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Discussion Starter #1
I was putting new primary jets in my carbs (78 to 82). I went to try to start the bike and the left carb was spilling gas out the drain hose. When taking the bowl off I noticed the small gasket that goes around the accelerator shaft was one the ground. It must have fell off.

I am assuming this is the problem but being that I was completely in the dark about carbs until a few weeks ago, I want to make sure nothing else cold be causing this.

The bike was running well but did not like to idle without the choke pulled a bit. This is why I bumped the size of the primary jets.

I am not quite sure the purpose of the accelerator (does it facilitate gas transfer to the second carb??).

Thanks for helping the ignorant.
D93DC255-5DED-4071-AB17-5593ABB6FC3D.jpg
 

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First off the size of your jets has nothing to do with how the bike idles. That is controlled by the idle mixture screws as well as the condition and cleanliness of the carb and it's passages, vacuum leaks, valve adjustment, spark plug condition, etc.

The accelerator pump provides a bit of additional fuel as the throttle is opened. It's there to prevent the hesitation that is common when coming off idle. The pump is present only on the left carb. A crossover tube provides part of it's output to the right carb. The little "gasket" around the shaft is actually a dust cover, has nothing to do with fuel leak.

Most likely cause for fuel coming out the bowl drain (assuming the drain screw is tight) is a float valve not closing. Could be some debris in the seat, could be the needle just got out of alignment and is sticking. In any case, that's where i'd look first.
 

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Discussion Starter #4
Thanks. Everything is clean and new. IT was running fine except for the idle. My idle screws are already 3.5 turns out.

6sigma suggested bigger primary jet as it is engages at idle.

I will check the float. That was my next area to look


I think stock was a 72 and sigma gave me a 78. I have jets 85, 88 and 90. Since it was not too far off I thought I would start with the 82.
 

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The fuel for the idle circuit is fed from the slow jet which in turn is fed from the primary main jet. The purpose of the primary main jet is to limit the total amount of fuel that gets to the engine up to about mid-range. The slow jet limits the total amount of fuel that gets to the engine from off-idle to about 1/3 throttle. The idle jet (mixture screw) limits the fuel at idle. Unless your slow jet or primary main jet is smaller than required to supply the flow required by the idle jet it can't make a difference. Here's the sticky that shows how it works:

https://www.hondatwins.net/forums/63-fuel-supply-carburation/16943-vbulletin-carb-circuits.html

The suggested starting point for the mixture screws is exactly that, a starting point. From there you adjust each mixture screw to achieve highest idle rpm, usually a bit richer than the staring point but not 3.5 turns as you are experiencing. I'd be looking for vacuum leaks or possibly carbs not properly synchronized. Since float levels are not adjustable that's not likely the problem.
 

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Discussion Starter #6
Thanks for the diagram, it is helpful.

I think my terminology is wrong. The jet I swapped is the SLOW jet. I have seen it called PRIMARY before. I changed it from 78 to 82 at the recommendation of 6SIGMA. My Primary (I have seen it called MAIN) is a 127.5.

As I mentioned it ran fine from 3000 rpm and higher. IT was just struggling at idle. I have messed with the idle screws but to no success. I really think my float got knocked when working on the bike causing the gas to come out. I will make sure the needle is seated all the way like I had it originally. As you mentioned the floats are NOT adjustable.

The bike had not been run since 1986 and had a lot of bad gas in the bowls. I cleaned the entire carb so I do not think it is dirty, especially since it ran so well above 3000 rpm.

I will keep you posted.
 

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The slow jet on your carbs is the one under the rubber plug, probably a #38, and not removable (not impossible but you'll probably ruin it getting it out).

The 78 jet you replaced is the primary main jet. Putting pods on throws the stock jetting out the window so 6sigma's suggestion is as good as any. It's discussed in the topic Jim referenced in post #3.

The 127 is the secondary main jet which is controlled by the vaccum piston and metering rod (jet needle).

Since your idle mixture screws seem ineffective and you have performance problems below 3000 I would suspect you have plugged or restricted passages in the slow jet circuit. It is very common for folks to end up cleaning these carbs multiple times. There is a very good tutorial here that covers the job:

https://www.hondatwins.net/forums/63-fuel-supply-carburation/24191-rebuilding-vbulletin-carbs.html
 

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I grind or file the carb cleaner straw to a point so it seals tight into jets so you can really flush it out and verify you have flow out of the ports near the throttle plate

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