Diagnosing an engine and retuning a carb?

Emcee

Active Member
Local time
3:38 PM
Joined
Jul 12, 2022
Messages
210
Hey,



So my bike is already running on the lean side. I recall reading someone saying that you'll have to retune your carb after you break in.



1. I get white smoke coming out the exhaust when I idle it until she warms up. I know white smoke means too much gas and blue smoke is oil.



2. If white smoke means too much gas, then why is my spark plug black?


3. When I ease off the gas, my engine makes this noise that is between a whining sound. Unsure if this is normal.


4. I can only max out at 20mph. So I'm unsure if moving the C clip would be in my best interest. Which side is leaner and which side is more rich on the C clip because I can't find anything that just gives a straight answer.

5. My MPG sucks. I'm only getting about 60mpg. I also weigh 220 and my cruiser is heavy too. I'm unsure if these two things contribute to the poor MPG

Specs : Ridgeyard 80cc with stock NT Carb with 4 positions on the jet needle.

Video of if my engine sounds healthy when de-accelerating
 

Cisco

Well-Known Member
Local time
12:38 PM
Joined
Jun 9, 2021
Messages
648
Location
Northern Shasta Valley
Burning oil makes white smoke. What is your mix ratio? Moving the needle clip up drops the needle down and your engine will run leaner at idle up to about half throttle. If your sparkplug is black and oily looking, your engine is running rich. After breaking in, I switched my mix to 32:1, and raised the needle clip up one notch. It runs much better now.
 

Emcee

Active Member
Local time
3:38 PM
Joined
Jul 12, 2022
Messages
210
Burning oil makes white smoke. What is your mix ratio? Moving the needle clip up drops the needle down and your engine will run leaner at idle up to about half throttle. If your sparkplug is black and oily looking, your engine is running rich. After breaking in, I switched my mix to 32:1, and raised the needle clip up one notch. It runs much better now.
I'm running 24:1 w/ Lucas. I'm thinking about going to 32:1 when I fill up next.

I'm confused. I thought if your spark plug is white you're too rich and if it's black you're too lean.

By "raising the needle clip" is that closer to the rounded off end at the top or closer to the pointy edge?

So when you "raised the c-clip" you were making it richer?

Also I should note, I'm only getting about 60mpg. I weigh 220 and my cruiser bike is on the heavy side.
 

Emcee

Active Member
Local time
3:38 PM
Joined
Jul 12, 2022
Messages
210
Will somebody post the sparkplug chart again, please? Here is a link to an older post regarding NT carbs: https://motoredbikes.com/threads/nt-carb-tuning-basics.24867/
I know how to read spark plug colors, the tip is covered with black and it's black around the first couple threads of the plug.

This is what stumps me. I don't understand how a C clip will actually change anything, in regards to how does clip positioning play a role in lean or rich gas.

For example, if let's say I was running 1000:1 and said "my plug is white, I will move the C clip to make it more lean" that isn't really the problem if you think about it, the problem would be you don't have enough oil which is making it rich. Maybe I don't understand how the C clip works. I don't understand how clip positioning will change the gas that's combusted in the cylinder
 

Wrench

Well-Known Member
Local time
12:38 PM
Joined
Nov 14, 2018
Messages
5,335
Location
so cal
I know how to read spark plug colors, the tip is covered with black and it's black around the first couple threads of the plug.

This is what stumps me. I don't understand how a C clip will actually change anything, in regards to how does clip positioning play a role in lean or rich gas.
The C Clip or "E" Clip position changes the Needle height
The lower the Needle position the Leaner it runs. Lets less gas thru
The Higher the Needle position the Richer it runs. Lets more gas thru

When ya move the E Clip down on the needle it makes the needle position go up
When ya move the E Clip position up on the needle it makes the needle go down
 

Emcee

Active Member
Local time
3:38 PM
Joined
Jul 12, 2022
Messages
210
The C Clip or "E" Clip position changes the Needle height
The lower the Needle position the Leaner it runs. Lets less gas thru
The Higher the Needle position the Richer it runs. Lets more gas thru

When ya move the E Clip down on the needle it makes the needle position go up
When ya move the E Clip position up on the needle it makes the needle go down
So let me ask you this, how does it change if it runs more rich or more lean? If I make it more rich, won't I burn more gas than I already am using? I already have poor MPG.
 

Wrench

Well-Known Member
Local time
12:38 PM
Joined
Nov 14, 2018
Messages
5,335
Location
so cal
Excuse me for laughing :LOL:

Don't forget that the carb controls the amount of air that is mixed with the gas for combustion
Besides the fuel air mix screw ya also have to adjust the needle position So the engine runs smoothly thru it's throttle positions
Idle, 1/4, 1/2, 3/4 and Full Throttle

Fuel air mix screw and the needle position changes the amount of fuel to air that your burning in the cylinder

More air make the engine run lean - less gas
Less air makes the engine run Rich - more gas
 

Wrench

Well-Known Member
Local time
12:38 PM
Joined
Nov 14, 2018
Messages
5,335
Location
so cal
Maybe a member will put up a link for Jet sizes, Fuel air adjustments ,needle positions and throttle positions for ya.

It's all about how your engine is running thru out it's throttle positions depending where ya put the needle position along with using the correct jets and how ya adjust the fuel air mix screw, Your altitude has alot to do with it too as where to put the needle position and fuel air adjustment screw.
 
Top