Pressurized oil cap 1980 kz440 ltd

I bought a 1980 kz440 ltd for a project bike someone had parked a few years ago when it was running and now it doesn't. just in turning it over a bit, making sure it had a good oil level, and as I was unscrewing the oil filler cap it was very pressurized. So I turned it over as I had my hand over the hole and sure enough, was moving a lot of air in the compartment. What could this mean? Is it normal?
Thanks.

Check the breather, it must be clogged.

Regarding the seller saying "parked a few years ago when it was running" consider the following-


Seller says: "The bike ran great just before I parked it."

Seller thinks but does not say: "The bike ran great just before I parked it 23 years ago in the cess pool out behind the barn where the mud daubers, mice, spiders, and other creatures used it for a nest for 2 decades and before my nephew stole parts off it; removed the head, filled the cylinders with cement, and replaced the head."

Don't believe anything the po says. People tend to forget or simply flat out lie... sad but true. Metallica

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Thanks for the tips. I'll check that stuff. Here are some pics. Don't mind the pozer in the pic.

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What 650ed said,clogged breather.
When the 400/440 is running they will blow out the breather(on top of the rockerbox).
This happens when the pistons are on their downward stroke.
And there is nothing wrong with a cargo net,they will hold a 12 pack

The cargo net was the previous owners idea of holding the seat down. Dont need to go to the hardware store get any bolts that way. The main thing with this bike is it appears to be leaking out of every gasket. So when pulling it apart to replace all gaskets, anything that would be a good idea to have done in the process? I will be powder coating at least everything but the lower engine case in satin black. It has 24000 registered miles on it.

Nebr_Rex wrote: What 650ed said,clogged breather.
When the 400/440 is running they will blow out the breather(on top of the rockerbox).
This happens when the pistons are on their downward stroke.
And there is nothing wrong with a cargo net,they will hold a 12 pack

Could it be clogged because I plugged it thinking it was some wort of vac hose? :whistle: long story.

Jay98 wrote: The cargo net was the previous owners idea of holding the seat down. Dont need to go to the hardware store get any bolts that way. The main thing with this bike is it appears to be leaking out of every gasket. So when pulling it apart to replace all gaskets, anything that would be a good idea to have done in the process? I will be powder coating at least everything but the lower engine case in satin black. It has 24000 registered miles on it.

Hold on. Before you pull anything apart consider the following. You plugged up your breather. This created a situation in which pressure would build up inside the crankcase. This pressure, which would not normally be present, would try to push oil out through the seals and gaskets. That may have been why you had leaks. If mine, I would clean the engine very well, make sure the breather is operating properly, change the oil and filter, and drive the bike. If after driving it a few hundred miles you still find leaks you will be able to identify the source of the leaks. However, you may find that without the unwanted pressure in the crankcase it no longer leaks. 24000 miles is not much on these engines, so unless a previous owner has screwed something up the engine shouldn't be leaking. Ed

It was actually saturated with oil before I even got the bike. What I had done was remove the carbs and look at them, and drain them. Because the intake rubbers where so stiff, I had to remove the rubbers going into the air box. The carbs looked pretty clean although full of nasty varnish so I thought, well let me just put a little fresh gas in the carbs and see if I can get it to fire. I have a new battery for another bike so I put it in. I have heard about the vacuum system being problematic and causing the bike to not run correctly but heard you can just remove and cap off certain lines and tune the bike to it. (dont remember where I heard it). So I stuffed something in the breather, and the two lines coming in from the petcock since I didnt have the tank on it and turned it over a few times. That is when I decided to open up the oil filler cap and noticed the pressure and stopped everything.
So, all the leaks have been there and all gaskets need replaced. I have yet to hear it fire and would like to change the gaskets and the oil before doing so since I want to powder coat most of the engine anyways. This is a project for me, I am in no hurry to get it running, I have another bike for that.

Ah, too bad. I was hoping it was an easy fix. Oh well, it will be an interesting project. Ed