Mech

The throttle cable is sure to have some adjustment somewhere. Polaris bikes have a kill switch built into the throttle and if there is slack in the cable, such as you would get if the throttle stuck on and your thumb was off the pedal, then it kills the engine. If those get too much free play in the cable at idle they kill the engine. It wouldn't surprise me if JD did the same. Apart from that though, if the throttle is held too far open, by the cable or someone having adjusted some stop somewhere, then the idle control motor or valve can't compensate enough and keeps the idle speed wound right down to zilch as much as it can, and that sets off a cycle of compensations and counter compensations that often ends in an engine not idling. I don't have the book, but I'd bet it says to check those things, and do a standard sort of tune and inspection of hoses etc.

It's likely that the O2 sensor wasn't defective. It quite likely was just struggling to control the mixture within acceptable limits and so reported it as not working. That's quite common with O2 sensors. They are one of the most miss-diagnosed components. I'd be checking the throttle cable adjustment, the fuel flow and pressure, the IAC operation(might operate on 5volts so be careful), and the spark plug gap and condition.

You have power to the relay, so now you need to check the relay is getting power to activated it, and that it has an earth on it's activation windings. If that side of the relay is operating, you need to check whether the power is getting from the relay to the pump, and that the pump has an earth. If you tell us what year and model this is I'll try to check in a manual how the pump and relay are actually wired. It's possible that the pump, or the relay, are powered and then get switched by connecting an earth to one or both of them.

Service manuals are out there in the web, free to download. You don't need to join up to anything to get a manual. This is a good forum though, one of the best. If you have trouble finding the cause of the idle problem, yell out and we can probably talk you through to the cure... even without a manual.

Good for you. Perseverance always wins. Giving up never does. You normally just check and top up the reservoir bottle. If you suspect it's using water you take the radiator cap off when the engine's cold, you top the radiator right to the very top, then you put the cap back on. As the engine heats the level in the overflow bottle will go up, and when it cools the level will drop. It's a good idea to familiarise yourself where the two levels are and always check they are moving from cold to hot. If the radiator gets a small hole or blown gasket the level in the overflow bottle will probably change with use, but sometimes the radiator sucks air in instead of drawing water from the bottle, then the level stops changing from cold to hot. Glancing at the level before starting, then again after it's warmed up, is a good way to spot any problems at an early stage.

Good for you.

Yup, the setting in the book is just to get it running, then it needs adjusting while it's running, and warmed up.. A tool is a huge help.

Not sure about the dial thingy but it should have a knurled thumbscrew on the side somewhere to adjust the ilde speed, and the idle mixture screw is at the front underneath and hidden up a tube. Did you check the rubber inlet manifold wasn't split, or that it doesn't have an air leak somewhere ? Tight valves can make them hard to start and not idle well too.

Good work Admin. I'd give it a "like" except... "like"s not working.. haha.

Ha.. And the price we like too ! Good score..

The relay likely clicks because the power to it is being intermittently disconnected. A bad relay shouldn't make the lights flicker, but a broken wire/bad connection will make the lights flicker and the relay click. Did you check the switches are making good contacts inside ?

Gw's right.. check the earths as well.

Good stuff.. and is the fancy screwdriver nicely made ? Worked good did it ? I've been thinking of getting one for a while.. but wanted to make sure they were good quality first.. haha.

This might be the right diagram.. Check it carefully.. Check the cdi and start button are wired like that diagram, if they aren't then you need a different diagram. 1997-Bigbear-350.pdf

You need to be sure the key switch you fitted is the right sort for that model. There are two different switches. You need to get a manual with a wiring diagram. Then you need to start tracing the power to the ignition switch, through the switch, and then through either the kill switch or the cdi unit, depending on what wiring that's using. Some models the start signal to the start solenoid goes through the cdi unit before going to the start button, and in other models the power goes to the start button then to the solenoid. And there are the start cut-out relays as well. The bike needs to be in neutral or have it's brake light on for the starter to work..

What ever it is, it's always best to try adjusting the mixture first because that is (even the hard to get at adjusters), the easiest thing to try. It checks the mixture screw is changing the mixture enough too, which is a good thing to check. If winding the screw a full turn each way didn't have a dramatic effect, then it would be a guide/helpful in the diagnosis.

I don't have one, but these look quite good.. There are other designs of special tools for adjusting the hard to get to bike carbs as well.. https://www.amazon.com/dp/B0BHYW1PBF?tag=qcforum-20

Look the original yamaha part number up on Babbits or Partzilla, and then put that part number into google..

The inner most bearing would be easy and cheap to machine out and fit a caged needle roller bearing, which I've done several times before on honda engines, but that sprocket flange is a problem at the other end. On a honda you can fit a common ball bearing race on that end, but not on the suzuki.. It does look like a repair or replace of the head is going to be the way to go. I'd clean it all up and go pick the brains of a competent engineer, he may be able to build the bearing surfaces up and machine them easier than you think. Other than that, I see that both versions (different years) of head listed for your model, use the same cam. Each of the two head designs get used in several other years, but it's far from clear just quite all the small differences are. In these links you'll see they say which other model bikes each head fit, and you'll notice that they aren't just earlier or later consecutive years, they jump around a lot. https://www.partzilla.com/product/suzuki/11100-19B01?ref=64703b8d4d387f224d0394c7c7e590909bddd469 https://www.partzilla.com/product/suzuki/11100-19B10?ref=64703b8d4d387f224d0394c7c7e590909bddd469

If this fuel gauge is an analogue, with a needle, then it's probably damped and so slow to move. You should get a test light or a small bulb, about two watts would be good, and use that to short the gauge wire to earth, but leave it on long enough to see if the needle works. If the gauge is digital then it's possible that the ECU could be contributing to your problem, possibly, or in any case it could be a wire broken or shorted to earth. It's hard to tell without looking at the bike, or a wiring diagram which I haven't been able to find, but the variable resistor in the tank could short towards earth potential for full or empty reading on the gauge. You really do need to get that tank unit out to be completely sure it's not the sender unit. The lock detent I was looking at was just a bit of dark metal I think. Not white. Check for locking tabs on the retaining ring, then bigger screwdrivers/levers crossed and a steady pressure. Lube helps and lube it all when it goes back together. I like the "Clydaho" too by the way.. Very good.

I'd warm it up and adjust the idle mixture and speed first, then see if it still does it after it's cooled off. It might be too rich at idle when warm, and so have the speed wound up. Then when it's cold the rich mixture is just right and the wound in idle speed screw makes it race. Could be....

In the upper left of that photo, about 11 oclock, is that an indented sort of notch you have to overcome to get the ring to move ?

As far as I can see in that photo it should just turn, but a better lit photo might reveal something.. a lock tap perhaps, though that's not usual. Two big screwdrivers normally get those undone. They can be tight though. Lube might help.

Lol... You won't need luck.

Two screwdrivers crossed above the center of the unit, with their tips hooked in behind the lugs, and then both used to lever against the other so it turns the flange thingy. Have you ascertained it is the sender unit faulty ? When you put it back in, a smear of vaseline/petroleum jelly on the seal will make it go together real nice.