Nikki 791230

Hi , does anyone have an instruction sheet for installing a Nikki 791230 carb on a 22 hp Briggs v-twin intek . I would like to know whether or no to use the stainless steel plate that comes with the kit ?

roger49 said:

Hi , does anyone have an instruction sheet for installing a Nikki 791230 carb on a 22 hp Briggs v-twin intek . I would like to know whether or no to use the stainless steel plate that comes with the kit ?

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Did it have a plate on the carb you took off?

What is the plate for? heat shield?
How thick is it?
Do you have gaskets for both sides of it?

I didn't use it when I installed the carb on my 22hp . It was on the 20hp I removed it from and yes it did have a gasket on both sides. I was led to believe it was a restrictor plate on the 20 hp engines and when removed it would make 22 hp.The reason for this info is that the carb off the 20 hp is running really lean . the porcelain is white and the electrode has a white ash like substance on them. Also does anyone know the numbers that are stamped on the jets for a 26 hp intek ?

roger49 said:

I didn't use it when I installed the carb on my 22hp . It was on the 20hp I removed it from and yes it did have a gasket on both sides. I was led to believe it was a restrictor plate on the 20 hp engines and when removed it would make 22 hp.The reason for this info is that the carb off the 20 hp is running really lean . the porcelain is white and the electrode has a white ash like substance on them. Also does anyone know the numbers that are stamped on the jets for a 26 hp intek ?

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Yes and yes.
20Hp to 22Hp quite arbitary and yes restrictor plates do get used to "create" an engine of the required Hp out of one which is a higher Hp.
However this also goes hand in glove with different governor spring or the spring in a different position.
Don't expect to knock 2hrs off you weekly mowing times.

I would suggest (IMHO) that you get your engine Model # ( I assume you are using the 22HP eng. ) parts manual and order either a NEW carb .. $$$$$ or a replacement carb ( the ROP-SHOP on Evil-Bay ) I've bought, and am using carbs from there with no regrets, the cost of each jet, is AROUND $12-16 bucks, gets expensive quite quick, as far as I know B&S only lists the P/N of their jets, ( NO jet size #s ) an authorized B&S dealer MIGHT have that info ..??? lots of experimenting, time, & parts along with considerable cost when you start playin around with jet changes ........

you might care to see this post ....

https://www.lawnmowerforum.com/showthread.php/50891-2-Barrel-NIKKI-CARB-INFO

I have looked up the jets using the model and date code of my 22 hp and they are 791501 and 791502 which are 113 and 116 respectively. These are the original jets that are in the carb now. In my original post I was looking for jet sizes rather than part numbers . I guess what I neglected to mention in my original post is that I got bored one day while waiting for parts for this engine and ported the heads , intake and port marched the intake to the heads which increased the air flow and now it needs more fuel to compensate . This comes from the days when I was building automotive racing engines, hard to kick old habits I guess. I know the jets are to small and that is why I was asking if anyone knew what size jets were in a 26 hp .

roger49 said:

I have looked up the jets using the model and date code of my 22 hp and they are 791501 and 791502 which are 113 and 116 respectively. These are the original jets that are in the carb now. In my original post I was looking for jet sizes rather than part numbers . I guess what I neglected to mention in my original post is that I got bored one day while waiting for parts for this engine and ported the heads , intake and port marched the intake to the heads which increased the air flow and now it needs more fuel to compensate . This comes from the days when I was building automotive racing engines, hard to kick old habits I guess. I know the jets are to small and that is why I was asking if anyone knew what size jets were in a 26 hp .

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Ahhhh Yes, THAT put a light on the subject, I wish you well and sorry I could'nt be of help .. Boo

Thank you for taking your time for trying to help.

just letting more air in doesn't necessarily change the mixture by itself. Most engines are jetted run leaner these days than yesteryear to satisfy EPA specs. Running leaner raises EGT but can result in a cooler cylinder temp - also depending on the mixture it can also allow the engine to run with more advance because the fuel molecules are farther apart. During the years that I raced, the hottest temps in the combustion area also give one the most power.

roger49 said:

I have looked up the jets using the model and date code of my 22 hp and they are 791501 and 791502 which are 113 and 116 respectively. These are the original jets that are in the carb now. In my original post I was looking for jet sizes rather than part numbers . I guess what I neglected to mention in my original post is that I got bored one day while waiting for parts for this engine and ported the heads , intake and port marched the intake to the heads which increased the air flow and now it needs more fuel to compensate . This comes from the days when I was building automotive racing engines, hard to kick old habits I guess. I know the jets are to small and that is why I was asking if anyone knew what size jets were in a 26 hp .

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Governed engines are a slightly different beast.
In a race engine you look to get a steep increase in the power curve for maximum acceleration followed by a flat peak torque line so all you have to do is keep increasing the revs and you power on to victory.
But these engines are governed, at 3600rpm, they spin quite slow compared to a race engine doing 3 to 4 times that speed.
So much of what you would do to get more out of a race engine produces little outcome on a governed engine.
The mower factories work out the power requirements of a mower then add 20% to 25% to that figure then go looking for an engine .
Briggs rates engines in 1/2 Hp incriments and they do this by detuning the engine down to what the mower makers want.
The first 2 numbers in your engine model is the capacity in Cu inches which in your case I am guessing is 44 ( 742cc ) which is a 26Hp engine .
Briggs chokes it down to make a 24 Hp , 22 Hp & 20 Hp engine.
Back in the Pre EPA days the simplist thing was to fit different main jets, now days they choke down the engine & fit different governor springs.
AFAIK the jet sizes do not change within a capacity group.