Oil in Air Cleaner

[ricklee4570]

I recently had slightly overfilled my 97 bandit 1200 with oil. At hight rpm blasts (8500 to 9500) I noticed some leakage around the filler cap. I reduced the oil level and all is ok, no more leak. However......I did notice when I pulled the air filter that there was some oil in the assembly (slight amount on the screen). I wiped up what I could.

Will that cause any problems with the carbs down the road, having oil shot in there? So far it runs fine. Also does anybody reccomend any kind of fuel treatment? I have heard that Seafoam works well in motorcycles.

[pmackie]

If you slightly overfilled, it is likely that some of the extra found it way up the crankcase vent into the air box.

There is a drain hose from the airbox that exits under your right foot. It is plugged with a plug and clip. Remove the clip and plug, drain the oil (you may have to tilt the bike a little to get it all out). Make sure you replug the hose c/w clip, otherwise you will be sucking unfiltered air into "clean" air side of the airbox.

Mine buids up a little oil overtime, so you should check and drain on occassion anyway.

[Red01]

As Mac implied, but didn't outright say, a slight amount of oil in the airbox is normal since the crankcase breathes thru there.

Pooling of oil in the airbox is caused by overfilling or excessive blow-by from poor piston ring sealing.

[ricklee4570]

How good can it really be for the engine to "recycle" the gases and oil mist that come from the crankcase ventilation tube?  Since I have changed my oil, and now keep an eye on things, I have noticed that I drain some oil from the air  box every few days. (not much, just a bit)

Introducing oil through the carbs cant be good for anything, especially power. I would think limiting it to fresh air through the filter would keep things cleaner and better running.

Has anybody just unplugged the crankcase vent tube and maybe installed a catch can instead?

[pmackie]

It's mostly an emmission thing...the intake air then sucks any vapours from the crankcase through the engine cycle again. Any blow by from the top end then get recycled.

You could likely just route the hose from the crankcase vent up high enough to prevent any significant oil migration and then down beside the rear master cylinder area. You want to keep it away from the tire so that you don't but any oil mist on to the tire.

Then make sure you plug off the hole in the airbox.

I doubt it would make any significant difference in the way the engine runs however.

[Red01]

How good can it really be for the engine to "recycle" the gases and oil mist that come from the crankcase ventilation tube?  Since I have changed my oil, and now keep an eye on things, I have noticed that I drain some oil from the air  box every few days. (not much, just a bit)

Introducing oil through the carbs cant be good for anything, especially power. I would think limiting it to fresh air through the filter would keep things cleaner and better running.

Has anybody just unplugged the crankcase vent tube and maybe installed a catch can instead?

Cars have been doing this since 1967 (in the US anyway), when PCV replaced road draft tubes, which is basically what Paul suggests above.

Just about everyone that goes with aftermarket pod filters on their bike gets rid of the stock breather system since there's no airbox to run the vent to anymore. The usual fix here is to just put a filter on the end of the hose and stow it up under the tank something like this:

[Blade]

Dang Red,

That bike sure looks familuar!

[Red01]

Why go take pictures of mine when you've done such a fine job!