cleaning carb jets - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 5 (permalink) Old 10-10-2013, 11:04 PM Thread Starter
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cleaning carb jets

I don't remember seeing anything about this on here before, and it never occurred to me before. I did have my carbs off and apart before, but that was over 30,000 miles ago. My bike recently got to where it wouldn't hardly idle, sometimes running on one cylinder. But it ran fine at highway speeds. So I figured the pilot jets were plugged up. I was not looking forward to removing and reinstalling the carbs to clean them. I tried soaking them in Seafoam, to no avail. Then I got to looking at them, and remembered how they were designed. I removed the bottom covers, which cover the jets. On my bike they are held on with two 7mm bolts. I could not get a socket in there, but I was able to bend a 7mm combination wrench where I could reach them with it. This did require removing the front cylinder cam chain tensioner for clearance, but that was not a big deal. I had already cut off the oil line tab with a Dremel when I switched to TOC tensioners. Once the bottom covers were off, I was able to remove the emulsion tubes fairly easily, with a screwdriver bit and a tiny wrench which fit onto the bottom part of it. I left the main and pilot jets in place, laid down next to the bike, and looked up, where I could clearly see them. I cleaned them with a piece of guitar string and spray carb cleaner. I cleaned the emulsion tubes and put them back, then put everything back together. The bike now idles perfectly, and it took under an hour, with no carb removal.

I am a motorcyclist, NOT a biker.


1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
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post #2 of 5 (permalink) Old 10-11-2013, 04:40 AM
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Well done on a good result. The purists will tell you that wire up a jet is a bad idea as it can damage the hole and change the flow rate. You need to know that there are a series of very small holes drilled horizontally in the part hidden when the jet is screwed in. Should these become blocked you will have to remove the jet. Just re-read your post and I am a little confused. If I remember correctly, the main jet screws into the emulsion tube which itself screws into the carb body. The emulsion tube requires a small spanner or socket to remove it, unless it comes out as one with the main jet. The pilot/slow running jet can only be removed with a small screw driver. I'm just trying to understand what part you poked with the wire.

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post #3 of 5 (permalink) Old 10-11-2013, 09:24 PM Thread Starter
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Ok, I explained it wrong. These are some weird carbs. What I actually removed was the main jet/emulsion tube combination. It sticks down farther than the pilot, or idle jet. Both parts came out together, with a straight screwdriver bit. Normally they would probably come out separately, the main jet with a straight screwdriver, and the emulsion tube with an 8mm socket. The emulsion tube is the part with all the little holes in the side of it. I decided not to try and remove the pilot jet (also known as an idle jet or a slow jet) because of the limited clearance. I didn't want to chew it up trying to get it out, so I cleaned it in place.

The main jet and all the little holes in the emulsion tube looked clean, but I ran a piece of guitar string through them anyway, and sprayed them with carb cleaner. After running a piece of guitar string through the pilot jet while it was still installed, I then sprayed carb cleaner through it by bending the straw on the can of carb cleaner so it lined up with the jet.

I used the high E string, which is the smallest string on a guitar. It is smaller than the hole in any jet, and the holes in the emulsion tube, and will not cause any damage. It is a precision made and very stiff wire, so you can wiggle it around in the jets and clean out whatever might be in there. I have been cleaning jets this way forever, and have not damaged one yet. The emulsion tube is described as the "needle jet "holder" in parts diagrams, and the main jet is called a "needle jet" I'm assuming that is because the needle goes down through it. It can get confusing because the part that shuts off gas to the float bowl is called a needle valve, at least that's what I call it. On every other motorcycle carb I have ever worked on, both jets are located inside the float bowl, along with the float and the needle valve. On the Vulcan carbs, the float and needle valve are completely separate from the jets.

Here is a link to a fairly decent video I found on Youtube about cleaning Vulcan 750 carbs. http://www.youtube.com/watch?v=nKIzpdmX5m8

I am a motorcyclist, NOT a biker.


1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike

Last edited by VN750Rider/Jerry; 10-11-2013 at 09:33 PM.
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post #4 of 5 (permalink) Old 10-12-2013, 04:33 AM
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Now I have the complete picture, thanks. There are still a series of holes drilled at right angles (similar to the emulsion tube/needle jet holder) in the idle jet, these are hidden until the jet is removed. I only mention this in case you have more idle problems.

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post #5 of 5 (permalink) Old 10-12-2013, 07:54 AM Thread Starter
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I just realized there is a better way to get the needle jet/emulsion tube out without damage. Instead of using a screwdriver bit with a small wrench on it like I did, take an 8mm socket, and grind it flat on each side with a Dremel, so you can put a wrench on the flat part of the socket. Then you can remove the emulsion tube/needle jet in one piece. It seems odd that both mine came out in one piece with just a screwdriver bit on the jet. You would think just the jets would have come out, leaving the emulsion tubes in place. I did not have a manual when I did it, and had forgotten just how it went together.

I am a motorcyclist, NOT a biker.


1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike
VN750Rider/Jerry is offline  
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