where to drill for my sensor?

[wornknobby]

i now have the idea if drilling a hole just big enough for an o2 sensor to fit in my exhaust pipe of my 90'cr125 so i can calculate rich and lean spots to the exact. but where in a 2-stroke pipe can i put this sensor? i wasn't sure if too close to the head pipe would hurt the gas waves travleing throughout the pipe. i would greatly appreciate any help as i'm trying to finish tunning in my bike. :)

 

[tyesai]

That my friend is Hard Core Tunning. :ride: :boss:

 

[wornknobby]

well i got the idea from a dial-a-jet kit, which is supposed to make it so that you can tune your carb in without having to swap out mains, but i figured for $100-$200 cheaper i could by an o2 sensor from napa for $14. then wire it up to read on my multi meter. the voltage reading tells you if your too lean or too rich. and whats cool is that the meter reads to like .01 or something(i'll have to go back and look) but it can read to the perfect air fuel ratio of like 14.7 to 1 or something like that. But since these devices come off of 4-strokes witch don't have the pipe waves which send back fresh fuel i really don't want to go and just start drilling. if any one could help a brother out it could save some money, plus many of us could learn a whole new world of jetting. :) :cool:

 

[Zerotact]

The Pre-mix oil will foul the O2 sensor quickly.
Also, most conventional O2 Sensors are narrow band and have some lag in output sensitvity. In laymen's terms, you will not get instant feedback on your Oxygen level.

 

[wornknobby]

do you think maybe if i ran a lighter mix of oil in my premix, say 40:1 i would still have a problem?

and as far as instant feed back, do you mean it may take alittle while to show results? :coocoo:

 

[Rich Rohrich]

Unless you use a heated wideband O2 sensors like the Bosch LSM 11 or NTK L1H1 all you can "accurately read" is the exact Lambda point and only when the exhaust has heated the sensor element to the correct temperature. Cheapy narrow band O2 sensors have a HUGE temperature dependent slope in their outputs once the O2 content starts moving away from Lambda. So as a device for trying to setup an engine for best power mixture, the simple O2 sensors are a poor choice. Based on the price you listed it appears to be a narrow band setup you are trying to use. It's a waste of time, especially on a two-stroke. ;)

A good heated wideband oxygen sensor that will read accurately over the range racers are interested in costs upwards of $250, and that's without any logging device to read the output. You need to sample the output at a very high rate to get any sort of useful information. Something like the Drack EVO3 would be required to log the data properly from a wideband sensor : http://www.aim-sportline.com/MOTO/evo3.htm#family

 

[cb23]

Rich is right. I use an oxygen sensor to tune my 2 stroke (to within an inch of its life. . .).

It is a heated, wideband sensor, hooked up to my Aim system.

I have to turn the heater on 60-70 seconds before I start the engine or it will be INSTANTLY fouled. Oh, and once fouled it is done for. I suggested dipping the sensor in boiling nitric acid or some such, but the manufacturer said that nothing could clean the ceramic pores. . . We'll see.

As far as lifespan, they said that properly heated, a sensor should last longer than an EGT sensor (which still isn't very long, so I only use the sensor when I am tuning for fuel), in an oil rich environment.

And reducing oil for such a test. . . Surely you can figure out a half dozen reasons this would screw you up and make the test of no value? :blah:

And to work WELL, you need to use it to adjust low, mid, and full throttle, which means recording the data. Though I suppose you could find a long abandoned highway. . .

I tune for fuel based on Oxygen, EGT's, piston wash, CHT, spooge, header inside color (which gets very weird out on the edge), and very lastly and leastly plugs.

And there is debate on location of the sensor. Best info I could find on 2 strokes was on the largest diameter of the exhaust, a couple inches behind the prior cone.