The oil eating engine sometimes takes dirt bike owners by surprise because in our haste or long term laziness the #1 "to-do" on the pre-ride checklist often gets overlooked.
Therefore, check the oil level using the dipstick or sight glass (if equipped) - before every ride.
OK, we get it, even the best rider/mechanic slacks off a bit and gets blindsided by the need to top off the engine oil. In this situation, once you've determined it is engine oil consumption rather than an oil leak now you need to figure out why. Fortunately, just a few causes exist and the repair usually a simple one.
Oil consumption is normal - if you fail to properly change the oil on time. Check the service intervals. Have you stretched it past acceptable limits? Eventually, oil breaks down and loses viscosity then works its way into the combustion chamber. Now you're burning oil.
So, change your oil and see if that cuts back on the oil consumption. Another step you can take is using higher quality oil, like synthetic and/or heavier weight oil. In older engines, like a car, heavier weight oil protects better and prevents oil burn off.
Now what if this doesn't work?
Keeping tabs on the oil level keeps you riding
You're probably looking at worn out piston rings, valve guides and/or seals. In fact, a tell-tale sign of oil burning, without checking levels, is heavy exhaust smoke upon start-up which dissipates once the engine gets warm which is usually from bad valve guide seals.
Therefore, tear down the motor and get ready for a top end job. If any of the rings, guides or seals need changing then just replace everything. A piecemeal approach simply ensures stepping on square one in a month or so. Most top end kits include new rings so you're covered on all fronts.
After this, if you've done all the above and the engine still consumes oil check the oil rings to ensure correct installation.
Finally, continued oil consumption moves you from do-it-yourself work to finding a trusted mechanic. The next course of action is probably a compression test which uses a compression tester (looks like a tire pressure gauge) and then a leak-down test, which forces compressed air into the cylinder and measures the rate of leakage. Both tests help identify the exact cause of the oil consumption problem.
Remember, regular oil changes and replacing parts after the recommended use-hours noted in the bike's owner's manual helps prevent needless wear-and-tear including oil consumption problems.
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