Proper way to adjust fuel mixture?

[infinkc]

Been trying to adjust my carb since its running rich, by looking at
the manual the screw on the side which you adjust the mixture inwards
(clockwise) to decrease, outwards(counter clock) to increase. How do
i properly determine the optimal fuel setting? turning the screw to me
had no effect. The manual says to use a CO meter but how many people
at home have one of those handy. I was thinking on running an o2
sensor on the car for easy adjustment with a meter, has anyone added
one? if so at what point of the exhause was it added? I just know
there has to be an easy way to adjust this thing.
-Kris

[dana]

Turn the screw in (clockwise) and back it out 1 to 1 1/2 turns. If you move
it out more, you will experience an intermittent miss at highway speeds.
Richard Morris
-----Original Message-----

[MarkN]

Hi Kris-
I've been using an Innovate Motorsports wideband O2 setup (search on
google) to tune mine. It's pretty cool; you can log throttle position,
rpm and mixture all at once and then make adjustments to the carb and
see if you're going the right directions with your adjustments.
Before I rebuilt the my honda's motor, I had it running from 13:1 to
15:1 (air fuel ratio), depending on throttle position. I'm super
paranoid about running air cooled motors lean, for fear of total meltdown.
It's an expensive tool (starts at $250 ish, gets into $550 range with
a few options) and it requires some learning and wiring and welding in
a bung for the sensor and a laptop and a throttle position sensor
(potentiometer).
When I rebuilt the motor (haven't tuned it yet) the machinist I was
dealing with complemented me on the shape that my valves and seats
were in, saying, "Whatever your doing, it must be right, 'cause these
valves don't show any pitting like you'd see if your mixture was off."
-Miles E.

--- In
2cylinderhondas@yahoogroups.com
, "infinkc" wrote:
> Been trying to adjust my carb since its running rich, by looking at
> the manual the screw on the side which you adjust the mixture inwards
> (clockwise) to decrease, outwards(counter clock) to increase. How do
> i properly determine the optimal fuel setting? turning the screw to me
> had no effect. The manual says to use a CO meter but how many people
> at home have one of those handy. I was thinking on running an o2
> sensor on the car for easy adjustment with a meter, has anyone added
> one? if so at what point of the exhause was it added? I just know
> there has to be an easy way to adjust this thing.
> -Kris

[zinc2u]

You mention in your msg that turning the idle mixture screw had no effect on
the rpm. Are you able to set the idle rpm at 1100 and does the engine hold
the speed at 1100 or does it exhibit problems (surging, varying up and down,
or runs for a little and stops). If you are not able to set the idle rpm at
1100 (using the throttle stop screw), you have a plugged idle circuit on
your carb. You will need to clean the carb.
Before taking the carb apart, verify you have a tight connection where the
carb meets the intake manifold (the rubber inlet piece). Also, there is an
o-ring under the inlet where it enters the engine which can cause idle
problems if you are getting air leaks.
Also, check that you do not have a dirty air cleaner which is restricting
air flow (you can temporarily remove the air filter).
You mention that your carb is running rich. Have you checked the float
level? And check the needle and seat at the float to see if it is shutting off
properly.
good luck,
Dale
Been trying to adjust my carb since its running rich, by looking at
the manual the screw on the side which you adjust the mixture inwards
(clockwise) to decrease, outwards(counter clock) to increase. How do
i properly determine the optimal fuel setting? turning the screw to me
had no effect. The manual says to use a CO meter but how many people
at home have one of those handy. I was thinking on running an o2
sensor on the car for easy adjustment with a meter, has anyone added
one? if so at what point of the exhause was it added? I just know
there has to be an easy way to adjust this thing.

[friend]

Just a note of caution:
If you need to replace the "O" ring under the intake manifold, an "O"
ring too thick can cause you to crack the base. Too thin and it will not
seal. I believe Honda still has them # 91325-568-000. If not, I still have
a few.
Bill
-----Original Message-----
From: 2cylinderhondas@yahoogroups.com
[mailto:2cylinderhondas@yahoogroups.com]On Behalf Of goinhm@...
Sent: Thursday, July 06, 2006 11:55 PM
To: 2cylinderhondas@yahoogroups.com
Subject: Re: [2cylinderhondas] Proper way to adjust fuel mixture?
You mention in your msg that turning the idle mixture screw had no effect
on
the rpm. Are you able to set the idle rpm at 1100 and does the engine hold
the speed at 1100 or does it exhibit problems (surging, varying up and
down,
or runs for a little and stops). If you are not able to set the idle rpm
at
1100 (using the throttle stop screw), you have a plugged idle circuit on
your carb. You will need to clean the carb.
Before taking the carb apart, verify you have a tight connection where the
carb meets the intake manifold (the rubber inlet piece). Also, there is an
o-ring under the inlet where it enters the engine which can cause idle
problems if you are getting air leaks.
Also, check that you do not have a dirty air cleaner which is restricting
air flow (you can temporarily remove the air filter).
You mention that your carb is running rich. Have you checked the float
level? And check the needle and seat at the float to see if it is shutting
off
properly.
good luck,
Dale
Been trying to adjust my carb since its running rich, by looking at
the manual the screw on the side which you adjust the mixture inwards
(clockwise) to decrease, outwards(counter clock) to increase. How do
i properly determine the optimal fuel setting? turning the screw to me
had no effect. The manual says to use a CO meter but how many people
at home have one of those handy. I was thinking on running an o2
sensor on the car for easy adjustment with a meter, has anyone added
one? if so at what point of the exhause was it added? I just know
there has to be an easy way to adjust this thing.

[infinkc]

Miles-
my friend has the same unit which i plan on using, where did you put
the o2 bung? thanks
-kris

[MarkN]

Kris-
I welded in my bung (heh heh) about 10" downstream of the
header/downtube joint. No particular reason for that distance, it's
just were I had space. I've made my own headers, etc, so your mileage
may vary.
-Miles E.

--- In
2cylinderhondas@yahoogroups.com
, "infinkc" wrote:
> Miles-
> my friend has the same unit which i plan on using, where did you put
> the o2 bung? thanks
> -kris
> --- In
2cylinderhondas@yahoogroups.com
, "wanna600"
> wrote:
> > Hi Kris-
> > I've been using an Innovate Motorsports wideband O2 setup (search
> on
> > google) to tune mine. It's pretty cool; you can log throttle
> position,
> > rpm and mixture all at once and then make adjustments to the carb
> and
> > see if you're going the right directions with your adjustments.
> > Before I rebuilt the my honda's motor, I had it running from 13:1
> to
> > 15:1 (air fuel ratio), depending on throttle position. I'm super
> > paranoid about running air cooled motors lean, for fear of total
> meltdown.
> > It's an expensive tool (starts at $250 ish, gets into $550 range
> with
> > a few options) and it requires some learning and wiring and
> welding in
> > a bung for the sensor and a laptop and a throttle position sensor
> > (potentiometer).
> > When I rebuilt the motor (haven't tuned it yet) the machinist I was
> > dealing with complemented me on the shape that my valves and seats
> > were in, saying, "Whatever your doing, it must be right, 'cause
> these
> > valves don't show any pitting like you'd see if your mixture was
> off."
> > -Miles E.
> > --- In
2cylinderhondas@yahoogroups.com
, "infinkc" wrote:
> > > Been trying to adjust my carb since its running rich, by looking
> at
> > > the manual the screw on the side which you adjust the mixture
> inwards
> > > (clockwise) to decrease, outwards(counter clock) to increase.
> How do
> > > i properly determine the optimal fuel setting? turning the screw
> to me
> > > had no effect. The manual says to use a CO meter but how many
> people
> > > at home have one of those handy. I was thinking on running an o2
> > > sensor on the car for easy adjustment with a meter, has anyone
> added
> > > one? if so at what point of the exhause was it added? I just
> know
> > > there has to be an easy way to adjust this thing.
> > > -Kris

[infinkc]

Thanks just wanted to make sure i dont put on too far down the
header, not sure if it would hurt the readings or not. If i cant
find space on the stock heater tube header i guess it gives me a
reason to put the hawaiian/japanese header on thats been sitting in
the shed. sounds like a fun weekend project.

[tommyjayallen]

The o2 sensor should be as close to the junction of the two pipes as possible for temperature reasons. The cooler the exhaust temp., the less accurate the reading. Also, the non U.S. spec exhaust system will not fit on an American model head. The Euro heads have angled exhaust ports.
infinkc wrote: Thanks just wanted to make sure i dont put on too far down the
header, not sure if it would hurt the readings or not. If i cant
find space on the stock heater tube header i guess it gives me a
reason to put the hawaiian/japanese header on thats been sitting in
the shed. sounds like a fun weekend project.