Mech

I always try the brand dealer to identify the parts. These guys look like they have a shock.. https://www.yamahapartsonline.com.au/parts/

We need the year... Someone might know of a common cause on that model and year etc, but if we are to diagnose it, we need more detailed descriptions. Have you read the owners manual, or a workshop manual ? You might spot the answer.. Have you tried giving it a service.. spark-plug, air-filter, valve adjustment, idle speed and mixture, fuel filter and vacuum hoses. It's always recommended to check the service and hose conditions etc. And, when you say it overheats and shuts down, how sure are you about those two things being linked ? It could be that some electronic part is overheating, or the engine might be getting hot and running lean at idle, or perhaps, getting a tight valve, or, perhaps the fuel tank vent isn't clear and it's not heat related at all. Describe how it "shuts down", is is instant or does it come stuttering to a stop, does it restart immediately, after five minutes, after an hour or more ? Does it start easy from cold, and hot ? Hope that doesn't sound harsh, but we can send a lot of money doing things and replacing parts that aren't needed if we start guessing..

Some parts places online, will let you check what else any part fits. You look up your year and model, then chose the part, then look for the link telling what else that part fits. Sometimes just choosing the part with the mouse will lead to the info, sometimes there is an arrow or button leading to the info.. Some common parts are common for years, decades even.. You might find springs on some other model. Other than that, there should be a spring or suspension maker somewhere that has a quad listing.. there are for cars and two-wheelers..

First thing would be to check the idle mixture is set right. If it's a two-stroke, I'd check the oil/fuel mixture is right, and what I'm always going to use in future, then I'd adjust the idle mixture screw. If it doesn't respond to the adjustment, or if it doesn't cure the problem, then we can look a bit deeper.

Well.. I'd say you probably disturbed something when you were working on it.. That's the most likely..haha.. Was the filter really dirty, could it be running correctly now(and high because someone had wound the idle up to compensate for poor running)? Have you tried slowing the idle ? Could you have routed/pulled the throttle cable out so it's sticking where it fits into the carb, or perhaps you've knocked a vacuum hose off, or the choke isn't returned right in because the cable is snagged somewhere ? Are you are sure it was the fuel line and filter you changed(some of those have a restrictive/one way valve that looks a bit like a fuel filter, but it's on a vacuum hose to the tap..,

If you have a timing light, fit it and check the spark isn't failing then resuming..

Blocked exhaust ?

Some carby have a vacuum port...

This, " It will only fire up with the choke on then it revs real high and dies", as the guys suggest, does sound like low/lack of fuel in the bowl. Check for air getting sucked in between the carb and manifold first though before you pull the carby off.. Or air getting sucked in anywhere. The float should probably not get out of adjustment.. There are ways, such as bending a brass float, or not seating the float needle seat, but mostly float needles/seats are pretty simple and reliable..

Ha, good one, and well done. Have fun... but don't get caught.

The way it's angled in it could be a tacho drive option, blanked off, or it could be an oil feed/pressure check point.. It will pretty surely not be a place to get vacuum. You really want to draw vacuum straight off the manifold, that's the black bit on the back of the head, or a vacuum port off the carburetor. If that make? has a part list online, you could look up the pictures and identify parts, and see if that bolt has anything under it.

Yup, sounds like charging or battery. Charging system check is he first step. Download a manual..

Some makes start in gear if you have the brake light on.. Perhaps your front or rear brake light switch was stuck on.. or came on with the slightest touch of the brakes.. but now doesn't.

I also see the adjusters are right back in. Are you sure they were adjusted out correctly when you were trying to bleed and get pressure. You might have trouble bleeding, or getting pressure, if the shoes have to move too far before they contact the drum.

Those dust covers aren't going to do much good with that gap between them and the cylinder. And the pistons look pretty dirty too ? I presume you did have the brake drum on when you were bleeding the brakes. I'd check at the master cylinder that there was actually pressure. I'd take the pipe/hose off somewhere and block it with my thumb and try pumping fluid through. If it got fluid, and some pressure, then I'd reconnect and try bleeding at the wheels. It's always a good idea to pump the lever up to as much pressure as you can, then undo the bleeder suddenly so you get a fast flush of fluid through, which will carry the air with it. If you pump slowly, or open the bleeder slowly, an air bubble can rise up against the downward flow of fluid. I think though that you need to check the condition of those cylinders.. The springs should pull the pistons back in.. the rubber boots should fit, and stay over the cylinders. I'd get two screwdrivers and hook them into the backing plate and pressing against the brake shoes, and then keeping pressure on both shoes, I'd lever them both right in, then from side to side a little to make sure they moved nicely.

Were you rocking the bike back and forwards as you tried changing gears ? If the engine isn't spinning the shafts, and the drive line isn't spinning the shafts, then you get two gears bumping into one-other when they are meant (by virtue of one being rotating), to mesh. You might just need to lift the bike and turn the wheels back and forwards while you are shifting. It might be in a high gear, and it might move down one gear with a forward rotate of the shafts, then need a bit of a reverse, or more forwards rotation, to get into the next down. They nearly always need both forwards and reverse rotations to get them all the way down from a high gear. Also, are you sure that what's happening, isn't by design(meant to be)? Have you read the owners manual ? It might be something to do with some interlock system..

That Paul, is a model and frame number, not a vin. A vin number has seventeen digits. You may have a vin plate, made of aluminum, riveted to the steering head perhaps. It might be riveted on somewhere else, or it may not have one if it's really old. Your model appears online and the model is always preceded by JSA. So your vin(if your bike was issued one) should start JSA, then AJ45A. According to a vin breakdown that prefix would mean, made in Japan, by Suzuki, and an AVT. And your model.. A means ATV, J means 200-249cc, 4 mean four stroke single, 5 means the fifth model version, and the last A means tenth version or variation.

Yup. Look up under the left front guard.. Squarish thing with two visible hoses, and another hidden from view hose.

If the rod's blued at the top I'd be very reluctant to reuse it. That said, they are often a little blue from the manufacture. If it's been overheated though then I'd biff in. After that no oil situation the crank needs stripping for cleaning.. in which case new pin, bearing, rod are all pretty much mandatory. All those parts I mention will be available I'm sure.

Yup well quads are a bit more fussy about their gear changes than two wheelers even. If you want nice gear changes, it always pays to wind them up/out to a few revs(more the better I think), and then close the throttle off sharply and then back on again as you change up. Same as on a two wheeler. And changing down it always works much nicer, both the change and the bike behavior, if you give the throttle a quick blip as you press the gear-change down a gear. A blip, then a bit off, and then back on enough to match the needed revs. The very momentary bit off takes the load off the gears so they can slide, and the blips gets the two shafts spinning at near the right speed to synchronize the gears. Bikes and quads need a lot more active participation in the driving techniques than a car. And quads the most of all in my opinion..

It's always a good idea to read the owners manuals..haha. Some quads start in gear if the brake light is on.

You need the battery in there to do any meaningful output tests. The regulator will get hot if it's trying to control an open circuit voltage. They work by shorting the excessive power to earth, but they are also designed in anticipation of about one to two amps(make and model) load always going into the battery. The starters wear out brushes regularly. it's an easy fix. They sell new brushes, springs etc all on new brush holder plate. cheap !

Ha. yeah Bro... Good leaning for junior.. Get a beer and a chair and tell him how to do it. Everyone benefits..

Oh ok. Well....

If this make and model of bike has an oil filter, you could check there for oil flow, or blockage, and you could probably use an oil can and pump a little oil down there in an attempt to prime the pump, and then see if that oil comes out when it's started... Bit you know, different makes and models all have differences.. so it's pretty hard to say.