Selection of carburettor 2

[kmpillai]

Hi friends
How to select a carburettor for single cylinder Carburettor engines?
Advance thanks
KMP

 

[patprimmer]

I like yellow ones

Regards

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[Tmoose]

These guys could get you up to 100 HP or so, non governed.

http://www.sudco.com/mikuni.html

 

[EHudson]

Your application is a bit unclear but as a very rough guide, determine the maximum piston velocity or at least the crankpin linear speed in feet per second or some similar units.

Using this speed and the area of the piston find out how much air the engine tries to suck in on the down stroke at max piston velocity.

Using that volume of air per second find a carburetor with a venturi that will pass a similar volume of air at a speed below the speed of sound. How much below? Say 85% for a utility engine and maybe only 50% for a race engine.

Hope this helps.

 

[kmpillai]

Hi Mr Pat,
I couldn't follow your answer.

KMP

 

[Warpspeed]

Another rule of thumb is that maximum engine airflow in CFM will be very close to 1.5 times the engine horsepower.

Most carburettors are rated in CFM, that should give you a reasonable starting point.

 

[franzh]

I too had problems with Pats answer, as I have ALWAYS seen the red ones perform better.

Please rephrase what you are looking for in terms of engineering technology.

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[patprimmer]

Hi KMP

Your question did not define any parameters on which you wish to base your selection.

Are you looking for cheap parts for a lawn mower for instance.

Are you looking for a carby for a particular class in racing.

What rpm range.

Does it need to operate at large angles, say like in a brush cutter or chain saw.

Is it 2 or 4 stroke.

I was attempting to highlight that lack of the required data is making it impossible for us to help you by selecting a property that might influence selection of fashion accessories, but probably not the selection of a carburetor, unless you consider a carburetor a fashion accessory.


Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MacRae]

in the auto motive world I've been taught: (disp cu.in.)X (max rpm)/(3456) X (volumetric efficiency assume, about 80%)=(carb size in CFM)