TOPIC:

So, what kind of fuel economy is NORMAL for a 1978 KZ1000? Because as it stands right now, I'm getting about 15 mpg, and that just CAN'T be right...
I rejetted my carbs, so now I'm running #102.5s and 17.5 pilots.
What can I do????? Please help....ANYONE???

Sumpn's wrong.

I get about 40 mpg on my '78. My jets are 107.5/17.5.

Have you done any/all of the following:

Check/adjust points
Coil Power Mod
Check/Adjust Valves
Check Brakes/Wheel Bearings
Clean Carbs
Sync Carbs

15mpg is all but impossible. Over the years I've dropped below 30 a couple times when the carbs were out of sync. This can hurt your mileage. Otherwise I could always depend on 35-40mpg, sometimes even 45-50.

Haha....thanks

RonKZ650 wrote:

15mpg is all but impossible. Over the years I've dropped below 30 a couple times when the carbs were out of sync. This can hurt your mileage. Otherwise I could always depend on 35-40mpg, sometimes even 45-50.

Well, impossible or not it's what is happening to me right now. I filled up my 3 gallon tank a few days ago, drove it about 42 miles and had about a quart of gas left in the tank before refilling with another 3 gallons.
I KNOW something is wrong, I just don't know what and that's why I posted

How much milage were you getting before or at least do you think you were getting. My bike was dumping a bunch of fuel into the crankcase when the bike was parked. The mission case is cracked from my t-shirt getting sucked into the chain at about 50mph on Lakeshore Drive. My back wheel locked up for 100ft or so then I got lucky and the chain popped off. The pressure of the shirt in the chain cracked the mission cover. I put the chain back on and rode that way for awhile until I noticed that oil was blowing all over my back wheel and chain out of the mission cover. Very scary. That's when I realized I was dumping tons of fuel into the crankcase. Sorry for the long story, I just wanted to tell it.

I drop sizes in jets, from 125 to 112.5 and figured that a smaller jet would improve mileage, but it hasn't changed a bit.

With that kind of milage I would guess you have a leak somewhere. Most probably a needle valve or two or three that aren't closing and you are losing it to the ground or into your crankcase. On the highway I will get as high as 52 MPG, if I keep it under 60, and about 40 to 42 around town. Better check. A leak that bad could be dangerous.

I agree that you probably cannot get mileage that bad except by leaking the gas. If the gas is not in your crankcase, it is going onto the ground. If it leaks while you are parked, you should notice the gas on the pavement. If you do not park on pavement, park on top of a mat, or a piece of cardboard, then you will see the problem. If it is only leaking while you are riding, then the leak is somewhere downstream of the petcock. Check all of your lines, float bowls, and overflows, and see what you learn.

There is also the possibility that someone is stealing your gas. Since I grew up in New Jersey, I have heard of such a thing.

My bike was gettin 50 miles to the tank when i first
got it after spendin 200$ gettin the carbs fixed i
got 55 miles to the tank. found out the accelerator pump diaphragm had a hole in it fixed it myself for 9$
now i get bout 110 miles-3 gallons i couldnt find it leakin it was just blowin out the exhaust.

Do you have a vacuum petcock. I was getting pretty lousy gas mileage for a kz400 (~20 mpg) and when I talked to my mechanic and told him that along with my carboned up plug, he checked and found my diaphram cracked.

Not sure if it fixed the problem, still haven't gotten the bike back yet.