davefrombc

Pull the carb and clean it . It is quite possible when he rolled it some dirt that was in the float bowl was shaken loose and is now plugging a jet. Bogging, quitting when "nailing it" and backfires are symptoms of too lean or no fuel flow on open throttle.

My best guess would be to go with the stock jet. In the good ole days of carburetted cars those symptoms would point to a faulty acceleration pump. Sudden opening of the throttle causes a drop in vacuum and with it a momentary starving of fuel . That's where the accelerator pump gives it a shot to make up for that momentary starvation .. It could be with the larger than normal main jet and air screw opened up ( most of them work best around 1 1/2 to 2 turns out from seated ) you are getting that vacuum drop and fuel starvation when you suddenly open it up. By opening the throttle slowly you don't lose the vacuum and fuel delivery.

Here is a direct link to the Warrior service manual in the forums Download section .. The wiring is the same throughout the Warrior model years.

The two metal tabs with the holes are for mounting the coil . The only electrical connection is to the thin flat tab your black probe is touching .. The trigger from the CDI connects there. the spark coil earth side connection is through the mounting tabs .

Quite possibly some water laying in the bottom of the float bowl again.. Some carbs have a bowl drain so you don't need to remove the whole carb to drain it out. Very possible there was a little water left after the carb and tank cleaning .... or a little bit of rust/ crap came loose from somewhere and is blocking a jet.. I'd pull the carb and give it another blowing out and check jests and passages . No need for a new kit . .... just pull, clean and it'll likely be fine . If you don't have air available to blow out the carb passages, the "canned air" used for computer cleaning works well.

I can't give you any specific instructions on how to access it, but can give you a tip on breaking loose and removing the nut holding in on the shaft. Most try to do it with just putting the quad in gear to try to keep the shaft from turning , but the nut is usually so tight it turns anyway .. Put the chain on the sprocket and then clamp the chain so it holds the sprocket and keeps it from moving while you undo the nut .. There are videos on Youtube showing others changing the drive chain so you can see how it is done and adjusted. I didn't see one on changing the Polaris sprocket though . Search Youtube for changing the front drive sprocket on your machine . You may not get a full video of your machine but you will get videos of others being done . . I didn't see any mention using the chain to keep the shaft from turning when you go to remove the nut but it is a trick I've used many times removing sprockets on machines a lot bigger than a quad.. LOL... Wrap that chain around the sprocket and clamp it so the chain can't move and the nut will come off without the shaft moving.

It is likely labeled pilot air jet on your carb . Most carbs have only two adjustments . .The idle speed screw which is the throttle stop setting and the idle air ( pilot) mixture .

Nobody in your quadding acquaintances have a small wire feed welder? They're pretty common out here among the ATV and 4x4 clubs. A light duty flux core wire feed is not expensive and will do all the welding you want to do on ATVs and most things that need welding repairs around a home and yard. They're not hard to learn to use and it's surprising how many projects you will come up with if you have one. Sorry I can't help out from the other side of the continent. My wire feed gets a fairly regular workout.

Rock it back and forth a bit as you try to shift it into neutral.

Likely all it needs is the idle air screw adjusted .. Turn it in until it just seats, the back off 1 1/2 to 2 turns . Adjust in or out 1/4 turn at a time to find where it idles. Adjust it until it starts to "lope" and then enrich it about 1/8 turn. \

Is it something a little cleanup and re-weld can't fix ?

I can't help directly , but there is a service manual in the forum's Download section . . Click Browse / Downloads then ATV Service manuals / (and 9 more) and look in the Yamaha section .

I've never tried it. Glad it worked for you; but I'd keep that new box handy. As long as you're riding with at least one buddy and not too far off the beaten path I'd leave the resurrected box in the machine. It may live on forever or it may die tomorrow, but that can be said about just about everything.

Try running a hose from the overflow to a small bottle to catch the water. . If the hose in the bottle stays below the water level in it , it will draw back as the engine cools . If it continues to push out it could be a very small leak on the head gasket .. One just enough to allow combustion gasses to push out , but not large enough yet to allow water to get into the cylinder. If it only does it for a short while after you fill the rad to the top , it might just be the excess water being pushed out past the pressure cap as the motor heats up. If that's the case, it will stop bubbling once the motor is fully up to temperature.. When the motor cools , water will be drawn back in. After it does that for a few cycles , you should not see any bubbles in the overflow bottle, only the level change a little as it heats and cools . Continued bubbles would indicate a head gasket going bad , or less likely , but possible , a small crack in the cylinder or head if the rad did not have antifreeze in it and froze. \

Check the radiator cap. The system is supposed to use a 13 pound rad cap.. If it is faulty, it will let rad fluid spill out as the motor heats up.

Is it just carbon fouled or is it oily ? Have you tried a hotter spark plug? If it is oily , check the oil level to be sure it is not too high. Have you cleaned the air filter? and made sure there is no restriction in the air ducts . . Did you try running it with the air cleaner disconnected from the carb?... Beyond repeating those places to look , I am at a loss to help more. It doesn't make sense that it only runs such a short time before fouling the plug.

Yes . The pilot jet is mainly for idle , but it also has some effect throughout the throttle range. The service manual spec is the starting point for the adjustment .. Where it will end up is usually within a half turn or so + /- from that initial setting.

Petcock wouldn't be the problem if it was getting too much fuel to the carb . The floats and float needle valve control the fuel height in the float bowl. Most likely the old carb doesn't need a rebuild kit , just a good cleaning. Check the setting on the long needle for the main jet. Try setting it down one notch ( move the circlip that hold it up one groove so it sits deeper in the jet, reducing fuel flow in the main jet )

Are there oil seals on the valves? or intake valve guide so badly worn it's letting letting a lot of oil be drawn in? Compression sounds decent , but what shape is the oil control ring in ? The only other thing beyond those items is easy to check... Is the crank case over filled with oil and oil being drawn through the carb from the crank case vent? Those are the only ways I can think of that it can get oil fouled. . If it is just carbon fouled it has to be running super rich, and I can't see it running well at all if it can foul the plug that fast. Is the plug the recommended one ? Have you tried one with a higher heat range?

One thing about being retired .. The pay may not be so good but I have lots of time to play on the pc and with my toys. Growing up on a hobby farm, then living in the north and working as a millwright, messing with mechanical and electrical / electronic things all my life I've learned a fair bit of how things work.. I can very seldom answer specific questions in the forum , but I can often offer clues on where to look. Being able to search things out on the net is a huge bonus in looking for solutions .

I'd double check all the jets and passages too. I did a search on your carb and see there is what appears to be a stiff rubber part between the block and carb. It could be cracked.. I saw in another forum that the floats actually have two tabs to adjust them . One sets the float height ( I believe it said 13 mm), and the other limits the amount it can drop controlling how fast the fuel can enter the bowl .. Since the high speed juts are fed from the bottom of the flaot bowl ,choking the carb the way you do could put vacuum pressure into the bowl and pulling fuel up from an inadequately filled one. I found a video on rebuilding the carb. I don't know it it will help you, but I'm posting the link. In similar carbs I've worked on, I have found some very small holes in the long jet that can be blocked and not easily noticed. Make sure you remove the jests and check closely for missed blockages . Welders "tip cleaners" have a variety of wire sizes that fit for cleaning pretty much every jet.

check for an air leak between the carb and the engine .. Double check the carb again.. Float height ? .. a passage or jet blocked that you missed ? ... Sounds to me it is not getting gas or it is extremely lean unless you manually choke it by blocking the intake. Try turning the idle air screw in until it just seats and then back out about 1 1/2 to 2 turns initially. Does it run if you only half to 3/4 block the intake? Completely blocked it can only run momentarily until it no longer is getting any air through the carb.

Unless you see any drips when it is sitting , I'd suspect possibly the pressure cap is faulty. It could be allowing water to escape out the overflow when the engine heats up . Can you fit a small container to the overflow to see it it catches coolant ? The only other check I can think of if it is a leak elsewhere that does not show up easily is to use a dye check and fluorescent light to find it. .

The only way I can think of would be to disconnect the line from the oil injector pump at the carb and temporarily plug the fitting so you wouldn't have a vacuum leak. . Fill the gas tank with 32/1 mix and run the engine .. See if oil comes out of the line from the pump to the carb. I suspect t is exactly because of an unreliability of that oil pump that so many eliminate it and go for premix. Your piston displays the classic scuff marks of an oil starved 2 stroke.

Since it is a 2 stroke it requires an oil /gas mix . My guess is either the oil injection pump has quit working or it was out of oil . A lot of LT 80 owners just premix the gas and oil and forget the injector. Here are instructions stolen from another forum on completely removing the injector pump. Most owners recommend a 32/1 oil mix although some say a 40 or 50/1 mix works for them . I'd go with the 32/1. LT 80 Oil injection/premix If you want to DC it, I would just pull everything off and keep it in the event you ever want to put it back on. Chances are you won't, but it would only take a minute to put it all back on if needed. To disconnect, pull the cover on the left side where you access the clutches. (not the small round one, but the whole side cover).. There will be a plastic piece on the front clutch that turns the oil pump, just pull that off. If you just want to DC it and leave everything intact, that should be all you need to do. You probably could plug the hose coming from the resevoir and then hook it back up, but not sure if that's necessary to prevent some minor draining into the carb. To completely take it all off........... Disconnect the hose coming from the oil resevoir. If you want to keep it attached, plug the end and roll it up and wire tie it out of sight. If you want to remove the pump itself, you can fabricate a cover that will bolt right on. Use the bottom of the pump as a template. Or you can order a block off kit I believe. Pull the tube from the carburetor and plug that hole.