New Gas Analyser for my GS

[terry]

Well I got bored on the weekend, it was cold and wet (C'Mon Summer!) I didn't have any orders for oil cooler adapters to build, so I went back to an earlier project, where I bought an exhaust gas analyser from Jaycar electronics in kit form.

It was too scary for me to contemplate, lots of little diodes, resistors and led's etc, so I got one of my staff who was a telephone company technician to assemble it for me. It's a good unit, and has both a digital readout for the oxygen/gas ratio, and an LED bar graph for lean - rich readout. (looks kinda cool, I'm thinking about mounting it on the bike permanently)

Anyway, it had been sitting on my bench for a couple of weeks, so I drove over to a car wrecking yard and bought a single wire gas sensor (looks like a little spark plug) from a little jap fuel injected car, and punched a hole in my exhaust just after the 4 into 1 collector, welded in a special nut that I modified to suit.

Then with a little judicial wiring last night I hooked it all up, and it seems to work! I say seems to work, because my battery was so flat it wouldn't crank the engine, so I put it on the charger and I'll try to fire it up today to check my readings. Anyway, have a look at the site (you'll have to wade through all the oil cooler stuff to get to the pics) and tell me what you think!

http://members.optusnet.com.au/~sherriffbuck/gallery.html

 

[lecroy]

Re: New Gas Analyser for my GS

Anyway, have a look at the site (you'll have to wade through all the oil cooler stuff to get to the pics) and tell me what you think!
http://members.optusnet.com.au/~sherriffbuck/gallery.html

You need to put your pictures into a few different files now with all of these little projects of yours. It's an interesting little project. I would be interested in hearing how you plan to use it??

 

[saaz]

I would be more interested in an analyser that went down the end pipe, so to speak!

 

[AOD]

very neat...i've always wanted to put something like that in my car.

i have a simliar reader at home on my dresser...it doesn't display the AFR in a number, but a series of LED lights indicating rich or lean. i believe its a 3 wire hook up. maybe i should do that when my new exhaust comes, it'll be easier to weld with it off the bike.

how much did the kit cost you for the AFR unit? can you provide a link for it?

~Adam

 

[Anonymous]

Here is a link to a page that shows you how to make your own
http://www.markvanderkwaak.com/dbbp/tech-tips/mm.html

The hardest part is getting the pcb sorted out

 

[terry]

The hardest part is getting the pcb sorted out

Very true. I'm more of a "nuts and bolts" kind of guy, so I was happy to let a friend build mine, I just hooked it all up.

The one in the link is a very basic affair with only the bar graph that indicates a rich or lean mixture. That in itself is fine, but having an inquiring mind I was interested in knowing exactly what my carb setup is doing.

Although this analyser is a very complex item compared to the one on the Dutch guys website, (there are actually 2 pcbs and heaps more circuitry in mine) the beauty of my analyser is that it tells me exactly what the fuel/air mixture ratio is, at any throttle opening.

I fired up the "beast" last night, and with the stock carbs fitted, was horrified that the ratio is actually 20.8 parts air to 1 part fuel! No wonder it would bog down under load. (the ideal is around 14.7:1)

As I've modded the engine somewhat over the last couple of years with a high comp Yoshimura 1085 kit, Yoshi stage 2 cams, Dyna 3 ignition and coils and Megacycle race pipe, the last thing that I need to sort out now is the carburation.

I've got several choices, but for this weekend I'm going to re-fit the 33mm slide carbs with a freer flowing foam air filter (not pods at this stage, I'm not a fan) in my spare stock airbox that's had a few more holes punched in it, and see how that goes.

Ozman has offered me a loan of a set of 29mm smoothies to try out, (he's a great guy!) plus I have a set of 34mm flatslides, and a set of 34mm Cv's with a new dyno jet kit fitted. I think it'll be interesting to see how each setup works with the existing mods, and the analyser will prove to be an invaluable tool to ascertain the best setup. :twisted:

 

[AOD]

wow, you are running wicked lean. not good!

i found my AFR meter. its a Halmeter AF30.

if i ever get my new exhuast...which i paid for and have been waiting three weeks now :x i'll try to get an O2 sensor bung welded in.

~Adam

 

[AOD]

got my new exhaust today...very nice. i went out and picked up a new single-wire O2 sensor and a bung. gonna try and get the shop to weld it in for me!

~Adam

 

[AOD]

drilled a hole in the collector today (and part of the baffel, hehe) and i'm having the bung welded in right now!

can't wait to get this new exhaust bolted up, then i have to wire and mount the AFR display.

~Adam

 

[terry]

I would be more interested in an analyser that went down the end pipe, so to speak!

I was trying to think of something funny to say, but then I thought no, maybe not. You could probably put the probe in the end of the pipe, but I'm not sure whether the surrounding air would effect the readout.

My cousins analyser has a probe that is designed to be shoved up a tailpipe, and I suppose you could buy a probe particularly because the old leaded fuel eventually "poisons" the probes, maybe JC Whitney or the Eastwood Company would sell the probes, and you could build your own kit?

Ok, I better get out there and try another carb setup :twisted:

 

[AOD]

what year is your bike? just wondering.

i'm gonna try and get my new exhaust on in the morning.

 

[AOD]

got my new exhaust on today...

and my O2 sensor...not hooked up yet, but soon.

 

[saaz]

The o2 sensor needs to be within a certain heat range to work properly, so it has to be close up in the headers. many modern ones have heaters so they work earlier when cold. When mine in the car acted up I did some net research, lots of sites explianing how they work.

The tail pipe readers are usually hooked up to nice big analysers....

 

[AOD]

it'll get plenty hot there...ever feel your muffler?

 

[terry]

it'll get plenty hot there...ever feel your muffler?

Quite right mate, I had a look at several sensors on fuel injected cars and the sensors were all a similar distance from the headers as mine. By the way, they were all watercooled engines, so I'd suggest that our air cooled GS engines would run a little hotter than the average car engine.

It's not practicable to move the sensor closer to the head than it is now, or else I'd need to fit a seperate sensor to each of the four header pipes, which apart from looking rather ugly, is unnecessary as well.

The dutch guy who sparked my interest initially recommended placing the sensor about 1 foot from the exhaust port on one of the two harley headers, I can understand his logic as his bike runs one carb between two cylinders, so hopefully his mixture would be the same in either. I guess it's possible that Harleys run cooler than multi's like ours, but I guess there's probably more technical reasons too.

I refitted the carbs that I "Dyno Jetted" a while ago, raised the needles to the second highest position and turned the fuel screws out 2 full turns. After warming the bike for about 10 miles I came back not too happy as it still felt lean, hooked up the analyser and was surprised that it was still way too lean, only showing a ratio of approx 17:1. I wound the fuel screw out another turn, but it made very little difference.

This weekend I'm going to raise the needles all the way up, and hopefully it'll be fine, or else I'll look for some larger jets, or take them off alltogether and try some slide carbs again. Anyway, I'm getting closer, and that's fine, the weather here in Australia is just starting to warm up. Roll on summer! :twisted:

 

[AOD]

if you have CV carbs on the bike...then it doesn't have a fuel screw. you have the air screw up on the front side of the carbs toward the intake boots. maybe you're getting too much air.

~Adam

 

[saaz]

It is the exhaust gas temp that matters with O2 sensors. And not all sensors are alike in the way they handle temperatures and how accurate they are away from the ideal air: fuel mixture. So you will have to know the specs of the O2 sensor you are using to see how far off the mixture may really be. The sensors just supplies a voltage figure based on the input it senses. It is not an absolute measuremet. On cars the idle circui is usually not a closed loop circuit, so the O2 sensor does not control idle mixtures, same as it does not control wide throttle mixtures when power is needed. The O2 is great for constant throttle situations, but is an indicative tool possibly in other situations. The setup you have to read mixtures while riding sounds like a good way to go, but I don't know whether all sensors will read what you need to know.

The following is a quote from a simple magazine piece on modern engine management systems (the 14.7 ratio is cruise mode):


However, a typical oxygen sensor used in mass-produced cars can measure the air/fuel ratio only over a quite limited range. The sensor is designed to be very sensitive around 14.7:1 air/fuel ratios, because that's where its input is most important.

 

[terry]

if you have CV carbs on the bike...then it doesn't have a fuel screw. you have the air screw up on the front side of the carbs toward the intake boots. maybe you're getting too much air.
~Adam

Is that right mate? Well bugger me, K&N have really screwed up! Let me quote direct from their Dyno Jet set-up manual for CV carbs:

"The fuel mixture screws control fuel. They are used in conjunction with all the carbs other jets to allow a means to compensate for difference in seasonal temperature, and geographical locations. Turning the screws in restricts fuel giving leaner mixtures at idle and in the cruising mode. Turning the screws out increases fuel flow giving richer mixtures which can improve cold weather operation."

I'm often wrong (just ask my wife) but this time, I think I'm on the money. :twisted:

 

[first timer]

terry, k and n is right, the screw being discussed is a fix mixture screw, not a air screw. when you turn the screw out you increase the mixture, not to be confused with altering the mixture (air/fuel). you are just simply increaseing more air and fuel at the same time. so if you are running lean you want to turn your screws out a couple turns to add more air and fuel mix into the combustion chambers. i found the best way to tune your carbs is leave your needles in the middle postion like k and n recomends and then adjust the mixture screw until you get a nice mix, in the lower end of the rpms 2k to 6k ish if you notice you bike laging or hesitateing then try to adjust the needles up or down one step and see if that improves or hurts the bike. i was having all sorts of troble until i got my mixture screws set right, and had to do it by spark plug color not one of those fancy sensors you got you lucky... here is a basic idea of what does what

but the mixture screw at least for me seems to have a affect all the way acrossed the board, up to about 6k so go ahead and turn the\ose screw out a couple time. this is information regaurding CV style carbs i don't know how the vm carbs work

ryan

 

[AOD]

hmmn...a tad dissapointed i am. i went out after riding today and finished the wiring on my sensor reader. it has 3 wires, black, red, white. i hooked up the red to the + side battery, black to the - side battery, and white i spliced to the wire on the O2 sensor.

got a red light on the sensor when i hooked it up to the battery...with the bike off it was sitting at 'lean'. i started the bike up...and the sensor readout never moved. i let it run for at least thirty seconds (fuel tank was off).

maybe my splice job at the sensor was bad...i'll try it again another day. for now, i tore all the wires off the bike and threw them in the trunk. i was kinda mad. :x