AFR Installation - PX200

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Wed Feb 28, 2018 10:31 am

Hello,

I am planning to install a lambda sensor in order to better tune my Malossi 210 kitted PX. I have a PGM Bigbox in place and I was wondering what the ideal place to install it would be.

I thought about two seperate locations, marked with green and blue arrows here:

https://www.flickr.com/photos/150884345 ... ed-public/

Or this?

https://www.flickr.com/photos/150884345 ... ed-public/


Your suggestions are all welcome.

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Muttley McLadd
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Wed Feb 28, 2018 9:04 pm

My coop has a temp guage in a similar position to your second pic. It's fine there.. but if it was much longer, it'd be inconvenient.
Although, it does have a 90 bend in it, which makes it easier.
How much clearance would you have, if it was in the lower position?


Image
CakeAndArseParty

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coaster
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Wed Feb 28, 2018 10:27 pm

This is for an Air Fuel Ratio sensor not an EGT and I believe they need to be further away from the cylinder as the Lambda sensor is analysing the air/fuel mix rather than temperature. The one on my GTS is around 7"-8" down the pipe (the first pic would be about right) EGT's are about 4".

You won't be able to leave it fitted permanently though as the Lambda sensors don't like 2 stroke oil apparently. Having said that though, they are cheap as chips so if they last a thousand miles or so its just a maintenance item to change.....if its every 100 miles it would be a different matter.

I have a cheap digital AFR meter and will be welding a boss into my Lambretta Supertourer pipe soon for the same purpose as you.

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Thu Mar 01, 2018 9:10 am

Thanks for the information. The installation is for tuning purposes only. I will take it off and plug the hole as soon as I am done collecting the data.

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RManson
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Tue Apr 24, 2018 5:56 am

I use one on my Rotax-barrelled Lambretta. Here's a shot of the pipe before I welded the bung in that shows where I located it in relation to the header. I was very pleased with the capability and how quickly I was able to set up the carb. Good luck!

ImageRotax Lamby build-203 by PotvinV8, on Flickr

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Fri Jul 20, 2018 8:47 pm

I decided to continue this thread to share the preliminary results with you. My PX has a Malossi 210 Sport kit, that is ported. It has a BGM Big Box exhaust, KyTronik SmartBooster 2016-2, a X360 reed valve, a mechanical Dell'orto fuel pump and a Pinasco 1600g flywheel.

I decided to use my GoPro to film the AFR gauge and the SIP speedometer which I adjusted to show the rpm, but I couldn't line it up properly and ended up filming only the speedometer. I remembered to narrate some (not all unfortunately) of the readings though and here they are:

AFR Values at peak rpms
1/4 Throttle 2/4 Throttle 3/4 Throttle Full Throttle
1st Gear 11.7 11.5 10.7 11.8
2nd Gear 10.7 ? 10.7 11.8
3rd Gear ? 10.7 11.8 ?
4th Gear ? ? 12.8 12.5-12.8

I did not narrate each gear&throttle run but I seem to remember that the question marks were also around 10.5 - 10.8.

I'd imagine that I need to get a smaller idle jet and change the jet needle for a leaner mixture. I was hoping that you could give me some advise.

The configuration of the PHBH 30 carburettor is as follows with Malossi product codes:
*X3 Needle, art. B09477.003
* 262 AV atomiser, art. B09695.262
* 138 Main jet, art. B06413.138
* 55 Idle jet, art. B01486.055
* 30 Slide, art. B09374B030
* 225 Float valve, art. B09436.225 ( I changed this after installing the Dell'orto mechanical fuel pump, I can't be sure what this exact part is now. I'll check and edit this part)
* 70 Starter/Choke jet, art. B07746.070
* 9010.2 Float – 6.5 grams, art. B09010.002

I hope the post is clear, my apologies for the length, I thought I should give you all the information I have.

Thanks!
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coaster
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Fri Jul 20, 2018 9:29 pm

Watching this with interest

Colin

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Sat Jul 21, 2018 12:26 pm

I tried to line the values for the AFR/gear but it didn’t come out right in the previous post. I hope this is better:

AFR Values at peak rpms
1st Gear: “1/4 -11.7”, “2/4 - 11.5”, “3/4 - 10.7”, “Full - 11.8”
2nd Gear: “1/4 - 10.7”, “2/4 - ?,” “3/4 - 10.7”, “Full - 11.8”
3rd Gear : “1/4 - ?”, “2/4 - 10.7”, “3/4 - 11.8”, “Full - ?”
4th Gear : “1/4 - 12.5 to 12.8”, “2/4 - ?”, “3/4 - 12.8”, “Full - 12.5 to 12.8”

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joeythescooterboy
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Sun Sep 09, 2018 2:07 pm

Just fitted one on mine, what would be "ideal" values to aim for?
Nemo saltat sorbius, nisi infanus est.

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Mon Dec 10, 2018 9:27 am

joeythescooterboy wrote:
Sun Sep 09, 2018 2:07 pm
Just fitted one on mine, what would be "ideal" values to aim for?
Hi,

I had not been able to login for a long time now, so I am not sure if you found the answer to your question.

Please check this link, I found it very helpful:

https://scooterlab.uk/lambda-probes-jet ... road-tech/

Short answer is as follows:
"When you reach the maximum peak revs according your throttle position, you should be reading around AFR 13.1. Less than that is too rich, more than that is too lean. Following most people’s experience, a safe AFR measuring at full throttle is about 12.5."

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