Nikki carb jet sizes dia in decimal inches

[Arkie]

KE4AVB or anyone:

I have a pile of old Nikki carbs and jets and I can get jet sizes part numbers after IDing the carb BUT I need to convert Briggs jet part numbers to decimal inch sizes so as to jet the carb correctly for different HP engines or check that existing carb has the correct size jet in the left and right.
I cannot ID numbers stamped on the brass jets when checking with a magnfying glass.

Checking jet sizes in Nikki 2 barrel carbs vs part numbers.
I have carb jet gauges in decimal inches.
Trying to check jet sizes in Nikki carbs vs BRIGGS PART NUMBERS.

for example: If I know a carb needs these jets
What is the jet size in decimal inches of a Briggs 79501 (left jet) and a 79502 right jet?

[KE4AVB]

Don't you mean the 791501 and 791502 jets.

Don't have the decimals per-say but the 791501 is 1.13mm (.0445) and the 791502 is 1.16mm (.04567).

As for a chart of the jets I asked everyone here to help me create a chart for everyone's benefit but no one responded. No one has the time to help others. There is a chart of what I have used over the years posted in the Briggs Service manual directory. A couple jet don't have the sizes listed as they were before I started the chart. BTW the jets when numbered are done in hundredths of a millimeter. And even this partial chart has gotten me out trouble a few times already this year. And yes loose jet will rub the numbers off and it doesn't help that Briggs is now shipping jets without the sizes stamped on them.

KE4AVB or anyone:

I have a pile of old Nikki carbs and jets and I can get jet sizes part numbers after IDing the carb BUT I need to convert Briggs jet part numbers to decimal inch sizes so as to jet the carb correctly for different HP engines or check that existing carb has the correct size jet in the left and right.
I cannot ID numbers stamped on the brass jets when checking with a magnfying glass.

Checking jet sizes in Nikki 2 barrel carbs vs part numbers.
I have carb jet gauges in decimal inches.
Trying to check jet sizes in Nikki carbs vs BRIGGS PART NUMBERS.

for example: If I know a carb needs these jets
What is the jet size in decimal inches of a Briggs 79501 (left jet) and a 79502 right jet?

[Arkie]

HMMMMMMMMMM:

Yes that was a typo on the part numbers. 791501, 7791502

from your experience or opinion.

Only .0017 difference in the sizes of the Left and Right Jet.
In your opinion or experience?
Are the jet sizes actually that critical for a Twin Briggs engine?
For example: If the jets were swapped L and R would a 445577 1187 B1 Briggs Intek engine not like that for smooth operation, or if both were the larger size or both the smaller size. The carb part number 791230 carb for this engine and 20-25hp engines calls for the Briggs jet part numbers being discussed.

Have you ever tried installing two of the larger jets or two of the smaller jets or increasing the size of the jets and change engine performance from lean to rich or vice versa in the Briggs Nikki two barrel carbs?

One reason I ask is only .0017 difference in jet sizes at idle or lower rpms can be the difference between smooth idle and rough idle, etc??? (seems really critical)

[KE4AVB]

I have always left that up to the engineers at Briggs. They have their reason for using different jets. It probably to with keeping the power on each cylinder balanced with the other.

IF I not mistaken these carbs to have idle mixture jets too.

Now the old carbs did have only one main jet.

[Arkie]

I have always left that up to the engineers at Briggs. They have their reason for using different jets. It probably to with keeping the power on each cylinder balanced with the other.

IF I not mistaken these carbs to have idle mixture jets too.

Now the old carbs did have only one main jet.

You are correct.
I was mistakenly thinking that the 791501 and 502 were also for low speed but the main low idle jets are fixed and buried in the top of the carb casting.
Shame that these carbs do not have little bit of manual jet adjustments.
I've got couple that I've cleaned all the passages and the idle jet holes and cannot locate why they just won't come around as smooth, YET. I'm reluctant to start swapping parts from one that runs good into one that is just not quite right so as to find out. With my luck I will end up with a carb that was good before being bad when I put it all back together and back on the engine.

These are the real Nikki's and not clones so at one time they were OEM installed onto Briggs engine and most likely operated correctly.

Thanks for the info.