I have seen mentioned in many rejet & max HP discussions that the only way to really tell if you got optimum jetting is a with a Dyno and an Exhaust analyzer.
Since there is probably no DYNO I can get my hands on and it sounds like they are about $50 a session I am thinking I would consider an exhaust analyzer as it cant hurt. Also I like tools!
I did a quick ebay search and see that they are priced there from $35 for a 1970s version to $1700 for a "4 gas model with printer"
I have a couple used CO moniters that I could put into service with a new $90 cell they are from breathing air compressors but I think I could adapt them to flow exhaust thru the sensor and CO is CO. I also have 02 sensors and could wire them into panel meter to read out in %02 so I could easily mesure both those gasses & would cost me less than $200 to build a 2 gas analyzer. although I think my O2 analizers tempature stabilization circut may be insufficient to handle exh temps since it usually has to compensate for cooling not heating.

Here are my questions
1. Would 02 and or CO be sufficient to determine optimum air to fuel ratio?
2. anyone here have some experiance and willing to throw out some free tribal knowalage?

 

I suppose it would be an adventure if you had the time, but I'm not sure it's worth the trouble.

The O2 sensors used for the purpose you desire need to be of the 'wide band' variety and are made to withstand considerable heat. If you just have a bunch of stuff laying around and wanted to give it a go, I suppose there'd be no harm done though.

 

The heat is not the issue, any automotive 02 is built for the same environment. What you need is a 4 wire, heated sensor with a 0-5V output, but you also generally need a controller to heat it, and convert the 0-5V output to a meaningful value.
Do a google search for wideband 02

 

What you need is a wide band CO system. The circuitry for it is very complex. The cheap air/fuel systems are narrow band and will only be accurate at 14.7:1 ratio. I built one (narrow band) several years ago just to see how valid the claims for them are.

Ride on
Brewster

 

Pretty much.

There are other factors involved, but O2 and CO by themselves will get you pretty close.

CO is produced when combustion is not complete. High CO indicates a rich air/fuel ratio mixture. If the air/fuel ratio is just slightly richer than the stoichiometric range (14.7:1) CO will increase rapidly.

The O2 that the sensor sees is the O2 remaining after combustion. With a lean condition there is incomplete combustion and there is O2 left over. So, with a lean condition, O2 rises. On the other hand, if the mixture is rich, there will be too much fuel in the cylinder and all of the O2 will be used up. A lean condition gives high O2, a rich condition gives low O2.

If we start with a lean condition and start adjusting for a richer mixture, there will be a cross over point where O2 and CO are both zero. That (or maybe slightly richer) is where you want to be.

One problem I see is that you may not be able to get as much resolution with your sensors that you need.

Have fun.

Ron

 

I have an LM-2 Air/Fuel ratio meter from Innovate, I use it to do jetting on all the bikes I work on.

After using it I can't see being with out one, the jetting can be way effin' off the bikes still kind of run. Even very small changes to idle circuit or air box make huge difference in A/F ratio. Without a way to MEASURE the A/F at different RPM and throttle openings, I have no idea how anyone would ever get the jetting right.

With the meter you can see the effect of every change and analytically bring the A/F to about 13 across the throttle opening range. Then from there you can optimize things like throttle response and "snap" just by the feel during test runs.
But the meter is invaluable in bring things to +/- 5% range of the optimal.

Right now the meter is hooked up on the KLX while I'm working on a TM33 I got off Ebay. With just "seat of the pants" testing I'd be dorking with it for ever....

--
Mikko

 

There's more to it than just measuring the contents of the exhaust. You need to be able to load the engine so that you can very the throttle opening (and CVslide position) to varying degrees at varying rpms.

 

Both points are correct.

The exhaust gas analysis gets to very close to optimum. Much closer than simply doing guess work based on "seat of the pants". But for the last little optimization you can use dyno or just tweak for best throttle response.

And obviously all work is done with load on the engine.
Either on a dyno or riding the bike with gas analyzer hooked up. Only idle settings can be adjusted with bike sitting in neutral.

I really like doing the work with meter hooked up while riding the bike in real conditions. Then you see all the funky things that happen when you vary the load/RPM/throttle opening.
Many times there is a bog or stutter or what ever "flat spot" that shows up in specific riding situation. With portable A/F meter you can actually see what happens when you feel the bog.
Then you can focus on how to fix that and not trying to guess why it boged.

--
Mikko

 

Flying fin Thanks for the input. What did you pay for your unit if I may ask?

RE wide range Oxygen sensor putting out 5V- The o2 sensors I have put out milivolts and we use them from about 8% to 100% which is a very wide range. I can use them while rideing and mount the display on the dash. I am thinking I would run the exh thru some 3/8 stainless across the sensor face and then out to atmosphere. Letting it cool a little.
It sounds like I dont really need super acurate readings of actual percentage but I need comparison and look for the peaks/valleys.

RE CO moniters the ones I have may be pretty narrow range and are also low range as they are reading in PPM and are calibrated with 20ppm. So I think the PPM of unburned fuel would be out of range high.

 

I didn't ever find any "deals" on the LM-2 so I paid what ever was the lowest retail I could find at the time. Can't remember anymore where I bought it from but I'm sure it was very close to the current MSRP of $350
http://www.innovatemotorsports.com/products/lm2.php

Earlier I've only used welded bungs on the exhaust header for the O2 sensor but this time I decided to try something else.
I have a contraption now that allows me to sniff the exhausts from the end of the pipe without getting outside air mixed in.

I'll take a picture of the setup later when I get home.

--
Mikko