TOPIC:

I give up - what are "open filters?"

650ed wrote: I give up - what are "open filters?"

Your favorite... pods. As in, not enclosed in a box.

$20 seems steep for simple jets. If they are pilots with emulsifier tubes attached, then those are usually a little more costly. If it were me, I'd be drilling the jets to get to the correct size, then once I find the required size, I might buy new ones in that size (if they are even available).

The real problem with jetting is the amount of time you will spend on experimenting, (especially on CV's). For me, it was much cheaper to buy a wideband setup than to spend all of the extra time.

Have you tried re-seating the CV piston covers and cleaning/oiling the slides so the slides both drop evenly and freely?

Yes i meant pods. By the way I am only working with pods because I can not find the rubber boots to go from the air box to the cabs. + the filter and air box with no boots cost alot. The bike came with out. I would never remove an air box. Deffinitly not on a kz 400.. Unless you have those boots for sale it wont help making this a you shouldnt have removed the air box thread. Just wanted to make that clear I do bot want pods. Anyways what are you refering to when you said " a wideband set up" sorry if thats obvious but im here to learn thanks!

A wideband oxygen sensor, and related gauges and controller can be used on the bike temporarily (or permanently) to allow you to see actual mixture in real time. This lets you monitor jetting and correlate it to RPM and throttle position. It makes jetting way easier once you learn how to use it properly. But there is a learning curve to it.

Here's my initial thread from 5 years ago.
www.kzrider.com/forum/3-carburetor/30748...g-wideband-o2-sensor

I use the LC-1 with an analog gauge to view as I ride. You can also datalog it, but I find real-time monitoring tells me a lot more.

There is apparently a new version out.
www.innovatemotorsports.com/products/lc1.php

By the way, those piston CV's can be made to work well with pods. I did it on a 76 KZ400, and that was before I had a wideband. But there are a lot of variables to juggle on those carbs. I wish I had the 2-into-1 manifold back then. It would have made life a lot better. I spent months dialing in those carbs (mostly because we were altering the exhaust a lot as well). A single Mikuni VM would have been so simple.

Thank you for all the input, now when you say reseating of the carbs is there anythjng special you are refering too? I want to make sure I understand thats not an issue. With the bike off the slides feel really slow in my opion. They do go up the whole way but when I let go they do not drop very fast, also seems incosistant. I removed the slides before to oil them but could you explain what you meant by reseating?

I am going to give the stock carbs a couple more tries but am starting to womder if going with vm30 carbs would be better. Jets are cheaper and they seem to be alot easier to tune with pods. Its either that or spend alot of money and time getting a stock exhaust and air box with useable intake boots. Any reasons I shouldnt be looking into a vm30 swap?

Regarding the slides; try this:

Disconnect the throttle cable(s) at the carbs. Then raise the slides by hand and let them drop. If they move more freely you need to lube or replace your throttle cable(s). If they still stick you may need to clean the carbs. The slides should not require any lubrication. By any chance have the slides ever been removed from the carbs? If so, maybe they were not returned to the carbs they originally were in. Carb parts wear together and don't like to be shuffled between carbs. Ed

Should verify that tank cap vent is clean & unobstructed...Tank "breathes " through key hole...Air can't get in top of tank, gas doesn't want to come out the bottom like it should...usually manifests itself by feeling "strangled" at higher rpms...Something free to try, anyhoo!

The single carb setup is the simplest to tune and maintain, and it's nice to work with a brand new carb, but it is not necessarily the "best" option. It has it's problems as well. For one, it may not have the same power, that is, it may have a different power band. Usually single carb setups have a lot of torque on the bottom end, which is nice, but they sometimes give up some of the top end horsepower. Also, it will work great in hot climates, but in a cold winter area, the carb will stay cold a lot longer, and under certain conditions, the manifold can ice up. And of course, since it will be a manual slide carb, you can't be ham-fisted on the throttle like you can on a CV. But then, throttle control is a skill everyone should learn, so it's not really a downside in my opinion. I just prefer simple things... far less to go wrong.

Reseating the top covers on the carbs.

On those carbs, as they wear, the pistons get finicky about moving smoothly. As Ed said, make sure each piston is in correct body.

You don't have to take the throttle cable off, and it's actually better if you do this with the carbs on the bike where they will sit. Make sure the pistons and the sliding sufaces are absolutely clean and put 1 drop on the piston grooves and one drop on the center post surface, basically any surface that rubs should get about 1 drop of oil. I usually use 10w40 motor oil.

When you remove the top covers, there should be a gasket under it. Make sure that is in tact. It might be good to put a tiny bit of antiseize on the gasket so it doesn't stick to the cover. This will help in the re-seating.

When you put the cover on, you should reach into the intake of the carb and be able to slide the piston up and down with your finger. When the cover is loose, it will drop down real nice and smooth. If you just crank down the screws on the cover, it may move and the piston will not drop as smoothly. So what you do is very slowly and carefully tighten each screw a tiny bit at a time, alternating screws, all the while moving the piston up and down with your finger. If the piston seems to stick, try to "massage" the cover into the right position, while still moving the piston up and down. There will be a sweet spot where the piston will all of sudden move freely. Then continue tightening the screws slowly by alternating.

When you are done, both pistons should move up and down smoothly, and should drop at the same rate. When you test it, let both drop at the same time, and you should only hear one clunk as they both hit bottom. If you hear two distinct clunks, one is too slow.

This all probably was not necessary when the bike was new, but with age, it needs to be just right. I've had to do this as early as in the 1980's when these bikes were only about 10 years old. Without it, and without oil on the pistons, I had one bike that would not go over 40 mph. After doing nothing else but this, the bike went near 100 mph (according to the speedo).

By the way, I realize how the description sounds... once you have this technique mastered, your girlfriend will appreciate it.

LOL. ill give the slides a closer look. I have replaced the rubber seal in the gas tank cap and have tried leaving the cap open to see if that changed anything and it did not. Thank you for the ideas though. I know for a fact the slides were not falling at the same time. Ill give them a closer look. I also have had them apart to clean them but I mad 100% sure all the parts from each carb stayed with the carb it went to. However maybe a previous owner switched them up? Ill give that a try

Alright Its been a while but I have tried everything suggested so far and balanced the carbs again and still no luck. If anything it runs worse and then ill mess with them and get the bike running like it was originally.. Running fine until around 5-6k rpm and it has no power and will sputter and pop under hard acceleration.

I am now at the point I am wasting so much time with these old carbs and parts for them are hard to find. So im thinking why not go with the two mikuni vm 30's? I see them for sale with the intake boots, k&n pods, a 2-1 throttle cable and some spare jets for 399$ Power barn claims they are set up for a kz 400 but even if they are off I would guess new mikuni vm 30's would be a lot more enjoyable to get running than my old carbs

Any one have any experience with these carbs? Any reasons not to go this route other than the cost which I am at the point id rather spend 400$ and get better results than spend a lot of time getting no where..
I would appreciate any ideas on this before I pull the trigger and drop 400$ thanks

Cyclerider636 wrote: .
The bike has pod filters and aftermarket pipes so im trying to figure out if its related to jetting. !

The pipes are part of the problem.
The pods are the other.
How far have you gone from the stock jetting?


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Cyclerider636 wrote: Yes i meant pods. By the way I am only working with pods because I can not find the rubber boots to go from the air box to the cabs. + the filter and air box with no boots cost alot. The bike came with out. I would never remove an air box. Deffinitly not on a kz 400.. Unless you have those boots for sale it wont help making this a you shouldnt have removed the air box thread. Just wanted to make that clear I do bot want pods. Anyways what are you refering to when you said " a wideband set up" sorry if thats obvious but im here to learn thanks!

You can use radiator hose for boots. You can also try jetsrus on line.