82 xj750 maxim stared to dump oil out of air box?

so last night on about to take a long drive home about 80 miles. i got on the highway that was 70mph but i was doing around 75 or so my speedometer says. after going that speed for about 3miles i pulled off at the ramp to go on to a county road and my bike quite i pulled off still on the ramp and stopped the bike. i noticed a lot of what looked to be oil on the ground and got off the bike and say it was coming from the hose that is attached to the air filter box. i pulled the seat off and the top of the box off and pulled the filter out. had oil on it. and oil in the bottom of the box i soaked it up with a rag i keep under the seat. and reinstalled the air filter and seat the bike stared but up but was really weird to drive in first and second gear it would not move very fast then speed way up and shoot off. but once i got going it was fine in filth gear until i got to another exit ramp then i died again but i hit the start button and gave a little throttle and it started again i pulled off and went into a restaurant to sit with some friends for about an hour. I cam out to check on the bike half way through. to find only a dime sized amount of oil on the ground. after eating I got on and the bike started right up and drove just fine. i drove the rest of the 70 miles just fine with no issues at all. I followed behind a friend the whole way back and she say she had the cruse at 65 but my bike said 60 and i notice that when i doe 65 on the highway im flying by people. could it be my speedometer is slow and i was doing way faster than i though and just over heated the engine. and what is the best way to find out if my speedometer is off? thanks guys.

 

If you didn't overfill it then your carbs are filling the crankcase up with gas.

Pop the filler cap and have a whiff. If it smells like gasoline, you have carb work to do.

EVERYTHING THAT APPLIED TO YOUR 550 APPLIES HERE except now you get to deal with Hitachis.

Have you checked the valve clearances and the brake line date codes on your new "main ride?"

 

I worry about the Oil in Airbox before sweating that Speedo.

Oil in the Airbox:

Leaking-by Petc0ck flooding crankcase with Fuel?
One of the more common problems.

You need to check your Oil for Gas contamination.

If the Petc0ck is leaking, ... so are one or more of your Carb Floats.

Put the Speedo on the back burner and address the Oil getting into the Airbox.

 

I agree. But---

It doesn't have to be the petcock. The petcock could be operating properly, and only supplying fuel when the motor is running. Meanwhile one or more stuck floats are dumping excess fuel.

It IS possible for it to be only the floats; but the petcock does indeed bear investigating.

 

Well when i first got the bike i had it in the garage over night and the next mourning there was a lot of gas on the floor i took the tank off and found that gas was leaking from the petcock. so i took it off and cleaned up the hole in the tank. and put some gasket paper in between the petcock and tank and now it didnt leak any more. maybe should i just replace the whole petcock then or just rebuild it??

 

And yes i did the valve clearances that were all spot on. and bought new lines waiting to get them. And when i said new main ride is cause i ride it rain or shine, day or night. my car hasn't moved in 3 weeks. SO yes its my main ride of transportation.

 

I blame the Petc0ck much the same way as the TV Cops like the husband for the murder when they find the wife murdered and no sign of forced entry.

PRIME suspect.

IF there's Gas in the Sump that was formerly in the Fuel Tank, ... arrest the Petc0ck and bring it in for questioning.

For the Gas to get from where you bought it, ... to where you definitely don't like to find it ... it has to escape the Fuel Tank, ... first.

See what the Petc0ck was doing on the leak in question.

 

That's all fine and dandy, HOWEVER:

If the float valves were doing their job, the petcock could be left on PRI for all that matters.

The more serious problem is that the floats aren't shutting off; the petcock is only "enabling" the issue.

IT'S A CARB/FLOAT ISSUE. Yes, fix the petcock. But that won't cure the root problem.

And don't be riding the bike with the oil contaminated with gas or you'll damage the motor.

 

Just curious.... I just got done rebuilding my carbs. Besides being dirty, the floats were off. It was easy to diagnose the float issue because it was dumping gas thru the overflow (when I set the petcock on prime) and also producing smokey, wet exhaust fumes when running.

After reading this post I'm wondering if I should also be concerned about contaminated oil. I just did an oil change before this happened so I would like to avoid having to do another one if possible.

Do you think I should be concerned? I only ran the bike with the "bad" floats for maybe 30 minutes or so. Is there any way I can check the oil? It seems to look, smell, and feel okay...

Thx

 

The "sniff test" is generally pretty accurate. If you stick your nose in the filler hole and have a whiff and it only smells of toasty oil, you're fine. If it smells of gasoline, it's not.

 

If you even suspect contaminated Oil, ... get rid of it.

There are Bearing Surfaces sans Half-shells that need the highest lubrication protection available.

 

well doing the "sniff" test i dont smell any gas just oil. the oil that was in the air box smelled like gas but the oil out of the oil filler hole smells like only oil. soooo. oh and i found out that my speedometer is 10mph off so when it said i was doing 85 i was doing 95mph. SOO could that have caused an issue cause i dont think the oil has been done it a while it was really dark. so im gonna change it and the filter. but could this have been the issue cause it runs great now and has no issue and no more oil in the air box after that first time... thanks again for the help guys.

 

How is inaccurate speedometer the cause of leaking oil?

 

if you read the whole thing the oil started to flow out after doing 95 for many miles on an old bike that the oil hasnt been changed in awhile. so i was thinking that the issue was because i over heated the engine. the oil was leaking from the air box meaning it came back from the carbs. and enough to saturate the air flitter.

 

NO, oil was leaking from the airbox because it PUMPED UP THE BREATHER TUBE from the crankcase. It didn't come back up through the carbs.

What you need to do and asap is check your float levels. WET-check them. Then it they're fine you can quit worrying about it once you change the oil.

Then religiously check the oil level before each and every ride so you'll catch a sudden rise (meaning a stuck float is adding gas to the oil.)

An inaccurate speedometer didn't cause your problem. And if the bike were in a proper state of tune, running 95mph for a good while wouldn't cause any issues whatsoever. You can pretend everything's fine if you want; but you've got a problem somewhere. Leave it un-diagnosed and un-attended to for long enough and it will reveal itself with a failure. Hopefully not a blown-up bottom end.

 

Bigfitz is absolutely right......take his advice......like the saying goes.....wise men dont need it....fools dont heed it......

There is a lot of experience & knowledge on this forum.....

Change the oil & filter....& take the carbs off the bike & wet-set them....

 

In a nutshell:
Drain your OIL!
It may be one of two things! One, You or PO overfilled the oil causing it to overflow into the airbox, dripping onto the ground. Two! GAS IS LEAKING FROM YOUR CARBS, INTO THE AIRBOX, THEN INTO THE CRANKCASE.
In either case its not good.
You said it WAS leaking from the overflow on the carbs. Hopefully you replaced float needles and wet set the floats. If your floats are set, and your needles are working properly you wont ever have to worry about a leaky petcock.
Be sure you refill with the PROPER amount of oil. check on level ground, standing upright.
If gas is in your oil you could potentially damage your engine and wash out your cylinders!!! NOT GOOD
Worry about your speedo later
-CR

 

Ok so i found out the the PO of my bike did the oil before selling me the bike. but he used 10w-30 and used about almost 4 quarts of oil witch as far as i know is to much. and the 10w-30 is not the kind to use during the summer for long rides i took the bike to a shop and the talked to the guy there and he thinks that because of the extra oil in, and the kind, plus the speed(speed cause i was doing almost 100mph, mades the engine very hot) and temp out side and the distance is what caused the issue. Can anybody agree or disagree with this statement?? thanks again guys.

 

and also since i cant find any 20w-40 what would be better.

-10w30
-10w40
-15w40
-15w50
-20w50

thanks

 

Yep. 4 quarts is enough to find its way up the breather and into the airbox, even on a cool day, and at legal speeds. In the sumer I use 20-50. The 750 takes 2.6 quarts (2.5 liters) without a filter change, but most of us like to fill it until there is just a tiny bubble of air left in the sight glass (makes it easy to see if fuel has leaked into the sump).