Carb tuning
#1
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Carb tuning
When changing from 25:1 to 40:1 mix would I expect to have to richer my needles or lean them ?
My own view would be to screw in the needles as less oil means more fuel which is a richer mix, but just want to check with you guys who have done it before
My own view would be to screw in the needles as less oil means more fuel which is a richer mix, but just want to check with you guys who have done it before
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RE: Carb tuning
ORIGINAL: Xairflyer
When changing from 25:1 to 40:1 mix would I expect to have to richer my needles or lean them ?
My own view would be to screw in the needles as less oil means more fuel which is a richer mix, but just want to check with you guys who have done it before
When changing from 25:1 to 40:1 mix would I expect to have to richer my needles or lean them ?
My own view would be to screw in the needles as less oil means more fuel which is a richer mix, but just want to check with you guys who have done it before
#9
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RE: Carb tuning
ORIGINAL: acdii
So when you add 8 ounces of oil, do you put in 1 gallon of gas minus 8 ounces?
So when you add 8 ounces of oil, do you put in 1 gallon of gas minus 8 ounces?
Random thought, why I got it reading this post, don't know.
I would think when quoted as 25:1 it means just that, 25 parts to 1 part. It is when quoted as a % it gets confusing.
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RE: Carb tuning
The oil mix question is tricky, because it defines the amount of oil in the mixed product.
So 20% oil is 1:5 (100/20) ; 1 part oil and 4 parts fuel
4% is 1:25 (100/4) ; 1 part oil in 24 parts fuel (1+24 = 25)
2.5% is 1:40 (100/2.5) ; 1 part oil in 39 parts fuel.
working with % is easy.
The leaner the oil mix gets, the less important the 1 part oil correction becomes. For 2.5% I just mix 2.5% oil in the 5 liter jar. 0.025x5=125cc oil
Who cares if I am off a little on the rich side? I am sure the engine does not notice.
So 20% oil is 1:5 (100/20) ; 1 part oil and 4 parts fuel
4% is 1:25 (100/4) ; 1 part oil in 24 parts fuel (1+24 = 25)
2.5% is 1:40 (100/2.5) ; 1 part oil in 39 parts fuel.
working with % is easy.
The leaner the oil mix gets, the less important the 1 part oil correction becomes. For 2.5% I just mix 2.5% oil in the 5 liter jar. 0.025x5=125cc oil
Who cares if I am off a little on the rich side? I am sure the engine does not notice.
#12
RE: Carb tuning
I would rather have too much oil than not enough, the motor will still run, although not as well as a perfect blend, but a heck of a lot better than not enough oil where galling and scuffing could happen.
#13
RE: Carb tuning
I sure don't know why tou would want to lean the needles out. If you put 4 ounces to 1 gallon to say make 40 to 1 ratio. Then take away 3 ounces of the oil the motor will run leaner and probably burn up. Because you have leaned the fuel mixture out. If you put more oil it makes a richer mix if you take oil away you are making a leaner mix. Maybe Im stupid but Im not going to take oil away and lean my needles you are destined to burn it down. Hey take all the oil away and tell me what happens. It sure don't take a rocket scientist to figure that one out. But all the pro's in here can tell you to lean it out Im not going to!!!
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RE: Carb tuning
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
#15
RE: Carb tuning
ORIGINAL: Xairflyer
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
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RE: Carb tuning
Don't think of it as 1 gallon. Instead think of it as a ratio. 20:1 should mean 20 ounces of fuel and 1 ounce of oil. Dosen't matter how many gallons you make. Mix by ratio. Correct me if I am wrong. I am used to abuse.
#17
RE: Carb tuning
Plain and simple 32 parts gas 1 part oil Now take that and go 50 parts gas to 1 part oil. You are deluting the oil by adding more parts fuel, which will run leaner. You can never go wrong by adding a bit of extra oil, most you might do is foul a plug. But others will tell you too rich is not good either which is true rings will start sticking and carbon deposits are not good either.
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RE: Carb tuning
ORIGINAL: unclecrash
You have it backwards !!! The more oil the richer you run. Take the oil out and you run lean and burn your motor up Period!!!!!
ORIGINAL: Xairflyer
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
In a 2 stroke if you remove the oil the damage is caused mainly by the lack of lubrication, the oil is not really needed or wanted in the combustion cycle.
You mix air and fuel to make combustion, the higher the ratio of fuel to air the richer the mixture, so if you add more oil you are reducing the amount of fuel (gas) so less fuel means higher air content which means a leaner burn.
#20
RE: Carb tuning
ORIGINAL: w8ye
I run 8oz oil in 2 gal gas in all my true gas engines with the needle bearing rod and ball bearing cranks
I run 8oz oil in 2 gal gas in all my true gas engines with the needle bearing rod and ball bearing cranks
#21
RE: Carb tuning
ORIGINAL: Xairflyer
What we are talking about here is the air/fuel ratio not the oil/fuel (gas) ratio
In a 2 stroke if you remove the oil the damage is caused mainly by the lack of lubrication, the oil is not really needed or wanted in the combustion cycle.
You mix air and fuel to make combustion, the higher the ratio of fuel to air the richer the mixture, so if you add more oil you are reducing the amount of fuel (gas) so less fuel means higher air content which means a leaner burn.
ORIGINAL: unclecrash
You have it backwards !!! The more oil the richer you run. Take the oil out and you run lean and burn your motor up Period!!!!!
ORIGINAL: Xairflyer
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
In a 2 stroke if you remove the oil the damage is caused mainly by the lack of lubrication, the oil is not really needed or wanted in the combustion cycle.
You mix air and fuel to make combustion, the higher the ratio of fuel to air the richer the mixture, so if you add more oil you are reducing the amount of fuel (gas) so less fuel means higher air content which means a leaner burn.
#22
RE: Carb tuning
ORIGINAL: unclecrash
So what happens when you run less oil you get more heat which will make it run leaner. Also you loose power with less oil.
ORIGINAL: Xairflyer
What we are talking about here is the air/fuel ratio not the oil/fuel (gas) ratio
In a 2 stroke if you remove the oil the damage is caused mainly by the lack of lubrication, the oil is not really needed or wanted in the combustion cycle.
You mix air and fuel to make combustion, the higher the ratio of fuel to air the richer the mixture, so if you add more oil you are reducing the amount of fuel (gas) so less fuel means higher air content which means a leaner burn.
ORIGINAL: unclecrash
You have it backwards !!! The more oil the richer you run. Take the oil out and you run lean and burn your motor up Period!!!!!
ORIGINAL: Xairflyer
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
In a 2 stroke if you remove the oil the damage is caused mainly by the lack of lubrication, the oil is not really needed or wanted in the combustion cycle.
You mix air and fuel to make combustion, the higher the ratio of fuel to air the richer the mixture, so if you add more oil you are reducing the amount of fuel (gas) so less fuel means higher air content which means a leaner burn.
#23
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RE: Carb tuning
To the Original Poster. It really does not matter. Just start the engine with the new mix and adjust needles accordingly to what the engine needs to run at idle smoothly and then transition to top end with no hesitation. I would on the first flight leave the high speed needle (after adjusting on the ground) a tad on the rich side. Fly a few laps and see how she does. Adjust for best RPM after.
I think you will be fine just be diligent when tuning on the ground first.
However all that said there is nothing wrong with running 32:1
Just my 2 cents.
Regards
Glenn Williams
I think you will be fine just be diligent when tuning on the ground first.
However all that said there is nothing wrong with running 32:1
Just my 2 cents.
Regards
Glenn Williams
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RE: Carb tuning
ORIGINAL: Xairflyer
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
so 25:1 is one part oil 24 parts fuel not 25 ? interesting.
If you have tuned to 40:1 and decide to add a bit extra oil next time so it is say 37:1 you would now be running it too lean !! so not really a good idea to add a bit extra oil.
How about tuning those needles like they should?
#25
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RE: Carb tuning
Pe I dont think many guys even touch the needles again once they have them running ok, but yes you are quite correct everytime you mix new fuel you should be re tuning anyway.