1980 kz440

hello, i bought a kz440 that didnt run and got it running recently it runs really good as far as idling, i dont think it could idle any better but when i ride it there is a lot of stuttering and boging down i just have cheap pods on it because it didnt come with airbox my question is would it be cheaper to rejet or just get the stock airbox i am trying to keep cost as low as possible i dont know how much jets are or where to get them

thanks!

From what some other knowledgeable folks have reported, the KZ440 needs the stock airbox properly installed to run right. Apparently, the stock CV carbs are sensitive to changes in the stock setup & air leaks.

Yeah, I'm an airbox advocate too, but it should still *run* either way.

Since you mention the stuttering and bogging, but a perfect idle, you need to look at the things that occur as the bike rises in rpm. By that, I mean your auto-advancer (make sure it is extending to full advance), your carb diaphragms (make sure they don't have holes or tears), your main jet (probably need to go larger without airbox), and also make sure those pods aren't blocking any of the tiny passages around the outer lip of the carb.

I'm a stock air box fan myself.. you can mess with exhaust without Honda fears of cherry red valves.. chuckle, but the box is the only true cure when your stuck with cv carbs, imo.


After checking what others have already mentioned, air mix settings, boots for cracks/rips, intake rubbers for the same, timing advance working right, blocked holes on intake side, etc.

(I hate cv carbs... oops did I say that out loud!)

I've have problems with both 440s and 750s that came with the original air box missing.. so I came up with a quick simple little cure that at least gets you a smooth throttle through the curve until you can replace the stock air box. Might still get an odd pop or crackle here and there.

(1) Grab yourself a $1.00 bag of cheep sponges. I usually cut say a 2 inch thick one in half with a razor knife, like lengthwise, then wrap it (for the time being) around the cheap air pod and use a couple big elastics to hold it in place. Once I have it cut to the size it needs to be I attach it permanent with good ole zip straps.

(2) I turn the air mix screws to the factory starting place and fire it up, do a light adjustment in lane if you have to and take a screwdriver with me and go for a ride, pull over and make adjustments if needed, as I test all the throttle ranges for smooth operation. Once home, if you have them, you can put on a set of vacuum gauges and fine tune, but usually you can get it close to perfect by ear.

On occasion I've had to remove the cheap foam and thin it out a bit, or just remove a slice and give it a bit more air flow, some have required a little dabbing of oil to increase the constant flow... I'm sure it sounds silly but, it'll let you work them junk air pods into creating some constant air velocity for you and save you from further hassle (aka ripped boots) until you can get the box...

thanks i will definitly give that a shot....i found a 1982 kz440 airbox on ebay, does anybody know if that would work for my 1980 kz...im building a custom framing so i dont care about it fitting any the actual carbs...i would think they have the same carbs on both models but im not sure and dont want to order it and it be the wrong o.d. on the boots thanks!!!!

Use the cross-reference at Kawasaki.com - the KZ440s have different airboxes depending upon the model (standard/ltd &/or year). To reiterate the KZ440 w stock carbs is known to be virtually impossible to tune without the stock airbox.

Now, you could get different carbs & use the pod filters.
Here's a topic - My Custom Bobber 440 ... And a quote:

harm-
Thanks for the good comments! The manifold was made using copper tubing, I believe 1.5" diameter. I took 3 90's and brazed them together. I'll post pic tonight.

The carburetor is a mikuni cv off of a 2004 kfx400 atv. I added larger jets and shimmed the needle. I need to get a bigger pilot jet for the cold mornings...