TOPIC:

I ride an '84 zn 700 that I just recently got running after it sat in a barn for 5 years. I pulled the carbs and cleaned them out, replaced the plugs and cleaned the tank and it started up just fine. When I'm warming it up with the choke on I adjust the choke to get it to idle around 2000, but it won't stay put. It slowly creeps up to 3000 and as soon as it hits 3000 it shoots up to 4500. I adjust the choke down a little and then it does the same thing again. Any ideas? The bike has 4 Keihin CV34s with a lever style choke. When it did this at first I decided to just ride it for a few hundred miles and hope that the kink would work itself out. No such luck. Thanks.
-Spencer

It sounds to me like you've got a vacuum leak somewhere.
You didn't say though as to what else has been done to your bike.
Did you synch the carbs after the rebuild and cleaning of them?
Is the ignition functioning properly and the timing set correctly?
Are the valves adjusted within specs?

I had the same prob with my ZN700, it turned out that the intake boots and manifolds all had hairline cracks in them that couldn't be seen with the naked eye, the valves were slightly out of spec, and the carbs were WAY out of synch!

Try this to test for vacuum leaks:
If possible, get her running at a steady idle and spray some carb cleaner at each individual boot and manifold to check for problems, also check all vacuum lines for damage or pinching.
If the idle increases, that's where your problem is likely at.

If the boots or manifolds are indeed leaking, you can get new ones from Jeff at Z1 Enterprises.com for much less than a Kawi stealership will rape you for.

I almost forgot, please be sure to post some pics of your ZN. I'm sure everyone would love to see it!

Here's a few pics of mine.




Post edited by: RetroRiceRocketRider, at: 2007/01/06 17:36

The ignition is set correctly as far as I can tell. I didn't sync the carbs after I cleaned them out. I didn't totally rebuild them. Just blasted out all the passages with carb cleaner. I don't have a manometer or vacuum gauges, so I think I might end up doing more harm than good if I try to resync them. I didn't check the valves yet because it runs just fine with the choke off. It's only got 14k on the clock. As for pics, I've been messing around with a few ideas for how to chop her up a little. The top pic is what it looks like now (except for the broken turn signals which I just replaced) and the bottom pic is a photoshop composite of what I'm thinking of doing to her. Any thoughts? It's good to see that someone else in the universe owns one of these things. I'll check all my rubber fittings. The carb boots DO look a little dried out and tired. Later.
-Spencer

Photos:

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No, as soon as I turn the choke off it idles rock solid at 1000. The airbox boots are fine, but the intake manifold boots are a little dried out, but still definitely flexible. I'm going to try the carb cleaner check that RRRR suggested. The vacuum hose that goes to the petcock could also be the culprit. It's looking a little dry and stiff. Thanks.

-Spencer

Your ZN pretty much looks complete and original, and a heck of a lot better than what I got mine in!

How is the paint on all parts?
I'm no purist, but if it's in good condition, and if it were my choice, I'd be tempted to leave it that way. Kawi only made the ZN700 and ZN1100 in '84/'85, and in limited numbers. Although it doesn't sit high on the collectible food chain, it is a rare model.

You could always find a set of body parts for it on eBay with bad paint for fairly cheap to redo, and then list your original painted set of body work there for a profit.

I like the p-chop pic you posted. Something about the size/shape of the body parts and the way it sits reminds me of a Honda Magna or a Kawi KZ750E.

If you do go ahead with your vision, be sure to keep all the OEM parts you remove. They can be listed here in the classifieds or on eBay to help fund your project.

The original paint isn't in great condition. The clear coat on top of the paint seems to have separated in a few places and formed little bubbles. There are also some scuffs and scratches on the tank and some spots that are pretty faded. The seat is also pretty bad. It's so dried out and sun damaged that I put a new crack in it just about every time I ride it. I really want to change the seat because I really don't care for the lines of the stock ZN seat. All in all though the bike is pretty complete and functional. It was definitely a steal for $200 even though it isn't titled.
-Spencer

I'm having similar, erratic behavior with my '79 Mk-II. There are times when she purrs like a kitten: strong, smooth and quick; and then there are times that I'd swear I'm only running on 3 cylinders. I pull off each ignition cable while the engine is idling and she bogs down accordingly -for the most part-. There will be times when I'll set the idle at 1,200 and then, inexplicably, she'll start to idle north of 3,000. These are the times when she runs -really- well. I suspect a vacuum problem. Anyone have any ideas as this is *really* annoying.

Some basic mods:

4-1 V&H;
Pods;
Step1 Rejet because of the 4-1 and the pods;