Should a 2 stroke tick over?

As long as it is case oil and not an automotive oil for a car Because your dirt bike uses a wet clutch and some oills wil clog Up the friction plates

I would suggest a 250 2-stroke or a 4-stroke. Lots of power, lots of pull and the motor would likely last you for years. I've raced both the 125 and the 250 2-stroke at the pro-am level (A-class) and the difference in engine life is tremendous. I would re-ring a 125 every week (running 26:1), while with a 250 I could go for 2-3 months or more without doing the top end while running 32:1.

A YZ 125 will definately be a bit of maintenance - primarily because it has a single ring and the ring doesn't last long. A pro or semi-pro racer would re-ring every race (when the 2-stroke was popular) - some races I would re-ring in between motos. I know you won't be racing, but I would still imagine you would want to freshen up the top end at least every other month at the most. Granted - you can re-ring a 125 in about 45 minutes for a cost of about $18 if you know how and it costs a LOT more for a 4-stroke and is more of a job.

Other than the ring, the rest of the maintenance will be about the same between a 2-stroke and a 4-stroke. You'll still have to do your air filter every ride and your engine oil (tranny oil in a 2-stroke) every other ride. Tires, spokes, sprockets, clutches, chains, brakes - all pretty equal maintenance between the two. Lots of variables, of course.

The difference will be keeping the motor fresh and for that, the 4-stroke will beat the 125 2-stroke. Not the 250 2-stroke, though - these motors last as long or longer than the 4-stroke and are a LOT cheaper to maintain/rebuild.

This is MY experience and my opinion. Your mileage may vary.

Scott

You have a 2 stroke dirt bike, off road only, without oil injection. Get a gallon of 2 stroke oil, get the mix from the owners manual or the dealer, should be about 1 pint per tank? Or 4 oz per gallon. It might be more. Don't try to get away with burning motor oil in there, it won't work, it will overheat the engine and could do some damage. Hope this helps.

Clean the carburetor. The idle circuit is plugged up with trash or varnish or a bit of both. Disassemble the carb and soak the parts in denatured alcohol for 30 minutes. Now finish the cleaning with spray carb cleaner. An air hose also helps. The factory setting on the air screw and throttle screw is one and one half turns outward from a lightly seated position.

NGK BR9EG is the stock plug for your bike. You are one heat range hotter already. I suggest you go to a BR8EG to keep you in the racing plug style but one range hotter than stock. I question what 2 stroke engine oil you are using. Stick with Yamalube 2 stroke oil and you should be okay. If you are using standard motor oil like you have in the gearbox then the fouling is definitely the oil.

Keep the correct plug in it.
If the plug looks black, it's due to too much fuel. You need to go smaller on your jetting. (You need to buy these at a dealer)
Your pilot jet will have a number on it. Get the number off of it and try a smaller step smaller. This effects your jetting from idle to 1/4 throttle.
The needle has a clip on it so you can raise the needle (lower the clip) up or down to effect your jetting 1/4 to 3/4 throttle.
The main jet also has a number on it, and this effects your jetting from 1/2 to full throttle.
Do your jetting by plug color. You don't want white (Lean) or black (Rich) You want chocolate brown.
Keep in mind that crank seals can screw up your mixture, as well as worn out rings, dirty air filter, or poor spark.

let the bike idle for the first min or so then give it a few quick burps on the throttle let it warm right up to operating temp then drive it go through the gears nice and easy first couple times after that you should be able to start opening it up and riding it like you normally would.

Black spark plug means too rich , you will have to replace the spark plug since it has foul up and reset the air mixture screw on the carburator 2 and 1/2 turns outwards.
Check the air filter too.
Hope this helps.

Your bike is water cooled. Some of that water is leaking into the gear box. The cylinder gasket is the likely leak. I would let the shop take a look at it instead of trying to fix it yourself.

But be sure there is not an external source for the water. Do you wash the bike often? Ride the creek bed often? Leave the bike where the lawn sprinkler gets the bike wet? Leave it out in the rain? Change the oil and keep the bike dry. If the problem comes back then go see the dealer.