Checking the Oil

FrontTire1024The F650 has a dry sump system. Most of the oil is stored in the oil tank cavity in the frame just behind the steering head. There are two oil pumps. The first pumps the tank oil into the pressurized oil delivery channels to the valves, bearings, etc. This oil eventually falls down into the sump where the second pump returns it to the tank. I’m not sure how the oil gets to the transmission gears and the wet clutch, but the “dry sump” seems to preclude any splash lubrication. I’m guessing it’s a combination of pressurized lubrication and the flow of oil returning to the sump pump.

When the oil in the bike is cold, it takes longer to flow into the sump and get pumped back into the tank, so the tank level will be lower than it is when hot. That’s why you need to check the oil when the engine is hot. Put the bike up on the center stand. The dip stick is just behind the handlebars at the top of the oil tank. Unscrew it, wipe it off and stick it back in without screwing it in. For my F650 I like to keep it at least half way from min to max. If it gets towards the min, the tank can momentarily run dry when accelerating in a left turn with a cold engine. The engine oil light comes on and immediately goes out. That’s with 20W50 oil in the fall when the temp goes near freezing overnight. For the winter, I run 10W40.

Why does the oil get low at all? On my last oil change I didn’t replace the crush washer on the sump plug and it leaks ever so slightly. If I park the bike nothing drips off it, but the plug is wet with oil if you wipe it with your finger. From now on I’ll always replace the crush washer.  Also, motorcycle engines typically use a small amount of oil.

So don’t let the oil get near minimum unless you are going to fully warm up the engine before riding. There will be scenarios in which you are obliged to accelerate in a left turn while revving the engine a bit.