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Discussion Starter · #1 · (Edited)
I finally got around to a dyno run today, just for a baseline of where I am at. I found a local shop that would do just the run (no tune) for $40. I knew my numbers would not be anything staggering. Likely fairly close to factory.

I think the only mods I have that would affect the tune are the supposed EV13 cam, the Thunderheader, and higher flow K&N Air filter. There is a single fire ignition installed also, but I don’t know if that would affect it. If there are other mechanical mods, I am unaware of them.

I had a Harley Service Manager do the Thunderheader install, and he was supposed to tune for it. Clearly he didn’t.

I’ve been experiencing some popping on decel and the occasional backfire.

Turns out I am pretty lean. He didn’t even go all out, as he said it was too lean.
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The shop recommended raising the needle valve one notch, and going up about 3 sizes on the main jet. Then bringing it back for another run. I could have left the bike with him for a few days and let him do it, but I am wanting to continue learning so am hoping to do it myself.

My roommate is a diesel mechanic, and a Harley rider who does his own work, so I’m not totally alone jumping into this. Still, I have run into some issues that I want to ask you all about.

First... based on the EV13 and Thunderheader, where do you recommend I begin with jet sizing? I would like to compare your recommendations with his, once I actually pull the bowl to see what I have installed in mine. I ran into issues with the needle and have stopped taking it apart to investigate the main as I am a bit stumped.

Now… to the needle. My roommate had a spare CV laying around and suggested I take it apart to see what I was getting in to, before I took mine apart. It supposedly came off of one of his friends FXR with California emissions that he had worked on years ago. I took it apart and all looked pretty simple. I don’t see how to adjust the needle though. No C clip or washer/s installed. Here is the pic...
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So, I go ahead and take mine apart. It is a bit different. It also does not have a c-clip for adjustment, or any washers installed. The needle appears as if it cannot be removed at all though. I showed it to my roomie, along with the innards of the first one to clarify the differences and he is convinced it’s an EPA thing, so as to prevent adjustment. Pics of mine...
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He has another CV laying around. Is not sure what it came off of, but he said he knows it’s been modified before is modifiable so I might be able to use that one, or parts off of that one. This is the first time I’ve ever done any sort of carb work, and I don’t want to have three carbs apart right now. I don’t really know what I am doing. Just figuring it out as I go (or not).
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What are your recommendations? How should I proceed with the needle? Main jet size?

Thanks in advance. You all have always been a great help in the past.
 

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First. If you cant ID the needle, don't use it. You can end up chasing your own tail because some one put a Kawa needle in it.

Oem needle. 180 main jet 45 low speed jet. Might need a 48 with that pipe. Clip a complete coil off of the oem slide spring. Make sure the accelerator nozzle sprays right down the center of the suck hole. Drill out the epa plug that covers the mixture screw. Use a new needle valve.

As for the pop on decel, all you can really do is make sure there are no leaks at the flange gaskets. That pipe is not really built for good manners, its more about WFO power and damn the rest.
 

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Discussion Starter · #4 ·
So to get that needle out of mine, I just cut it then? That ring (seems like its pressed or formed into it, almost like a rivet) prevents me from pulling it out. Or am I likely to run into another EPA infused problem with the other jets as well, and better off just using one of the other carbs? So far, I am doing this with the carb still on the bike.

I read that bit on nightrider (appears to be a great site). Did not see a video, but it was late and I may have missed it. I did see where he discussed drilling out some holes and listed some needle and jet recommendations. Of course, those seemed kind of a generic starting point and did not take into account the exhaust (not that I saw anyway).

I did not see where they discussed cutting the spring. I have a few from the various carbs, so I guess it is no big risk if I cut a ring off of one.

Brands of jets recommendations? I'm in a rush... trying to get out of town for a job, so will likely just get what I can find quickly and local. Am hoping to trailer the FXR, and have it road ready before I leave. I'll call Route 66 HD when they open. Maybe they have a kit or some jets. I doubt they will since carbs are a thing of the past though.
 

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Did you turn the slide upside down to see if the needle just falls out from the top, where the diaphragm is? There should have been the spring and a guide inside the top, over the needle and clip.

I see that keeper on yours, don't know about that. Your pic is sort of blurry. Did you try and pry it off with some needle nose pliers?
 

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Are those two diaphragm slides from the two different carbs, along with the corresponding needles? I've never seen one with the washer/circlip on the bottom side of the slide. As rootintootin said, it comes out the top. The exploded diagrams in the websites will you understand how these things go together (and apart). A parts manual is most helpful. A magnifying glass will help you see the part number on the needle shaft close to the top.
 

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Discussion Starter · #8 ·
Did you turn the slide upside down to see if the needle just falls out from the top, where the diaphragm is? There should have been the spring and a guide inside the top, over the needle and clip.

I see that keeper on yours, don't know about that. Your pic is sort of blurry. Did you try and pry it off with some needle nose pliers?
Ya, it's off now. Like you said, with some needle nose. I thought it was actually formed in, Haha. No harm risking f'ing it up though, as it was unusable as it was. Now I can see the numbers on it.

N86E

When it is mentioned here to use a new OEM, I assume that is to use the same part number then and to use washers for tuning rather than to get one a bit richer, like the N86F or one of the N72s?

I know I'm asking some pretty 'OCD' questions. Sorry, it's how I am built....
 

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Discussion Starter · #9 ·
Are those two diaphragm slides from the two different carbs, along with the corresponding needles? I've never seen one with the washer/circlip on the bottom side of the slide. As rootintootin said, it comes out the top. The exploded diagrams in the websites will you understand how these things go together (and apart). A parts manual is most helpful. A magnifying glass will help you see the part number on the needle shaft close to the top.
Ya, the first is the spare that I took apart to 'see what is up' before getting into mine. Mine had the little clip. My mechanic buddy had never seen one there either. It appeared part of the needle itself, rather than removeable, but it came off with a bit of force. Had it not been for that circlip, I likely would not have started this thread....
 

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Discussion Starter · #10 ·
Route 66 has the 180 main & the 48 Low. The only needle they have is the 27094-88 for the 1200 sportster, but 'they say' it works great in the big twins. Thoughts???

Found the 45 at Myers Duren.

I don't think he had the new needle either, or the brass washers. Is going to check with a mechanic to see if he does.
 

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Route 66 has the 180 main & the 48 Low. The only needle they have is the 27094-88 for the 1200 sportster, but 'they say' it works great in the big twins. Thoughts???

Found the 45 at Myers Duren.

I don't think he had the new needle either, or the brass washers. Is going to check with a mechanic to see if he does.

Everything you need for that carb, to include tech support is here:

CV Carb Parts
 

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Discussion Starter · #13 ·
I found all the jets locally. Ended up having to go to a mechanic for the 45 as MD didn't actually have one. The shimming washers were the toughest find, but a different mechanic had those.

He actually recommended that Sportster needle also. Said with that and two shim washers, he wouldn't even change the main to 180.

He said if I was after fuel economy, not to mod the slide at all. Said if I wanted better throttle response, to drill out the vacuum hole in it to the 1/8" and to cut a ring and a half off the spring.

I'm still unclear on why the Sportster needle and washers negates the need for the 180 high speed jet, but I have been running around town looking for the parts instead of checking out these sites and videos. I'll get around to those later today, I hope.

Maybe someone here will explain it to me (like im a child, please) in the mean time.
 

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Well I would not cut the spring or drill the slide both those things are a waste of a good spring and slide. With the sportster needle you don't need any washers either it will just be pig rich. A 45/46 slow jet and a 175/180 main and the sportster needle will get you in the ball park but without a O2 sensor it is all just a guessing game.
 

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Discussion Starter · #15 ·
I'll agree that I don't personally have a need to drill or cut at this point. That is something I can do later and does not have to happen now in order to get out running right.

It sounds like everyone is pretty much in agreement on needle and jet sizes, which increases my confidence. The other stuff seems like things I may want to do in order to fine tune or increase throttle response. All decisions to be made after the next dyno run...
 

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I found all the jets locally. Ended up having to go to a mechanic for the 45 as MD didn't actually have one. The shimming washers were the toughest find, but a different mechanic had those.

He actually recommended that Sportster needle also. Said with that and two shim washers, he wouldn't even change the main to 180.

He said if I was after fuel economy, not to mod the slide at all. Said if I wanted better throttle response, to drill out the vacuum hole in it to the 1/8" and to cut a ring and a half off the spring.

I'm still unclear on why the Sportster needle and washers negates the need for the 180 high speed jet, but I have been running around town looking for the parts instead of checking out these sites and videos. I'll get around to those later today, I hope.

Maybe someone here will explain it to me (like im a child, please) in the mean time.
The Sportster needle has a sharper taper so when it's lifted higher out of the jet orifice it's basically like a stock needle with a bigger jet. Let's more fuel in...
 

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The Sportster needle has a sharper taper so when it's lifted higher out of the jet orifice it's basically like a stock needle with a bigger jet. Let's more fuel in...
That's only the N65 needle, the rest of the sporty specific needles are thicker.

The first CV's used on Sporties were sans accelerator pumps, and they used that rapid taper needle to make up for it.

Dropping it into a big twin will fatten them up. But usually fattens them more than they need. General rule is N65 - 165 Main jet - 42-48 Low speed jet.
 

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I'm running a 45, a 185, and the Sporty needle. A modified diaphragm (drilled to a little under the 1/8") and a lighter spring. Actually Bob Yost himself set it up so it has the Yost Tube as well. And yes, it runs fat. But not so much that it leaves big deposits on the tip of the ThunderHeader.
 
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