Cv40 carb
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6th Gear
Joined: May 2022
Posts: 10
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From: GA
Cv40 carb
I'm new to the group... recieved a harley and cleaned the carb, replaced accelerator pump diaphragm. At idle if I wide open throttle it bogs and dies. Going down the road under light acceleration it dies. It will idle all day long but once you start using throttle it dies.. any suggestions from you seasoned veterans?
Road Warrior
Joined: Dec 2015
Posts: 1,826
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From: Southwest Desert
I had a similar problem but not so severe sounding. The culprit was my CV carb diaphragm. There is a compressed air test for that. I cant remember where I saw it. You basically blow low pressure air up into the carb and if the venturi slide doesn't open, you need a new diaphragm. I remember that it was important that you didnt use high pressure (100lb) air or you might just tear up the diaphragm.
Start with this test, it costs nothing, but remember NOT to use high pressure air. Turn down your regulated air flow to less than 50lb and blow sparingly and indirectly. If you pass the test just have your CV carb cleaned and rebuilt. They are usually trouble free, but with the way ethanol fuels gel up during storage these days...Also check your fuel valve for crud build up, and check the tank if you have problems there.
Start with this test, it costs nothing, but remember NOT to use high pressure air. Turn down your regulated air flow to less than 50lb and blow sparingly and indirectly. If you pass the test just have your CV carb cleaned and rebuilt. They are usually trouble free, but with the way ethanol fuels gel up during storage these days...Also check your fuel valve for crud build up, and check the tank if you have problems there.
Last edited by SirHarley; May 22, 2022 at 08:17 PM.
Road Warrior
Joined: Dec 2015
Posts: 1,826
Likes: 1,046
From: Southwest Desert
Diagrams can easily be installed wrong, pinched, torn or otherwise. And carbs need to be put into an ultrasound cleaning machine. The tiny orifices and jets can still be dirty after a cursory service procedure. ..FYI....
Ask me how I know
Ask me how I know
Last edited by SirHarley; May 22, 2022 at 08:13 PM.
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6th Gear
Joined: May 2022
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From: GA
not sure. I haven't messed with it.
Where is it? How do you set it?
Where is it? How do you set it?
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Tourer
Joined: Nov 2015
Posts: 378
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From: Here
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 ?
Last edited by crzoomb; May 23, 2022 at 08:02 AM.
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Thread Starter
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6th Gear
Joined: May 2022
Posts: 10
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From: GA