Proper oil level 2004 big dog mastiff

Energy One
BigDogRick

BigDogRick

Well-Known Member
The manual will tell you your recommended oil fill volume. Time will tell you to err on the side of under-filling. Your reservoir is essentially make-up oil that insures you have plenty in the crankcase as it wet sumps as it circulates. Your Evo style motor breather tubes terminate at your carburetor breather and oil will wick up that tube. If it reaches the air filter, it will simply soak into the filter and is, for the most part harmless. However, if you over-fill even a tad, that wicking will produce continuous drops of oil that will eventually begin to drip out the bottom of your breather and deposit somewhere on the right side of your bike. Everybody calls it "blow by". Usually it deposits at speed on the front right side of the oil reservoir and around the right side of your rear cylinder and somewhere on your exhaust. If you over-fill enough, the system will simply evacuate the excess oil through this process at a pretty high volume all over the right side of your bike. I am unsure whether the geometry of your Mastiff matches my Vintage Classic so far as the mounting angle of your reservoir, probably close enough. I recommend you stop the fill at the bottom of the weld that attaches the fill neck to your reservoir. For me that is almost 1/2 quart less than the recommended capacity. Then check the level frequently. In 80,000 miles I have never had a low oil condition. I have, however, cleaned a lot of oil deposits off the right side of my bike. Mostly after I let someone else change my oil as a convenience while something else is being done. I keep a turkey baster handy to draw oil out of the reservoir. I prefer to change my own.
 
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