Rotax 125cc Senior Motor issue

Hi, I’m new to the karting scene, total noob.

I’m looking at a used Kart for sale $1850 CAD:
CRG Black Diamond Frame
Rotax 125cc

The two issues I noticed:

  1. fluid coming out of the air vent (the discord community figured it’s the breather for the balance gear). It shoots up to 12inches high on throttle.
  2. quite a bit of smoke from the exhaust.

Are these two issues a result of the kart sitting idle for an extended period of time? Will it go away after running the engine for a while?

What should a noob look for when buying a used kart with rotax 125cc?

Any help/input would be greatly appreciated!

Quite a bit of smoke will be common especially if it is cold outside. Fluid should not be shooting up 12in high do you have a picture? I am going to assume it is the tube looped over the carburetor? If so the carb needs to be cleaned out as something is clogged making fuel back up and come out of the tube.

Hey there! Please make sure you update your profile to show your first and last name.

The fluid from the air vent concerns me a bit, especially at 12 inches. That makes me wonder if there is a crankcase leak going on. I’m not sure if it goes quite that high if it’s merely overfilled.

Smoke isn’t unusual at idle, it depends how much of course. But once you get out on the track and it’s being driven hard it should clear out.

If they have the log book for it that’s always a plus.
Details of when it was last rebuilt, what was replaced, by whom and how much time it’s got on it since then.
The “Evo” models of the Max are preferred, but at $1850 even pre-evo is a good deal if everything is in decent shape.

If it is coming out of the balance gearbox breather and it is oil, check to see if it is not overfilled first. If it still does it and the smoke doesn’t clear then if is probably the crank shaft seal on the gearbox side has failed.

Can be replaced without stripping the entire engine.

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this is where it’s coming out from.

Read @Marin_Vujcich comment above. That is most likely your issue

So two stroke engines, you mix fuel and oil together in the fuel tank. Does the balance gear box automatically fill up when the engine is running?

Or do you manually fill it with oil like you do in a car engine?

Thanks for all the responses!

You have to manually fill it up with 125cc of oil made for the engine

That 125cc measurement is incorrect.

Its either 50cc or 100cc depending on if you have the metal gears or plastic gears. Can’t recall which is for which but I am almost 100% sure on the volumes.