Three common reasons for dirt bike oil leaks

How-To Guides & Tutorials

Three common reasons for dirt bike oil leaks main image

Oil leaks are something that are bound to happen on every dirt bike, although good cleaning and excellent maintenance are the best ways to prevent them. 

Oil leaks can occur in many different areas of the engine, however there are generally three commons areas that are prone to leaking oil.

Worn countershaft seal: The countershaft seal is one of the most common spots for an oil leak to occur. The countershaft seal sits behind the front sprocket and is really prone to dirt getting inside and causing wear and tear. Dirt can slip over the seal and will eventually grind into it, and since a sprocket rotates at such high frequency, it wears out the seal and subsequently causes an oil leak. Sometimes it can just be a case of cleaning out the area, but if the leaking persists, it's an easy and affordable fix.

Worn gaskets & o-rings: Many oil leaks come through worn gaskets and o-rings. The crankcase gasket is one of the most common to cause a leak, followed by the timing chain gasket/o-ring, oil filter cover gasket/ring, and the outer clutch cover gasket/o-ring. These gaskets and o-rings generally wear over time and will need to be replaced, and if you're rebuilding your engine, we always recommend using new gaskets to prevent an oil leak from happening.

Oil drain plug washer: One of the simplest oil leaks occurs through the oil drain plug washer, which is generally made from copper (also known as a crusher washer). We recommend changing this every oil change to prevent oil leaks, although some riders will try to get a number of oil changes out of the one washer. If the engine is leaking oil from the drain plug, then it's likely to be an easy and affordable fix.

Comments (3)

Leaking oil 2023 KTM 250 SXF

Need some advice! I have a 2023 Ktm Sxf with 12 hours on it. I’m leaking oil out of the breather tube underneath the engine/swing arm of the bike. The oil that leaks is clean and there also is barely any oil in my sight glass, at any point in time. I cleaned the air filter and made sure it wasn’t overdressed, no solution there. Easy fix I’m hoping? Thanks.

Stone Churby on 2 April 2024
Hey! Sounds like it is most likely overfilled with oil, which would be why it 'looks' like there is barely any oil in the sight glass at any time, it's usually pretty hard to tell the difference without looking at the line. Best practice when doing an oil change is leaning the bike from side to side and replacing the filter at the same time, this will ensure majority of the oil is drained and you do not overfill when measuring out your new oil! If this does not fix the issue, it would be best to contact the dealer as its a brand new bike and shouldn't have any failures to cause this. :)
MXstore Response

Leaky head of the engine

I have a little oil leaking from the head of my engine and hat could be the cause of this ?

Cooper Papp on 29 September 2023
Hey mate, there could be a variety of reasons you may have an oil leak in this spot! A worn gasket may be the culprit but it would be a good idea to get this checked by a mechanic to diagnose
MXstore Response

Leaking oil rm85

I have drips of oil coming out of where my pipe enters the engine why is this happening and is the normal?

Ben on 9 June 2023
2 Strokes run oil in their fuel so they can have oil coming out the exhaust hence why 2 strokes are smoky compared to 4 strokes. It might be a good idea to pull the exhaust off and give it a good clean. Also need to make sure the bike isn't running too rich and check your owners manual for recommended fuel mixture! Run good fuel at the correct mixture with standard spark plug and jetting and you shouldn't have any issues. It might be worth taking to a mechanic to ensure there isn't something wrong.
MXstore Response

Leave a comment

Comments have to be approved before showing up