Jets measured with pin gauges is not very accurate.
Jets measured with a laser might give you 'a' measurement but won't take into account any tapering of the orifice and certainly won't tell you the flow rate so I dismissed them quite early on.
Dellorrto jets can vary but this is normal for manufactures as the carb is basically not a race carb.
Dellorto say the number relates to a flow rate but they can't say if it's weigh or volume, in pints or millilitres or buckets!
Fluid flow is the way to measure the jets but the flow must be constant , as should the temperature and air pressure, so that you get an accurate measurement of all your different jet sizes under the same conditions.
So how do you achieve a datum point from which to measure and compare all the other sizes of jets if none of the jets you have can be confirmed as accurate enough to plot the graph from?
Well I suppose you should have a 'GMT' or a 1metre type jet that someone keeps under controlled conditions and use that as a start point when you come to measure your jets.
You don't need to know if your 152 is a 152, you need to know how much your 152 varies from the 1 metre measurement and the plot the others from that datum.
I recently built some flow apparatus which measures flow to within a 1/10 gm to test Dellorto jets but we've gone X30 so I mothballed it while I develop it to measure all the other jets in the Dellorto carb.
Drop me an email Dave before you spend out on lasered jets and I'll offer you a free solution, you can be my guinea pig and get your jets measured under controlled conditions.
Just you Dave.
[email protected]
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