Installing an Air/Fuel guage.

[Iliketogofast]

I'm going to install an air/fuel guage to make jetting easier. I'm doing it based on another user's idea from his 400EX. He drilled a hole in his header and welded a threaded block onto it so he could install an O2 Sensor. He then wired it to an automoive O2 guage. The guage used LED's to determine on a scale whether the jetting was rich or lean.

I've got a few questions about it. Firstly, will the readings be correct with two stroke exhaust gas since it burns oil as well as gas? Also, where would be a good place for the sensor? I figured if I installed it too close to the bladder it would screw up the way the exhaust works and I might loose power. I'm worried that it will impede exhaust flow. Is there a big piece on O2 Sensors that goes into the inside of the exhaust, or is the main part supposed to be outside the pipe?

One more thing: I want a coolant temperature guage too, but I want it on my handlebars. The one from ESR has the guage directly on the sensor, which is in line with the hose. Are there any that have a remote readout?

Thanks in advance for the input.

[Aceman]

Here's some reading for you:

http://www.macdizzy.com/egt.htm

For your remote water temp gauge you would need an electric one. I don't think a mechanical one would last twisting handlebars back and forth. It's nothing more than buying some fittings and a T fitting, installing it in the hose, screwing the sending unit in it and mounting your gauge somewhere on your handlebars. Then splice into 12v power somewhere and you should be golden. Me, I think I would rather just stop every once in awhile and look down at an inline gauge. I don't know how well an electric gauge would last with water, mud, etc getting splashed on it.

ETA:
Check this site out. They've got a lot of stuff!!
http://www.exhaustgas.com/Catselect.asp?DepartmentID=10&RepID=&MenuID=sub1&BasketID=

[GPracer2500]

Big props on your efferts. I've wanted to go the A/F meter route for a while now.

What I've picked up about o2 sensor installs is that 24" downstream from the head is where many meters suggest mounting the sensor. You can't always put it right there though and I've heard of no ill effects from varying from that distance.

Some of the sensor does protrude into the exhaust pipe. How much depends on the height of the sensor's bung (the bung is the threaded shank that gets welded to the pipe). I think the sensors themselves are all very similar in dimension--the bung is the variable on how deep it goes into the exhaust flow.

I think that a wide-band o2 sensor will work on a two stroke, but I've been told they don't last long. I'd be worried about getting erroneous readings unless the sensor was just installed....don't really know from experience though. EGT guages seem more prevalent on 2 smokers.

Keep us posted!

[wilkin250r]

I'm not too keen on O2 sensors on 2-strokes. I'll admit, I haven't tried it, but my experience and education says to me that it won't work properly.

When the incoming fuel/air mixture comes up from the crankcase and fills the cylinder, some of it escapes out the exhaust port. The return pressure wave from the exhaust pipes stuffs it back in, but that is ONLY in the powerband, and one would have to wonder if it's 100% efficient. If even a small bit of unburned fuel/air escapes before the piston closes the port, the O2 sensor will pick that up as a lean condition.

You can obviously see that if you're NOT in the powerband, you have LOTS of unburned mixture escaping, there is no way you could get an accurate reading.

Then, there is the added complication that burning premix oil is bound to foul your O2 sensor rather quickly.

I think Exhaust Gas Tempurature (EGT) would be preferable for a 2-stroke. It's only reading tempurature, so it won't give false readings because of unburned oxygen, and it's not prone to fouling because of premix oil. You could also get a unit with dual inputs, and you can read head or coolant tempurature AND exhaust temp, all from the same unit.

www.digatron.com

[Iliketogofast]

I'm not sure if that link was right Wilkin. It was in German.

I didn't know EGT worked as an input for these sensors. Would I have to look on the guage box to make sure, or does it work for all of them?

[Iliketogofast]

Originally posted by GPracer2500
Big props on your efferts. I've wanted to go the A/F meter route for a while now.

What I've picked up about o2 sensor installs is that 24" downstream from the head is where many meters suggest mounting the sensor. You can't always put it right there though and I've heard of no ill effects from varying from that distance.

Some of the sensor does protrude into the exhaust pipe. How much depends on the height of the sensor's bung (the bung is the threaded shank that gets welded to the pipe). I think the sensors themselves are all very similar in dimension--the bung is the variable on how deep it goes into the exhaust flow.

I think that a wide-band o2 sensor will work on a two stroke, but I've been told they don't last long. I'd be worried about getting erroneous readings unless the sensor was just installed....don't really know from experience though. EGT guages seem more prevalent on 2 smokers.

Keep us posted!

I'll post pics when I'm done, but it will be a while before I can get the extra money. It will probably cost me about 200 bucks, cause I'm gonna go have someone build me a dash.

There are two threaded holes on the handlebars under the crossbar, and I was going to mount them there. I might mount them somewhere else though. I don't know how it would look with a couple of guages sticking up - it would be nice if I could find a small digital unit that would give me coolant temp and a way to determine the jetting at the same time.