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Discussion Starter · #1 ·
I got a 75 FLH that I'm running a 90's CV carb on. It's running really rich. I tried to adjust the air/fuel by turning the screw in until it bogs and then backing it out, but it never bogged. Does this mean the seat is damaged? or is there something else going on.
 

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Some where you have a intake leak despite the richness.....
 

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Is your rich diagnosis based on plug color or some problem with the way it runs? The fuel circuits overlap quite a bit on a CV, which tends to mask slight jetting inaccuracies. Here's a chart:



First double check your intake seals as the Roach suggested. Then, if you can't get any change with the idle mix screw fully seated, your pilot jet is probably a bit rich. Drop the pilot one or two sizes and check again.

Here are my settings on my 1974/74" FLH. With a stock "H" cam, low 7.5:1 compression, 2-to-1 headers, cigar muffler, stock points ignition and a stock round CV airbox/filter, I'm running 2.5 turns out on the idle mix, a 50 pilot jet and a 190 main jet with an unshimmed stock slide needle. The slide is also stock (the vacuum hole has not been drilled, and the slide spring is stock, no DynoJet crap). That should get you close, with slight adjustments needed for your particular setup.

Don't give up. The CV is a great carb for the Shovel. It'll be worth your time to get it sorted.
 

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Dave, what size main jet and what size slow jet are you running? Also, is it an 80" or a 74". Give me that info and I can get you straightened out no problem.
 

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Discussion Starter · #5 ·
I got the rich deal figured out. Ended up being that my choke cable was messed up and even though the plunger was pushing flush, the cable was about a 1/8 inch from pushing in all the way and cause my erichener to stick. Wierd. Anyways I also order a jet kit so I can play with that if needed. What is everyone running in there cv powered shovels?
 

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Discussion Starter · #6 ·
Sorry forgot to add more details. It's a 74" bored .60 over. I'm pretty sure it's an Andrews A cam, it may be a AB though. for pipes I'm running straight pipes with long baffles. I may cut though down though.

Can anyone recommend a starting point?

Bobb,

That is great info, thanx
 

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A 45 slow jet with a 180 main should be real close. Go 2.5 turns out on the mixture screw as well. Try that and tweak from there. I mean tweak the carb, not tweak on meth.
 

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Discussion Starter · #8 · (Edited)
I got the kit in and it has the new springs, mainjet, drill bits, needles etc. I thought this was going to be a jet kit. Anyways. I don't think I need to do all that shit. I think I need to just rejet it. Here's the background on the bike. I was jetted spot on until I added baffles to the straight pipes and added a new aircleaner. It seems to be running rich off idle. so If my logic is right I need to bring the slow jet numerically up a bit? and then fine tune with idle adjustment. I will post the jet numbers once I get it torn down. I do know that my main jet is a 170. not sure about the slow jet though.

A few more ?'s should I swap the spring and shim the needle? drill the holes?
 

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>I got the kit in and it has the new springs, mainjet, drill bits, needles etc. I thought this was going to be a jet kit. Anyways. I don't think I need to do all that shit. I think I need to just rejet it.

Yep. A rejet will do ya fine...

>Here's the background on the bike. I was jetted spot on until I added baffles to the straight pipes and added a new aircleaner. It seems to be running rich off idle.

Probably is, and that would explain not being able to adjust it via the idle mixture. If it's too rich, the idle mixture won't respond...

>so If my logic is right I need to bring the slow jet numerically up a bit? and then fine tune with idle adjustment.

Backwards. Drop down a size, pro'ly need a 45 or 46 in there, unless you've got cams and compression bumps. With the right pilot jet, your idle adjustment should work.

>I will post the jet numbers once I get it torn down. I do know that my main jet is a 170. not sure about the slow jet though.

170's a good start for the high speed on a stock motor, might be a bit lean if yours is warmed over at all.

>A few more ?'s should I swap the spring and shim the needle? drill the holes?

Wait on the shim thing 'till you're closer with the basics like low and high speed sizes. I would NOT use the lighter spring OR drill the slide. Makes it much much harder to tune, and too light a spring can make a hesitation that's a bitch to tune out. It'll speed up throttle response a bit, but it ain't worth it to me. As for the shimming the needle, no, not as a matter of course. You do that when you've got problem to solve, like a transition problem or a hesitation to fix. I'd wait on that...

-Kuda
'49 panchop
 

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I got the kit in and it has the new springs, mainjet, drill bits, needles etc. I thought this was going to be a jet kit. Anyways. I don't think I need to do all that shit. I think I need to just rejet it. Here's the background on the bike. I was jetted spot on until I added baffles to the straight pipes and added a new aircleaner. It seems to be running rich off idle. so If my logic is right I need to bring the slow jet numerically up a bit? and then fine tune with idle adjustment. I will post the jet numbers once I get it torn down. I do know that my main jet is a 170. not sure about the slow jet though.

A few more ?'s should I swap the spring and shim the needle? drill the holes?
No, leave the spring, needle and slide vaccum alone for now. You should only be changing one thing at a time, testing, then adjusting before moving on to the next.

The jetting recommendation that BadMonkey or I gave you should get you very close. Pick one, go back to your original air cleaner housing, leave the baffles in and try it. Don't expect much change in idle characteristics when adjusting the idle mix screw while the bike is running. The circuit overlaps of the CV make those changes less perceptable than with a regular carb.

Tell us about this new air cleaner housing. Is it really small? Does it include a new backer plate? Make sure it's not blocking the vent that is in the front face of the venturi. I think that CV's perform best with an air cleaner housing that has some volume to it.
 

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Discussion Starter · #12 · (Edited)
No, leave the spring, needle and slide vaccum alone for now. You should only be changing one thing at a time, testing, then adjusting before moving on to the next.

The jetting recommendation that BadMonkey or I gave you should get you very close. Pick one, go back to your original air cleaner housing, leave the baffles in and try it. Don't expect much change in idle characteristics when adjusting the idle mix screw while the bike is running. The circuit overlaps of the CV make those changes less perceptable than with a regular carb.

Tell us about this new air cleaner housing. Is it really small? Does it include a new backer plate? Make sure it's not blocking the vent that is in the front face of the venturi. I think that CV's perform best with an air cleaner housing that has some volume to it.
you guy's rock. So here are my actions. I will rejet the slow jet to get the carb leaned out a bit, Then dial it in with the idle mix screw. After that I will bump up the top WOT jet a bit to fatten it up a bit. Since my motor is .60 over with a mild cam

If ever thing is smooth I'm done. If not i will be back.
 

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Discussion Starter · #13 ·
Update,

So I dropped the slow jet down from a 45 to a 44. also blew everything out. runs great in the garage. took her around the block and I'm having throttle stutter starting at 1/2 throttle. I forgot to add this, but I did have the valves done also which means I had to adjust the valves. I will double check the valve adjustment. There are just to many things that were changed all at once.
So am I on the right track?
 

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Yes, you're on the right track, but you won't be able to tune the carb if the valve lift is wrong because of improperly adjusted pushrods. Do you have the service manual? If not I can scan a few pages for you from the valve adjustment section.

After confirming the valve adjustment there's a few things you should probably check. Given the number of times the carb has been disassembled and blown out, here's a few things that might be causing problems other than jetting issues.

First, the idle mix screw has a packing assembly that consists of a spring, washer and small o-ring, in this order of assembly:



The o-ring and washer typically stay in the seat when the idle screw is removed, but if you've been blowing it out they may have disappeared. The o-ring is essential for a good seal around the threads and if it is missing you will be drawing air from a place the carb was not intended to. Check that they're there. If not, I can give you a source for replacements.

Second, the slide needle collar has a seating ring/ledge that is offset from center, making one end of that seat longer than the other. It is possible to install that seat the wrong way. It rests above the main jet and the main jet holder/emulsifier tube, in this order:



If the needle collar is intalled the wrong way it can cause a stumble or hesitation as the bike begins to transition into the mid-range. If installed incorrectly, the top of that seat will be flush with the bottom of the venturi. If installed correctly it will stick into the venturi a bit and will look like this:



While you're checking things, here's a quick and easy way to confirm the proper float height. You can do this with the carb still on the bike. Stick a clear tube on the bowl drain nipple, raise the open end of the tube above the top of the carb and then crack the bowl drain. You can access the bowl drain from the primary drive side of the bike, between the jugs, and it is the screw in the center of this picture:



Once that drain is cracked, the fuel should rise in the tube to the same level as in the bowl. The proper height is level with the top of the bowl, and you should see this:



And just for shits, here's a basic diagram. It's for a CV off a Kaw without an accelerator pump, but everything else is the same:



Start with your valve check. Then check the easy stuff with the carb attached to the engine: visually check that the slide needle collar is sticking up into the venturi, and check the float height. Check the idle mix screw packing assembly last, as it probably can't be done with the carb still on the bike.

Don't you love the smell of gasoline!
 

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I've been following this thread since it's debut.
Mostly because I'm trying to work out some issues that I'm having
on one of my bikes.

I've hesitated to hijack the thread from Dvanecek, but the time has come, and I figure it's better than starting yet another CV thread. So here it goes:

1. History

67 900cc XLCH, 2600 miles since engine overhaul(new pistons & rings, jugs 0.020 oversize, heads re-done w/new valves & guides).

168 psi. static compression in each hole. Running drag pipes w/baffles & magneto ignition.

I bought a used CV carb for the bike to replace a leaky S&S "E". The carb as I received it had a "dynojet" kit in it. I put it back to stock with a new vacuum diaphragm, new seals, adjusted float, new stock length diaphragm spring, and 44 slow / 180 main jets. Lead slug was gone, so I put mixture at 1.5 out from seated.

2. problem
Bike starts hard cold, starts real easy warm or hot.

Idle is very low and choppy, turning idle speed screw has no effect for about a full turn, then idle jumps to around 1300 rpm (yes the screw is touching the throttle cam the entire time)

Low RPm performance is terrible! It runs like a bag of assholes untill about 3600-4000 rpm, at which time it comes alive and runs like a raped ape. Below 3500, it has relentless "lean pops" or "hiccups" out of the carb. It sometimes stalls when shifting from 1st to 2nd.

I've found that if I leave the choke pulled out 1/8" - 1/4" the bike will run much better and will pull smoothly at low rpm's. But at high rpm's she will "blubber out" and run like shit, so I have to shut off the choke once I get the Rpm's up. This gets tedious, as I'm constantly fussing with the choke as my engine speed changes.

3. What I've Tried
I fussed with the mixture screw - to no avail.
I upped the slow jet to a 46 - no different.
Manifold O-rings replaced and re-positioned a dozen times - no help
raised & lowered float level - no help
Upped the slow to #50 - still no better!
checked for O-ring and washer above spring on mixture screw as per Bobb's post above - it's all there and in good shape & order.
Checked needle guide/sleeve for correct orientation(also as per Bobb) - it's correct.

4. what's next?
I'm ready to toss this POS into a lake and go back to an "E"
Can anybody give me a reason not to?

Thanks in advance for any help/suggestions.
 

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I got the rich deal figured out. Ended up being that my choke cable was messed up and even though the plunger was pushing flush, the cable was about a 1/8 inch from pushing in all the way and cause my erichener to stick. Wierd. Anyways I also order a jet kit so I can play with that if needed. What is everyone running in there cv powered shovels?
thanks for the tip. I was having the exact same problem with mine. Fixed now, thanks to you.

I haven't really looked into mine too deeply to know which jets are in it. I traded a friend some artwork for it (and $ome Dough), who just happens to be a genius with the CV carbs. I got it in the mail, swapped it with the old $uper B I had on it, and it ran great, minus the previously stated richness.

thanks again.

this is what i love about this board. ya thought ya had a problem, and ya fixed mine at the same time.
 

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I'm ready to toss this POS into a lake and go back to an "E" Can anybody give me a reason not to? Thanks in advance for any help/suggestions.
Yea, I'll give you a couple reasons not to. The CV is a great carb. It'll give you better fuel economy than an "E", which probably isn't your prime reason for making the switch until you realize that it translates to better range. Which on an XL with a peanut tank is a good thing. It also will give you easier starts and smoother running because of the better fuel atomization.
<O:p</O:p
The CV gets a bad rap sometimes because, as a conversion carb, the donor is by definition someone else's take off unit. The previous owner cares about what he is switch to, not switching from, so it gets pulled and boxed with no consideration for its preservation. Gas gums up, seals get brittle, moving stuff stops moving until some poor bastard tries to put it back in service. Add to the fact that many of these have been tinkered with by their previous owners, like yours with the DynoJet kit. That conversion fucks up the carb and, as far as I'm concerned, it's the leading cause of previous owners pulling them in the first place.
<O:p</O:p
You were smart to junk the DynoJet shit and go back to stock. You're smarter that the idiot previous owner. Don't give up on this carb. You'll be happy in the end. I suggest starting from scratch. Pull the carb and completely disassemble it. Pull everything. Don't worry, we have plenty of pictures to help, and we have diagrams:



I have a monster sized version of this, so check your PM. I put my email address there and I'll send the big version directly to you if you need better clarity showing the reassembly order.

I'm going to post some more pics of trouble spots on the carb, so watch here ...
 

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I think it's pretty clear that your low rpm circuits are causing a lean condition, either through fuel starvation or through an unintended air supply. Strip that carb down to its bare body. You can leave the venturi butterfly and shaft, but the bowl, jets, idle mix screw (don't lose the packing assembly) and upper end including the slide and its components should be separated. Also pull the accelerator pump assembly. Get two big aerosol cans of Gumout carb cleaner. One is a spare, the other you're going use to blast every orifice of the carb with. There are a lot of very small orifices in that body that are essential to a good mixture and get easily clogged with grit or gum during storage. Here are a few:

<O:p</O:p
Put the spray tube into each the jet ports in the bowl area, get as good a seal as you can and let her rip at arm's length (wear eye protection). Those circuits should vaporize the spray, and you should see a nice steady well-atomized mist coming from these ports. Do the same thing with the accelerator pump ports, which should come out of the accel pump tower. Clean the accelerator pump cavity:



Also, there is an internal stoper valve below the accel pump tower:



After doing this you should hear a little rattle coming from under the accel pump tower. That's the check valve. If you can't hear it, protect the tower with some rubber, grab it with some pliers and twist while you pull it up and out. It's a light press fit. The valve will drop out for cleaning.

That will clear the fuel circuits, but you need to think about the air circuits too &#8230;
 

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The fuel jets don't work without an air bleed supply to the emulsion tubes. They're on the front of the carb in the venturi intake next to the accel pump tower. The front of the carb face also has to air supply ports. I don't have a great close up picture, so this one will have to do. One is the crescent shaped port at the noon position, the other is to the left of that at about 11 o'clock. They sometimes get blocked by aftermarket air cleaner housings:



The air ports are visible in this picture, to the left of the accel pump tower. On the far left is the pilot jet/low speed air supply, and between it and the tower is the main jet/high speed air supply. Blast Gumout in there.
<O:p</O:p
Now, with everything clean, inspect the casting for cracks and bunged up threads, especially in the idle mix screw area.
 

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By the way, when you junked the DynoJet kit did you replace the slide too? The vaccum port in the bottom of that slide gets drilled out as a part of the "mod" and can create some problems. If you didn't replace the slide, you should:

 
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