Adjusting the air/fuel mixture

[mat...@ecf.toronto.edu]

Hi,
I think I've finally understood what's wrong with my bike (thanks to the
generous help of people from rec.motorcycles.tech... thanks!) ... the
air-fuel mixture is wrong in one cylinder.

I guess it is too lean because when I cold-start the bike, the right
cylinder misfires badly and is noticibly cooler. After I ride for a while
the right cylinder is hotter and turns the exhaust pipe manifold a
different color.

My bike is a Kawi KZ440. I couldn't see any adjustment screws on the carbs
other than the throttle stop, and the screw that syncs the carbs. How
would I adjust the air-fuel mixture for one cylinder to make it richer?
Would I have to remove the carbs, and open them? I checked my Clymer
manual a couple of times but this was not mentioned (it talked about idle
mixture only).

Thanks!

[Palle Clausen]

Hi,

The idle mixture screw is actually the same as the air/fuel mixture screw.
As far as I remember, the screw is located on top of each carb at the engine
side of the carbs. Its a small brass-like screw, probably covered by a small
cap.

From your description, you probably need a full synchronisation of your
carbs. This requires the use of a vacuum gauge to be done correctly, and is
maybe better left for a mechanic to do?

If you want to give it a try yourselves (and hope that the carbs doesn't
need syncchronisation), you should start by turning both mixture screws
fully in (do not overtighten), and turn them 1 3/4 turn out.

Start the engine (it should be working temperature) and set the idle stop
screw to approx. 1200 rpm.

The mixture screws should now be unscrewed by an equal amount in 1/4 turns
until the engine runs at the lowest possible idle speed with becoming
hesitant or misfiring.

Use the throttle a couple of times, and check/reset the idle stop screw to
1200-1300 rpm.

If it still gives problems, you will most likely need a carb
synchronisation.

Good luck,

Palle
KawaZ400

********************

mat...@ecf.toronto.edu skrev i meddelelsen ...

[TriRyder79]

hi, just wanted to offer a few suggestions,
the idle mixture screw does adjust mixture.
i would check for a vacuum leak at the intake where the carb bolts to the
head,or the valves on that cylinder could be slightly over adjusted, or the
needle setting in the carb could be wrong...so...all of those are
possibilities..check them all... you can sync the carbs with two vacuum
gauges...good luck

[Tim Root]

How about a clogged pilot jet in the carb? I had one on my '82 KZ1100,
damn thing would start on 3 cyl and generally only idle on 3 till I
hauled the carbs off, flipped 'em over, removed the float bowls one at a
time, and cleaned out each jet. #1 pilot was surely clogged. After
replacing them, all was fine. The symptom was a cold pipe on #1 till I
got a mile from home or so, then she's pick up fuel whenever I was over
1/4 throttle. Give it a whirl if all else fails.
--
Tim - '88 Concours
"The Red Flash"
COG # in the mail
"Is what you're doing
getting you where
you want to go?"