No Acceleration Above 45mph or 1/2 Throttle

The red stuff is probably silicone rubber gasket maker which dissolves in gas. It should NEVER be used on carbs or intake manifolds.

Good evening everyone!

I finished cleaning the carbs and put them back together. I am waiting to see if there will be any leaks around the float bowl o ring.

I took apart the air filter to see if maybe the filter was clogged and this is what I found...



Just a piece of shirt folded in half in place of an oiled air filter element. Would this possibly have an effect on air flow at WOT?

Upon inspection of my vacuum pistons, one of them has a slide on the inside around the entire circumference, whereas the other one only has four tabs, as opposed to a ring around the inside. Pics are below

Ring all the way around


Four tabs


Is there any significance to that difference?

I checked further into the difference between the size of jets suggested in the digital FSM I have it says 62 but in another manual I read it said 1980 and on kz440's had 65, so they are stock jets.

So there was some gunk in a couple of the jets and in the float bowls.

She started up but didn't want to idle without any adjustment. I figure it was from messing with the air filter "element" and so a bit of a turn on the idle adjustment and she idles at around 1300. WOT she goes just about up to 9k, but that is in neutral with no load. The real test will be tomorrow morning, let's see if we can't hit 60. I would be surprised if she had no problems, as that shirt folded over HAS to be restricting compared to an oiled foam element.

Was that the problem all along? No, I refuse to believe that.

I also adjusted the throttle cable so there is about 5mm of play on the throttle to be sure the butterfly valves close fully, and I made sure it opens them fully.

When I was reinstalling the carbs, one of those spring o rings somehow found its way into the air box. Needless to say my fingers are chewed up from fingering that box for ten minutes getting that damn spring back.

Now that I think about it, the messed up idle may be coming from the bent jet needle LOL

So I probably didn't fix anything, cleaned a lot, got some asphyxiation symptoms, and bent a jet needle.

But I did find out when I was trying to put my carbs BACK IN that my air filter was a shirt folded in half...

So it goes...PO gets me once shame on him...fools me twice...well shit I'll just blame it on the carb cleaner fumes

Cheers

Oh I also forgot to mention that I found one of the diaphragms was slightly bunched up at one point between the top cover and the carb body.

The shirt, the gunk in the jet and the bunched up diaphragm could all be causing the problem. It would be best to get a proper air filter. Pity about bending the needle. Does it move up and down freely when in position ? When you put the carbs back together it would also be worthwhile checking the fuel level in the float bowls

Sorry I cant comment on the differences in the diaphragm photos. I dont know enough but am sure someone who does will be along soon. I wonder if the PO replaced one with a unit from a different bike. Do they look to be the same size ?

Here's a website which has some very usfull info on the 400.
www.kz400.com/

The difference in the needle retainer, the piece that is holding the needle to the bottom of the slide, may have a minor effect on spring rate pre-load. Since one is thicker than the other. You can get the correct one easily enough, but I doubt that you could tell the difference. They both hold the needle and its clip down against the bottom of the slide.
The T-Shirt would have been awful for a filter, and was costing power for sure. Hopefully you put a good in-line filter in place before hooking them back up.

JR wrote:

The shirt, the gunk in the jet and the bunched up diaphragm could all be causing the problem. It would be best to get a proper air filter. Pity about bending the needle. Does it move up and down freely when in position ? When you put the carbs back together it would also be worthwhile checking the fuel level in the float bowls

Sorry I cant comment on the differences in the diaphragm photos. I dont know enough but am sure someone who does will be along soon. I wonder if the PO replaced one with a unit from a different bike. Do they look to be the same size ?

Here's a website which has some very usfull info on the 400.
www.kz400.com/

Hey JR, thanks for responding! I ordered a sheet of 5/8" UNI foam filter that will go where the stock element went. Should have it installed by next Saturday. The needle moves up and down just like the straight one. I neglected to check the float bowl level, but am going to get the air filter installed before I disassemble the carbs again. The vacuum pistons behave exactly the same in terms of sliding up and down and size. The diaphragms that are in there are a royal PITA to get the rubber to seat around the whole lip. Easy to see how the PO bunched the corner or one. Are they supposed to not want to stay in that lip? I imagine new diaphragms would have a tighter fit into the space, but I want to order them from the german dude and his website says he won't be working until next year so I'm going to wait on those I think.

I have been perusing the kz400.com site for a week and a half now, what a wealth of information! I wish every other motorcycle and car had such an effective online service manual.

Motor Head wrote:

The difference in the needle retainer, the piece that is holding the needle to the bottom of the slide, may have a minor effect on spring rate pre-load. Since one is thicker than the other. You can get the correct one easily enough, but I doubt that you could tell the difference. They both hold the needle and its clip down against the bottom of the slide.
The T-Shirt would have been awful for a filter, and was costing power for sure. Hopefully you put a good in-line filter in place before hooking them back up.

Hey Motor Head, thanks for posting! I agree in thinking there would not be a significant difference in how the vacuum pistons function, with what little mass is added from the additional metal in one of them.

As of now the t shirt is still in there! She runs smoother at low speed than before the cleaning and I needed to adjust the idle screw a bit as she was idling at 2k. I imagine this is because I adjusted the idle screw the other way yesterday as she didn't want to idle, but now realize she probably wasn't warmed all the way up.

When you say a good in line filter, you are referring to a fuel filter right? I did pick up a new one at autozone as well as some new fuel line.

I haven't seen any leaks coming from the float bowl o rings, which is good because I cleaned all of that nasty red liquid gasket off of the o rings and they seem to be sealed on their own. I am ready to buy two new o rings for the bowls if they do start to leak though.

I think that I am going to remove one of the two layers of t shirt filter element and take her around the block to see if she can breathe a bit better.

Yea sorry I meant a in-line fuel filter. Don't know which 1 you got at Auto Zone, is it for a gravity feed system? Some of those Auto filters won't flow at WOT on a bike. There made to have 5psi or more by a pump. In a Huge place like LA you should be able to get a replacement air filter and such any day of the week, probably 24/7.
Saw the Pic's that's one clean bike.

Motor Head wrote:

Yea sorry I meant a in-line fuel filter. Don't know which 1 you got at Auto Zone, is it for a gravity feed system? Some of those Auto filters won't flow at WOT on a bike. There made to have 5psi or more by a pump. In a Huge place like LA you should be able to get a replacement air filter and such any day of the week, probably 24/7.
Saw the Pic's that's one clean bike.

The fuel filter I got is made by Luber finer part number G6529



Thanks for the compliments on the bike, I am trying to keep her in this good condition for a long time. Keeping my eye out for an extra tank that hasn't been lined so I can POR 15 it and paint the outside a nicer black with a gloss and clear coat. Need to have two so that I can get to school and work on it at same time haha

I unfolded the t shirt element so that only one layer is filtering air and took her around the block. WOW! felt like she had twice the power. I was in second gear at 40mph and 6k rpm I believe and she felt ready for the freeway!

Sucks I'm stuck at home waiting for my tire to arrive, but it should arrive today. Then it's a matter of waiting on the balancer, then I can install the tire and take her to top speed!

Cheers

The diaphragms that are in there are a royal PITA to get the rubber to seat around the whole lip. Easy to see how the PO bunched the corner or one. Are they supposed to not want to stay in that lip

The diaphragms should sit easily in the groove. The PO was probably just sloppy. If you have them in place correctly now then perhaps they will conform to the groove and be easier in future.

Great to see you are making progress. You're almost there

If you like your un-ripped diaphragms and want them to stay that way, and want that machine to run right, you'll get the proper air filter in there before you go screaming it around. From what I've read of your post, that has been your main problem all along. The 440s are rather picky. :blink:

I forget who made it, but I used to buy replacement air filters that where a paper/metal combo and replaced that entire stupid metal cage and it's useless foam, they provides a much more consistent flow than the little foam piece ever did. Might be worth your while to make a couple phone calls.

I got them directly from my local Kawasaki dealer though, I remember that much, LOL. I see kawasaki site still list just the stupid little foam piece.

Best of luck.

JR wrote:

The diaphragms should sit easily in the groove. The PO was probably just sloppy. If you have them in place correctly now then perhaps they will conform to the groove and be easier in future.

Great to see you are making progress. You're almost there

It felt like the diaphragms were stretched around the edges, so that when installing them the edge wants to pop out of the groove unless you strategically place your fingers. The PO stripped one of the screws to the point where I had to use pliers and pinch the head of the screw. I definitely want to purchase allen bolts for the carbs and engine. I wonder if there is a complete kit somewhere?

Capt America wrote:

If you like your un-ripped diaphragms and want them to stay that way, and want that machine to run right, you'll get the proper air filter in there before you go screaming it around. From what I've read of your post, that has been your main problem all along. The 440s are rather picky. :blink:

I forget who made it, but I used to buy replacement air filters that where a paper/metal combo and replaced that entire stupid metal cage and it's useless foam, they provides a much more consistent flow than the little foam piece ever did. Might be worth your while to make a couple phone calls.

I got them directly from my local Kawasaki dealer though, I remember that much, LOL. I see kawasaki site still list just the stupid little foam piece.

Best of luck.

Thanks for the advice Capt America, now I am not going to run her much until the foam arrives and definitely not at all above 5k rpm or 50 mph. I would very much prefer to not have to replace my diaphragms any time soon! It would be sweet if I didn't have to remove the carbs out again, but I know each time I will get better at it. Today I will check my brakes instead of running her around town; my Clymer's manual finally came. Even though I've seen all the information online, it is definitely good to have a full version on the bench next to you

I will contact my local Kawa dealer this week and ask about replacing that stupid metal cage. The fact that she ran as well as she did / does with a folded strip of cotton t-shirt makes me confident she will do freeway speeds, but we shall see.

In the U.S., Ace Hardware Stores carry a great selection of Metric and American threaded fasteners in SS and plated steel. Bring along your old screws and match up new ones.

If they don't, try www.boltdepot.com I use them if a project has a long lead time and I can wait.