I have a x-flow engine with newly-fitted bike carbs. In the very near future I will need to check that the mixture is OK before I take it to a rolling road.

I was wondering whether a lambda sensor would work to indicate whether the mixture is weak-good-lean. I know that their job is to feed back info to the ECU for fuel-injected engines, but has anyone tried them with carbs?

If there's a remote possibility that it would work, what size thead is the mounting boss?

Where should the boss be fitted? The last junction in my 4-2-1 system would seem ideal...

BTW: I know that wide-band lambda sensors are expensive, but this is a lunchtime random thought after all!

A narrow band sensor will give an indication of mixture and help you to adjust carbs .It has a sharp transition point so more use to decide if its rich or weak rather than correct stoiciometric point.
There are a few articles on constructing read outs on the net if you do a search or maybe a cheap gauge from ebay would work.
Thread size is M18 x 1.5.
Paul.

Wideband sensors are very useful. Although the Innovate LC1 is relatively expensive it's also very useful

A narrow-band just tells you which side of stoich you are. It's not so useful. But it's better than nothing.... It'll get your mixture "centered" around 14.7:1 but you can't say (unless you use a wideband) "I want to run 12.5:1 under load and go up to 16:1 on trailing throttle".

TTS lent me their Innovate LC1 for 45 minutes whilst I drove round Silverstone area. It was very informative (and interesting). You just had to try and not get so engrossed on the mixture that you were flooring it to the horizon whilst staring at the floor

Ive got a AEM wide band sensor on my zx10r,it works independant of the ECU,it just tells you the air fuel ratio what ever rpm the engine is running at.They work fine with carbed or fuel injection engines,and are very accurate with either.But like you stated David they are not cheap.
You could run the car steady for a few miles,then remove a plug just to ensure its not running extra lean,but if your taking it to a rolling road anyway,tell them what you have done to the engine/carbs etc,and they will run the car steady on the rollers with this in mind,and adjust the fueling as they go,to ensure your engine is not damaged.

Good info - thanks.

What sort of price is a wide-band sensor? I am happy to put some electronics together to do something with the output.

One issue is that there aren't too many rolling roads that are happy to deal with bike carbs AND megajolt. I was looking for a way to get reasonably close before driving a long way to someone who knows what he's doing.

I might fit a boss to my exhaust anyway - now's a good time as the engine's 'in maintenance'. I can fit a plug with a copper washer to seal it. You never know - I might go fuel-injection at some time in the future!

[Edited on 12/3/08 by David Jenkins]

You need to do two things to operate a wideband lambda:
Maintain heater temp, using internal nernst cell (actual lambda cell) internal resistance, keeping it to 80-100 ohms.

Keep lamda voltage output to 0.45v, by feeding current to the pump cell. The amount of current is measured to determine the actual a/f ratio.

Darren

Plenty of information around this site, which is based on a Jaycar kit which I think are now available in the UK.

http://www.techedge.com.au/vehicle/wbo2/5300.htm

Uses a Honda sensor
http://www.techedge.com.au/vehicle/wbo2/wbntk.htm

The rolling road will probably use a wideband to jet your carbs so the boss will be useful then anyway.

There is a wide band controller called JAW it is discussed on the megasquirt site and has some satisfied users , it is a self build unit and costs about 75 dollars for the kit.
I have been considering buying one to play with but delivery seems a bit slow at present.
There is a web site and forum for it.
Paul.

Very interesting...

JAW linky

Good spot, Paul!


[Edited on 13/3/08 by David Jenkins]

I've just ordered one of these...

Linky

To go with the all the other kms bit's i've also ordered !