Honda gc190 burning oil

its burning oil! could be worn out piston rings/bore or valve stem seals/guides but check the engine breather system is not blocked first

Sometimes oil runs down the valve stems overnight, as long as it is not using much oil, no problem.

Bad valve stem seals will cause smoke under these circumstances. It will get worse. The reason this happens is because the higher engine vacuum present in traffic will pull oil past the worn valve stem seals into the cylinder. When you accelerate again, the engine burns this small amount of oil causing the smoke.

blue smoke is burning oil
I gather that you let the engine idle and when you give it rpms that there is a cloud of blue smoke
if that is the case it indicates that the valve stem seals are hard /failed and when the engine is at idle ( 15" mercury vacuum in manifold) the oil around the valves is sucked past the stem seals and into the combustion chamber
AS you have restricted use of the machine (every 3 weeks ) it is not a great problem as when you are on the road it is not happening (Only at idle )
It is repairable without removing the head if you find an accredited service shop that has experience in the procedure.

You may have an oil leak from the engine or valve covers that is baking off on the exhaust and you smell it. or you may be burning oil due to the rings or valve stem seals.

If you smell burning oil, you may have a leak in the engine compartment reaching the exhaust manifold and burning on contact. The most common cause for that is leaking valve cover gaskets. If you are losing oil with NO signs of external leaks, the engine may be burning it internally. Valve stem oil seals, worn piston rings, blown/leaking head gasket are a few causes of that.

If the car has not overheated before, the reason you have oil burn are the valves stem seals became hard due to the engine age and can not hold oil going through valve in the combustion chamber and mixed with fuel mixture and burned,causing your back exhaust emitting blue smelly smoke. For repair a qualified mechanic is required.

Grinding the valves will not affect the oil consumption or carbon build-up in the exhaust. Carbon can be from a rich mixture of fuel, but then the carbon will be a light powder that will rub off easily. If the carbon is hard and baked it will be a combination of fuel and oil, and the only ways you can get excessive oil int he exhaust is if the valve stem seals are leaking or if the rings are worn. Worn rings will make the machine smoke all the time but valve stem seals will make it smoke on first start-up of the day and also when you have rev-ed the machine and suddenly closed the throttle.

If you still have good compression, and motor runs strong, then the problem is in the head, eg, usually valve stem seals, letting oil in the cylinder. Have your head reconditioned, valve grind, and some new valve stem seals should solve the problem. It is fine to keep riding it, just keep your eye on the oil level, as it will be burning oil.

I would think this is valve stem seals that are letting a little bit of oil down on top of the piston and when you go to start the car you get a bit of oil smoke when you start the car