inexpensive mods to a kz440

So ive been told that the kz's are pretty peppy bikes and with hardly any work and money you can make them go even better.....well, obviously a dirt bike has more power than most street bikes, so i think my kz440 is pretty gutless compared to 55 horse engine on a 215 lb dirtbike. What kind of mods can I do to this thing to give er' a little more horsey's? thanks.

header ,tweak the carbs etc,same things a 4-stroke dirtbike likes!goodluck,happy wrenching!

wireman wrote:

header ,tweak the carbs etc,same things a 4-stroke dirtbike likes!goodluck,happy wrenching!

what exactly do you mean when you say header? Like get an aftrmarket one.....or pull the baffles?? And for carbs. I know the basics of how they work and how to adjust them, should I just get them tweaked perfect as in mixture? or are there any other mods? I know with the dirtbikes, opening up the air box, pulling baffles and tuning the carb mixture to just right helps a bit.....but is there any other mods? Also, has anyone installed an aftermarket, more agressive cam in there kz before? if so, where did you get it and for how much?

xr350guy wrote:

obviously a dirt bike has more power than most street bikes

Bold statement -- I'm not as familiar with dirtbikes, so help me out: what dirtbike has that kind of power? Sounds like fun (actually like insanity, but I can call that fun). Of course to me, my friends 130 or so HP 400 or so pound Ducati is insane in a different way. And his is stock, well, as stock as a Ducati can be.

wireman was referring to replacing the whole exhaust: from the exhaust ports to the rear wheel area. Airboxes are pretty OK from what I have heard on street bikes. I ran individual pod filters for a week or two: the howling drove me away, but also told me how restrictive the airbox really is in factory form. But did I mention the howling?

If that is a chain model, I'd look at sprockets too.

But if you are really into the speed, any 600 or above sport bike from the 80's up will change your power ideas significantly. Find one of these KZ900's these guys are running: 1976 model, and the one I rode changed my concept of speed forever. A GSXR made me realize I could look at the road sideways at nearly triple the recommended curve speeds and still feel confident because the pegs were like 4 inches from touching. And hate it or love it, that Habusa thing is powerful. Look at Lorcans post a few days ago: his bike is uber cool, and an 84/85 to boot (well, the frame says so, doesn't it?).

Inexpensive is getting the biggest bike for your bucks. My mods for a 440 would come up to the price of an interesting bigger bike, but I would do suspension, brakes, and tires too, because HP only gets you there in a straight line, and doesn't stop you or get you around that corner.

Welcome to the forum from another newbie.

Comparing a dirt bike's power band to a street bike's power band is like comparing apples and oranges. You can, however, do some things to put more power to the ground. Rejet the carbs and put pods on, do WiredGeorge's coil mod (you can find it in the filebase), put a less restrictive aftermarket exhaust on, and play with your sprocket ratio. If you want faster off the line response, go up on the rear sprocket or down on the front sprocket. If you want faster top end, go up on the front or down on the back. When I bought my KZ550 I liked how it ran, but just wanted a little more pep. Rejetting the carbs, putting pods on, doing the coil mod, and changing my gear ratio helped to put my bike where I like it.

Bold statement -- I'm not as familiar with dirtbikes, so help me out: what dirtbike has that kind of power? Sounds like fun (actually like insanity, but I can call that fun). Of course to me, my friends 130 or so HP 400 or so pound Ducati is insane in a different way. And his is stock, well, as stock as a Ducati can be.

a piped honda crf450 will put out 55 horse, and that bike weighs 219 pounds, a stock husaberg fc450 will put out 65 hp stock, and weighs about the same. Even though the ducati puts out 130 hp, it also twice the weigh. So my guess, weight to power ratio, the ducati and the husaberg are about the same. So, what size jets are you guys running then? Whats stock and how many sizes should I jump up?

It depends on what you plan on doing. If you are going to be running pods, go at least two sizes up on the main jet and reclip the needle to the next one down (assuming it is adjustable).


As for your assumption about the Husaberg and the Ducati, not even a comparison. They were bred for very different applications, so thier power bands are very different. So please, stop comparing a dirt bike to a street bike, two different animals.

I would say that around 90 percent of all older bikes (like a KZ/GS/XJ/CB etc) could be made to run much better by doing basic tune up techniques and overcoming problems associated with old age... poor spark, bad rubber bits, etc. Most motorcycles; even those that are 30 years old have more pep than most other things riding on tires on any road. If you are interested in performance, I suggest you get the most out of your 440 without putting a large amount of money into it then work your way up the food chain as far as displacement and performance go. It is far cheaper to buy three times the power your bike has than try and add it to your bike. Doesn't matter what you ride...

2-1 exhaust system, individual filters, sprocket change for more accleration. Put flatter bars on it. Makes you lean forward and makes you think you are going faster.

I had a KZ400 when I was little: great bike, right price, cheap on gas, reliable, not too heavy to pick up when I fell over, cheap insurance. It was also a great bike for someone to gain experience on until they were ready for a buttrocket. Theres a limit to what you can do with the displacement and number of cylinders. It'll be a great daily rider but it will tire you out running down the highway. I put a cafe fairing on mine and flatter bars, and yeah I thought that helped a bit, mainly with staying out of the wind, could never get it much over 85 though. I agree with wiredgeorge, get it running good, don't spend a lot of money on it, enjoy and save up.

DasTeufel wrote:

It depends on what you plan on doing. If you are going to be running pods, go at least two sizes up on the main jet and reclip the needle to the next one down (assuming it is adjustable).


As for your assumption about the Husaberg and the Ducati, not even a comparison. They were bred for very different applications, so thier power bands are very different. So please, stop comparing a dirt bike to a street bike, two different animals.

thanks fore your input, but the question was..what kind of dirtbike has that kind of power, and i was comparing the weight to power ratio, not the bike it self. Im not an idiot, I dont need you telling me that they are two totaly different bikes!

Back to the original question...

I hate to be a wet blanket, but if performance is what you want, a KZ440 is probably not what you want to start with. A couple of other people have said something along those lines, but I'm not sure any of them has done 350 miles of I-95 on a KZ440 in one day...

The motor ain't got the oomph, & if it did, the chassis couldn't take it. The chassis can barely take what the motor does have: when I went over 75MPH on that bike, it was like hitting a "vibrate" switch, & I thought it would shake apart under me when I hit 85. (The left mirror did actually shake apart about halfway there, & something killed the motor 50 miles into the return trip.) That was on a bike with Progressive shocks; I'd hate to think what that trip would've been like on the stock shocks...

My advice would be to appreciate what you have: a great city bike that'll still smoke most any car stoplight to stoplight.

Cheers,
-Kit