78 KZ400B Tuning Help

Hi trietz
I think this may be a case of fortunately unfortunately.

I got my delivery yesterday which was a couple of days earlier than expected and to my surprise none of the O rings worked - either to loose or to fat - but the caps did. So I pressed them in and rode around last night and some more today and they seem to be working just fine so I am sorry to say that they are not available for donation.
This is what I ordered
www.z1enterprises.com/ItemDetails.aspx?i...84%29&item=KL18-4689
$8.48 for a pack of 4
Unfortunately it looks like Z1 Enterprises are out of stock though ou might be able to get them from a Suzuki dealer or some other supplier

Below is a photo I took yesterday evening. I'll give them a few weeks and if they continue to work out I'll probably post the information as it might be useful to others.

Sorry again to hit you with bad news

Trietz,

I am sure a good machinist can do them for you.

Update from my post a of last week.
Ultimately those suzuki GS pilot caps/plugs were not a success. They worked fine for a week and then this morning the bike started coughed sputtered and died and when I opened the carbs I found 3 out of the 4 caps had fallen out. And the spark plugs were wet with gas. - to much gas
Oh well. It was worth a try
Dug out the fat o rings put them on the old polyester caps and filed them down with Emory board until they fit.. hope it works

New coil came. Getting good spark, starts right up. Good power throughout, just won't idle smoothly. Can't tell of its a fuel or ignition issue.

Fuel wise, I noticed the carbs were missing the pilot plugs. Put those in. So maybe the small hole by the main jet that feeds the pilot system isn't completely clear?

The plugs I got were from a different bike, but I shaved them to fit.

Remember to wear eye protection when spraying pressurized carb cleaner. Because it always backfires. Always.

Good Fortune!

Sprayed some liquid through, and shot some compressed air through. Didn't make it any better.

Think I need to start with some fresh spark plugs and go from there.

I just cant tell if it's a fuel or electrical thing. Just feels kind of like inconsistent spark, but I have a brand new points and condenser and a brand new coil on it.

Currently it idles, just pretty roughly. Then it'll accelerate, again pretty rough, but if you let off the throttle to cruise at 35 MPH it sounds just fine.

I don't know if you already have it, but the link below shows some good info on the KZ400 carbs. Ed

www.kz400.com/Workshop%20manual%20bilder...nual%20p.150-155.pdf

treitz wrote: Sprayed some liquid through, and shot some compressed air through. Didn't make it any better....

Sprayed some liquid through, and shot some compressed air through -- must of course be done precisely and not hap-hazardly.

If turning a carb pilot screw fails to produce a noticeable effect on rpm, there's probably still something wrong inside the carb (likely an imperfectly clean pilot circuit).

Good Fortune!

Sometimes there is a metal clip that holds in the main jet, and that clip has a small tab that also holds the jet plug in place.


I think I ended up making an aluminum plug using an oring to seal it. But it's been a long time. And now, the current alcohol-gasoline fuel will eat aluminum and almost any rubber except Viton.


Seems like such a simple thing... plug a small hole... but turns out they are a royal pain in the ass.

Okay... I will take the carbs off one more time to make sure all of the passageways are clean.

But seriously, is there a trick to getting these carbs off with the air box installed? Sandwiched between the motor and air box, these things are a nightmare to remove.

Your signature says it all, really.

But I always sit on the bike, put my feet on the motor, and pull the carbs into the airbox, and tip them up or down to get them out of the manifolds.

Make sure all of the airbox screws are out.
Loosen the battery box screws if necessary, or anything else that stops the airbox from moving back (it's usually the fram that determines the maximum rear-ward movement).
Make sure all of the clamps are super loose, not just loose enough, but super loose. The rubber expands as the carbs pull out.
I use a tiny bit of anti-seize on the carb outlets so they don't stick next time. But only a tiny tiny bit.

loudhvx wrote: Your signature says it all, really.

Haha yes. There is a reason I went 2-1 on my 400. HATE these stock carbs so much.