Jetting CV carb

I'm new to this forum, so bear with me if this question has been asked a million times. Recently bought a 2006 883 custom. The bike is basically stock except for a set of Screamin Eagle II pipes. Unfortunately, I don't think the previous owner rejetted the carb. I bought a jet kit with a new main jet and pilot jet. Here's the problem: the stock main jet is smaller in diameter than the new main jet. The new main jet is too big to screw into the jet holder. Is it possible that I have the wrong main jet, or has someone replaced the main jet holder?

You probably have a Dynojet (Dynojunk) kit. If all that was done was a pipe change, you may not need to rejet. Hows the bike run? Are the plugs bone white? Any specs or blisters on em? You usually don't need to rejet until you open up the intake with the SE breather or Ness Big Sucker to name a couple of popular ones.
Art NJr is the Sporty guru here an he'll prolly chime in to help you set it up right, if need be.
Hang in there and Welcome :devil:

Carb jetting

I do believe the problem is a dynajet kit. I only rode the bike a short time but it had to run with the choke out a bit before the weather got bad and I would occasionally get a pop through the carb. I want to install a K&N filter so I believe jetting is in order. Does the dynajet kit replace the stock jet holder. Are any other mods performed on the carb that would keep me from replacing the holder with stock and rejetting. Thanks

They'll pop thru the carb when cold. Was it a Dynojet kit you bought or stock CV jets?? The dynojet kits emulsion tube(jet holder) is a different thread pattern than stock CV, so stock jets won't fit and vice-versa.

When you open the intake with the K&N filter, try starting with the stock 42 pilot jet(you may need to go to a 45) 2 1/2 turns out from gently seated on the mixture screw. Get the idle set then move to the needle jet. You can either shim it or buy the N65C (88Sporty needle part # 27094-88) and then a 165 or 170 main jet.

The mixture screw has a silicone(tamper proof plug) you'll have to get out to get at the screw...then reseal it.
Hope this helps so far.......Kenfuzed on this site sells a CV kit you may want to check out. Good luck, let us know how you're doing.:devil:

Here's a link for the EZ adjust mixture screw
EZ-Just Mixture Screw

Carb Jetting

I just bought the CV adjustment screw kit and jet holder. I have a new main jet and pilot jet. The carb must have been worked because the plug for the adjustment screw is already out. Hope going back to near stock will help. Thanks for the reply.

Most likely was,if you got CV jets,my guess its a DJ tube installed. Stock tube and CV jets. The "tamper proof" plug is supposed to be resealed to make it air tight not just hard to get at. Did you get a mixture screw kit like the one in the link??

Carb jetting

I bought the mixture screw kit and jet holder from CV performance. I have a new main jet and pilot jet. The main is a 180 and the pilot, I believe is a 44. The bike the way it was setup before I checked the carb would "cough" and sometimes pop back through the carb even when it was warmed up. Is it true that some dynajet kits replace, or cut the slide spring?

Yeah, but no need to, or drill the hole either. Clipping 2 coils off the stock spring is better than using the DJ spring, but just jetting is all you gotta do. Just make 1 change at a time, start with the mixture screw and move on.
The carb farts could be because the mixture screw wasn't resealed.

If the EZadjust mixture screw is installed I am assuming that the resealing is no longer required. Is this a correct assumption???

You've already gotten good advice but I'll toss my 2 cents in. Definitely sounds like a DynoJet kit was used before, stock parts are not interchangeable & the only place in a good tuner's shop you'll find those kits is in the trash can. Baseline for an 883 with improved air-cleaner & exhaust is 42 slow, 165 main, 2.5 turns out on the idle mixture screw & for 2004-up models, the stock needle.

The needle was the major problem with earlier models but from what I've seen on '04-'06 Sportsters, the stock one works fine. A couple guys ended up shimming theirs .020" but you only get into that after everything else is already right. And I think, but I'm not 100% sure, that your bike came with the W grind cams that were previously used only in the rare 1200S model - if that's the case, then you'd want a 170 main to try too. But a 175 is too much for an 883 with stock heads.

There's a big misconception about the '04-up Sportster heads - yes they are the same basic casting as the new XB Buell heads, which are the best ever offered on production bikes - but while they look the same on the outside, they're not on the inside & 883's retain the combustion chamber shape & valve size of previous Evo models thru 2003. So with the exception of the W grind cams, which @ some point from '04-up were put in all Sportsters, not just 1200's, an 883 is still an 883 & you tune '04-'06 models the same way as before.

Which includes NOT drilling the stock slide out, replacing it with a plastic one like the Thunderslide, or going to a super-soft spring. Sounds like you now have the kit "kenfuzed" has & while I haven't tried one yet, it appears to be a good one, which does the same thing experienced tuners have been doing for years. Until the '04 models came out, you'd always get the "carb farts" & the most common way to deal with that was throw in a 45 slow jet. The"seat of the pants dyno" says the problem's gone but it's not - you just drowned it. Put the stock 42 back in & replace the needle if necessary, which it was thru '03 models.

Get the low end & mid-range dialed in & then worry about the main, which the needle controls the flow from & you're not all the way on until full throttle from about 4500 rpm on up. The needle & slide functions are more important than anything for day-to-day riding. Drilling the slide out, using a lighter one, soft spring, etc. will make it raise quicker, but then the side "hunts" going down the road - moving up & down trying to find the right spot, which it never does.

Then someone will talk you into buying a Mikuni carb & while they are great, they're certainly not worth the $$$ for a basically stock bike, as you can get the same power, throttle response, et al. from a stock CV with $15 worth of carb parts & a screwdriver. And a stock CV carb with minor jetting & needle changes will make up to 101 HP @ the rear wheel on a Sportster - it's been done many times.

Carb Jetting

Thanks for all the advise. Beginning to get things squared away and hopefully have this thing running normally by Spring. Once again, my appreciation to all.

What would the baseline be for an early '78 shovelhead with 2 into 1 exhaust with a fairly free-flowing muffler and an S&S style aircleaner? I have put in a 45 slow with a 165 main and new o-rings and float.

I'm just waiting for my EZ - just mixture screw (ordered last night) and then it's time to put it on, put on the exhaust and go ridin'

Hey crew, doing my first stage 1. It is a 06 1200R , starting with a 46 slow and a 185 main while keeping the stock n4nn. K&N lifer with V&H slip ons ,,,,,any Opinions on Backup jets?? also have EZ adjust already in carb. I figure it will be like MOST..... longer than expected, etc etc and PROBABley end up on the Dyno anyways. Any sound Advice out there??

Don't know Shovelheads like I do Sportsters & the only Big Twin I've ever owned was a '47 Knucklehead, loooong time ago. But the same tuning procedures apply with a CV carb on any H-D - get the low-end of the rpm range dialed in 1st. 45 slow might be right for your application, but I'd go with a 42 first, as for example, a 45 is too big for 1200 Evo Sportster, with heads that flow a LOT more than a Shovel.

And I'd use the infamous N65C needle (part # 27094-88) which'll cost you about 8 bucks at a Harley dealership. Top tuners have been using that one for 20 years because it meters so well in the lower rpm range most folks actually use. As I've said, the biggest problem folks encounter with a CV carb is the "carb farts" & putting a bigger slow jet in doesn't fix the problem, it just drowns it. The needle IS the problem & the N65C will almost always fix it.

It's the transition phase off the idle circuit where the problems almost always are & you can see it on the charts when using a dyno with an air/fuel ratio "sniffer" - the carb spikes way lean for a moment, usually in the 2500 rpm range. That's the needle & throwing a bigger slow jet in just masks the problem, turning the spike into a bump, but then the idle & low rpm range is way too rich.

Also, your 2-1 exhaust works best only in an rpm range about 1500 rpm wide, usually 3000-4500 rpm. That's fine, as that's where you probably run the bike when you get hard on the throttle & a Shovel definitely is not a high rpm screamer. The needle is every bit as important in that range as it is from idle to just starting off from a traffic light.

You don't get all the way onto the main jet until you're really winding the engine @ full throttle, so you can be off a bit on the main & the bike will still run well - you're "on the needle" almost all the time. So again, just work on getting the idle, off-idle, low rpm range dialed in 1st - then you can try different main jets to get the best top end.

Lordy-mercy - let me guess - the dealer put those jets in. Your baseline is 42 slow, 175 main, stock needle. You may need a 180 main but I doubt it & the 46 slow would be too big if you had the heads worked & race cams installed too.

http://bike-talk.com/forum/attachments/motorcycle-tech-talk/903d1208346402-making-sense-jets.jpg

42 Slow 180 Main on an 06 XL1200. In 04 HD changed a lot on the Sporty, to include factory baseline on the jets.

That chart is copied from the 06 Sporty Manual.

rejetting

the stock jets for 06 Roadster are 42 slow 180 main. Ive talked to NUMEROUS people have NUMEROUS Opinions.......It seems maybe the n65c would be a good place to start, then again the KIT SELLers all SWARE by THEIR jet size Choices as Being the absolute best. Gee..... if only i owned a 50K$ dyno...mmmmmm......maybe in the Livingroom Honey..?? sure babe:fight:

It is very definately a CV. The bike as I bought it has an S&S Super B on it, but the seller threw in a CV (complete with adapters) that he was going to put on. I have now put in new o-rings and float and a 45 slow and 165 main jet, waiting for my EZ-just that I ordered the other day and will then be ready to install. I just want to know if my choice of jets is reasonable for that motor as a starting point.

Thanks all.