Aisan carb jet sizes

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

May 16, 2010
Madison, Wisconsin
Well, I am going for it - rebuilding my carb. I have a 1973 FJ-40 original F engine with a #60201 Aisan Federal (U.S.A) 2 barrel carb. Ordered my Keyster rebuild kit. Off the bat I noticed that my current jet #'s / sizes do not match with the #'s / sizes in the carb kit. I confirmed with Spector that the right kit was sent to me. I realize you can select different jet sizes depending on your driving conditions & preferred performance. I am looking for a general purpose suggestion on which jets sizes I should put where.

I have 7 locations where jets should go (see my diagram below) and 7 different jets provided in the rebuild kit.

  1. For my slow jets my options are #80 (the long one) and #60... which goes on the left and right?
  2. For my main passage plug and the power jet jets (the threads are all fine pitched) my options from the kit are #55 and #90... the kit only sent two fine pitched jets?? which one goes on the left and right and power jet?... I am not a carb pro, but it appears the main passage plugs are just holders for non-used jets??
  3. For my main passage jets (the threads are not fine pitched) my options are #114, #120, #130... the kit sent 3 non-fine pitched threaded jets?? which of these three go on the left and right power jet?
Any advice from you carb rebuild guru's would be great.
10-0605-73CruiserCarbRebuild - Jet Sizes.jpg
Last edited:
How about putting the jets back where they were? Is there a reason for moving them around?

FWIW, the jets in the kits are rarely correct. They are packaged for world market and US carbs are jetted weird.

PS: the 130 oughta be a 180.
If you are below 5000 feet elevation, you will use the 120 main jet in the port on the left as you are looking into the sight glass, this is the primary. The smaller slow jet goes in the slow jet well on the left or primary side. The larger slow jet goes in the secondary slow jet well-on the right-and that 130 main jet_which is prolly a 180, goes in the secondary main jet port. Use the larger power valve jet and store the smaller power valve jet in the right(secondary)bowl plug. Store your small main jet in the primary bowl plug. Big ball goes in the small hole, and the small ball goes in the big hole. Make sure the countersunk part of the pump discharge weight is pointing towards the ball(down in its well). If you live above 5000 feet, then use the smaller primary and power valve jets. Got mine done yesterday- pulling 19" vacuum!:)
Hello Guys!
Hope you don't mind me posting my question here aswell. I opened my 2F Aisan carb today and first thing I found is the slow jet on the left is a 75 and the one on the right is a 80? The carb ran like crap sins I had it but do these numbers make any sense! I have not gotten to the mains yet but I wonder what they will be.

Hello Guys!
Hope you don't mind me posting my question here aswell. I opened my 2F Aisan carb today and first thing I found is the slow je
It is unclear what left & right means. Please say primary or secondary.

Also identify the year & market of the carb. :cheers:
It's a Aisan carb on a 77 Fj40.
The primary slow jet is 75 and the secondary is a 80. Shouldn't there be a bigger difference between the sizes of the two? I'm also below 5000 ft.
My '78 carb has 75 and 80 respectively for the primary and secondary slow jets.
Yeah, those are stock slow jets for 77-78 USA carb. They are too lean. Drill them both to .85mm.

...if you don't have to pass CA smog, I assume.

I'm still trying to figure out the right combo to get mine to run good enough to get to the smog shop and then pass.

It runs great as setup by you, but doesn't pass. I have a thread on it around here somewhere. The .120 jet is too lean to drive, and I ran out of time, so there it sits for now. I need to have it done by Rubithon.
A CA legal 77 carb has different specs than USA. IIRC, the stock CA main is 124. 120 is definitely too lean. 124 is leaner than optimal running, but does pass the sniffer.
I'll bump it up to 124 when I get a second. [Read that as: sometime in June ]

Ok, so here it is June. I pull out what I believe is a 120 jet and compare it to my drill bits. The drill that fits best is a .046", which is 1.17mm. Presumably the 120 means 1.2mm? My next largest bit is 0.051", or 129. I'm gonna do it and see how it runs.

Probably not making Rubithon at this point. :( I dunno. I suppose it could happen. Next stop will be the Lakes Basin trip.
My carb kit from Cruiser Corps PN 21100-60191 didn't have the pump bellows but I see your kit did. Bummer! My bellows is junk!
I was lazy and only changed out the float needle valve, power valve using old jet and then reset float settings. Works great. FJ40 1969 Carb #60191.
It passed smog this morning! Thanks to @Fj40Jim, the Cruiser Whisperer for the carb rebuild. Third time ever for this rig. Last year I drove it around and took it camping/wheeling on moving permits and hope.

Last time I smogged it I ran it on E-85 and ran the EGR to manifold vacuum so it would be on. This time there were no shenanigans. The computer seems to be working as it should after some solder-joint repair.

O2 was up a bit from about 5% to 7%, HC was down a touch, but the CO% went down from 2.8, which is gross polluter level to 0.13 where the max is 1.4. The NO went down from about 1500 to 900 where max is about 1400. 15mph on the dyno in 2nd gear is about the same rpm as 25mph in 3rd gear, so the readings were similar. I pumped up the 315-75/16s to about 38psi.

Last time I swapped over to some 33-9.5s I have, but that didn't seem to matter much from the results of the previous previous test.

With it being this clean, I probably won't swap back to the really big jet. I may pick through the Mikuni options and find something in between. I guess a 132.5 may run better and may still pass smog? Thanks for that link Stumpy.

My carb kit from Cruiser Corps PN 21100-60191 didn't have the pump bellows but I see your kit did. Bummer! My bellows is junk!

All those bellows are junk. My carb was rebuilt last year and it's already crapped out. It would be great to get someone to repro that part out of some decent material.
Last edited:

Users who are viewing this thread

Top Bottom