Mech

Good work.. The thing about things like this is that we have to be methodical, and really thorough.. we have to know absolutely that the first thing we checked really is right before we go doing any more steps.. otherwise we end up going around in circles.. Probably is a small split underneath somewhere you can't see. If you suck on that vacuum hose going to the pump it should build up vacuum and not keep flowing air. After you've fixed the rest adjust the mixture to best lean and it should be right. Good luck with the bolts on the manifold. Sometimes giving them a tap with a hammer and punch on top to spread the hex out a little works, and it lets the spray get down the threads.. and single hex sockets are good for rounded bolts. That manifold probably has an O ring between it and the head.. best change that too.

Sound's like a temp sensor problem to me.. no cold start enrichment. I'm not sure if these computers detect out of range readings like cars do to post a code. I'd use a gauge and check the temp sensor.

That's no trouble, these things can be frustrating. Even mechanics get frustrated, and often it turns out to be the simplest thing. Sometimes we walk away and have a coffee and when we come back everything just falls into place. You sound experienced and competent, you'll get it. I've been assuming that you've checked any vacuum hoses it has... Well if both carbies did it, and you say it was going right for a bit till you refitted the throttle cable perhaps it's just the cable ? Frayed wire in there perhaps ? No free play, routed wrong so it gets pulled when the bars are turned .. If you leave the cable off, and the duct from the aircleaner, then you could use a small screwdriver to operate the slide from the back, to test it's dropping properly when there's vacuum on it.

Yeah that's right mate.. air getting in before the carby is just more air.. it gets all the air it needs anyway through the aircleaner so a bit more unfiltered air makes no difference. Starter fluid is a good way of finding leaks. Try that around the manifold. If you wind the idle speed screw right out the slide should go right down and clack on the carby body, if you then screw the screw in you should be able to hear a different sound as the slide lands on the screw. If you make sure the slide is going right down every time that would be a good start. Then wind it back out till the slide's sitting on the carby body. Then, wind the idle mixture screw right in, gently so you don't damage the screw or seat, and it should not run at idle at all. Start it up with a bit of throttle and see whether it dies right back to stopped when you throttle right off. If it does die then, then wind the idle speed in a turn or two and wind the mixture screw out a couple of turns. After that you wind the speed up till it will idle, then adjust the mixture till it runs at the highest revs it will, then adjust the speed either up or down as needed, then the mixture in or out to give the highest revs it will do at that speed setting. Keep doing those two adjustments till you get it at the highest revs it will with the least amount of slide lift. If it will idle, wind the mixture screw in and out to find the highest revs, then wind it in slowly till the revs just start to drop.. That's called best lean mixture and is where it should be when hot. If those adjustments don't work, then you must have done something wrong in the rebuild. Perhaps the slide needle is in the wrong place, or the float level's to high, or the choke mechanism isn't operating properly.. Is the choke a butterfly, or a plunger ? If it's a plunger, check it's going right in. It all started since the carby work, so it's either a bad(very rich) mixture combined with an air leak, or something wrong with the carby work. Try those checks and adjustments, especially the slide going right down, and for an air leak around the manifold, and let us know how it goes. Perseverance always wins.. giving up never does.. You'll win.

https://www.manualslib.com/s/suzuki+atv.html

If it's sucking air in from anywhere before the carby, it will just mix that air with the air going through the air cleaner, and not do anything.. except let dust in ..haha. If it had a big air leak after the carby, between the carby and the engine, it should just run lean, or not run at all.. It would only make it race if it was also getting more fuel than it's meant to. I've seen them race when the idle mixture screw was set wrong. So... is the idle mixture screw near the engine or near the aircleaner end of the carby ?

They have manuals in here, under "downloads". In my collection of manuals your year doesn't show a hose routeing plan, but in the later model manuals(which have the same systems) it does, so perhaps get a later model manual. Ok, so I'm presuming your throttle cable goes to the left side of the carby. On that model there's one hose fitting on the left rear, that's the fuel pipe. The fuel pipe comes from the fuel pump which is under the front fender on the left side. The fuel pump has three hoses, one at the rear comes from the fuel tap, the front feeds fuel to the carbies left rear, and on the flat side facing the center of the bike there's a vacuum hose. That vacuum hose goes to the carby on the right front, but since you have a vacuum operated fuel tap it goes to the carby via a three way junction. The third junction goes to the fuel tap. On the carby at the right rear there is a hose fitting, that's the carby vent pipe and it goes up under the range selector panel. At the end of that pipe it quite often has a three way junction fitting.. but nothing goes on the other two branches. I think it's just so it can't get blocked so easily. There are two other model carbies that I know of so if that doesn't sound right let me know and I'll run through the other models. All the hoses need to be thick walled. If you go to an auto shop they may sell you thin walled vacuum hose.. It doesn't do, ask for fuel hose of the size you need. The small component you describe, it's either the fuel pump, or part of an emission control, but, if I'm reading your model number right you are in Africa ? And I doubt it has emission controls. If it's not the fuel pump, post a picture and we will see if we can identify it.

So a mikuni without a diaphram .. the cable goes straight to the slide ?

Well... Is this a diaphragm carby or an old fashioned one with the throttle cable going straight onto the slide ? If you throttle on and then off quickly with the engine turned off, can you hear the throttle clack back against it's stopper ? What's the idle mixture problem, seized screw or damaged so the screwdriver doesn't engage ? If you are sure the throttle is closing right off, and it races, it might be just the idle mixture. The needle in the slide only effects from 1/8 throttle and up, so it shouldn't be the problem. The only place an air leak in would effect things is if it's between the carby and the engine, on that rubber manifold.. which can get old and cracked when you work on them.

The manuals do normally have a diagram showing the hose and cable routeing. Are you looking in a genuine suzuki manual or something like Clymer/haines ? Failing that, does it have a manual fuel tap or an automatic one controlled by vacuum ? How many hose fittings does it have on the carby ? Does it have any emission control systems on it ? Does the carby have a diaphragm on top, or does the throttle cable go straight into the top of the carby ?

I liked the look of those two "wheelers'.. they looked like fun. Here's what it's like over here.. My sons and their mate who runs adventure bike tours all over the world.. He's the one with the camera. These are nine to twelve hour rides.. https://bit.ly/341yGMH https://bit.ly/3IsN1Aw

I knew that snow was trouble !

Oh. that sounds like a good deal from Ebay.. I'd jump at that. Then it's just a quick swap job.. No wondering about worn things and hassling around finding parts.. I'd be inspecting all the rubber bits on it, like the rubber boots on the drive lines. Give them a bit of a twist and bend looking for cracks in the bottom of the corrugations. The carby has a rubber diaphragm in the top of it, I'd pull that out and give it a bit of a gentle stretch to see if it's got tears or is going to tear. There are rubber hoses to the fuel pump and tap that are probably getting old by now, and are pretty cheap to replace with fuel or vacuum hose from an engineering supply place.Those brake hoses at that age are probably suspect if they've never been changed, apart from the internal delamination and swelling they get cracks you can see on the outside. The front suspension bush bolts have a habit of seizing into the bushes, then turning in the chassis till they wear the bolt holes in the chassis, then they start hammering in there and really wear things up bad. It would be a good simplish job to take the bolts out and grease them. When you tighten them back up you do it with the weight on the wheels because the rubber bushes aren't meant to turn on the bolts, the rubber's meant to flex as the wheel goes up and down. It's important to tighten them up the last turn or two in their sitting position so they aren't preloaded with twist/flex. If you drive it up onto a couple of thick planks or hunks of wood to get a bit of ground clearance it makes that easy. In theory the rear suspension should be at risk of doing the same thing, but I've never seen it on the back.. but you could pull the bolts and grease them as well.. then they won't be seized if you ever have to do the bushes or take it apart. You could check all the wheel bearings for play or noises. Grab the wheels top and bottom and try rocking them feeling for play, then give them a spin listening for noise, and turn them while twisting them top and bottom(to apply a load on the bearings) feeling for roughness. You could adjust the valve clearance because that doesn't seem to get done ever.. Air cleaner element can be cleaned, oiled and reused. Oil the gear change and brake lever pivot.. I've seen a lot of those worn out. Cables are nylon lines these days and aren't meant to be lubed. Inspect the chassis for rust, especially on the bottom rails. Inspect the wiring looking for frayed insulation, tape it back up and secure it so it doesn't move if you find any. There are small struts under the front bodywork, from near your knees, they run into the bottom chassis, I've seen those two bottom bolts rust solid to the bit's of tube they go through, the tube's a part of the strut. The bolts go through about two inches of tube and when they seize, they really seize, a bit of grease on those bolts saves a real sh** of a job if they seize in and those two bottom bolts are the best place to undo if you want the front body work off. All the small bolts holding the plastics on are made soft so they can be drilled out if/when they seize up or get chewed screwdriver slots. Hope that all helps.. I've been fixing and owned suzukis for ..err.. about forty years haha.

The 1999-2004 suzuki manual has a detailed description of overhauling that diff. The special tools could be improvise with threaded rod and washers/plates, and feeler gauges instead of the DTI gauge.. There is a bit more back and forwarding than car diffs, but it's not really as complicated as they make it sound. Any competent/experienced mechanic should be able to do that.

And what about the brakes ? Do the pistons slide in the cylinder ? Your bike looks tidy enough. It's probably worth repairing. The diff comes out easily. You could take the diff assembly to a bike shop or find someone to do the work on it, a mechanic that's familiar with diff assembly would be best. Perhaps take it apart yourself first to check it's not got too many broken bits. If you strip it you lay everything out on a bench in the pattern it is in the bike, left parts to the left, right to right, front to front. The good thing is it's not like a diff in a car where if you get the adjustments wrong it will whine bad and wear out early. That front diff only has any load on it when you're using the 4x4. And most of the time, if you just fitting new bearings, nothing else needs adjusting. I dare say that even a new set of gears(OEM ones) and bearings will be ok with all the old adjustment shims.

I just had a look at parts for the front diff.. and the prices aren't too bad.. $500 aussie for the two main gears. Over here, that would be about 1/24 of the cost of a new quad. You never know how much it's going to cost,(or how little), till you pull it apart and inspect it. It could be that a bearing has collapsed and it's letting the gears skip..

Second hand diff ?

No trouble Chris.. Have fun... but don't get caught !

You're talking about using an empty location in the fuse box I presume ? Haven't seen a fusebox off one of those things, but generally you get two new terminals of the right sort, connect wires to them, then insert the terminals into the fuse box till they click into place. Most terminals push in from the back where the wires are. If you want to pull an existing terminal out to connect an extra wire to it(or to see what sort of terminals they use), then you look in from the front and back and identify the clip they use to lock the terminals in. Some things have a metal tag that's part of the terminal, in which case you slide a pin in to force/bend the tag flat, pull the terminal and then rebend the tag so it will lock again, or they have a plastic tag that's part of the box, in which case you either slide a pin in between the plastic and the terminal to bend the plastic tag aside while you pull the terminal, or you have to use the point of the pin to stick into the plastic tag and lever it aside while you pull the terminal. Unbolt the box so you can flip it over and look down beside the terminals front and back and you should be able to see what sort it has.

Loud clonking sounds like a tooth off a gear. Just the fact it's got flakes of metal(which could come off a bearing), on the magnet, means it's time for a strip down and find where that's coming from.

Yeah you can change back to petroleum oil. No worries. It's done all the time. Get the motor hot, drain the oil, change the oil filter, and then put in your new oil. The tiny amount that sits in the cam box and oil galleries etc is not enough to cause a problem.

Drain the oil and check it for metal flakes, or lumps.

Did you check there wasn't hydraulic pressure keeping the brakes on ? By loosening the bleed nipple.. Brake hoses when they get old can start to delaminate inside and a flap of rubber can start acting like a one way valve stopping the brake fluid returning, or, the hoses swell up and the pressure you apply with the lever is enough to force fluid down to the wheel, but the springs aren't strong enough to make it return. You might have forced the fluid back now in the process of getting the drum off. I doubt you need any of those parts you mention. If the shoes have their friction material still attached then they won't be the problem. You can check the cylinders are free by using two screwdrivers, one on each side tucked into the lip on the backing plate, and levering against the shoes. By levering harder on one side at a time alternatively, the shoes will move left and right by making both pistons in the cylinder slide across left and right. If they slide they are won't be the trouble either. Put the drum back on, pump the brakes hard, check whether the brakes are jammed on, if they are, undo the brake bleeder and see if they free up.

Are you sure it's not running in safe mode since the overheating issue ? Some of those things, if there's a problem that could damage the engine, they restrict the revs until you've fixed the problem, and in a lot of American stuff, taken the bike to a dealer to cancel the safe mode. I suppose you have read the manual regarding this problem ..

Yeah I looked it up Ajm. Not something we get here. I don't think you are going to get a manufacturers wiring diagram Jerry, and there are no generic wiring diagrams for something like that switch, or bike. You could take the switch apart and you should be able to see where the wires go, check which wire/pin goes to which switch and when they are connected or isolated from one other, then pull your old switch apart(if you have one), and do the same with it. If you don't have the old switch you will have to try and figure which wire on the bike goes to the power for the headlights and to the headlights, which wire goes to the starter, and which wires kill the ignition and whether the kill function is by shorting two pins/wires or by disconnection them.