How do I know if I'm running too lean or rich?

[coreyman]

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?

[bull]

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.

[coreyman]

Originally Posted by bull

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?

[bull]

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.

[coreyman]

Originally Posted by bull

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.

[rks]

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.

[cheapeto]

If it helps anyone,https://www.ngksparkplugs.com/about-...d-a-spark-plug

[wheelbender6]

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.

[rks]

Originally Posted by wheelbender6

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.

[wheelbender6]

Yup. I meant say lean.

[Irish]

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