Hot Street PCV from crankcase?

:S OK so I finally got my shop back from my wife who thinks a shop doubles as a storage shed :pinch: and the old Z is getting a chance to shine again as the center of my life.:woohoo:

Just shoot me if this is pretty basic, but I seem to remember seeing Z1's that re-routed the crankcase tube back to the cam cover?

Anyone else remember this or have any pictures?:huh:

Thanx

Don

i dont remember a vent going to valvecover on z1,mkII and 79 and newer ltds used that though.nice looking little project you got there ,how about some more pictures? that aint the picture i was trying to post?:blink:

Post edited by: wireman, at: 2007/01/27 15:56

Nice looking project ya got going there! What paint did you use on your frame? I'm planning something similar...

You're probably thinking of the smog stuff that comes stock on most later KZs, the same stuff that we all seem to pitch. Are you keeping your airbox or going with filter pods? Mormally the breather cover has a hose leading to the airbox, and there's another hose that connects the airbox to a vacuum operated valve thingie that splits off to the two smog covers on top of the valve cover.

I used a piece of hose to connect the smog covers to each other and ran a filter on my crankcase breather port. Some people use a piece of hose with a filter on the end.

If you have a Z1, there is a plastic pipe that is kind of zig-zag shaped that connects the crank vent to the the Z1 airbox. There is a fitting for it on the bottom of the Z1 airbox.

Thanks for the input but I'm thinking more along the lines of bikes I've seen at the 1/4 mile and on the speedway.

Some of the bikes I've seen were all custom modded (word?) and they had a brass threaded fitting back to the cam cover. I am looking at making the mod but I want to be sure where to put the fitting? Should I use a check valve?

Project quote: The frame has been powder coated with a match to pure red not yellow or green dominent. It was a nightmare getting it done as the guy that did it twice to get it ok. If you go this route find someone reliable who has powder coated more than one bike and who will offer to help you prep the bike. Don't skip out on the prep work you'll regret it later!:ohmy:

Thanks for the comments.

Here's the ref pic I tried to upload but it was too big at first :woohoo:

don

The reason we vent the crankcase to the air box is to creat a little vacuum in the crankcase. This in turn helps the rings seal better. Its not much of a vacuum but it does help. Most guys will just run a filter on the crankcase though.

Thanks again guys for your input. Perhaps I'll need a little help from the guys that have been around for years and have 'seen it all'!

If anyone is interested: The original idea that Kawasaki had with the "Oil Breather" was- "Oil vapours created in the crankcase are vented through an oil breather to the air cleaner hose where they are recirculated into the crankcase, providing an oiltight system.":ohmy:

-1973, 1974, 1975 Kawasaki Z-1, Z-1B Service Manual

Well at least that is what they wrote 25+ years ago. Perhaps they had hoped to improve emissions at that time but I doubt that was the main focus. I expect history has proved that it didn't work exactly as planned and many Z1 owners including myself have vented the tube out under the swingarm and onto the road. Some bikes had so much blow-by that they had to watch their oil levels! :ohmy:

During the 80's those of us that customized our Z1's did so without the help of professionals and we experimented with many ideas. The development of Positive Crankcase Ventilation in the automotive industry as well as on modern bikes prodded some to try venting the crankcase on the Z1 back to the cam cover by drilling and tapping a hole into the cover and fitting a brass nipple to accommodate a hose. Any blow-by would cycle back through the top of the engine where a potential vaccuum exists.:S

Again, thanks for the replies I was just hoping a flat-tracker or a old bike pro would remember the mod.

Don;)

how about venting it to the header collector,weve had this discusion before.

Ive been wondering about that myself.At the track they run the vent to a catch can as im sure you know.This seems to still be popular today.I see it on a lot of photos of high end japanies bikes.Some run it into the swingarm.I see you can get an oilpan gate.This would help some.I do like the idea of rerouting it to the cam cover but i think there must be a need for it to be open to releave suden preasures?I see some whith lines going into the side of the valve cover but have not seen a good enough photo to figure it out.The problem is worse with bigger pistons and realy bad if you have worn rings.Keep me posted

Post edited by: mark1122, at: 2007/01/29 21:52

CoMIYC wrote:

If anyone is interested: The original idea that Kawasaki had with the "Oil Breather" was- "Oil vapours created in the crankcase are vented through an oil breather to the air cleaner hose where they are recirculated into the crankcase, providing an oiltight system.":ohmy:

-1973, 1974, 1975 Kawasaki Z-1, Z-1B Service Manual

During the 80's those of us that customized our Z1's did so without the help of professionals and we experimented with many ideas. The development of Positive Crankcase Ventilation in the automotive industry as well as on modern bikes prodded some to try venting the crankcase on the Z1 back to the cam cover by drilling and tapping a hole into the cover and fitting a brass nipple to accommodate a hose. Any blow-by would cycle back through the top of the engine where a potential vaccuum exists.:S

Don;)

The original method was indead emission related because of the clever? designed way, to deal with the crankcase vent with a side benefit of lower crankcase pressure.
The method to which you refer involves running with "hardware store" brass fittings and clear tubing. Everything (valve cover,starter plug etc) routed back to the breather box. The breather box is then run to the exhaust collector to create a vaccume. Valve cover line seemed to dump a lot of oil back to the breather box so I just plumb in the starter plug. Old race stuff. Anybody serious today has a vaccume pump.

CoMIYC wrote:

Post edited by: modprod, at: 2007/01/29 22:30

Post edited by: modprod, at: 2007/01/29 22:33