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Old 09-10-2016, 09:06 AM   #1
coreyman   coreyman is offline
 
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How do I know if I'm running too lean or rich?

How do I know if I'm running too lean or rich? I just installed a new performance air filter, did away with the stock air box, and the engine actually sounds a lot different now, noticeably more air/exhaust is coming out of the exhaust now. How do I know if I need to upjet or adjust the carb?



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Old 09-10-2016, 09:32 AM   #2
bull   bull is offline
 
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You are running too lean. You can tell from the color of the plug ceramic in the cylinder, or from a gas analyzer, or experience.

I have been piecing together a FrankenScoot 49cc for a scoot repair shop owner. It had many parts were originally sold off including the exhaust, air cleaner box, body panels, etc.

He did not want to spend much money to get it sell able, so i was given a "performance cone air filter". That has become a nightmare to correctly tune. I have been able to get it to run great on sunshiny 80 degree days, but riding in the rain which you could get caught in- it won't get out of its own way!

The reason is the air cools off in rain, thus more compact molecules-- thus more oxygen is pulled in and VIOLA it is running lean.
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Old 09-10-2016, 09:46 AM   #3
coreyman   coreyman is offline
 
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Quote:
Originally Posted by bull View Post
You are running too lean. You can tell from the color of the plug ceramic in the cylinder, or from a gas analyzer, or experience.

I have been piecing together a FrankenScoot 49cc for a scoot repair shop owner. It had many parts were originally sold off including the exhaust, air cleaner box, body panels, etc.

He did not want to spend much money to get it sell able, so i was given a "performance cone air filter". That has become a nightmare to correctly tune. I have been able to get it to run great on sunshiny 80 degree days, but riding in the rain which you could get caught in- it won't get out of its own way!

The reason is the air cools off in rain, thus more compact molecules-- thus more oxygen is pulled in and VIOLA it is running lean.
Is that cone air filter from nibbi? Also how do you know I'm running too lean? How can I tell by the color of the plug ceramic? What color will I be looking for?



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Old 09-10-2016, 10:25 AM   #4
bull   bull is offline
 
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i have no idea 'where' the cone AF came from.

The ceramic color:

original- white

lean - white or almost white

proper - tan

rich - black

a proper running engine will take an overly rich plug and clean it to tan within about 500 miles of driving.
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Old 09-10-2016, 10:49 AM   #5
coreyman   coreyman is offline
 
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Quote:
Originally Posted by bull View Post
i have no idea 'where' the cone AF came from.

The ceramic color:

original- white

lean - white or almost white

proper - tan

rich - black

a proper running engine will take an overly rich plug and clean it to tan within about 500 miles of driving.
Thanks I'll need to get a new plug to properly test this I'm assuming.



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Old 09-10-2016, 12:40 PM   #6
rks   rks is offline
 
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Took this photo a couple of years ago, this is the color you are looking for...http://scootdawg.net/picture.php?alb...&pictureid=550

By the way....with 10,887 miles on this plug, it is still in my scoot, and doing fine.
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Old 09-11-2016, 08:10 AM   #7
cheapeto   cheapeto is offline
 
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If it helps anyone,https://www.ngksparkplugs.com/about-...d-a-spark-plug
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Old 09-12-2016, 10:05 AM   #8
wheelbender6   wheelbender6 is offline
 
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If you determine that you are running rich, either up the main jet or reinstall the stock air box. Running lean will definitely shorten your engine life.
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Old 09-13-2016, 05:48 AM   #9
rks   rks is offline
 
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Quote:
Originally Posted by wheelbender6 View Post
If you determine that you are running rich, either up the main jet or reinstall the stock air box. Running lean will definitely shorten your engine life.
The word rich in the post above, is wrong. It should be lean.
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Old 09-14-2016, 08:20 AM   #10
wheelbender6   wheelbender6 is offline
 
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Yup. I meant say lean.
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Old 09-14-2016, 12:53 PM   #11
Irish   Irish is offline
 
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I'm not positive on this but I was told that when "reading" plugs on motorcycles , you run to full throttle & then shut the engine off & "read" the plugs! You NEVER let the engine return to idle because you will get a "false" reading. Irish
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