E: Engine Comet Mongrel

timetraveller

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I'm a great believer in 'science' when it comes to this type of measurement and so am totally with Chris on this. Two lambda sensors up near the exhaust ports with two separate metres sound ideal but do any of these gadgets require a voltage stabiliser? On a 12 volt system then the volts could be anywhere between, say, 10 volts and 14+ volts so do these systems have there own built in voltage stabilisers or is this something to be wary of?
 

Cyborg

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I may take a leap and try the one in the second link. It's for the Comet, but even if I used it on the twin, I don't think I would leave it installed. On a twin, I would just do one cylinder at a time. Plugs for the O2 bungs are cheap and plentiful. If I get one, it won't be until spring before any sort of racket comes out of that engine, but I will post the results if and when that happens. As for voltage, it's the voltage generated by the O2 sensor that it is reading. The battery voltage would be for the heater and lights.

I just read some info that states the newer wideband sensors do rely on voltage input.

By the way... thank you oexing. Reminds me of the many times I'm racking my brain to figure something out and some kind soul saunteres up and points out the obvious. It actually makes me want to slam my head in the door a few time to clear the cobwebs.
 
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Cyborg

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In a blurb below the eBay listing, they do mention a "laser etched calibrated resistor in the sensor connector body". I guess the question is why.... to match the meter they are using, force you to buy replacement O2 sensors from them, or maybe that's the way the Bosch sensor comes off the shelf. The comment was relating to a question about whether or not you could change the sensor connector. My guess would be that is the way the sensor comes from Bosch.
 

oexing

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Well, basically you can aim for the ultimate perfection. So two sensors may seem to be a must on a twin carb engine. But then you are dealing with fifties carbs and their limited scope of fine tuning: Main jet, idle jet, needle, needle jet, slide with its cut out. There is no acceleration device on these so in the end you will opt for a slightly rich setting for max power and no hickup when wringing the twist grip for acceleration. You will soon find out that you had enough of trying various settings and components and accept a good compromise. And for that a single sensor will do fine on a twin carb engine. Or would your target be the highest possible fuel saving like in car manufacturers rolling road tests to be issued for motor journalists ? I did use O 2sensors to sort out puzzling behaviours on some engines after running out of ideas. I cannot tell in all moments if the engine is too lean or too rich while doing a test ride. I had funny effects on a Honda Clubman when I discarded the air filter box and mounted a bell mouth to the rubber diaphragm Keihin: Only after I placed an action cam behind the carb I could watch the slide jumping up and down half an inch at certain power settings - hopeless for road use. The Keihin was dumped and a classic Dellorto went on and with a little help from the O 2 sensor the Clubman does what we expect.
A simple four wire sensor at 20 Pounds will do the job for your orientation towards a nicely going bike. The single sensor thread in the pipe is plugged after testing and is not visible to bystanders normally, and even so, what could be wrong ?

Vic
 

Chris Launders

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Yep nicely running is all I'm after, you're probably right one sensor would do, I can only give it a try and see.
I'll still try and get some old pipes in case I want to try two though.
Chris.
 

oexing

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In that case you can go a bit leaner for road use of course. But even so, you will like a richer setting for best power in all conditions and most of us will not be very interested in maximum mileage per gallon. I was just saying that it is not too critical to have definitely one sensor per carburettor for best results, with same jetting in both carbs you will be quite close to optimum. With some bikes it is a bit of a hassle to get access to carbs for adjustments and changes so it is a question of perseverance how far you will go with striving for perfection in all conditions. One sensor per carb may provide all needs for that perfection - but it is another question how long your perseverance will last while fiddling with jets, needles, slide cutouts when doing road tests. It is great to have access to a rolling road so you can have the fuel tank off for tuning. One of my friends has got one in his private shop but I prefer to test on real roads so I can find a reason for short trips around home. Otherwise I don´t do much of motorbiking without purpose - living in my workshop most of the time instead.

Vic
 
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