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Tuning carbs with dyno?

  • Thread starter Thread starter MikeG
  • Start date Start date
M

MikeG

Guest
So my mechanic wants to install a small rivnut on each of my headers so he can hook up O2 sensors and tune the power band on the dyno. He says that being able to directly measure the exhaust will allow him to more finely tune the carbs than just syncing them would.

Has anyone else done this? I totally trust him but wonder if it's necessary on this setup (82GS750E stock)
 
I tried searching for a posplayer thread but didnt find it. I agree about the mechanic, Mike is a true professional!
 
Unless you want to jet each carb individually you really only need 1 (one) O2 bung, located after all 4 pipes come together, either the collector or the muffler. I haven't done it on a bike (yet) but I have done lots of cars.
It has to be welded in, and when he is done he has to plug the hole.
 
Buddy deal, he wants to put in a threaded insert in each pipe then seal after with ss bolts.
 
Unless you're racing it, a single reading point rear of the collector cone is all that's needed.

After that, you can confirm that all carbs are tuned optimally by plug reading.
 
MikeG said:
Buddy deal, he wants to put in a threaded insert in each pipe then seal after with ss bolts.
Click to expand...
It actually uses a standard O2 sensor bung and plug. Be sure and get SS bungs and plugs, and make sure the plug is the Toyota type with a bolt head on it. Most of the cheaper ones use an allen fitting and it gets stuck and then strips out. And use some anti-seize on the threads.
AFA doing all 4, you may gain a couple or three horsepower, but you will end up with different jets and settings on each carb. So be sure and track what he puts into each carb.
 
Is this to be done on stock pipes or an aftermarket header? :-k

I ask because the stock pipes are double-walled. After installing the bung, how are you going to assure that the inner pipe is also sealed against the bung?

.
 
If it were being done on stock pipes you would have to first bore the hole in the header, slightly smaller than the exterior diameter of the bung you would use. Weld the outer and inner pipe together inside the hole then weld the bung to the exterior pipe.
 
If it is a stock exhaust and carburetors, I don't see any gain, work has already been done.

Aftermarket header and pods on the stock carburetors, it makes it easier to set up the jetting, but most that work has already been done as well. IE: jet kit.

Aftermarket carburetors/pod filters and header would make it much easier to tune with a wide band O2 set-up.

I'm running a set of VM29s with pod filters and a V&H exhaust, which I have also installed an Innovate wide band O2 sensor on a GS700E, and it is worth every penny.

But, you say it is stock.

Have to agree with blowerbike, overkill............
 
tejasmud said:
Aftermarket carburetors/pod filters and header would make it much easier to tune with a wide band O2 set-up.

I'm running a set of VM29s with pod filters and a V&H exhaust, which I have also installed an Innovate wide band O2 sensor on a GS700E, and it is worth every penny.
Click to expand...
Hi!
What model, etc. did you get? What kind of $$$ is required for such a set up? Do you have a link?
Thanks! :)
 
quexpress said:
Hi!
What model, etc. did you get? What kind of $$$ is required for such a set up? Do you have a link?
Thanks! :)
Click to expand...

Here is a link to Innovate Motorsports. http://www.innovatemotorsports.com/products/lm2.php

I purchased a LM1 several years ago, which is now obsolete, but next Gen is the LM2.

A basic LM2 Kit is all you really need for data logging AFR, $349 off their site, but they can be found for a little less. Then there are accessories if desired, but not really needed.

I have a LM1, and a LMA2, which connects to the LM1. For the LMA2 I have a RPM clamp, thermocouple for CHT, a string pot for TPS, and a speed sensor for MPH (magnet split collar type). Use it to tune the bike, but then I take it all off after I'm done.

Also have a LC1 with DB gauge (digital), but it can't record any data. They run around $200.

http://www.summitracing.com/parts/INN-3795/
 
If your "mechanic" can't tune without an o2 sensor, you need to find a NEW mechanic! Preferably, an older guy that has experience with CARBURETORS instead of some MMI tech that doesn't know how to tune a carbureted bike. There is absolutely NO reason to put bungs in your header other than he doesn't know how to tune without the gauges! Ray.
 
tejasmud said:
Here is a link to Innovate Motorsports. http://www.innovatemotorsports.com/products/lm2.php

I purchased a LM1 several years ago, which is now obsolete, but next Gen is the LM2.

A basic LM2 Kit is all you really need for data logging AFR, $349 off their site, but they can be found for a little less. Then there are accessories if desired, but not really needed.

I have a LM1, and a LMA2, which connects to the LM1. For the LMA2 I have a RPM clamp, thermocouple for CHT, a string pot for TPS, and a speed sensor for MPH (magnet split collar type). Use it to tune the bike, but then I take it all off after I'm done.

Also have a LC1 with DB gauge (digital), but it can't record any data. They run around $200.

http://www.summitracing.com/parts/INN-3795/
Click to expand...
Thank you!
Does this LM1 or LM2 require you to weld threaded insert in each pipe?
 
Interesting project to do for fun but, as Ray says above, completely unnecessary to tune your carbs in. Please also note I am not an 'older guy' as hinted at by Ray. He might be but I'm not....:D
 
Last edited:
We used to install rivet-nuts on header system to hookup an EGA for emissions not AFR gauge. But that was a factory dealership in the 80s and we had to set the emissions. The only reason we used a rivet-nut on each exhaust header is for fine-tuning the mixture screws but the other jets could be set with the sniffer at the end of the muffler. It?s been 23 years since I did that and I?m not up to date on emissions laws or even if an o2 sensor will read at the end of the pipe. I just jet by ear and do plug chops now. Like rapidray pointed out the new techs haven?t been trained to jet carbs without using a machine or even how to clean a carb that hasn?t seen gas in 3 years.
 
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