Smoking Yamaha moto 250

[Need-help-with-quads]

Ok I just checked timing and it 180 out of timing I’m not sure how I did that but whatever I’ll fix it and rider her again

[Need-help-with-quads]

Ok so I fixed the timing and it runs the same so I’ll go through everything else tomorrow

[Mech]

The timing can't have been 180 degrees out.

[Gwbarm]

It wont run 180 out

[Need-help-with-quads]

Weird because there was two marks on the flywheel and they were on opposite sides, the one put it to had a capital t and a line the one it was at before was just a regular line, but anyway everything else is good I got an oem carb needle so maybe that will fix it if not I’m gonna sell it as is with a box of parts

[Need-help-with-quads]

Ok so it’s being weird last night I messed with it I pulled the carb and cleaned it and replaced the plug and needle and it ran like a dream and it went full speed and it had a lot of power so o had a buddy of mine come and check it out so he gets on it and it goes right back to running like crap so I don’t know what’s going on, did dirt or something somehow get in the carb that fast? Is the choke sticking or something?

to clarify my buddy came and looked at it about 40 minutes after it was going good so I don’t know what happened I’m lost

[Mech]

Key or kill switch has dirty contacts/lost movement ?

You would I presume have used one of the switches to turn it off between your ride, and the buddy arriving.

[Need-help-with-quads]

Yea it was just the key switch I don’t really mess with the other kill switch and it doesn’t really move but I could try a different kill switch 

[Mech]

But it was the key switch you used..  That's the one that would logically have the problem.. You should/could try bridging the key switch with a small jumper wire.

[Gwbarm]

If the kill switch does not move there must be corrosion in there also i would check it out. 

[Mech]

That's true too Gw.. The kill switch could have a partial short/contact caused by corrosion.

[Need-help-with-quads]

Ok so o haven’t messed with the switch yet but I looked at the spark plug and it was wet so I had an extra one so I put the new one In and it rode great, but about 2 minutes in it started riding badly again so I took out the plug and the new one was wet so is it flooding somehow while I’m riding? Float maybe?

I will check the switch though just to make sure that it’s good

[Need-help-with-quads]

Also the spark plug is white and checked the switch and it looks fine

[Mech]

You are going around in circles here NHWQ. It's really really important you work through your possible faults eliminating them one at a time by doing a really thorough job and making sure that one thing at a time is right. Just looking at things and deciding they look fine isn't enough, you have to know they are fully functioning and correct.

By now your carb should be clean and set up right. The only thing that should possibly alter/go wrong in the carb is the fuel level if the float needle or seat is defective, has dirt getting to it, or is leaking under the seat. Those problems, which do occasionally happen temporarily, can generally be cured by turning the fuel tap off for a while.

Try turning the fuel tap off and start riding, when it starts running out of fuel turn the tap back on and keep riding. Check whether it goes better as the fuel runs out in the carb, or when the tap is on. Do it repeatedly till you are familiar with how it runs at all speeds, loads and throttle openings both with a full carb, and as the fuel level drops/is low. That way you will diagnose whether it's a fuel problem, and you will hopefully become familiar with the symptoms of low or enough fuel, or if it turns out it is flooding, what a flooding carb does.

[Need-help-with-quads]

Alright how would I go about testing the switch?

[Mech]

Switches can get no or dirty contact because of dirty contacts, or they can have wear that gives them lost movement, so when you move the key or button they don't slide the contacts far enough to turn right on or right off. In the case of the kill switch it could have rust in it that could be enough to partially short out and give bad running. Dirty contacts can generally be found using an ohms meter, but for the key switch it's better to do a "voltage drop test"..Google voltage drop test. Make sure you understand how a voltage drop test works, and how that relates to a key switch.

[Need-help-with-quads]

Ok so I tried my best with what I could find, so on the ignition switch I tested the negative side and the positive side, the negate read .6 something and the positive read .8 something and this was when I cranked the engine, I will send a picture of where I connected the probes to make sure I did it right

The middle left wire is the negative and the middle right is the positive, first I connected the negative probe and then I connected the positive probe to the far left, which should be the signal that lets it crank and then I swapped it with the positive to test that, is that the right way to test it? Also when I cracked it I hit record on the multi meter and that’s how I got those readings they were the max

[Need-help-with-quads]

Or do I need to do that again but from the actual battery terminals?

[Gwbarm]

You should have 12 volts on the red wire going to the keyswitch, when you turn the keyswitch on voltage goes to the start button when you press the button sends voltage to the starter to rotate the engine. If it is starting you do have voltage or it wouldnt start. Not sure what the .6 and .8 is, do you mean less than 1 volt. But from the looks of the switch you either need to dig deeper and clean up the contacts or replace the switch.

[Need-help-with-quads]

Oh yea I was getting 12.25 from those but when I cranked it the minimum voltage read that for some reason I guess I’m not really 100 percent sure how to do the record feature but it was reading 12 when it was off

And I’ll clean up the switch

[Mech]

#107, Not sure about those figures. They might be ok. But unless the starter works by turning the key against a spring for start, then I think you've misunderstood the wiring diagrams.

Try using the ohm gauge and check which contact/wire gets connected to which other wire on the back of the switch's plug, and then check that when they are connected they have less that one ohm resistance. I think you'll find there are two wires that get connected when the key is on, and disconnected when the key is off, and another pair of wires that are connected when the key is off, and disconnected when the key is on.

[Need-help-with-quads]

Ok the switch seems to be fine after doing that

Edited January 27, 2025 by Need-help-with-quads

[Mech]

You need to read up on "voltage drop test". Some polaris manuals have a good description and explanation. The web also has it.

Then you need to find where the bad connection is that's causing the voltage to drop when a load comes on it.