MPG's Does this sound right??

Even my piped and re-jetted GS1100 was getting a combined 39 mpg

You might have weak compression, or simply over jetted. Have a look at the plugs, if they are sooty black now you know your rich. It's very common knowledge that pods kill bottom end hp, and fuel economy, but your numbers seem pretty poor.

My honest advice put the stock airbox back on (If you have it) revert back to stock jetting, and you will gain street friendly hp, and gain 15 mpg !

So do you think changing the sprocket to 17/38 would be pretty good. Also a new chain.

One correction, 16/40 is stock for a KZ550A. The gpz is 16/38.

So you already have stock gearing. I wouldn't recommend changing sprockets.

However, do they look worn? Then they should be replaced with chain. Sprockets are pretty cheap.

Since you say the bike runs fine, and the plugs look tan, then either you are leaking gas somewhere, or there is some drag on the bike while you are riding.

I wonder if the carbs are leaking out of the drain hoses when you are moving. You would likely smell a strong gas smell when you stop, though.

Does your front brake disk look blue or otherwise discolored? If so it may be hanging up. That'll require rebuilding the caliper to clean out the seal groove.

Make sure the back brake is adjusted to be free.

Do you think 17/38 would be too high geared?

I still think the RPMs are high.

The sprockets are a little worn I was planning on getting some anyway. Can you just flip the front sprocket and run on the back of the teeth, it doesn't have any offset to it? I think the chain being old may be a little problem. Looking at a new o-ring chain. I don't think the one on there now has o-rings.

I'll do the clear tube test and see if my floats are right. I don't smell any gas when stopped. But if I leave my petcock open over night it makes the garage stink. I usually shut the petcock off as I come onto my neighborhood so I won't have much gas setting in the carbs.

andy9802gt wrote: My bike gets about 35mpg so I would be really dissappointed by getting less than that on a little old 550.

I remember getting 45 mpg on my 1000 , I hope it still gets it when it's running again.
of course I put on some weight since then. :whistle:

I think your a big dude on a small bike, what happens when you have a passenger ?

JD

Hi Flyn,I believe there is something going on with the tuning of your bike other than gear ratio. Even if you ride it hard, the mileage should be much better than what are are getting. My KZ 650 E gets over 50 MPG with my wife and I on board, and we're not light weights. A good carb cleaning and tune up seems to be in order. Check the timing and the advancing mechanism before trying to change the gearing. I would venture to guess your mileage, with a properly tuned engine should get 55 plus MPG, or even more. Bob

loudhvx wrote: I wonder if the carbs are leaking out of the drain hoses when you are moving. You would likely smell a strong gas smell when you stop, though.

Had this issue - never noticed it myself - my buddy rode behind me and said it stunk like fuel. You may not notice it, someone behind you in your exhaust stream might.

So I think I may have found some of my problem. I was trying to do the clear tube test (which I think is a pain in the a**) and my no 1 carb was going way up. I think the float needle was not seating, so I've been probably just dumping gas like crazy. I've tried cleaning it up a little. I put the needle seat in a piece of tubing and blew through it, using the needle to stop ,the air seemed to work better. We'll see tomorrow when I can put it back on the bike.

I still am going to change the sprockets a little to see if it will help on the highway. I'm not going to be drag racing anyone with my little 550.

Flyndrive wrote: ...trying to do the clear tube test (which I think is a pain in the a**)....

Clear tube test should be quick, easy and painless.

If carbs have the combo overflow/drain screw, just attach the tube to the overflow nipple on bottom of empty bowl, hold the free end steady against the carb, and allow gasoline to flow by opening the screw about one turn.



Good Fortune!

It would probably be easier if hey were on the bike, but then you would have to take them back off if you had to adjust something. Not that it is hard to do, just my situation wasn't ideal.

.

Of all the carbs i've checked, I think the tk-22's on the 550 are the easiest to check fuel level since they already have the valve and pipe feature built in. But it's still not fun. you have to play with it a lot to make sure you have the correct reading.

As Martin mentioned, if there is a ring on the tip of the needle, you will have problems. As the needle rotates, it may seal in some positions, but not others. You would do yourself a big favor by replacing the needle and seat on all 4 carbs if they have the rings. You can get just the valve and seat from Z1 enterprises. They also come in the rebuild kits, which usually come with adjustable needles and extra jets.

FYI, the new needles and seats will usually require a considerable change on the float tongue. The needle seems to sit taller when the carbs are upside down.

However, if you were dumping that much gas (like half of your gas) I would expect you to smell it unless you only ride on the highway. Maybe, as DoubleDub mentioned, you need someone to take a ride behind you. Also, on right turns, I would expect the occasional slip of the back tire.

By the way, your bike was originally equipped with a vacuum petcock. There is no "off" position until the motor actually stops turning. Then the off position is the same as the on position (straight down).

If you notice, there is a lot of kz550 info in my signature. Carb details and kit info is available there.