Re-Jetting a Honda GX110 (3.5hp)

Clayon

Clayon

#1
#1
I am putting a K&N air filter and a custom header on my Honda GX110 (3.5hp) motor. I was wondering what would be the proper size to drill the pilot jet and the main jet out to? it has a Keihin carb on it. The help is greatly appreciated.

The reason for the performance air filter is because it will be under a lazy boy recline on a lazy boy recliner disguised go kart and it is bound to get stuffy under there for the motor, so I am just trying to let it breath a bit, and the header is so it sounds better. :thumbsup:

Clayton
 
65ShelbyClone

65ShelbyClone

Well-Known Member
#6
#6
Altitude, temperature, humidity, ethanol content...

Jetting is one of those things where there is no "one size fits all" number. Like JamnNM said, keep drilling larger in small increments until the mixture is right. It's a really good idea to also mark the jets as being drilled to avoid confusion.

FYI: Keihin jet sizes are numbered by hundredths of a millimeter, so a #60 jet is 60/100 = 0.60mm, a #168 is 168/100 = 1.68mm, etc. The sizes are usually spread a couple numbers apart like 50, 52, 55, 58, 60, etc. NOTE: This is entirely different than the numbers on number drills.

FYI²: Twist drills make a hole slightly larger than their actual diameter. At the small sizes involved here, I would use a drill 0.05mm smaller than the intended size. Reamers are necessary to get precision diameters like this and just one will cost five times+ what a new jet does.
 
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