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What does the Jet Size Indicate ?
Posted: Thu Apr 12, 2007 2:56 am
by topgun
Ok here's one for the brain's trust ...
What does the Jet Size indicate ? I know it is not the physical size of the "hole" in the jet
I think it relates to the amount of fuel that flows through the jst in a given time period ??
Just curious ...
Anyone with a definitive answer ?
Posted: Thu Apr 12, 2007 3:29 am
by Aussiecrf230
Generally it is the hole size in millimetres, but I know for a fact some carb manufactures(cars at least) numbers refer to flow rates.
Re: What does the Jet Size Indicate ?
Posted: Thu Apr 12, 2007 5:56 am
by mustang
topgun wrote:Ok here's one for the brain's trust ...
What does the Jet Size indicate ? I know it is not the physical size of the "hole" in the jet
I think it relates to the amount of fuel that flows through the jst in a given time period ??
Just curious ...
Anyone with a definitive answer ?
The numbers on the jets are the size of the hole thru it .
A main jet that is 100 =1 mm hole
200 = 2 mm 175 = 1.75 mm etc. , etc.
pilot jets are the same 42 pilot =.42 mm
Posted: Fri Apr 13, 2007 1:49 am
by topgun
Mustang
Not doubting your answer but are you sure on that ? - OK so I am a little skectical ...
Checked some old Mikuni jets I have and no way would a 1 mm drill bit fit thru a # 100 main jet so that led me to theory of flow rate ...
Posted: Fri Apr 13, 2007 2:01 am
by Crazy_Steve
topgun wrote:Mustang
Not doubting your answer but are you sure on that ? - OK so I am a little skectical ...
Checked some old Mikuni jets I have and no way would a 1 mm drill bit fit thru a # 100 main jet so that led me to theory of flow rate ...
He's right.
And the Honda's carb is a Keihin.
Posted: Fri Apr 13, 2007 2:13 am
by topgun
Ok .... yes I am aware of the carbs Honda use
But do all manufacturers use the same method to size jets ?
Tried Googling it but no real answers to be had ..
So I am trying the definitive source ... you guys !!!
And yes I am not being very receptive to your answers which is very rude of me so I apologise ....
Posted: Fri Apr 13, 2007 7:05 am
by Asmith
topgun wrote:So I am trying the definitive source ... you guys !!!
I think I found the error in your thinking...
Posted: Fri Apr 13, 2007 5:13 pm
by topgun
OIC .... my bad ...
Posted: Fri Apr 27, 2007 7:52 pm
by nminus1
I believe Mikuni uses flow rate, Keihin uses size. Ex Mikuni 100 = 100cc per minute. However this is further complicated as I dont know what psi they are measuring at, I bet at 500 psi it would be more like a litre per minute, must be a nominal value used. I bet some smart M.E. aka AS would know....
Posted: Sun Apr 29, 2007 6:12 am
by Aussiecrf230
The standards for flowing heads is a either a vacuum of 10 or 25 inches of water.
For some reason I think small items were done at 2 inches but I would have to check.