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Author Topic: Jetting a CV Carburetor  (Read 1055 times)

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Offline scrappyjon

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Jetting a CV Carburetor
« on: October 26, 2015, 11:38:35 AM »
 As long as this bike is in my possession I will make improvements on it. I haven't really listed it anywhere other than here and bookface, mostly because I want to tinker with it for a little while.  I'll probably try to sell it this spring and hopefully make a little bit back on it from the improvements I am putting in it. 

 I'm sure it wasn't the poor guy who owned this bike before me but at some point in it's life,  bigger cams and a high flow aka., LOUD exhaust was added to this bike. The genius who did this left the carburetor and airbox STOCK.  :o Needless to say the bike was running lean.

Symptoms of lean
-Runs better with choke/enrichener  left slightly on
-Slow to return to idle
-hiccups and cough under low acceleration
-popping during deceleration. 

The bike was showing all of these symptoms.

Harley has different stages of performance upgrading.
Stage 1 is air delivery. Freer flowing exhaust and intake with the correct mapping and jetting done.
Stage 2 is cam upgrade.

So stage 2 was done and only the fun part of stage 1.
I know this is all old news for a lot of you but I am posting this because I am bored and MAYBE someone will find this useful.

This is going to be my write up on the steps completing stage 1, rejetting and adding a more free breathing air box. 

First thing I did was turn the gas to off and run the carb out of gas.Then, take off the air cleaner box and you'll notice the cv carb on the HD is only held on by the two breather bolts coming out of each head.

 Once you remove those you can wiggle the carb off the motor. I loosened the throttle cables at the handle bar and removed them off the carb, popped off the vacuum hose and unfastened the choke cable from the mount and everything pulled off right away together as one unit. I then poured the excess gas that was still in the carb into my cup of coffee to catch a nice octane buzz.  ;D

Now I just have to wait until the new jets come in and I will continue the operation.

I ordered my parts from cv performance. They specialize in Harley CV carburetors.


Offline scrappyjon

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Re: Jetting a CV Carburetor
« Reply #1 on: October 26, 2015, 04:59:41 PM »
Also I am looking for a stage 1 air cleaner back plate if anyone has one laying around the garage. I'll buy it.

Offline lazeebum

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Re: Jetting a CV Carburetor
« Reply #2 on: October 27, 2015, 05:44:12 PM »
I'll be keeping an eye on this one.

Offline scrappyjon

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Re: Jetting a CV Carburetor
« Reply #3 on: November 02, 2015, 05:59:02 PM »
Done! Everything went pretty smooth. The kit came with a new spring and needle.

It is very hard to see the difference between them but there is. I made a rookie mistake and put the new spring next to the old one and walked away. When I got back, I forgot which one was which. So, I had to get my cousin to smell them to tell me which one smelled like gas. I couldn't do it because my hands smelled like gas. Problem solved.

That was easy enough, just drop in the needle and put the retainer and spring back in. They also give you a drill bit to widen the vacuum hole. In the picture, it is the one on the right.

 After doing that I checked the diaphragm to make sure there were no tears or cracks then put some spark plug boot grease in the groove to make sure the diaphragm seated right so it wouldn't get pinched when I put the top cover back on. 

Next, I flipped it over and took the float bowl cover off. I took out the main jet and replaced it, no problem.

old jet

new jet

The pilot jet was inside the tube and it turned out to be a royal P.I.A.

Apparently, the metal they used on the jet is some type of alloy of brass and ear wax. As soon as the screw driver touched it, the screw head began to dissolve like someone had poured acid onto it. It was not budging so, I had to run to Auto Zone and buy a screw extractor. I finally got it out. 

It wasn't pretty but it worked.

Again, boot lube on the rubber and I put the top back on.

Next was the mixture screw. These come from the factory with a plug on it so you can't get to it and adjust it. What Harley doesn't know is that you can go down to your local drill bit store and buy a drill bit, make a hole and pop that plug out. The kit actually came with a drill bit.

Once you get the new screw seated in there you just back it out 1 3/4 turns and that gets it to your starting point and then you can adjust it however you want.

Next was to get the carb back on the bike. The kit came with a new gasket for the intake and a new fuel line clamp.

(putting the choke back on.)

I was patient and found a really nice stage 1 air cleaner on eBay for around $50.

The one on the left is the new one, one on right is stock.

I had an extra stage 1 air cover laying around in the shop so I didn't have to buy one.

After priming the carb with some gas, it fired right up. I had to adjust the idle down little bit. I took it for a test ride and MAN it was like night and day! Amazing what $100 in parts and a little work can do! This is one fast stage 2 bike now. I kind of want to keep this one and get rid of the black one.  :o

This is what a healthy carbureted Harley twin cam is supposed to sound like.

I was really impressed with cv performance. Their instructions were great! They tell you which jets to use for the setup you have so you don't have to guess.

The point of this story is that 2 years ago I would have never had the courage to take on a task like this but if I can do it YOU CAN DO IT!

Don't be afraid to get your hands dirty on your motorcycle. The satisfaction of doing something like this yourself is AMAZING!

Offline JBMFT

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Re: Jetting a CV Carburetor
« Reply #4 on: November 03, 2015, 02:02:57 PM »
Good job man!