Well everyone I’ll be honest I’ve been fighting to properly tune my CV for 3 years now. Bike is an 2004 FLHRS, I bought it from original owner and he let the dealership do all his work, other then the Stage 1 SE slip-ons and SE Heavy Breather he had put on I assumed the bike was stock when I bought. At first it ran okay, but not great. Well enough that I could ride it for the rest of that summer. Following winter I did my own work, changed headers to S&S Power Tunes, White Bros. Slip ons(megaphone style) and cosmetics. That spring I wanted to re-tune the carb, added a Yost needle for easier tuning but was still coughing a bit, opened the carb up to check it out and what do I find, a DynoJet Kit that had been completely molested on install. Emulsion tube, needle jet, needle(shimmed to highest notch), slide drilled to 9/64!!!(yes I triple checked that part), chipped jets, basically all the stock parts were either modified in a bad way or replaced. I immediately did some research for some kits and come across CV Performance, I bought a new slide and their premium tuners kit. Installed it the minute it come in the mail, followed recommendations in instructions(7/64 drilled slide, jetting is 45/190, 2 turns out), it ran but was never perfect.

Now this past winter I did some more work, installed Andrews 21’s, adjustable pushrods, shoe tensioner, Baisley spring, etc. Basically addressed all cam chest issues and did cams while I was in there. Now it’s back to tuning the CV again. I tried a 48/195 first(CVP recommendations as per my setup)it cleared up and ran well, I never did check mileage but I did a plug chop and it was far too rich, brown/dark brown and I could actually seat the needle at idle and the bike would still run. I swapped back in the 45/195 jetting combo and took it out last night, it runs good power is great and feels snappy, but I still get the odd cough when I blip the throttle to match RPM for a downshift when coming to a stop. Currently at 2.5 turns out, going to try it again today and see if I can find some new plugs to do a chop to make sure I’m not too lean. I noticed with this setup as well the choke on a cold engine is extremely sensitive. To my knowledge I cannot find an air leak(did the propane trick). It’s getting to the point I had to ask the experts here for a little insight, or does a guy just say screw it and find an HSR42? Big Bore and head work in the near future as well so whatever I do I want to think ahead. Thanks everyone

 

What needle and emulsion tube is now installed?

 

Needle, Needle Jet and Emulsion tube all come from the CV Performance’s Kit, I still have the DynoJet ones but as everyone knows their emulsion tube calls for their jets, CVP uses stock jet style. The needle is non-adjustable, they boat on their website they had it figured out. Could put washers under it to richen the midrange if needed but that’s about it. Needle jet is installed correctly as well.

 

You might want to read through the below website. Lots of good information.

http://www.nightrider.com/biketech/hd_cv_mods.htm

http://www.nightrider.com/biketech/hdcvcarbappendix.htm

 

First, there's a lot of outdated tips and tricks pasted all over the net. I've (temporarily) destroyed many a CV following each and every one of them. Sounds like the OPs carb has evolved thru much of the same futility.

Seemingly all of them lead you to believe to tune them from idle up. Wrong! And they seem to all say that the main jet only affects WOT and the needle does 1/4-3/4. I call BS on all that, until someone can show me a bike that will run the same below 3/4 throttle using a 165 as it does with a 205 at part throttle... just sayin'

Obviously one needs to get it to start and idle, but start tuning at WOT. Then get the low circuit where it needs to be and 90% of the time, the mid-range will be good, provided it's not had the needle shimmed, slide drilled or a lighter/shorter spring installed.

Second, and no offense to anyone, doing a plug "read" by chop or a jewelers loop is only beneficial to evaluate a certain speed/load range. I'm not saying it's time wasted, because looking at them can tell you a lot, mainly timing, a general idea of jetting and overall engine health but dialing one in by the plugs can't be done thru the wide of RPM range of a road bike. But you can get close

Third, a small vacuum leak will not show up using any traditional method of detection, unless it's so bad it won't run and/or idle any where near correctly. And temperature of the engine can allow a leak sometimes and other times not.

A 45 is way too lean with an open exhaust, unless it's a Sportster and usually takes in excess or 3 turns to eliminate the of decel popping or coughing on throttle snap as you described (and explains the sensitive enricher). Much beyond that point, the spring isn't putting much pressure on the screw and they can vibrate to a point of thread damage in the carb.

Many use a 46 with success but a 48 is just fine, so long as one remembers - just because it'll idle with the screw seated, doesn't mean anything is wrong or that it'll act right all the time with that screw seated. Too many guys have thrown away money on aftermarket carbs just because they couldn't get a CV to die with the idle screw. Don't ask me.... It is possible get better mileage with a big slow jet, since it allows for enough that you aren't getting very far into the needle circuit at mild acceleration and low speed knocking around. But that does depend a bit on the needle.

So assuming you have the correct parts in it now, keep the 195, CVP needle/tube and use the 48 @ 1.75 - 2 turns out or try a 46 @ 2 - 2 1/4. Check you mileage and get back to us.

 

Joe Minton had a pretty good reputation for tuning carbs. He seemed to believe it.

http://www.braigasen.com/hd_jetting.htm

 

I've read his "book" many times and greatly appreciate his writing style. Also, I recommend reading his tuning guide - lots of good info and easy to read. Just bear in mind that most, if not all of it was written 2 decades ago and never a mention is made about longer duration cams or the scarcity of needles for the Harley CV.

With cam changes, I maintain the stock low jet usually won't serve one well and if the main is too small or large, you'll never get the mid range where it needs to be. Adjustable needles caused me to quit drinking years ago and shims are usually necessary to mask a main jet deficiency and most always kill fuel mileage.

Full disclosure - I've never ridden on a dyno - scenery never changes. And I've never owned or used a wide band o2 monitor, so all my opinions are based solely on real world riding experiences and roadside tinkering in search of the sweet spot between good power and decent fuel mileage.

 

Interesting read, I have never really heard of someone tuning from WOT down but it does make some sense for sure. As for assuming I have the correct parts in it now I believe I do. Current setup:

CVP Needle/Tube
CVP Spring
CVP slide(7/64 hole)
Pilot is currently a 45 at 2-5/8 turns out
Main is 195

I took it for a ride yesterday to do some further tuning/trials with a fresh set of plugs. I filled up, the wife hopped on the back, set my trip meter and headed out to put on about 230km(~145miles) on the highway average speed being 100-110kmh(~60-70mph). I filled up at the same pump when I got back and did the math. I got 5.24L/100km(44.9mpgUS). I still got the odd cough when blipping the throttle to downshift while coming to turn or stop, not as often as before but still there. Checked the plugs when I got back just for fun and front cylinder showed about an eggshell white, a little lean possibly but getting better. Other then that mileage was good(especially loaded 2-up and saddlebags full of beverages I thought) and choke consistency has improved and power felt normal. I’m not too keen on trying to 3 turns out on the needle as you stated, I would rather put in the 46 and try that. I believe their has to be an overlap position on pilots to find that sweet spot, example a 45 at 3 turns out may provide the same fuel as a 46 at 1.5 turns out. Not saying that they do, but I’m curious to know if it’s ever been tested. I do still have the DynoJet adjustable needle as well to improve midrange in the future if needed but I’m putting my faith in the CVP needle right now. I’m currently still in the midst of trying to find a shop to do my headwork and bore to 95”, with the borders being closed it’s difficult but in the meantime getting this 88” to run right is all I can do. Thanks again.

 

are you driving an 18 wheeler???? so why the blips on the throttle???
i run a 01 sport and tricked out for the street, designed for top end and i engine brake a lot even to the point of barking the tires, matching road to engine speed is funny.
i always tune top down and yes there are diff views, so the reason:
first it is the simplest to do ( jet size ) and once done you do not need to go back. the next would be idle or low speed because if not right, you will never get mid range right because the low must work with the transfer circuit, when you get higher up, then needle plays a part as it has to blend into the wot.
so what is causing the pop?? could be several things but of note, when you do a blip, the flow through the carb will diminish and severe enough can cause bog. also of note, the fuel will have a tendency to drop out and when it does, the mix is screwed. another thing is the accel pump, could cause an over rich or lean out depending upon what is going on, aka, suppose a leaky check allowing fuel to return to the bowl. old carbs used to be able to change amount and timing, the hd only the timing. also of note is where the stream is pointed, works better directly into mid stream air flow.

 

hahaha last time I counted no she’s not an 18 wheeler, luckily I have most of my fingers and toes to count for when I do come across one though. In all honesty the only reason to match engine to road speed for downshifting, especially this time of the year, is to prevent skidding. Our winters leave a horrible fine layer of sand and calcium/salt on our roads that can cause skidding on hard downshifts until we get a few good rainfalls. Smoothing out the downshifting helps and can just become force of habit. It’s not something I do everytime, but when needed yes I match for a smoother downshift.

Back to jetting....I tried the 46 at 2 turns out as recommended before, I seen a mileage drop to about 6L/100km(40mpgUS), although I was on the throttle more to get a better feel for my midrange so it may not be entirely accurate. But I did notice more hesitation in the lower Rpm range, 2200rpm-2800rpm seemed more doggy, which is odd because that’s where my cam is supposed to shine. I have not done a plug chop and I won’t, I see lots of you don’t recommend it anyways and more plugs is a waste of money. Tuning from the top down I believe I have that with the 195 main, finding the low-mid setting continues....