A/F Ratio Meter via OMR

Actually Ron... Not a stupid question at all for your correct where miss readings would occur as you mentioned... For the highest degree of accuracy, you'd want a sensor (x4) on each of the header primary tubes...

Unfortunately, NO FREAKING way I'm drilling holes in my Kerker! :S :laugh:

Same time, I'm not planning on using any of this to control anything or leave permanent, as mentioned, only measurements to aid if I'm in the ball park in my jetting. Also, being mechanical Carbs, no possible way to electronically control my CR's so no use even discussing further...

Makes you wonder how accurate these Dyno measurements are don't they for they use an exhaust tube sesnor copper tube insertion and if sensor heating is required for accuracies then they must be using narrow band sensors....

All of which truly only provides the 14.7:1 mixture or way lean/rich! :ohmy: Hmmm... Interesting indeed....

Ah well, off I go... I'll keep you posted as I learn more...

OMR

Old Man Rock wrote:

Unfortunately, NO FREAKING way I'm drilling holes in my Kerker! :S :laugh:
OMR

Drill holes to install what? Say it! :laugh: :laugh: :laugh:

In seriousness, though, if we go on the assumption that all four cylinders are in about the same condition (compression, valve clearance etc) and we are able to clean and rebuild each carb to the same degree, we can get away with one sensor at the collector.

For normal street use, we don't change jets everytime the weather changes by 10 degrees, and we don't have to. Normally we'll be jetting to the rich side of things and that will allow us to operate in a wide range of temperatures. Because of this, we don't really have to be worried about small temp differences in the cylinders.

Now if we are talking about racing, then yes, we will jet based on temp, humidity, barometric pressure etc. In that case we may want an o2 sensor on each header. But on normal street use, we are looking for overall drivability.

So we have to make compromises. We jet on the side of richness. This puts us rich in hot weather, but prevents lean conditions in cold weather. It doesn't have to be super precise if we are looking for good drivability. It only has to be precise if we are racing, but if we are racing, there is no one combination that will maximize power for all weather conditions.

Last summer I must have made over a dozen jetting changes (jets, needles, air-screw adjustments, etc) and the overall drivability didn't change a whole lot, but you could tell that the power was most notable at different temperatures based on the how rich it was. Generally, the richer it was, the faster it felt at lower temps. But if it was little leaner, the bike took longer to come off choke, but would really scream on hot days.

I don't think this is really news to anyone. I think we all know that the colder it is, the richer you will want to be. It would be wrong to think there is one perfect jetting combination that can give max power and max drivability under all conditions. Like I said, getting good drivability under all conditions is possible, but it compromises maximum power.

yamaha has for years have had rivnuts installed in the head pipes of most of their carburated multi cylinder bikes to allow taking individual ega readings we always tuned each carb independently at idle and part throttle settings

you guys are making my head hurt! :woohoo:

Old Man Rock wrote:

...Unfortunately, NO FREAKING way I'm drilling holes in my Kerker!....

Not to worry.
Some of these bungs can be made to look really nice. :lol:

Nobody wants to say bunghole, do they?! :lol:

OK, I think I have my first accurate measurements... In following the graphs and charts available on line, seems about right....

NOTE: These where not load tests!

Based on the math between the two sensor outputs (VS/IP & VS) measurements are as follows...

A/FR = ( 2 x Vdc Diff bwn VS/IP & VS ) + 10

Idle A/FR @ 11.4
4Krpm A/FR @ 12.83

Now onto a road test/measurements for mid range @ 4k - 65Krpm is where I want the measurements for power in my build to be @ 13.5 - 14.0....

LoudVHX... That seem about right from your design/testing?

OMR

I'm sure this will be answered when OMR posts the results from his load tests, but I'll ask anyway.

Does the mixture get richer under load?

Anybody have a quick and dirty explanation why?

Thanks

Just more amateuristic musings....

I don't think load necessarily affects lean/rich. If it does, it would be to the lean side as the engine would be trying to burn more fuel (?) under load.

On a more serious note.
BUNGEHOLE, BUNGEHOLE , BUNGEHOLE.:woohoo: :lol: :silly:

exhaust temperatures are also a variable that is required for accuracies.....

In review of the "Load" question, the engine would work harder under load henceforth run hotter that will fluctuate the sensor readings....