Kz400 with kz440 carb help hanging idle

Hello all.

I have a 79 kz 400 ltd. I put some kz440 carbs on my bike to see if there is any difference ( I had a feeling something was wrong with stock carbs and I was right. Butterfly is not working poperly) so Installed led the cv 36 carbs and idling much better at about 1200 rpms. The problem I am having is that after pulling in the clutch it revs up and stas up for a second or two then slowly returns back. Any ideas what it could be? Running k&n pod filters. Haven't rejetted yet. They came with 70 primary and 92 secondary. Still lean but I wasn't having this issue before with the cv 32 carbs before the butterfly malfunctioned. Any help would be great full.

Matt

Hanging idle means lean, commonly an airleak. Needless to say though, you must rejet any time you install pods. And hope you have real K&N's and not those junk generic imitations.

Have you check the throttle cables have enough play?
Have you vacuum sync the new carbs?
Pilot jets and main jets cleaned?
Pilot mixture screws on reference setting?
Carb body sitting correct in the intake boots without air leaks?
What is your butterfly problem on the cv 32 carbs,take some pics.

They are real k&ns. A friend ordered a 4 pack and we split it. I've checked and checked for air leaks and come up empty handed. I'll probably just have to order that sigma 6 jet kit or something. I've tried to find jets locally but nothing. I've heard plugging up part of the filters will help with the air flow reduce not sure if it's worth it or not.

No I did no vacuum sync the carbs just adjusted until they opened at the same time. Was told that wouldwork. I'll have to buy a sync tool. I need to do valve adjustment as well most likely. I don't have a picture of the 32s but I noticed a butterfly wasn't opening as much as the other and a float was crooked on one like it was stepped on and bent back. The joys of a project bike I guess. I did clean the carbs soaked them in carb cleaner over night and put a reamer through them. I have a set for refrigeration pistons that work lovely

And yes the throttle cable has enough play. Should I switch the throttle itself to a 440s? I just used the pull portion on the 400s

The hanging idle only happens when I pull the clutch when I'm up to speed

the butterfly looks bentin the first picture on the cv32. So can't get it to idle riight with them. Any chance they Make a replacement part?

I would try to remove the bend butterfly and flatten it between two hard flat and even plastic plates with light taps.
The only difficulty is to loose the screws, they are widened with a notch to prevent loosen the screws.
Remove all parts in the carburetor port to get better access and prevent damaging other parts.
File carefully down the screw threads until to the butterfly shaft with a little file.
Before you loosen the screws support the shaft from the other side to prevent bending the shaft and take
a right fitting screwdriver and some pressure on it to loosen the screws.
So i rescued some carbs for my friends bikes years ago and they are running to this day.

Edit:
Make some position markings on the butterfly. The upper and lower edges have oblique surfaces
to get fully close the port.

Michael

I did wind up bending back the butterfly and she's pretty damn even now. I did not end up making an airbox. The one box.I did buy did not fit and I didn't want to go through hunting one down that not on amazon. I ordered new jets for the carbs, real k&n filters and some other goodies. We will see this weekend if I really need to hunt down an air box or of just jetting will help me. Thanks for the reply guys ad sorry I'm late on mine. Yahoo was putting kz400 emails in my spam folder