please help! - oil leaking from air box

Hi everyone. I just recently bought a 1982 Maxim XJ650. It's my first bike, so I still don't really know what I'm doing at all as far as repairs or anything technical goes. When I got the bike there was a slight oil leak coming from the air box near the oil overflow tube, which I thought was due to a faulty tube and didn't think much of. However, I took it for it's first real ride (other than around the block) the other day, and after about 4 miles of riding, I stopped and realized that all of the oil was streaming out of the air box. All 4 quarts in about 4 miles. I was wondering if anyone else has had problems with this, or what I might be able to do about it. Any direction would be greatly appreciated. Thanks!

Marcus

 

You have a combination of things going on. First is that the fuel petcock has failed and is allowing fuel to flow at all times. The carb float valves usually stop the fuel but if they are leaking the the fuel keeps rising until it finds it's way down the intake of the carbs and into the engine crankcase. Once that is high enough the crankcase vent tube blows the extra fuel/oil mix into the airbox. Check your oil level and see if it is above the window rather than about the middle of it.
To fix you can either take a chance on a petcock repair kit or just replace the petcock. That will take care of the first failure and will allow you to ride. The second part requires pulling the carbs and installing new float valves and seats.

 

Marcus:

Provide us with the "Just acquired bike info" we need to help get right to the bottom of the problems you are having.

Compression Check. Mandatory. We need to know what the Compression is on all 4 Cylinders. Plugs Out. Wide Open Throttles. Charged-up Battery and do the test.

Stay cool and don't do anything in haste. You might have a couple of things or more to straighten-out.

Fill-out your "Signature Section" in your My Account with the following:
______________________________________________
Year - Model - Total Miles - Stock/Mods - Oil in AirBox

 

Hey guys.I had an similar problem this spring.I changed the filter and (I thought) drained the oil and added the 2.9 qts.Then,while up on the center stand,I'd start the engine.Oil would pour out of the crankcase vent tube,into the airbox.???? Talked to my friends with Triumphs,Nortons,BSA's????Went through this cycle a couple of times???Got out the CD,checked the location of the oil drain bolt,took it out and watched 5 qts of oil pour into and overflow the pan.As a new owner,I take full credit for ALL my mistakes(unless I repeat them.Then it must be someone elses fault.)

 

ok so today i pulled it apart and the air filter is completely soggy with oil, and the top part where the oil didn't get is dirty beyond all belief. the seal on the filter is completely gone because it's old. so i'm thinking maybe since the seal blew off the air intake sucked in air from the engine through the carb's and that's where the oil came from? does that seem like a reasonable assumption? please let me know. thanks!

marcus

 

No, not reasonable.

Likely to be either:

1) Way too much fluid in crankcase (oil, or oil+fuel)

or

2) Bad rings allow too much combustion blow by pushing the oil out.

So do the things that were suggested to you:

A) Verify that the oil level is not above the top of the window when on the center stand.

B) Check compression on all 4 cylinders.

 

Throw the filter away.
Check the oil level is correct.
Smell oil for presence of gas.
Smell gas?
No.
Run bike without Air Filter and do diagnostic testing that the Air Filter was so clogged it sucked-up Crankcase oil through the baffle. (Not likely ... the bike would have stalled-out, first)
Smell gas?
Yes.
Change oil and filter.
Run Bike without Filter (Airbox closed) after insuring Oil Level is correct and Airbox is ALL cleaned out and pristine.
Test Run Bike.
Airbox fouled?
No.
Air Filter was to blame.
Yes.
The problem still exhists.
Do:
Compression Test
Test Petcock
Shut down fuel supply to carbs.
Check Floats.

 

i'm sorry, i probably seem so dumb to you guys. i just don't know anything about any of this stuff yet. there is currently no oil in the bike because it has all leaked out. so should i just smell the oil intake for gas? or fill it up with oil and then smell it for gas? thanks for all the help, i seriously appreciate it a lot. oh and how do i do the compression test you were talking about? and then what am i looking for when i do it?

marcus

 

Marcus:

You need to have the bike looked at by an experienced Tech.

The situation you have is serious enough that you need to have your bike evaluated by someone that really knows his way around a Yamaha XJ-Bike.

Make a list of everything that happened and everything you have done.
Elicit the help of an EXPERIENCED Member in Denver or somewhere close ... or, take your Bike into a well-respected Shop and have them do the Compression Test for you.

In the Loooong run ... you'll know what your dealing with.
We can hope that your troubles can be solved with some adjustments and a few tweaks. Hope.

I fear that that you may have some serious issues that you need to be advised of and made aware of ... to determine what YOU can do, after YOU know exactly what is making your Bike behave as it does at the present.

You need the kind of help that cannot be typed to you!
We can only offer you guidance and instructions ... up to a point!

We are at that Point, now ... and our BEST advice is for you to put your Bike in the hands of a Trusted and Talented Motorcycle Technician for a thorough testing of the Power Plant.

 

Silly questions here, but I can't believe you have no oil in the bike unless you have pulled the drain plug.

How are you checking the oil?
Bike on the center stand? or side stand?

You can't get any oil reading if you have the bike on the side stand! It has to be upright and level, which means on the center stand.

 

Nick and Rick are dead on about this. Check the oil level and if it is that low then it is a serious engine problem and should be looked at by a pro. If you don't have an owners manual; there is a small window at the bottom of the right side engine case. Above the frame and below the brake pedal. Clean the outside with a cloth and with the bike on the centerstand see if the oil comes up about halfway to the top of that window. If you don't see any oil then I suggest taking it to a shop or finding someone who knows bikes to look at it.

 

ok well thanks for the help up to this point guys. i feel like i've got enough of an idea for what to look for now. i will definitely find an experienced tech in the area that can get me some help. i appreciate this a lot. haha hopefully i can be on here some day and not look like a total idiot. thank you!!

marcus

 

Marcus:

You're NO idiot. You came and got the right thing to do. Now, you're doing it.

We're pulling for you. I hope it's something easily taken care of.

 

And again, the forum comes to the XJ owners rescue.

I took my bike out for it's first rip. Seemed fine at first, then it started to be a dog when hot, then it just flatout died. Noticed there was fuel leaking out of the airbox hose. I had to wait about 10 min, then it started again and made it home.

Got a small mirror and flashlight and looked up into the air box. Found #2 carb was over flowing when the bike was running. Pulled the drain plugs on all, gave em a little tap. #2 still leaked. Pulled the carbs, which was surprisingly easy, opened the #2 float bowl and the floats were stuck. Carb cleaned them, checked all the others (since they were already off) and they turned out to be fine. Put it all together, changed the oil and it seems ready to go.

It's seems like a domino effect. The carb leaked into the airbox but also into the crankcase vent hole. The oil/gas now in the crankcase vented back into the fuel box, choking out the carbs.


Edit:
I think I may re-rout that crankcase vent hose to the side of the air box, on the outside of the filter. Seems problematic where it is.

 

ok guys so here's the update. i drained and changed the oil (you guys were correct, there was a bit too much oil in there), cleaned out the airbox, ran her, took her out and rode around the block a few times then came back in and things are running smooth, no more oil in the airbox. it was definitely a combo of too much oil and the air filter. thank you guys for all of your help!! now i just have the process of getting a new vin for my bike since the dmv doesn't believe that my vin is only 9 digits. ughg. haha. thanks again!

marcus

 

Yep, the dreaded 9 digit VIN problem! Actually you are not through with the oil/airbox problem. The oil was too much due to only two possible scenarios: 1. the crankcase was overfilled with oil. 2. the petcock leaked fuel into the oil causing an overfill and that is still going on.
So to check if #2 is happening just pull the fuel line from the petcock with the petcock set to either "on" or "res". If fuel flows out of the petcock then your petcock needs rebuilding or replacing.

 

Did you change out the contaminated airfilter? If you got oil on the filter, it will diminish it's capacity for airflow quantity. Swap it out for a new one (unless of course it is an oiled element type, then I would just clean and reoil it with the correct type of oil).

 

yes i am working on getting the contaminated air filter switched. the yamaha bike dealership near my house does not have them on stock, so it's on order, so i'm definitely not taking her out on any big rides until i get it. haha. i will check the petcock valve for sure. thanks for your help guys!

 

It's not if you count the 0's!

 

Marcus,

Exact same thing is happening on my new 82 XJ550. It was caused by the previous owner WAY overfilling the oil. I also have oil flying out of other areas on the left (driver's) side, especially around the chain area. Very messy.

2200cm3 means just that, I wanted to tell the last guy.