What Happens When You Have Too Much Oil In An Air-cooled Engine? – FAQ

Early on with my TaoTao TBR7 dual-sport motorcycle, an air-cooled engine bike, I learned that too much oil can cause problems. Messy problems.

Being an air-cooled engine, the motorcycle engine can run hot. This increase in temperature causes the oil level to increase due to the expansion of oil with heat.

This is why you check your motorcycle oil level when the bike is cold since you can get a false high with a hot engine.

Messy Problems Too Much Oil In An Air-cooled Engine Caused.

If you read some of my early posts about my TBR7 motorcycle, you will find that I had an odor in the air box problem( Fed Up With Oil In My Motorcycle AirBox ).  

The oil in the air box got worse when I had a higher oil level on the dipstick versus a lower one.

When the oil heated up, the oil level increased. Then, the oil splashed around at a higher level, causing more oil mist(tiny oil droplets) to be carried into the crankcase vent effluent.  

The crankcase vent vents into the dirt bike’s air box, and the oil collects in the air filter box until it leaks onto the engine and ground.

Now, each engine can have problems with too high oil levels, but this was my bike’s problem, which was further complicated by being air-cooled and having a habit of running very hot. Almost to overheating conditions( Air-Cooled Engine Overheating Symptoms ).