wow... like a whole new bike. everyone should check this.

I just spent the most worthwhile 45 minutes fixing the emissions crap on my bike. The old valve cover emmissions valve caps both had broken bolt holes and were jb-welded, so I ebayed a set off of a 83 gpz. since I was in there, I decided to see what happened if I removed the emmissions stuff too. (I believe this stuff is standard on all 79 and up motors)

I pulled out the vacuum canister from under the tank, removed my old emmissions covers. After cleaning the new caps, I took a pair of $0.39 rubber table leg boots from the hardware store and sealed them onto the open vacuum ports with red RTV. These went back on the valve cover with RTV.

some background...

Previously, the bike was a pain to start, and was super loud backfiring on deceleration, with a rough idle and uneven throttle response. I figured it was a carb issue, so I cleaned and rejetted without solving the problem.

Back to the emmissions junk....

After letting it cure awhile, I started the bike, which started instantly. It idled like a kitten, very smooth and quiet, not at all like before. I took it around the block, and instead of neighbor-waking backfires on engine braking, it just had a low, deep purr. Throttle seems much more linear and mid-rpm power is much better.

This is, by far, the best performance improvement I've made to this engine. Anyone who has the air injection / vacuum switch dealio on their bike and is experiencing rough running would be well advised to try this quick and cheap fix. It is definitely worth a few minutes of your time.

Hey....is the stuff you got rid of what Kawasaki called the "Clean-Air" system or something like that??
Ya got them large rubber hoses atop the cam cover and the breather hoo-ya under the air box?? That the thing?
I ask 'cause I got a not really rough, but unstable idle and "iffy" mid-throttle response....no vaccuum leaks anywhere tho.....
Looks like I may have to give this a whirl......

ya... that's the culprit. I'm not in favor of randomly ripping smog gear off, but this thing was definitely malfunctional. your bike will run and sound much smoother. I'm even thinking about pulling off my baffle to get an aggressive exhaust note again.

just be careful when prying old covers off. The old seal is pretty tough and the aluminum is pretty weak. don't stick yer screwdriver or blade under the part with holes... that's how my old one got broken. you may want to leave the your reed valve in, to get an extra layer between the head and the rtv seal in order to prevent vacuum leaks.

Gotcha....appreciate the "heads-up"

I went through the same thing. It's amazing!

I even made my own block-off plates.

Rather than go through the effort of making and installing block-off plates, you can get the same engineering result if you just run a small length of hose between the two spouts on top of the valve cover. (Also, don't forget to seal off the vacuum tube coming from the carb.) If you do it this way, it only takes a few minutes to do, and only a few minutes to reinstall if you ever have a need (i.e., if you must have the bike emissions system inspected, or if you just want to return the bike to bone stock).

Post edited by: apeman, at: 2006/03/02 12:44

Is this "Clean Air" system on an 81 KZ550 LTD? Might expain a similar complaint I have about my bike. Is there a down side to removing this system? Does it have any effect on other systems? Ya, I know...50 questions. :dry:

I have plugged the breather ports and it does make the bike quiet down a bit. It even reduced backfire.I must need rejetting because I lost most of my top end after I was done.
Any ideas?

It does not affect jetting. It works external to the engine. In other words it does not affect air or fuel in the combustion chamber. It only added fresh air to the exhaust system.

However, it did use engine vacuum as a control. The vacuum ports must get plugged or the engine will be sucking fresh air. Make sure to plug the hole in the top of the airbox too.

It's possible the system was leaking vacuum and so someone rejetted the carbs to compensate. Now that the system is removed, the carbs are not jetted properly.

Or if you have a 79-80 Mkll motor you can just replace the valve cover with a Canadian casting.Never had any EPA crap on our motors.PM if you want one,just happen to have a spare I'll sell.

I found the prob ... but now I have another one .
There was a cut in the hose I ran across to plug the two "vent" holes. and I put a plug in the vaccum line going to the carbs.

Now for the new problem...

Now it won't start at all. I try to start it and it seems like it wants to turn over for a sec, and then it backfires loudly and the whole situation starts ( or rather, doesn't start... pun intended )again.

BTW, I have pods, and and drag pipes (with no baffles)

Any advice would be great.

thanks for the help everyone,

NOS

Post edited by: NOS, at: 2006/03/03 22:59

You should now only have one vacuum hose from the intake manifolds to the petcock. The other three should be capped. The one to the petcock turns the fuel on with a vacuum diaphragm-valve. Without it working properly, fuel won't get to the carbs.

Also, did you have to touch any of the wires (plug wires or primary wires) on the ignition coils? It almost sounds like the coil wires got swapped.