View Full Version : my air/fuel gauge, no more jetting guesswork!
This has got to be the best $80 I've spent on my EX to date!
$25 SunPro air/fuel gauge
$22 Bosch 11027 Universal o2 sensor
$30 Bung welded in at local muffler shop(I don't have stainless wire for my mig)
This thing is really accurate. I had a 42 pilot 2 1/4 turns on the airscrew in my 450R carb and at idle the #1 light was flickering indicating it was lean. I went to a 48 pilot(didn't have anything in between) with 2 1/2 turns on the airscrew and the #10 light is on and the #9 light is lit dimely. My main jet is a #170 and it's also running a bit rich(8/9 lights flickering). Here is a picture of my midrange(needle) it is also rich(#9 light lit).
Here is a picture of the o2 sensor installed in my PowerBomb header. I had it welded in the PowerBomb buldge so it would allow maximum air to flow around it.
EDIT: I didn't have the sensor welded in directly, but rather a bung so I can unscrew the sensor when it's in need of replacement.
I even wired the gauges backlight so it lights up when the headlights are on. I'm leaving the jets/needle a little rich, because I'm not %100 sure how accurate the light scale will be, but it should be dead on. Ideally for power you want a 13:1 air/fuel ratio which should be the #6 and #7 lit. I can't wait to hit the dunes and dial this in!
BTW: I made it so I can easily remove the gauge when I'm at the MX track.
bayou boy
03-05-2005, 05:39 PM
where did you find the 02 guage and the sensor?
Oh yeah forgot to mention that.. I got them at Autozone.
Fred55
03-05-2005, 06:24 PM
Wouldnt that work for jetting in general?
Hammer trx450r
03-05-2005, 06:54 PM
very cool;)
Originally posted by Fred55
Wouldnt that work for jetting in general? Yep, with this puppy I can dial into the exact jet/needle setting for optimum performance or optimum fuel economy. It's the next best thing to dyno tunning your carb IMO.
300ex13
03-05-2005, 08:52 PM
sounds very very interesting
Just for reference, here is the thread were I got the idea(towards the bottom). He's also included some links with more air/fuel information and theory that are also quite interesting.
http://z400central.com/invision/index.php?showtopic=33503
Also, if anyone hasn't seen it, here is a commercially offered setup that includes everything except installation. It's a bit more money, but looks nice. There's a short video on the site that shows one in use.
http://www.jet4power.com
Kansas T
03-06-2005, 09:46 AM
I'd like to see that tested against a wide band o2 like they use on the dynos. Those narrow band o2's like you bought are usually only accurate at 14.7 to 1 air/fuel ratio. Anything other than that its only good for rich and lean, not an actual number.
Yeah that's true but to even get the ratio to 14.7:1 on the idle, mid and main circuit is more than most people can ever hope for when doing seat of the pants jetting. Plus once you are at 14.7:1 you can tweak the jetting/needle a bit richer to try to achive the 13:1 max performance ratio.This chart shows that the accuracy around 14.7:1 is still pretty good.
mx400
03-06-2005, 02:28 PM
if you bought a bosch narrowband your good from about 11:1 to up to 16:1. The bosch o2 sensors are nice. Your setup kinda reminds me of an onboard dyno in a sort of weird way.
250R-Dee
03-06-2005, 05:40 PM
Techedge makes a wideband for motorcyles and if you are good with a soldering iron you can order it as a DIY kit. I use their DIY wideband on my car and I LOVE it.
XCredrider
03-06-2005, 06:51 PM
on his air/fuel guage...where would the lights need to be to get a 13:1 ratio? Where would they be to get a 14.7:1 ratio? Also..do you think this would work on a 250r or would the premix throw it off? I am running maxima 927 castor oil if that helps.
Originally posted by XCredrider
on his air/fuel guage...where would the lights need to be to get a 13:1 ratio? Where would they be to get a 14.7:1 ratio? Also..do you think this would work on a 250r or would the premix throw it off? I am running maxima 927 castor oil if that helps. According to the guy on the z400 forum he tuned his on the dyno to 13:1 and then using this exact same setup as mine lights 5 and 6 were lit. For 14.7:1 I believe it's lights 4 and 5. Each light represents .1 volts and 14.7:1 is supposed to be at .45 volts.
I believe it will work on a 2 stroke however you will want to remove the sensor when you're not tunning it, otherwise you will foul it. You should also remove the sensor when using leaded gas as it will also make the sensor fail prematurely.
Originally posted by mx400
if you bought a bosch narrowband your good from about 11:1 to up to 16:1. The bosch o2 sensors are nice. Your setup kinda reminds me of an onboard dyno in a sort of weird way. Good info, thanks.
Originally posted by TRX250RJapan
Techedge makes a wideband for motorcyles and if you are good with a soldering iron you can order it as a DIY kit. I use their DIY wideband on my car and I LOVE it. I just looked at the Techedge DIY kit. Looks really nice! I couldn't find a price on it though..
400exguy
03-06-2005, 11:33 PM
I have to say good job man, thats a nice setup I had one in a Mustang and Loved to watch it I liked to spray it and watch the gage work.. does yours ever say lean?? like when you let off the gas it should show lean??...
autometer makes a nice gage and it works well
Originally posted by 400exguy
I have to say good job man, thats a nice setup I had one in a Mustang and Loved to watch it I liked to spray it and watch the gage work.. does yours ever say lean?? like when you let off the gas it should show lean??...
autometer makes a nice gage and it works well Yeah, it goes lean when I let up the throttle when I let up from WOT it runs all the way down the scale. Thanks.
wilkin250r
03-07-2005, 11:09 AM
Originally posted by khen
I believe it will work on a 2 stroke however you will want to remove the sensor when you're not tunning it, otherwise you will foul it. You should also remove the sensor when using leaded gas as it will also make the sensor fail prematurely.
I doubt it will work with a 2-stroke, especially when out of the powerband.
Think of how the expansion chamber on a 2-stroke works. Both intake and exhaust ports are open at the same time, and the pipe is pulling fresh fuel/mixture from the crankcase. Some of that fresh fuel/air gets sucked out the exhaust port. While in the powerband, the returning pressure wave stuffs MOST of it back into the cylinder, but not all of it.
So what does that mean to an O2 sensor? With unburned fuel and oxygen floating around in the exhaust pipe, you can't possibly get an accurate reading. An O2 sensor will read a lean mixture, because it is detecting the excess oxygen, thinking that it is left over after combustion, when in reality it was never part of the combustion process to begin with.
A exhaust-gas analyzer would probably read rich, because it would detect the unburned hydrocarbons floating around.
The presense of raw fuel/air mixture floating around in the exhaust pipe will throw all readings from the O2 sensor off, and the amount of excess fuel/air will vary with RPM and pipe characteristics, so it's nearly impossible to even determine a comparison or offset for any given reading.
Originally posted by wilkin250r
I doubt it will work with a 2-stroke, especially when out of the powerband.... You're right, I can't say if a setup like mine would give accurate readings on a 2 stroke for sure. I have heard of o2 sensors being used in 2 strokes, for example the Yamaha direct injection 2 stroke outboard engines utilize them to adjust the fuel mixture to their injectors. I don't know how the computer controller can obtain a reference, perhaps it utilizes this information in conjuction with ignition timing. I've also read that the Bosch LSU4.2 wideband o2 sensors work on a 2 stroke, but I can't determine if you have to use it in conjuction with a remote sampler unit http://www.performancetrends.com/wide_band_uego.htm. I might have to give mine a try on one of my 2 stroke engines.
XCredrider
03-07-2005, 03:28 PM
jet4power has them for 2 strokes but im not sure what sensor they use.:confused: i should call them and ask maybe. then i could get one of those and use the same setup on my R;)
dariusld
03-07-2005, 04:22 PM
I think that is cool. But I wonder how much the sensor cuts down the exhaust flow?
Ginxd00
03-07-2005, 04:32 PM
Originally posted by dariusld
I think that is cool. But I wonder how much the sensor cuts down the exhaust flow?
When you get it jetted right, all you would have to do is unscrew the sensor and put a bolt in it.
Too bad nobody has tried a EGT I had that setup on my blown and sprayed stang and it was a awsome tool for checking exhaust temps at high RPM's. :devil: Hmmmmm looks like I might have to try it out and see.
Originally posted by XCredrider
jet4power has them for 2 strokes but im not sure what sensor they use.:confused: i should call them and ask maybe. then i could get one of those and use the same setup on my R;) Oh yeah, that's were I saw the information on using it on a 2-stroke. I know they use a narrow band sensor similar to the Bosch I'm using, if their's works I would think the Bosch one would as well..
If all else fails you could probably buy the sensor from them for $35 and use the cheaper Sunpro gauge..
wilkins hit it on the head for the 2-stroke, not a good idea. On the 4-stroke make sure you're testing a loaded motor, not just sitting in neutral pinning the throttle.;)
MIKE400EX
03-09-2005, 11:24 AM
Might be way off here, but most outboard 2 strokes don't have expansion chamber type exhausts do they?
2001Toomey
03-09-2005, 01:38 PM
Yeah for 2-strokes an EGT is the way to go. You gotta put it 5 inches from the piston, on the pipe. It'll tell you how hot the exaust is, and you just richen to lower the temp, lean it to raise it. Theres a chart that has the correct temps for all the rpm ranges.
red2004 TRX450R
03-09-2005, 02:11 PM
ive been doing this for years on cars
read this about half way doen the page the sections called
The Trick Way and The Cheap Way
http://www.bob2000.com/carb.htm
you can do it for like $25.00 -$30.00
and yes it accurate its the save sencer the computer in EFI systems use!!
mikeminyard
03-11-2005, 05:54 PM
Khen, what did you end up with for jetting?
Originally posted by mikeminyard
Khen, what did you end up with for jetting? I haven't had a chance to really get out and run it yet, hopefully tomorrow. But right now I have the 48 pilot, 2 1/2 turns on the pilot screw, the HRC needle on the 3rd slot and a 168 main. I'm a little rich in all areas so I bet I can go up one slot on the needle run a 45 pilot and a 165 main and I would be spot on. The only problem I'm seeing is that it's leaning out pretty bad when I hit the throttle really fast so if I lean up the needle I'm sure it will exagerate that. I'm going to see if there is a way to adjust the pump shot on it to push more gas. This is the 450R carb on the EX btw.
motoboy66
03-11-2005, 09:17 PM
Looks like a trip to the jumk yaed is in order, Get the O2 sensor for 2 bucks, well three with the dollar I pay to get in. I have thought about this for a while, but didn't know anyone made a gauge. Looks interesting. Now lets work on a way to store data during a race, so i can put it up on the laptop after. Who can do that for cheep?
:D
itsallgood
03-12-2005, 03:55 AM
Originally posted by motoboy66
Looks like a trip to the jumk yaed is in order, Get the O2 sensor for 2 bucks, well three with the dollar I pay to get in. I have thought about this for a while, but didn't know anyone made a gauge. Looks interesting. Now lets work on a way to store data during a race, so i can put it up on the laptop after. Who can do that for cheep?
:D
Buy a digatron...cheap and easy to store download/upload settings...
plkmonster2
04-15-2005, 10:37 PM
Hey Khen, when you see that the gauge goes really lean when you gass it, is there sufficient load on the motor? If you are pinning it in first or second, the motor will most likely rev up too fast, and not suck in the proper mixture, and showing lean. In third though, it should have enough load that the motor won't spool up too fast, and stay on the rich side. It's hard to explain, but how you said it, it seemed like the motor would rev up hard, and be lean.
BUMP!
Anyone else using this set-up? How's it working?
400exrules
06-15-2006, 03:47 PM
bump!
thought this was very interesting!!!
GPracer2500
06-15-2006, 04:12 PM
Glad this was bumped. Air/fuel meters are THE ultimate jetting tool.
I'm very close to getting one of these: http://www.plxdevices.com/M-Series_productinfo.htm
http://www.plxdevices.com/M-300PlugAndPlay/M-300PlugAndPlay_Unit_Small.jpg
It's wideband and measures 10:1 thru 20:1. I want something I can move around between my bikes. I'll just have to weld an O2 sensor bung in all my headers. Oh yeah, and come up with $328.
krt400ex
06-17-2006, 12:34 PM
Originally posted by khen
Here is a picture of the o2 sensor installed in my PowerBomb header. I had it welded in the PowerBomb buldge so it would allow maximum air to flow around it.
EDIT: I didn't have the sensor welded in directly, but rather a bung so I can unscrew the sensor when it's in need of replacement.
did you notice any diff. in power after uinstalled it. it would seem like u'd lose power 'cause of more restriction.
Originally posted by krt400ex
did you notice any diff. in power after uinstalled it. it would seem like u'd lose power 'cause of more restriction. I've never removed it, so I can't say.. I have it installed in the bulge of the PowerBomb header so I don't think it's restricting the exhaust flow to any large extent.
wilkin250r
06-17-2006, 08:45 PM
I'm just not keen on using an O2 sensor for 2-strokes. I still thing the unburned fuel/air mixture will give false readings. You might get reasonably accurate in the middle of the powerband where (theoretically) all your mixture is being stuffed back in your cylinder, but I know that I wouldn't trust it.
I would suggest an EGT probe (Exhaust Gas Tempurature) for 2-stroke jetting. They aren't going to give false readings because of unburned fuel or air, and they won't foul because of oil contamination.
Iliketogofast
06-19-2006, 10:17 PM
Damn it! I can't do it on the R... No battery. I was fricken gung ho and gonna go to the Auto Zone and get the guage tommorrow... Man.
GPracer2500
06-19-2006, 10:36 PM
Originally posted by Iliketogofast
Damn it! I can't do it on the R... No battery. I was fricken gung ho and gonna go to the Auto Zone and get the guage tommorrow... Man.
For the setup I envision for myself I'll use a small rechargable battery pack. But I'm not looking for a permenant install.
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