Removing GL1100 idle jets

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mikenixon
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Removing GL1100 idle jets

#1

Post by mikenixon »

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In a previous article I mentioned that late 70s through mid 80s Keihin carbs had their idle jets pressed into place, thus they are conventionally non-removeable. No threads. This was the result of some peculiarly over-zealous people at Keihin, and you can read more about that in the other article. 1

Despite this state of affairs it has long been accepted by the carburetor rebuilding fraternity that these jets need to be removed during a carburetor rebuild regardless. The jets -- and their passages -- just can't adequately be cleaned any other way. This brief article will explain the why and how of idle jet removal on the early GL1100.

Of course we're not talking about later, 1982 and 1983 model GL1100s, whose idle jets are threaded. 80 and 81s aren't threaded and that's what we're dealing with here. Most folks use one of several ways to remove the idle jet. I have even heard of screw extractors being used! Ugh! Don't! The most common way the jet is removed is to force a carefully-sized machine screw into the jet (making the screw self-thread) after stacking a bunch of washers on the top of the jet tower. Then the screw is turned and the jet slowly "jacked" out of its tower. Fortunately, Keihin pressed the jet in only about 4mm, so very little jacking is necessary.

This is essentially how I do it also, though I use a much larger screw. The tiny screw most folks use would hardly stand up to the day-to-day use in a carburetor rebuilding shop. Instead I long ago fabricated a tool that incorporates an 8-32 screw, for durability of the tool and for other reasons. However, this in turn requires the jet's head be carefully drilled and then tapped. No forced self-threading. The mess that this machining creates makes my method unsuitable for removing idle jets on carbs that are not going to be unracked. The carbs cannot be sufficiently flushed out while still racked. 2

Does the idle jet really have to be removed? Yes. Three reasons. First, though years ago I used to poke the idle jets in-situ, I and others have found that with the wire bottoming out in the carb casting it is not always easy to tell if/when the jet is clear. Removal of the jet ensures both jet and passage get fully cleaned. Second, when the jet is pulled, you will discover clinging to its outside surface all manner of rust and varnish and junk that you would never have had the opportunity to remove otherwise. It's a revelation. Third, unfortunately that same crap buildup will be found at the bottom of the jet's cavity in the carburetor as well. Wow. Good things to be getting after. So the jet really needs to come out. 3

Replacement press-in jets are available, out of Japan, though not from Honda. Good parts though and all pros use them occasionally. But I find that they're seldom needed on the GL1100 as the removed jet goes back in just fine. I poke the jet with a guitar's high E string, which is 0.013" thick, very close to the jet's 0.35mm. 4 I often will heat the jet also to dissolve the varnish inside it.

Don't overlook removal of the pressed-in idle jet. Don't be afraid. Do it carefully but do it. It's worth the trouble. And now you know how and why.

Notes:
1 The article is "The Air Cut Valve".

2 You really can't get all the chips out unless the carbs are unbolted from the plenum and completely disassembled.

3 Part of carburetor cleaning necessarily includes using an aerosol cleaner to flush each individual circuit and passage.

4 By now everyone is aware that the old dictum about not using wire in jets has long been proven false. Honda actually issued a special tool containing various sized wires for the purpose.
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Re: Removing GL1100 idle jets

#2

Post by Old Fogey »

New #35 slow jets are available from Sirius in Canada. They list them for the CBX, you own't find them in the GL1100 section.

https://www.siriusconinc.com/pro-detail ... ct_id=1191
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mikenixon
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Re: Removing GL1100 idle jets

#3

Post by mikenixon »

Old Fogey wrote:New #35 slow jets are available from Sirius in Canada. They list them for the CBX, you own't find them in the GL1100 section.

https://www.siriusconinc.com/pro-detail ... ct_id=1191
Righto.
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Old Fogey
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Re: Removing GL1100 idle jets

#4

Post by Old Fogey »

Apparently they have changed the GL1100 listings since i bought these. now listed in 4s instead of 6s

https://www.siriusconinc.com/pro-detail ... ct_id=3808
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