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Discussion Starter · #1 ·
I've got a jet problem with my Gold Wing but since it's a generic problem to all Honda's I'll ask here.

I'm pretty sure that as the jet size number increases (i.e. 120 - 140), that the orifice size increases as well. However, what does the number itself equate to? For example, does a jet size of #60 mean .060" or .060mm?

It's a long story but the reason I ask is this. My GL1000 is a 76 but I found during my carb rebuild that someone has replaced the carbs with '79 model carbs. They have a smaller bore and won't performe as well with the hotter cams that came on the '76 but I'll live with that. What I can not live with is the secondary air jets are the wrong size. The '79'scall for #140's and they installed #120's which is what the '76 carbs use.

What I was hoping to do was to drill the #120's to a #140 but I don't know what size drill bit that would be.
 

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Discussion Starter · #4 ·
Thanks Bill, that helps and will save me some money since I have a bunch of extra 120's that I can just drill out.

Thanks for the link, you're correct, that will be a handy link to have.
 

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If you have a jet that is too large and need a smaller jet, just fill with solder and drill it to a smaller size. Don't delude yourself into thinking that altering jets to any size is hard.
 

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Another thing to consider is that more than likely, the jet size you will need will not be 120 or 140. It will probably be somewhere in between those two. I would start enlarging them one size at a time and test riding until you don't see any more improvement then go back to the size last size that made an improvement.
 

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Discussion Starter · #7 ·
rufusswan said:
If you have a jet that is too large and need a smaller jet, just fill with solder and drill it to a smaller size. Don't delude yourself into thinking that altering jets to any size is hard.
Thanks for the advice on how to modify larger jets. In fact, the early '75 & '76 Gold Wings had some pilot jets that were a tad large and caused an 'off idle' hesitation that was had to get rid of. A common modification was to do as you suggested, fill it with solder then dill it out to a slightly smaller size. I was fully prepared to do this before I found out I had later model carbs that were jetted correctly from idle.
 

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Discussion Starter · #8 ·
Rampage1967 said:
Another thing to consider is that more than likely, the jet size you will need will not be 120 or 140. It will probably be somewhere in between those two. I would start enlarging them one size at a time and test riding until you don't see any more improvement then go back to the size last size that made an improvement.
I hear what you're saying and back in out two stroke days where we were changing jets throughout the day to keep the things running correctly, we would make those sorts of changes.

My goal with the GL1000 is to get the carbs to stock specs and I'm sure it will run like a good production model which is the end goal.

I bought a couple of #54 drill bits tonight at the bolt store when I was buying some stainless hardware and it worked out great. I used the back of the drill bit to check for a 'go/no go' on a stock 140 jet and it was perfect. In reality, the 140 hole I drilled in the 120 jets is probably a thou or so larger but I think it will work fine and I should be able to get the carbs back on the bike and hopefully get it started and tuned up tonight.
 

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Discussion Starter · #9 ·
Here is the setup I used to drill the jets. It's just an el cheapo HF style lathe but it's a nice tool for making small parts or repairing things.



Here is a shot of the installed jet that I had to drill out. It's the larger holed one on the right. In addition to these two air jets in the top of the carb there are two two more jets on the outside and then there is 2 more inside plus the float seat, and emulsion tubes. Lots of passages to get plugged up.

 
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