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No throttle on EVO CV carb

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Rollinlost

Member
On my cleaned and rebuilt carb ('94 Evo H-D w/ OEM CV carb), I can start the bike with the enrichener pulled all the way out but if it is pushed in, the bike dies. With the bike running, if I try to twist ANY throttle in, the bike dies. Now I'm wondering if I have the vacuum jet needle in the wrong place. My install is: diaphram, spring, plastic spring retainer (support, with the 'feet' down), and needle. The head of the needle is below the spring support so if a vacuum pulls the spring support up, it won't lift the needle I don't think. Dunno; the bike will fast idle w/ the enrichener out but any other position, or twist of the throttle, kills the engine. I'm still learning about these CV carbs, obviously. Help!
 
Drop the needle first into the slide.Then the plastic spring retainer(feet down),then spring.Check you rubber diaphram for cracks,tears etc.Hold it up to a light.Place your cap on. Once the bike is running you should see the slide move up and down, freely, when giving it throttle. With bike off you can push the slide up and release it quickly. You should hear a swooshing sound.There is a video on here for viewing on that, I just don't know where.Look in Self help section near the top of home page. Hope this helps
tourbox
 
The diaphram is difficult to install correctly. Double check your work. What was the reason for the rebuild?
 
This may help.
 

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SledDog said:
The diaphram is difficult to install correctly. Double check your work. What was the reason for the rebuild?
Click to expand...
Hey there Sled Dog, the rebuild was because the bike (and carb) had been in storage for a few years and I couldn't get it started (varnish, etc.). Actually the diaphram gave me heartache until I put a very thin coat of rubber cement around where it seats. And I did check for light leaks on the diaphram... none I could see. I should mention that as per the drawings given, that's the way I assembled the carb -- needle first, then plastic seat, then spring, etc. Also, if I keep the bike running by fiddling with the enrichener, I do get throttle response so I don't suspect a diaphram leak. Oh, and yes, the throttle cabling is correct to the carb. I REALLY don't want to trailer this girl up to the dealer! I do have a rideable bike so this is kinda my project bike, but I'd like to get her back on the road. BTW, you guys are great!! I haven't lost hope... yet.
 
If i were in your position i would be looking for an intake leak between the carb and the heads either at the carb to manifold junction or at the manifold to head junction
The enricher adds extra fuel to the airflow if it will only run with the enricher there is either too much air or not enough fuel = intake leak or blocked jets
with the engine running spray carb cleaner/wd 40 on the manifold joints and if there is a change in engine speed then you have found a problem area

Brian
 
fin_676 said:
If i were in your position i would be looking for an intake leak between the carb and the heads either at the carb to manifold junction or at the manifold to head junction
The enricher adds extra fuel to the airflow if it will only run with the enricher there is either too much air or not enough fuel = intake leak or blocked jets
with the engine running spray carb cleaner/wd 40 on the manifold joints and if there is a change in engine speed then you have found a problem area

Brian
Click to expand...

Check the carb fits good at the spigot as well, nice and tight, you should have to lube it or wiggle it good to get it on:s
 
If it's been sitting a while, I wouldreplace the manifold seals. They are easy to do. Recheck your jets to make sure they are clean. Replace the seal between the carb and the manifold also. Does the bike have a vacuum operated petcock? If so check the vacuum line from the manifold, it may need to be replaced also.
 
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