Mech

The fan gets switched on when the oil temperature gets high. The fuel pump gets turned on when you first turn the key but then switches off unless it's getting a pulse from the cdi. The pulse from the cdi is the same pulse that fires the ignition coil, so if you have spark, you have the required pulse to operate the fuel pump relay, you just need to ensure it's getting to the pump control relay. When wires have no continuity, or have high resistance, it's almost right at the end of the wire where it crimps into the metal terminal, it either corrodes or breaks the wires inside the insulation. Wires do sometimes break if they have been chafing for a long time on something and worn right through the electrical tape, insulation, and then the copper wire, but that's easy to spot by the frayed insulation.

You operated a switch.. There's a bad connection/contact somewhere.. You need to be doing what's called a "voltage drop test" on every suspect part and all the wiring. The test is to check for any voltage drop along a wire while it's got power in it and flowing to/at the wires's usual load. Look up voltage drop test and it will be explained and probably demonstrated online.

It had the problem before the overhaul, so it's probably not blow by or bad rings. You'd have to fit the wrong size rings, or break a top ring, to get enough blow-by to cause the filter housing to get oil in it. And, if it starts easily, it's got enough compression. So.. blow-by, by itself, shouldn't be a problem once/if you get the engine running. Neither blow-by, nor oil in the filter housing should cause the engine to stop after only a few seconds. If the air-filter was so full of oil that it choked the engine, then it probably wouldn't start easy, and it wouldn't start easily after the oily filter had flooded it of fouled the plug. If the oil in the filter housing, and the cutting out, are related, it will be fuel in the oil. There is a chance though that the two are not related. If you have a timing light you could connect that up and watch it to see if you are loosing spark. If you don't have a timing light you can fit a plug to the plug lead, and then rest that against the fitted spark plug so that the spark has to jump the first gap to fire the second plug. If the spark is good it will do that jump and the bike will run, and if the spark dies you can see it on the first/external plug.

Cdi coils should have almost no resistance on their primary windings. 0.6 Ohm would be about right. Coils for switched 12v have resistance.

Good work finding the pushed back pin.. Time after time it's the wires not the electronic bits.. or Switches.. That flickering could be a key switch, or perhaps the kill switch, with dirty contacts. I'm pretty sure the flickering will be because the voltage to the gauge is dropping below the about 5volts the internals of the gauge usually work on.

I think these will be right.. The manual is for 86-89. If it's not right it probably means your bike is the previous model, up to 86. 86wiring.pdf 86 fuelpump.pdf

You need a battery too. That dash display going screwy is because the voltage is dropping too low when you are using the starter. The charger isn't supplying enough power to run the starter. If it cranks too slow because of not enough battery power then it might not make spark, and if the cdi uses 12v it won't work at the very moment it needs to, just as the piston's coming up on compression stroke and the dash dies.

You could try riding it in low gear till you hit the revs you do at 20 in high gear. If it keeps going past those revs then it says it's not a rev limiter. Then if you rode it down a hill so it had no load on it, and it still wouldn't go over 20, then it really looks like being a speed limiter. It's possible it has a speed(or rev) limit by design, that you've triggered by accident, either in the wiring or the ecu repair. If you figure which limit it is, )if it is not a load limit), then it might be a lead where to investigate.

Yup.. What Gw says.. What is this fouling like ? Wet or dry, oily or powdery, baked hard or fluffy ? And how does the bike run ? When did it last get a tune ? Is the fuel fresh ? Have you inspected the air-filter ? Is the plug the right one for the bike ?

I think that will have a decompressor and so that low compression is probably normal. If it starts and idles ok I wouldn't worry about the compression. The valves should have some clearance. Check the manual. You don't really describe the riding and it's topping out at 20 very well.. Does the power just slowly taper off till it won't go any faster, or does it pull to that speed and then abruptly limit itself, and is the limit absolute or can you coax it a little higher by manipulating the throttle, or going down a slope ? Is that speed always the same? If you use a lower or higher gear will it go faster, or in a lower gear does it limit at a lower speed ? Are you sure it's the speed it's limiting at, and not perhaps at certain revs, or throttle opening ? Have you tried doing a tune ? Checked the air-filter, fuel flow from the tank, valves, new spark-plug, checked the coil and and cap for the correct resistance, inspected the breather hoses and checked for vacuum leaks..

Most handlebar switches can be dismantled and cleaned.

The most common reason for that oil in the airbox, and especially if it starts doing it suddenly, is that the sump is full of fuel. A sump full of fuel would also cause the engine dieng once it starts to get hot. I'd suggest checking the oil level as the first thing. A lot of bikes also have restrictor valves or orifices in their breather hoses, and in some models if that restrictor blocks up it can cause problems like the oil in the airbox.

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.