CO-% : measuring problems !

[FLATSIX]

Hi  ,

Here I am again with this obsession of turning my pilotscrews like they should be.

For that purpose I bought a relatively cheap CO-meter : "GUNSON DIGITAL GASANALYSER"

Once calibrated it seems to work, because I checked with an expensive 4 or 5-gasanalyser from a garage, and the readings were +/- the same, so for the few times I shall need that meter it will be good enough.

Now it comes: I made an extension tube and drilled several holes in it to be able to put the thing into the individual cut piggies and measure the CO-% in there.

It works and I start to take the measurements from the 3 on one exhaust, it goes like this = 4,7 - 4,7 and 5,1

When a re-check those 3 then I measure : 5,9 - 5,6 and 5,5 ???   The same occurs at the other exhaust.

I do the measuring with motor on fully operating temperature, the lower (first) measurements are obtained before the fan comes on (4,7 - 4,7 - 5,1) - when fans comes 2 or 3 times on then I wait till it stops and measure again - this second measurement are the higher readings in CO (5,9 - 5,6 and 5,5)

The higher measurements stay steady till I shut down the hot engine.

Can the CO-% get higher - in a sort accumulate, because the gas in that tube does not can come out freely because my measuringtube is in it to mea80% in it and that way I get first lower CO and later (saturated) higher CO-'s??

Perhaps I should drill more holes in my measuringpipe to let go away more gas ?

I REALLY DON'T UNDERSTAND - CAN SOMEONE TELL ME HOW TO DO AS I WANT TO PUT MY PILOTS FINALLY LIKE THEY SHOULD BE - now they are all 6 out 2,75 turns - bike has a lot of power - beautiful sound - high speed, only the exhaustfumes do smell a little rich .

I was planning to set all 6 first to 3% of CO (but then I think I will have that misfiring at the left side as usual) - then to 4% CO and hoping that at 2500-3000 rpm I will not have the misfirings.

Thanks for your help ! 

[CajunRider]

I would think it's more of a temperature difference changing your readings.  The fan turns on at one temp, then shuts off several degrees lower... the first measurement is taken before the fan ever comes on.

Remember, engine temp makes a big difference in the way gas will burn.  FI can somewhat adjust for this, but carbs can't.  Not on the fly anyway. 

I would say go with the first readings since 95% of your riding will be in motion where the fan usually never runs. 

[FLATSIX]

Yes, I agree.

But I did the measurements once again a few minutes ago, this is what they say :

Cold motor (choke just off) :  left: 4,3-4,5-4,4       right: 4,3-4,5-4,4

Warm motor :                             5,5-5,7-5,7                5,1-5,2-5,5

Hot motor (fan came on)               5,9 -......-.....            5,6- ......-...........

So the hotter the motor- the higher the CO-%,  I also measured with choke on, then I obtain 10 C0%, but that I can understand.

How can it be that with a hot motor the CO-% is higher then at a colder ???

Should I set them to 4 % with hot motor?

Thanks for your technical help ! cause I don't get it ???

[Patrick]

I think you will continue to have problems, as this has been tried in the past.. Look and see how how the muffler is made and I think you will realize that what your doing won't work.. You're getting a carbon monoxide reading from 3 cylinders rather than one, unless you're doing something that we don't know about.. Just like trying to sync at anything above an idle doesn't work,, trying to get individual exhaust gas readings by sticking a probe inside a 'piggie' in an attempt to set the individual pilots won't work..

[Ricky-D]

I agree with Patrick, the exhaust gasses mingle inside the can, to what degree is conjecture, but they do mingle. So any accurate analysis for an individual cylinder is unlikely.

Carbon monoxide is formed from incomplete combustion inside the cylinder.  Lack of oxygen.  And, in a roundabout way indicates too rich a fuel mixture.

Best results would be obtained from tapping each individual pipe before they get to the can and measure at that point.

***

[FLATSIX]

I agree Ricky-D, the best way indeed would be to take readings from each pipe before they go into the "por", but I don't want to drill holes in my nice pipes at this moment.

I see differences between the 3 piggies , shortly I will try to adjust till all are the same and co is max.4%. Then I will see what it gives, you might be right that what I am doing will not work, but I'll give it a try....

Afterwards I will have to do the carb synchro again, especially for Patrick I will do this synchronisation by the book : at 900 rpm all 6 extremely close - then I will do at test ride and I will feel or hear the difference. When it is better , then I will let you know and you are right! - when my method is better I let you know and I am right: we will see!

You hear the results very shortly

[Dag]

ADJUSTMENT PROCEDURE I USE WITH MY BLANKE SERIE 2500 ANALYZER

Idle adjustment:
The engine must be at full operating temperature.
Adjust the idle mixture screws until CO in the exhaust pipe is between 2-4%.

Cruise adjustment:
While in neutral, accelerate to 2500 RPM and hold for 20-30 seconds until CO stabilizes.
At this RPM, CO should be 1/4 to 1/2 of the CO at idle.

[FLATSIX]

100 times thanks, Dag, this is what I needed to do my adjustment! 

I plan to do the following- if not O.K., please say so !

1) another synhronisation of the carbs, but then at idle (900rpm) as now they are sync'd at 2500-3000rpm.

2) with the same vacuum at idle on all 6 carbs I adjust the pilots till all 2-4% of CO

3) a testride to see how it works (vibrations - response/throttle - feeling)

4) a new synchronisation but then at 2500 -3000 rpm so that all 6 have the same vacuum at cruising speed

5) check at 2500 rpm  with the CO-meter if CO is 1/4-1/2 of CO at idle (so is 1 till 2%CO)

6) last testride ..... and then hopefully SMILE !!!!!

Thanks, I let you know how things worked out.

 

[98valk]

Yes, I agree.

But I did the measurements once again a few minutes ago, this is what they say :

Cold motor (choke just off) :  left: 4,3-4,5-4,4       right: 4,3-4,5-4,4

Warm motor :                             5,5-5,7-5,7                5,1-5,2-5,5

Hot motor (fan came on)               5,9 -......-.....            5,6- ......-...........

So the hotter the motor- the higher the CO-%,  I also measured with choke on, then I obtain 10 C0%, but that I can understand.

How can it be that with a hot motor the CO-% is higher then at a colder ???

Should I set them to 4 % with hot motor?

Thanks for your technical help ! cause I don't get it ???

http://mysite.verizon.net/tweakmenow/af-emissions.gif   
 hotter motor, two things can be happening and/or combination of both 1. the intake air is hotter, meaning less air thereby increasing the fuel ratio to be richer. 2. the intake manifolds and inlet port of head are hotter thereby causing more vaporazition of fuel droplets

[FLATSIX]

Yes, the higher CO-% with hotter engine must be these two things. 

[alan]

From my experiences with cars in the 70's, mostly Mopars with multiple carbs like 3-2bbls and 2-4bbls with a variety of custom manifolds, you can tune those suckers to a gnats ass on any analyzer on Friday afternoon and after a bit of weekend "cruising" they will be different on Sunday afternoon.

When calculating the amount of weight a helicopter can lift you start at "standard air" which is certain air temp and humidity and barometer and correct to the existing conditions. I would guess as long as the temp and humidity and barometer keep moving so will your CO readings.

[FLATSIX]

The gaz analyser "GUNSON" has to be calibrated each time you use it - you have to let it adapt to the environment air/humidity/baromter conditions and set it to 2,0. Once it keeps this 2,0 (10 minutes) then it is calibrated and measures to 0,5% accuracy.

On the other hand the display is in big red digital marks : 5,1 for instance and easy to see and follow.

The purpose is to bring down the CO-% to a level between 2 till 4%, and then to correct each pilotscrew to have +/- the same AFR in each cylinder - the fact that these readings change afterwards does not bother me, they only have to be all 6 +/- the same mixture fuel/air.

It is like synchronising : they have to be the closest possible to each other.

I believe in this method and practice will show if it gives good results or if it is worthless.

I let you know my experiences when I have some time to do it very shortly.