Oil Leak 73 Z1 900

Woke up one morning after a ride to a mess.
Oil was leaking out of my airbox. The odd thing about this is that I had just drained oil out of the bike due to a previous overfill, and the bike was ok for two days of riding. Then, this.
My question is--what else could be the cause besides an overfill? I have had the bike over a year, and on previous overfills, the bike never did this, just smoked until I drained to the right amount. It is set to the usual level: on the bottom sight line when on the centerstand.

Welcome Rob! Hey first off just a tip, attach a signature to you post that indicates what type of bike you have, it will save you a lot of time answering that question.

Second, do you have a breather going from you case to the airbox? I would first try to determine the source of the oil.

oops, there is your bike in the "subject":blush:

nonetheless its good to have a signature, maybe include a location just in case your lucky and one of these gurus here is local to you. Welcome to what I consider to be the most informative kz site ever!!

not sure how to attach a signature, but yes, the breather tube goes to the airbox. I was going to attach a pic, but I am having trouble with my Photoshp and the pic is HUGE. I will work on that.

[img size=400] kzrider.com/media/kunena/attachments/legacy/images/028.JPG
Here are pics of the breather / airbox and the mess.

Sorry, first post. User error. Here are the pics:

check your oil again i run in between the 2 lines myself.anyway might just be some oil that was trapped in the airbox from previous overfill episode;)

73's were notorious for that, So bad that there was a recall on the oil pan.
If you still have the old style pan, you live it.. Pull the pan and check.
If you pull the pan, put a oil gate in. Easy to do. You don't even have to take the motor out.
If this is not a show bike take the hose off between the case vent+air-box
and attach a hose from the vent to a small bottle to catch the oil.
MAKE SURE YOU DO NOT BLOCK OR PLUG THE CASE VENT.
You could also put in a 650 case vent that will give you more room to work with.
Last but not least... As Plummen said, keep it between the lines.

XENU

Wow, a vent tube without cracks......anyway, the oil you see could be dripping from your air cleaner which absorbed some of the overflow and is now leaking back out. I never had any oil problems with my 73 Z1. I put 30000 miles on it over 7 years. Never heard of any service bulletin either.......chris3

Thanks for the info! What is an oil gate?

FYI, I cleaned out the filter and the airbox the last time. There was nothing dripping for two days, then this:

Is the automatic chain oiler still operative on this bike? Or has drivechain been recently lubed?

Pictured oil on floor is not underneath the air box drain. Am thinking air box drainage would be a single puddle, and not several separate spots.

Would sniff-test crankcase oil for any gasoline odor.

Do carbs have a side-located drain screw for the float bowls? Or a single bolt on the bottom of float bowl?

Has crankcase vent been removed and cleaned? (It might be clogged and causing excessive presesure inside the crankcase),

Good Luck!

Oil gate. It keeps the oil from being pushed
too the back of the oil pan and up through the
case vent under heavy exceleration (spelling)
(I have some if you like. PM me)
That leak in the pic, doesn't look like oil bypass.
Looks more like chain lub or maybe the seals
in the counter sprocket cover. Is oil running
down the side stand? Or as asked above do
you still have the auto chain lubricator?
Now there is a classic pice of engineering!
But, Try to by one. To rich for my blood...
XENU

Auto chain oiler. Forgot about that. I think I may still have the one off my old, new at the time, Z1, somewhere in my garage. Yeah, from the pic, that looks like where the oil is coming from.....chris3