. If you do have the four switches I'd guess it's one each for high, low, reverse and neutral.. I'm not real familiar with yamahas though.. they aren't so popular around here..

Well... in some models the trouble codes get displayed automatically if there is a fault. They get displayed in the clock display. If you don't have that then it won't I think have trouble codes. I'm not familiar with those quads, and information is scarce. The manuals I've been looking at show different systems. It really needs you to look at several manuals and see if you can find one with a very similar set up. If you showed us some pictures of your switch gear, and dash, it might help me to figure what setup is on your bike, but I'd still have to keep coming back in asking you to confirm things.. The nearest model I've found is for the 500. It's wiring diagram(all of the wiring diagrams actually), doesn't have any things labeled. It all needs comparing to your bike and confirming.. About the only thing I can figure is that the two second delay before the light comes on is significant. There's two likely causes for that. One is that some electronic component is getting hot and making the light come on, and the other possibility is that the bike has a computer and it takes two seconds to do it's system checks and find a fault which causes the light to come on.. but I don't know whether your bike has a computer. a picture of the dash would help there.. Maybe. If you can identify a quad setup that looks like it has the same fuel system(fuel injected or carby),switches, ignition, fuses, relays etc, then we could probably assume it's wiring will be very similar, but possibly with different coloured wires, which is common. Then we might get somewhere. At the moment, having looked a few models, it's looking to me that the component they describe as the cdi is a suspect. They describe it as a cdi, but it has far too many wires and some of them go to the diff lock light.. It must be more than a cdi, perhaps a computer that does the ignition and other jobs as well. In the 500 model, power goes through that cdi, then to the diff lock actuator and to the diff lock light, then to a normally closed switch, which looks like it could be some sort of over ride for the diff lock light.. That switch isn't labeled though and it's unclear where it is on the bike. We really need to confirm what the bike has on it and which other models are similar.

Removing the body work is a common thing to get access on most quads.. As long as the screws and bolts aren't rusted up it's normally a fairly simple job. Because the bolts do rust, I always strip the body and fix all the bolts and grease them early in my association with the vehicles. It saves a lot of problems and swearing in subsequent jobs.

I see it's known as a Forge 400 too.. and that it's the same as a 360.. https://www.ebay.com/itm/332948942221

The 500ATV2 manual might be similar.. ? Have a look and see if the switches etc are the same.. Perhaps we can match up a wiring diagram even if the wire colours are not right. https://www.manualslib.com/brand/hisun/offroad-vehicle.html I see there is also a 450 model atv.. You need to inspect each of those links, the descriptions are not all accurate.. Some links take you to a different model than the link says..

The parts show there being four of those switches on the bike Gw.. do you know if that's right ?

Oh ok.. That manual I pointed to was for a 400xl.. There was no mention of a quad version.. I think we really need a wiring diagram.. Are you sure the wiring is different ? A lot of what you describe sounds much the same as that side by side.. Perhaps if you download the manual, and have a look, and see if it seem to be the same switch gear and relays etc we might be able to figure where to start. Do you know, does that quad have trouble codes, and have you read them ?

Tell me in the mean time.. when you say "When i put power on it takes couple seconds and difflock light starts to burn...", do you mean when you turn the key on, when you use the throttle, or when you start pushing it along a bit, using a lot of power ? And, do you have a manual for the vehicle you have, and is it for downloadable.. Best if we are both looking at the same manual..

Did you look at that manual ? There are a heap of solenoids, switches and fuses, and it's too much for me to walk you through if you don't do the leg work yourself. Start reading/following the manuals instructions and let me know what you find and I'll try to help.

Not exactly... https://www.yamahapartshouse.com/oemparts/a/yam/50045124f8700209bc791eef/electrical-1 Or these guys list more models... Still vague pictures though. https://www.yamahapart.com/oemparts/c/yamaha_atv_2004/parts

Good work Hagbard...