Honda PA Main Jet Sizes

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If you are running a stock Hobbit, then changing your jets may not be necessary. If you are performance minded, then this information is for you. Fortunately for us - the main jet on your hobbit is also the Air Bleed Jet on Keihin FCR carbs. That means that these jets are available. Not only that, but these jets are also used in Honda lawnmowers.

The jets come in sizes of 2 and 3. Here's what I mean. The stock PA50I used a 60. Up from there is a 62, then 65, then 68, then 70, then 72, then 75, then the stock PA50II jet (a 78), etc. Jets are available from 48 up to 150. The jets are stamped with their orifice size. The pic below is a 60 size jet.

MainJetSizeStamp.jpg

The Honda part numbers are 99101-124-0600 (for a 60) OR, the FCR part number is 99101-ZF5-0600.

I've found jets for about $6 each.

For those of us who want to try and save money, here's a chart of information to help you choose the right drill bit to use to drill out your smaller jet to a larger size. You will see that there isn't a very good alignment from numbered drill sizes to jet sizes . . . .


Jet Size (cc per min) Jet Bore (mm) Jet Bore (inch) Inch or Wire Size Bit Metric Size Bit
75 0.7490 0.0295 0.75
0.0296
0.0297
0.0298
0.0299
0.0300
0.0301
0.0302
0.0303
80 0.7730 0.0304
0.0305
0.0306
0.0307
0.0308
0.0309
0.0310 68
0.0311
0.0312 1/32
0.0313
85 0.7970 0.0314
0.8000 0.0315 0.80
0.0316
0.0317
0.0318
0.0319
0.0320 67
0.0321
0.0322
90 0.8200 0.0323
0.0324
0.0325
0.0326
0.0327
0.0328
0.0329
0.0330 66
0.0331
95 0.8430 0.0332
0.0333
0.0334
0.0335 0.85