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Jetting question

  • Thread starter Thread starter last337
  • Start date Start date
L

last337

Guest
1983 GS1100ES. Pulling carbs and man are these things filthy! The bike has a few aftermarket mods but it must have been 20+ years since those were added and these carbs pulled apart.

I am not sure jet recommendations on this bike other than stock. I can say that when it was running before, before it sat for too long, it was a hard start and although it had power, it backfired coming off load badly. Other than that it only hesitated recently when it got started again, #4 missing badly and then burning/popping through exhaust. After seeing the carbs and especially #4 its no wonder.

Anyways, it has following:

Vance & Hines 4 to 1 exhaust
K&N air pods

pilot air jet 180 (stock)
pilot jet 45 (stock)
jet needle x-1 (stock)
main jet 155 (112.5 stock)

Does this seem right with regard to main jet? Should I consider changing anything?

On another note, what carb kit do you recommend? And also what carb sync tool should I get (I have been putting off buying one but I will need one after this)?

Thanks!
 
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It would be important to know if that 155 main jet is a stock Mikuni jet or an aftermarket jet, like one from Dynojet.

Your actual jetting needs will depend a bit on the baffle that is in the V&H. If it has a "street" baffle, it will need smaller jets than if it has a "competition" baffle, which will need smaller jets than if it has "no" baffle.
nono.gif


I am also curious about your " '82 1100ES". I have always been under the impression that the ES was a one-year-only bike in '83. You have a picture of the bike?

With your intake and exhaust mods, there is no need to change the pilot jets. The needle could be "shimmed", which involves removing the plastic spacer above the clip on the needle and replacing it with a stack of washers that is about half the thickness of the plastic spacer. Main jets would need to go up about 4-6 sizes for the K&N pods and 2-5 sizes for the V&H pipe, depending on the baffle. That would be a range of 6-11 sizes larger than stock. If the 112.5 jets are, indeed, the stock size, then something between 127.5 and 140 could be close. A Mikuni 140 is about the same as a Dynojet 150, so your 155s are probably close, but a little rich.

One way to eliminate a bunch of guessing, trial and error is to just spring for the Dynojet Stage 3 kit. True, it's not cheap, but you get a small selection of main jets to fine-tune the top end and you also get different needles that do a LOT to smooth out the mid-range. The needles are what makes the kit expensive, but they are also what makes it worth getting the kit.

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The dynojet kit is 3133, for that configuration you use the stage 3 which has two options for the mains. Also the pilot jets should be moved up to 47.5.
 
Youre right, I typed that wrong, it is actually a '83. I have corrected that in original post.

I am not 100% sure but based on images I can find, the main jet does look like a dynojet main but it is hard to tell.

I am not sure what baffle is in the pipe. What is the easiest way to tell on that?

As dirty as this thing was and as well as it still ran, I am considering reassembling with existing jets to see where I am. Where should I purchase replacement gasket kits?
 
last337 said:
I am not sure what baffle is in the pipe. What is the easiest way to tell on that?
Click to expand...
How loud is it? :-k

I know that "loud" is rather subjective, but basic principles still apply. If it has any kind of baffle, it's a plus. Look at the diameter of the core of the baffle. Some competition models wil have a 2' or 2 1/2" bore and be straight-through. There might be a "semi-comp" model with about a 1 1/2" bore. A "street" baffle might be 1 1/4 to 1 1/2" and might be straight through or have an offset to quiet things a bit more. The more free-flowing (louder) the pipe, the larger jets you will need.

Ultimately, doing plug chops to see what's happening inside the combustion chamber will be the best guide, Use that to fine-tune and you should be good.

.
 
Steve said:
How loud is it? :-k

I know that "loud" is rather subjective, but basic principles still apply. If it has any kind of baffle, it's a plus. Look at the diameter of the core of the baffle. Some competition models wil have a 2' or 2 1/2" bore and be straight-through. There might be a "semi-comp" model with about a 1 1/2" bore. A "street" baffle might be 1 1/4 to 1 1/2" and might be straight through or have an offset to quiet things a bit more. The more free-flowing (louder) the pipe, the larger jets you will need.

Ultimately, doing plug chops to see what's happening inside the combustion chamber will be the best guide, Use that to fine-tune and you should be good.

.
Click to expand...


Looking at the rear of the pipe, the insert has holes around outside and measuring where the baffle opens at rear is about 1 3/4" opening. It may taper down a bit towards the front but not much.

It looks like all I really need to replace is the bowl gasket, o ring on plug, one spring for mixture screw, one screw for plate that was stripped, and one spring for mixture screw. Will a K&L kit do or should I buy OEM parts?
 
Do NOT waste your money on "carb rebuild" kits if you want to clean your carbs. Any of those kits will contain parts of questionable quality, and not nearly enough of the parts that you DO need. Much better to keep the parts that you have and get an o-ring kit from cycleorings.com. One kit is all you need, and it will cost just over half of one of those "rebuild kits", and you will need four of them, so you will save a LOT of money. That money will be spent on a can of carb dip, and will help pay for the sync tool you will need.

You had asked earlier about a sync tool. The forum favorite is the Morgan Carbtune. It comes from Great Brittain and costs 73 Pounds, delivered, with pouch. At today's exchange rate, that is just a few pennies over $91 USD.

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For what it's worth, I have an '80 1100 with '83 cams, a V&H super sport 4-1 ( canister) and k&n pods; I've gone through 137.5 to 145 mikuni jets and have settled on 142.5s. I did replace the shimmed up stock needles with factory pro needles, but it ran best with the same jetting even with the stock needles, at least at wot - the mid range seems to pull much better with the factory pro needles. I bought mine from rapid ray on this site, not sure if he still sells them though.
As for pilot jets, I have 47.5s in it right now... if I ever get the motivation, I might try a set of 50's since my pilot screws are turned out 3.5 turns and I still get some popping on deceleration, but not bad.
 
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Thanks for all the info!

I think the only other things I need are bowl gaskets, one of the plate hold-down phillips screws, and an air screw spring. Any recommendation on those parts?
 
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