# jet hole diameters



## Marty013 (Mar 14, 2014)

soo Ive dug out info on which jet to go from where i am (currently no 163 on a 10HP Tec) and ive come to the conclusion that needing the choke (means im lean duh) to run better.. service handbooks suggest a no 188 being the non altitude jet (why this had an altitude jet i dunno) to swap for.. so my question is.. does anyone know the hole diameters on these 2 jets? just so i know what to shoot for... maybe work my way to a middleground as a first try before boring it all the way bigger... but not knowing what to shoot for isnt easy!


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## Motor City (Jan 6, 2014)

I have a 8.5hp, that seems to be running lean. I swapped a 197 to a 169, and it ran worse. Playing with the jets on Tecumseh's doesn't seem to work out well. Either get the carb cleaned or replace it. The one I'm fighting with has a non adjustable carb, originally. I'm going to but on a new, older style with adjustable needles, in an attempt to solve the lean condition.


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## Marty013 (Mar 14, 2014)

i hear what your saying in going with an adjustable carb.. but it isnt in the cards at this point.. next best thing is fine tuning whats there.. and it seems you went in the wrong direction in your jetting.. everythings ive managed to find tells me the smaller the number of the jet the leaner the mix.. but nothing on the actual hole diameters which is what I`m after before i put the torch files to this one


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## Normex (Feb 21, 2014)

This might be a start for help...Good Luck

AGK - How To Drill the Main Jets - Affordable Go Karts


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## Marty013 (Mar 14, 2014)

yup.. its exactly what ill be doing.. but since teh drill bits sized close to this i have at hand vary too much from one o the next (unless of course.. the next jet really is THAT much bigger) ill be honing it out with files meant for torch tip cleaning  a rougher finish probably.. but it should still be better than the hunting at half choke


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## scrappy (Dec 7, 2014)

Pin size bits are a better way to increase the jet size.

Sets like this are the way to go.


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## greatwhitebuffalo (Feb 11, 2014)

Marty013 said:


> soo Ive dug out info on which jet to go from where i am (currently no 163 on a 10HP Tec) and ive come to the conclusion that needing the choke (means im lean duh) to run better.. service handbooks suggest a no 188 being the non altitude jet (why this had an altitude jet i dunno) to swap for.. so my question is.. does anyone know the hole diameters on these 2 jets? just so i know what to shoot for... maybe work my way to a middleground as a first try before boring it all the way bigger... but not knowing what to shoot for isnt easy!



I've found on more than one occasion, the original carb bowl nut/jet from the Tec. carbs, is richer than the replacement in the Chinese kits.

same goes for the 16Hp Briggs Flo-jet carb in my tractor, the original jet stripped and I had to put a kit jet in that, and it's leaner even when adjusted to best setting.

in some cases the idle feed hole size difference, it dramatic. I measured a Chinese kit jet and it was .015"
the original jet in the carb, was .020"

that is a 25% decrease in metering passage diameter under the stock size

if you have the original carb parts, clean them, poke the passages all out and clean with a pin or drill bit, and re-use the oem jet.

another thing that must be done, is the needle valve well walls must be polished with 600 or 1000 grit wet sandpaper, to shine it up. it gets a film on it and scratches in it, and the needle valve doesn't move freely in the well anymore. it will hang up in there and this delayed reaction will throw off the entire carburetor fuel metering across the spectrum, from idle through wot

there's only one way to be confident in a carb- every single air bleed and fuel passage must be cleaned, period. there's no way around it.


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## RoyP (Oct 16, 2014)

greatwhitebuffalo said:


> I've found on more than one occasion, the original carb bowl nut/jet from the Tec. carbs, is richer than the replacement in the Chinese kits.
> 
> same goes for the 16Hp Briggs Flo-jet carb in my tractor, the original jet stripped and I had to put a kit jet in that, and it's leaner even when adjusted to best setting.
> 
> ...


I just cleaned my Honda 1132 carb today. I used, as per recommendation from my local dealer, the NAPA Carb cleaner.....comes in a gallon can with a dipping basket......great stuff...Carb now runs great.


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