Im gonna to beat my CVs with a ball peen hammer

OK, so... I have an 81 KZ750H LTD, with 15k miles on it. I cut open the frame, welded up my own hardtail section, new fender, paughco tank that i cut open and friscoed, ran all new internal wiring using deutsch connectors, re-bled the brakes, went through every nut and bolt on the bike. But those damn carburetors...

Its an in-line 4 with Keihin CV carbs. I bought rebuild kits from Z1 Enterprises. The kits include new idle mixture screws with the corresponding spring, washer and o ring. Kits also had bowl gasket(which apparently expands after the first use to the point of no longer being usable). The kits also come with 2 other o rings which i could only figure out where one went: for the bowl drain screw.

So I went through the carbs. I separated each carb, broke them down, blew compressed air through the ports to ensure good flow, no build-up. The slides were pretty sticky, so i used a scotch brite pad very lightly on each slide, which freed them up fine. The diaphragms looked great, no pinholes, diaphragm springs also good, not bent, returning fine. After all assembled, each slide moved up and returned freely, and you could hear the vacuum in each slide as it went up and down. I also re-jetted the carbs so they could run with pod filters. I went up 3 sizes on both mains, but could not find the slow jets anywhere. Is that ok? Do I have to change the slow jets? So, put the carbs on the bike, I try to sync them, using home-made guages that I have used before, but this time I cant get the #1 carb in sync. #2,3, and 4 were idling all about the same, but #1 was way up, no matter what I did with the idle mix screw. #1 cylinder plug is also considerably more sooty than the others. It runs but runs like shit. The first 1/4 turn of the throttle is ok, fairly responsive, but after that, nothing. You can rip on the throttle past that and theres nothing, just a real slow acceleration. Takes a good couple of seconds to get any real momentum going.

I pulled the stock mufflers, and inserted 1” washers that I welded onto a bolt in order to get some back pressure. I have been thinking about getting some baffle inserts to put in there.

I pulled the mix screw on the #1 carb to check for debris, blew it out, looks fine, Ill try to sync it again in the morning, but I know theres something else going on. What do you think about the poor throttle response? Do I need to find larger slow jets? Ive heard that theyre not available, and I havent found them anywhere. Is it the exhaust? Im going crazy on this thing. I wish it had the mikunis, Ive heard that those are a lot easier to work with when doing some heavy modifications. Anyways, any help would be great. Thanks.

-Forrest

Since you had them apart from each other you need to synch the throttle valves.

Set all the mix screws the same first then work on the throttle valves.

If the one carb is off from the rest the engine won't rev.

Also you need to be sure going up three sizes is not too much for your motor.

If the mix screws are not open enough, it won't rev either without fuel.

The throttle vavle on the high one is probably closed too much.

this will cause the sooty plug and a very crappy idle.

Put the gauges on and try opening that carbs throttle valve and
see what happens.

If your getting a bog and run on your slides may not be opening.

If you suspect this go get a hammer and bash them to bits.

Just kidding,

Eyball all the throttle valves to see if they show the same amount
of hole on the engine side, this will tell you if they are close or not.

If the one carb is shut you should be able to see that.

When you get it straightened around and suspect the slides are not
opening, put the box on or make one from cardboard and tape it on.

go for a ride and should be a world of difference if that indeed is a problem
as well.

keep us posted and we'll get you dialed.

Sitting on the side of the road, using one hand to pick my nose,
fumbling a stubby screwdriver from harbor freight and turning the mix
screws with the other. Ouch burned my hand again.

Looking up and down the road for traffic coming,
don't want to get caught picking my nose,
cops arn't far behind I just know it.

Late for work again too.
almost out of gas, still have to stop and get cigs.

LIttle nervous I might be out of oil again.
Batt. is almost dead too. why me

why do I have to work?

why can't I have the time I need to fex this right?

I need to get organized.

maybe go to the other side of the bike and
pick my nose with the other hand and when the cop

passes he won't recognize I have all my belongings

stuffed into my socks. Standing there i began
to wonder if there will be a blood stain in the
helmet his dad bought him for his birthday and for his first bike). from the top of my head where the the cieling
fan whopped me while standing on a chair to find my weed
on the shelf. Or did I leave it in the garage? Who turned it on
anyway?

First thing is a better screwdriver, this thing sucks and

isn't cuttin it. Now I got a fuel leak from lifting up the tank

and stretching the line. Have to take a piece of wire from the

stuff I used to hold the batt. in place. What the heck can I cut it with
though? Bending the wire back and forth

back and forth
back and forth.

It is the stuff that just goes on forever.

I'm so late. Nervous now that I might not have made
the bike run any better.

And I might not have a job for long.

Least then I can spend more time with the bike.

O there's that cop.

Wonder if he's got some black tape.

A pliers? jumper cables, qaurt of oil,

Bullet? Well I know he's got a pen and some paper.
Could write a letter asking for some help.

But who would have a stubby screwdriver that size.

Forget it all for now just go to work and start over tomorrow.

Ok, so I pulled the carbs and eyeballed the throttle plates, they looked dead on, i set the mix screws all the same: 2 turns out from lightly seated. Then I took the vacuum cleaner and held up the hose to the engine side of each carb, and while doing so, opened the throttle. I did this on each carb, and every time, the slide only opened a little bit, but if you move the slide manually with your finger, it slides up no problem, and returns nicely. I also tried blowing compressed air lightly through the intake side of each carb while opening the throttle to try and lift the slides, but still, they would only come up a little bit. I also put on the stock mufflers. Then I put the carbs on, hooked up the gauges and fired it up. #3 is running super high, #1 super low, 2 and 4 are right in the middle. No adjustments I make to the throttle plates makes any difference, except making the bike die if i go too far one way or the other.

-Forrest

Ive looked over those diaphragms multiple times, and they look GOOD. The rubber still looks new and pliable no cracks or brittle parts whatsoever. And when you operate the slides by hand, you can hear it sucking and blowing, which leads me to believe the diaphragms are not the issue. Ive also checked the walls of the channel that the slide goes up and down in: smooth, no grit, obstructions, or wear marks. One thing im going to check is that maybe the needle is hitting up against some gunk built up in the port that the needle goes into.

ive also tried raising the needle in each carb. I put a small 5mm washer under each needle, to try and get some more fuel in there a little quicker. There was a difference, but still #1 carb is super low, #3 super high, and 2 and 4, just straight chillin in the middle. Any adjustment I make to the throttle plates or mix screws doesnt seem to matter except for making the bike die if i go to far one way or the other.

All I can figure is that I still have some serious buildup in the ports and channels of the carb, and thats what is making my adjustments seemingly useless. Someone has recommended soaking it in Berrymans Carb cleaner. Is that a pretty common cleaner found at most parts stores or should i order it online. And do i need to literally soak the carbs in it, or just spray the fuck out of them?

Im still keeping the ball peen hammer at the ready...

I just went by Nappa and got some carb cleaner. It looks like it's in a paint can, and you can just let the carbs soak in it, preferably for like 12 hours or so. However, you have to removed every bit of rubber from your carbs first. Every O-ring and diaphragm. NO RUBBER PARTS AT ALL. This stuff will kill it.
But I was actually thinking of a different thing... Have you lubed your throttle cable? I'm wondering if that's whats sticking... You say that each moves freely on its own... When you move the assembly where the throttle cable connects, (without the cable on there), does everything still seem to move freely? If so, that's what makes me think about the cable.
Oh, and hi, welcome to KZR.

Completely dissasemble your carbs and clean everything. If you couldnt find the pilots, its cause you didnt look under the little nylon plugs...



If you blow with your mouth on each of the slide ports, you should feel the same resistance across all four carbs and they should slide all the way up and then return to idle when you stop blowing.

Use the supplied diagram for dissasembly, and blow carb cleaner through the carb ports in the bottom while looking to make sure that cleaner blows through all the small holes into the carb bore. Visually verifying that fuel will flow unobstructed.

Install everything airtight.

Good luck - mix scres 2.5 - 2.75 turns out with pods.

Yeah i think im gonna break everything down again and soak the parts(minus any rubber) in some carb cleaner. I blew through all the ports the first time and everything seemed fine, but im thinking maybe theres still some buildup thats not allowing FULL flow.

And when i said i couldnt find the pilots, I meant that I couldnt find replacement pilots(I increased the mains 3 sizes and wanted to do the same for the slow jets). Could that be causing some trouble here? Do you have re-jet the pilot as well?

Anyways, im gonna do another tear down, soak in carb cleaner, and try again. I really appreciate all this help, guys. Pretty badass.

-Forrest

Just some additional thoughts to what Tek9iNe said

Those float bowl gaskets which are really big O rings dont like the ethanol in the fuel. I have tried the genuine Kawasaki ones and no difference from the ones in the rebuild kits. They swell up after one use and when you try to put them back they are to large. Solution - put them in the freezer for 20 - 30 minutes and they shrink down enough that you can get them in before they swell again.

That extra O ring in the rebuild kit is for that plastic/nylon/neoprene or whatever it is plug over the pilot jet. If you replace it it's a tight fit and might require some shaving.

You dont need to replace the pilots for pods.

When I had pods with 4 -> 1 exhaust on my 1980 750E1 I had #70 primary main and 140 secondary main jets and mixture screws out I think 3 turns. With your exhaust system or lack thereoff I can only guess.

I like my Keihin CV34 carbs and think they are much maligned. I have found that it is really important to have the fuel service level in the float bowls spot on and absolutely to spec. Not eyeball but measure fuel height and set floats and measure. Makes a world of difference to have the levels absoleutely correct. Do a search on (clear tube method). If you have not done this after rebuilding your carbs you really need to do it. If you mix up floats and bowls the fuel levels will probably be off and all your idles and vacuum will be way out of whack

Tek9iNe says "airtight" and I gotta say +1 !!!

Good luck

:whistle: I'm kind of liking the hammer idea myself :evil:

Yeah, the first thing I tried with the bowl gaskets was to throw them in the freezer overnight, but I still couldnt get them to fit in the groove in the bowl. They shrunk quite a bit, but just not enough. I was wondering about the o-rings being meant for the plugs, I think ill try that again. And thanks for the suggestion about the float levels. That is definitely something i need to make sure i have right. Thanks for everything guys, ill let you know what i find out.

Chalk up another suicide story for the member who is trying to unsucessfully jet CV carbs with pods....

Re: Im gonna to beat my CVs with a ball peen hammeson it has late model cv carbs with pod filters on it. Running like shit first 1/4 throttle ok after that spitters and sputters. But not now!!!!!!!!!!!! I have a lil truck for u. Pod filters generally suck on cv carbs and there is a reason for that. If u look at carb there is a kind kidney bean shaped port at the top of the opening. Well the pod filters cover that up,not good bike will run like shit. If u notch the rubber on the inside of the pod to where it mates with port the carb will breathe. The slides on cv carbs open by air (suction) when u twist throttle. With those ports blocked u dont get proper air flow. Give it a try I was lucky to get 3k rpm until I modded the pod. Keep me posted