Gas & oil in air filter box

Question edited for clarity and add maker.

Periodic oil change: 2.35 lit (2.5 US qt.)
With oil filler replacement: 2.65 lit (2.8 US qt.)
Recommended oil:




This is a terrible format, but here is the service manual

XJ750J (Maxim) Service Manual

xjcd.org https://xjcd.org > index.php > book > export > html
YAMAHA. XJ750J. Service Manual. FOREWORD. This model was originally covered only by a Supplementary Service Manual. For complete information on service ...

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http://frame.ninja/detail/1982-yamaha-xj1100-maxim-service-repair-manual-download.html

1,3,4,2

First of all, there should be no gas/oil mixture on this bike. If it is a crankcase breather and it has gas coming out of it then it means that gas has ran into your engine and diluted the oil. Check the oil and if this is the case then drain and change immediately. As for the gas getting into the crankcase; if you have a float stuck in the open position in your carburetor the gas freely runs through it, then into the cylinder where it then leaks past the piston and into the case. I hope you engine isn't filled with gas but it sounds like it is. If this is what happened then the oil change will fix your problem. If so, take the carburetors apart and make sure the needles and seats are clean and move freely to prevent it from happening again.

have you put too much oil in it?,,may sound like a stupid question.Only other alternative is to revert to the original oil asusing synthetic oil on some engines that were designed to run on 20/50 mineral oil maycause a problem called bearing skate. Stick with the correct oil

There should be an oil breather tube on the left side of the engine leading the airbox. Make sure it's there and cleared out. If the previous owner removed the air box and put on pod air filters, he may have plugged the breather line.

Also, check your oil level. Use the sight glass - only when the engine is off and the bike is level on the center stand. The sight glass is on the clutch cover - right side, bottom of the engine. There is a mark on the glass showing the correct level.

If you have a vacuum petcock malfunction (hole in the diaphragm) or if the fuel petcock is left in the prime position and a float needle sticks, then you get you get gas running into the cylinders, past the rings, and into the oil. When you start your motorcycle the oil/gas mixture has no place to go, the crankcase is too full, and the mixture exits through the crankcase breather into the air box where it will ruin a paper air filter. Always turn your fuel petcocks off when not driving. If the petcock diaphragms are bad rebuild the petcock with K&L rebuild kits or replace the fuel petcocks with new ones. If the float needles in the carburetors are bad or sticking, take the carburetors apart, clean them, and replace any worn or damaged parts You will have to change your gasoline saturated oil for it will no longer properly lubricate your motor.

8.7oz. in each leg,