Cv40 carb
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6th Gear
Joined: May 2022
Posts: 10
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From: GA
Factory air box or aftermarket ? you may be lean when transitioning from the pilot jet to the needle jet.
I have 40mm CV carbs on my GSXR 11100 , the pilot jets are tiny and would always get partially plugged.
Have to pop off the float bowl to access the pilot jet.
Probably best to pull, pilot, needle, emulsion tube, and main jets.Document the sizes, there will be numbers or letters stamped on them.
Is the petcock vacuum operated ?
I have 40mm CV carbs on my GSXR 11100 , the pilot jets are tiny and would always get partially plugged.
Have to pop off the float bowl to access the pilot jet.
Probably best to pull, pilot, needle, emulsion tube, and main jets.Document the sizes, there will be numbers or letters stamped on them.
Is the petcock vacuum operated ?
Road Warrior
Joined: Dec 2015
Posts: 1,826
Likes: 1,046
From: Southwest Desert
Sounds like you have a dirty carb or air leak somewhere like in the intake seals. You don't have a choke, because it's really an enrichened circuit on your carb. You don't have a butterfly either, since you have a slide. Since it ran while the enrichener was on, that tells us that something is clogged or leaning out the engine. There are small fuel circuits involved here besides main and small jets. The petcock is also a potential source of trouble. Remove it entirely, and look at the filter screen. You're going to have to work to eliminate all of these issues as they may exist. Did you find any crud, gel, or build up in your carb the first time? The entire system (Tank, Petcock, and Carb) may need to be cleaned and flushed out. Check your vacuum hose to the petcock. That may be leaking as well.
Remove, disassemble, and thoroughly clean the carb within an inch of its life. put the disassembled carb in an ultrasonic cleaner if at all possible. If you remove the idle and mixture screws document where they were at first, or you will have to dial them in later. it's good to document the jets as suggested as well. Don't make any shortcuts or hurry through the cleaning, or you may wind up back at square one.
Also, I wonder how good of a shape the intake seals are in? It may be time to replace those while the carb is off. They can wreak havoc on a carb and cause a lean condition. The intake seals are notorious for failing btw. If you have gotten more than 5 years out of them, then you are on borrowed time already...
Remove, disassemble, and thoroughly clean the carb within an inch of its life. put the disassembled carb in an ultrasonic cleaner if at all possible. If you remove the idle and mixture screws document where they were at first, or you will have to dial them in later. it's good to document the jets as suggested as well. Don't make any shortcuts or hurry through the cleaning, or you may wind up back at square one.
Also, I wonder how good of a shape the intake seals are in? It may be time to replace those while the carb is off. They can wreak havoc on a carb and cause a lean condition. The intake seals are notorious for failing btw. If you have gotten more than 5 years out of them, then you are on borrowed time already...
Last edited by SirHarley; May 23, 2022 at 10:08 AM.
Thread Starter
|
6th Gear
Joined: May 2022
Posts: 10
Likes: 0
From: GA
Sounds like you have a dirty carb or air leak somewhere like in the intake seals. You don't have a choke, because it's really an enrichened circuit on your carb. You don't have a butterfly either, since you have a slide. Since it ran while the enrichener was on, that tells us that something is clogged or leaning out the engine. There are small fuel circuits involved here besides main and small jets. The petcock is also a potential source of trouble. Remove it entirely, and look at the filter screen. You're going to have to work to eliminate all of these issues as they may exist. Did you find any crud, gel, or build up in your carb the first time? The entire system (Tank, Petcock, and Carb) may need to be cleaned and flushed out. Check your vacuum hose to the petcock. That may be leaking as well.
Remove, disassemble, and thoroughly clean the carb within an inch of its life. put the disassembled carb in an ultrasonic cleaner if at all possible. If you remove the idle and mixture screws document where they were at first, or you will have to dial them in later. it's good to document the jets as suggested as well. Don't make any shortcuts or hurry through the cleaning, or you may wind up back at square one.
Also, I wonder how good of a shape the intake seals are in? It may be time to replace those while the carb is off. They can wreak havoc on a carb and cause a lean condition. The intake seals are notorious for failing btw. If you have gotten more than 5 years out of them, then you are on borrowed time already...
Remove, disassemble, and thoroughly clean the carb within an inch of its life. put the disassembled carb in an ultrasonic cleaner if at all possible. If you remove the idle and mixture screws document where they were at first, or you will have to dial them in later. it's good to document the jets as suggested as well. Don't make any shortcuts or hurry through the cleaning, or you may wind up back at square one.
Also, I wonder how good of a shape the intake seals are in? It may be time to replace those while the carb is off. They can wreak havoc on a carb and cause a lean condition. The intake seals are notorious for failing btw. If you have gotten more than 5 years out of them, then you are on borrowed time already...
Grand HDF Member
Joined: Apr 2007
Posts: 3,712
Likes: 3,030
From: Brighton, MI
Make sure your needle jet is installed and installed correctly. It is an easily lost item especially if not familiar with the carb. When I say needle jet, I do not mean Main Jet. They are two separate things.
Also the holes in the emulsion tube and in the slow jet are very small. Take a good look at those items.
Hold your diaphragm up to the light to look for holes.
For giggles, replace your intake manifold seals and your carb to intake manifold seal. The carb to manifold seal is suspect if old and if you have removed and replace the carb multiple times.
The intake seals just get old. Replace them.
Also the holes in the emulsion tube and in the slow jet are very small. Take a good look at those items.
Hold your diaphragm up to the light to look for holes.
For giggles, replace your intake manifold seals and your carb to intake manifold seal. The carb to manifold seal is suspect if old and if you have removed and replace the carb multiple times.
The intake seals just get old. Replace them.
Road Captain
Joined: Jul 2020
Posts: 520
Likes: 635
From: Gainesville FL
I had a similar problem on a CV carb I rebuilt. Missed installing the needle jet as I was putting it together. Ran the same way yours did until I found the problem. You can see the top of the needle jet on the bottom of the venturi where the needle from the diaphragm enters. Make sure it's there and the correct right side is up (refer to a carb diagram if you need to).
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