High Altitude Jets

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Jan 3, 2003
McCall, ID
I just learned that my carb has buried in it high altitude jets that I can switch into my Aisin carb. I know that I read somewhere here that they are recommended above a certain altitude, 4500 feet IIRC. However, I wondered if some of you with experience could chime in and let me know if you agree that it would be worth doing. I live at 5150 and play at that elevation and above for the most part.
I put the smaller jets in mine and it worked out about perfect. I live at about 7000 and go to 12000 with no real problems. I've never had it below 4500 so don't know what it would be like lower. I'm running a stock F engine. I think you should try it and starte with fresh plugs so you can check them on how it's burning. Just don't get it too lean or you'll toast you engine over time.
I wondering the same thing, only I've dropped 4,000 from where I bought my 40, the jets that are in it are "136" primary and "171" secondary, at least that's what I can read on the jets, is there a table someplace with alt./jet recommendations that a person can use as a baseline? My 2f has a total of 8 miles on it since the rebuild, I really don't want to find out the hard way I was running way too lean.
If you email Jim Chenoweth, he's got all the poop on jets. He was very helpful to me. Sorry, I'm at work and don't have his data with me. FJ40 Jim@aol.com
Dave, if you feel like it is running rich, maybe you need the smaller jets. Anytime I've driven anything carburetted to the mountains, it smoked like a diesel and had no power. It was never worth rejetting because I had about 600 miles of flatland and about 150 miles of mountains.
I've got some extra jets if Jim reccommends some number you don't have.
GL :)
Thanks, John,

Yeah, I was wondering if someone knew of a table or specific recommendations, too. I am a little nervous about leaning it out, because I just don't know where the line is drawn. I was hoping someone from Denver or someplace else high could chime in.
I'll e-mail Jim. IDave, my cruiser came out of Denver, and those jet numbers are what my cruiser had in it, but that don't mean what I have is right for Denver.
Hey, Ed. Thanks, missed your note until now. I have a feeling I may be on the boundery of where rejetting would be worth it. I thought about JimC, too. I may just end up sending him my carb to see what he can do with it. I don't really know that I am running rich, certainly I have no carbon fouling of the plugs. But if things could be tweeked a little better, then I will, just because!

Folsom, if you are going to email Jim, I won't just yet. Hope you'll share what he tells you.
Hmm. Maybe I've just answered some of our questions. I just found a page in the Engine Manual that talks about this. Defines "High Altitude" as 6600 feet above sea level.

The primary standard jet is 1.12mm, and the spare/high altitude is 1.08 mm. The secondary main standard jet is 2.0mm and does not change. The Power Jet standard is .9mm and the spare/high altitude is .8mm. That is for NonUSA (which I have.)

Then it refers to the Service specifications which give a different set of numbers for the standard primary and secondary main jets. (1.16 and 2.0 mm for NonUSA, and 1.18 and 1.8 for USA FJs.) A bit confusing.

Unfortunately, I don't see anything that corresponds to the jet numbers you mention, Folsom. Maybe JimC will know. Or, I can look at my spares/high altitudes and see what numbers are on them and see if we can figure out what you have from there.
Hey, Dave, let us know what you find out. Where did you get those jet specs? Maybe we could quit bothering Jim C.
You still need to get one of those split blade flat screwdrivers. I'd try monkeying with the HA jets before pulling the carb and sending it anywhere, even to the Carb GURU, Jim.
Keep us posted,
ED :)
I e-mailed Jim, the carb that I have don't have the spare jets in the plugs for the bowls, there's not even a place on the back of the plug for a spare jet, does that mean I have a "non-usa" carb? It is aisin.
Hi, Ed. The specs come from the Toyota F Engine Repair Manual, under the text for the "FA/FJ" carb, which I believe corresponds the the Non-USA. At least, it looks like my NonUSA Carb for my 71. I am assuming that since I got my carb new, the jets installed in it are the "normal" ones, and the spares are the High Altitudes, since that is what the manual says to expect.

Folsom, what year/engine/carb do you have? I might be able to figure something more out from that. I think the older carbs may not have the spares built in, at least the text in the manual doesn't refer to them. (Which is why I didn't find the specs before).
Wierd, I've got four carbs and they've all got the spare jets.
Just picked up a GR starter and I'm going to put it in today, hopefully without welding my wedding ring to the frame! ;)
Hey, Folsom,

My spares were marked 108 for primary and 080 for the power jet, which would be the 1.08 and 0.8 mm high altitudes that the Toyota Engine Manual refers to. What did you say your's were marked again?

Hey, Ed,

Make sure you can reach a pair of bolt cutters if you get your finger stuck! :D
OK, the starter is on and it kicks, still have my fingers, all twelve of them.
Now back to jets. Checked the three carbs that are not on the cruiser and all the spares were either 114, 55, or 50. One of the carbs has a provision for only one spare, the other doesn't have a place for a spare, like Folsom's. Didn't want to drain the bowl in the one that's on the cruiser, cause its hot right now, but it makes me wonder exactly what's in it. I bought the thing locally, but it had a dealer sticker from Colorado. I feel like it needs more gas right before the secondary opens up. Kinda peters out on the primary, then WHOOSH, the secondary kicks in. I'll check it out when it cools off.
Well, HTH, and good luck Dave and Folsom. Really learned a lot fron this post, without bothering Jim!
Ed Long :)
Oh, that really DID happen. A guy working on a starter, hand wrapped around a wrench, touches the frame with the wrench and VOILA! wedding ring turns into a charcoal starter. Damn near burned his ring finger off. Happens real quick.
OK what has everybody else found out about jets???? I'm a flatlander (Kansas City 550 feet) but who knows where the thing was last when it was jetted? Cruiser is still warm, and I don't want to get into it tonight. What jets at what altitude is everybody running? ???
Ed Long
E-mail came back as user unkown?? My 40 is a 78, and I can't help but think it's a non-usa carb, because it was desmogged in it's previous life and it has a non-original electronic ignition. I guess it would be safe to assume that the 136 and 171 on my jets means 1.36mm and 1.71.....maybe?
Yes, I believe there is a correlation between #'s and mm size. That would make sense, mine is a '74 Fand a half with the smaller displacement, and you're running a 2F. Lack of spares might have to do with the smog issues. I think IDave has an older, non-2F motor, so you shouldn't go by our #'s.]
I've got no idea why I'd even have size 50 and 55 jets unless it is for the power piston/jet or whatever it is called. Maybe it is to be used in the Stratosphere!
If you're referring to Jim Chenoweth's email addy, it didn't highlight correctly...it is...FJ40Jim@aol.com.
Good Luck
I asked about this over at Pirate, to get opinions from folks who don't come over here. One of the guys pointed out that after 1/75 toyota started making "High Altitude" carbs (at least referring to them in the 2F manuals). And so, they quit putting the HA jets in the standard carbs. He then goes on to say that most cruisers sold at high altitude don't have these HA carbs, but are rejetted by the dealer. And he pointed out that for the 2F, "HA" is over 3500 feet. It's a good post.

Man, I guess that answers the first part of my question, according to that post I do have the HA jets in it. What are the standard jet sizes? I wonder if a call to my local Toy dealership (1.5 hours away) would help. I'm sure they would have the manuals that would say and I would need to order jets from them anyway. Thanks Guys!
great thread< thanks< learned a lot!

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