CV44 TUNING

[Sonny S.]

What is your bike & build and what are the carb specs ?  CV44 ONLY
Do you have AFR data or a dyno sheet ?  If not, that's fine.

Thanks,
Sonny

[mayor]

Build details:
2002 FXD
'06 WFOLarry ported TC heads, stock valves and springs (and quench grooves)
95" SE flat tops
82cc head chamber and .030" cometic head gasket
Andrews TW37b cams
44CV carb
Zippers filter upgrade on SE backplate
SE6200 -5 degree performance ignition
Cycle Shack slip-ons on factory head pipe

WOT AFR running a 46 pilot (3 turns out), 195 main, DJ spring supplied by Larry and N8EL lean needle:


The cruise was around 14.8-15 afr and the idle was around 18:1.   I changed the jets to 48 pilot (1 1/2 turns) and 200 main.  I also pulled the spring that Larry provided out and replaced with the stock one.  Wide open the bike seems to run better, but at cruise it doesn't seem as smooth as the previous set up.  I since changed the spring back to the one Larry provided.  I  made another dyno run a couple of months latter with the new set up.  WOT AFR running a 48 pilot (1 1/2 turns out), 200 main, DJ spring supplied by Larry and N8EL lean needle:


I've tweeked the set up a little since the last dyno run.  I'm now running a N8EM ("M") needle and the A/F screw is turned about 2 1/2 turns out.  I didn't have any mechanical issue with the "L" needle, but the sound of the engine just wasn't quite right.  I lost about 1-2mpg, but I'm still in the 44-45mpg range.  My elevation is about 1,100 and I've riden from sea level to about 3,300 ft with no real issues.

[mayor]

Build details:
2002 FXDL
'06 WFOLarry ported TC heads, 1.9" valves and stock springs (and quench grooves)
95" SE flat tops
80cc head chamber and .030" cometic head gasket
Andrews TW54 cams
44CV carb
SE filter on SE backplate
SE Adjustable ignition (curve 2, advance 0, Rev 6k
Cycle Shack 2 into 2 M-pipes

CV44 carb particulars are:
48 pilot (about 3 turns out), M needle and 210 main. 



cruise was around 14.4-14.6:1


I decided to play with the jets, needle and slide spring, so here's what the build's afr looked like with a 50 pilot (1 1/2 out), L needle and 220 main:

[Sonny S.]

Well Mayor,

Looks like carb's are starting to be a thing of the past.
Even our dear friend Max has crossed to the other side   

[Lovetoride007]

Just built a axtell 107 on a 04 flhtc, Dewey heads w/ grooves,9.8to1, HQ 575 cams, super trap 2-1, CV44 w/ 50 pilot 2 1/2 turns out,Woods KT3 needle and 220 main , running DTT wego 2 AFR meter have 300 miles on it ,AFR #s are in 35-40 DEG weather,my idle is about 13 to 1  cruise is about 14.5 to 15 and on a couple of roll ons it was about 14.5 , will have better info when broke in. Got 32 mpg first tank

[Sonny S.]

LTR,

Great info.  Thanks !

[Sonny S.]

FROM : Fxstchewy in another thread

I switch out from time to time on my Hippo motored FXST, I use a HSR 42 and CV44, the 44 works great and the bike starts better with the CV, jetting is 50pj approx 1.5 turns out, "L" needle and the stock 220mj, the HSR 42 seems to have a little better response but overall they are very close. Chewy

[mayor]

>Do you have AFR data<

Yes, it was a CV44, 95" T/C .57" lift cam

Right or wrong that's how I jetted it.

maybe I'm missing something, but I didn't see the jets you used to achieve the posted numbers.  Can you be more specific? 

[mayor]

Maybe I don't understand the question, are you asking for specific CV 44 jetting used for specific builds regardless if the jetting is correct? 

I think what Sonny was asking for is simply data-  jets and afr in relation to build, and after that caveat emptor.     I think I read on the internet that not everyone follows the guidelines you laid out for the AFR, so just data is best- that way we can make our own informed decision based from the data.   

[FLTRI]

>Do you have AFR data<

Yes, it was a CV44, 95" T/C .57" lift cam

Idle 12.25 - 13.5
WOT 12.25 - 13.2 (cold) 12.7-13.5 (hot)
Cruise 13.2 - 14.5
Decel 17.1 (Minimum)

Right or wrong that's how I jetted it.

IMO, this is just about as good as it gets, regardless of what anyone has read, these AFR numbers are excellent targets for any build. With a carb it is all about compromise and these ranges are very much within expected results from proper tuning. Very well done PHR.
As always, JMHO, Bob

[Sonny S.]

Bob,  you just created a monster..lol

I already KNOW what target AFR ranges are. Besides, cruise 13.2 -14.5 ...really ?   
That wasn't what this thread was about.
That post is like telling someone you ran 9.1:1 dynamic compression, and made 100 - 110 HP but not listing the combination of parts used. BFD

Bob, don't you use a starter map that you have created from a previous tune or do you just start from scratch every time ?

[FLTRI]

Sonny:
Sorry if I offended anyone. LOL!
"Besides, cruise 13.2 -14.5 ...really?" Answer:

Code Select Expand

Yessir!
As RPH correctly stated:
"It seems that as the throttle moves so does the air and the fuel."
This lack of consistency is common with carbed bikes, exacerbated with high overlap cams and open 2into2 exhaust systems. Another reason EFI is superior the carbs.

"don't you use a starter map that you have created from a previous tune or do you just start from scratch every time?"
This thread is concerning a CV carb, not sure what analogy you are using here, but to answer your question:
I always try to find a good base map for any tuning method where no changes can be made with the engine running (SEST, TTS, DirLink, etc), however I have no problem starting from scratch with a PowerCommander due to the luxury of tuning while the engine is running and I'm reading AFR changes live.

[Sonny S.]

" This thread is concerning a CV carb, not sure what analogy you are using here, but to answer your question:
I always try to find a good base map "

Yes, and I was asking for the same thing but instead of a base map.... jetting.
That's all...nothing more. Builds with CV44 carbs, how they were set up and ACTUALL AFR results.
Not AFR ranges, not what is best, not what does anyone think, not what someone heard at the water cooler one day.
Not even how a CV40 or 51 was set up on whatever.

I understand what you are saying about if the throttle moves while cruising..got it.
However, I've asked you in the past about a target AFR on my own carbed bike and you NEVER gave such wide ranges.

Bob I value your suggestions and pay attention to what you say.
Here are just a few posts from you about AFR, and I don't see you saying 12.25 idle. 12.25 WOT or 13.2 cruise.
IMHO these numbers are totally unacceptable for a street bike...carbed or not.


If you set your cruise AFR to 14.2-1 you will find the performance is good and the mpg is outstanding. Just adjust the cruise range for this AFR and the rest at 13.5 and you will be fine.
Only for racing engines used for racing do we tune any richer that 13.5 AFR.
As always, JMHO, Bob

mtm,
"Or do you just chop them from 13.5 to 14.2 and back again?"
Exactly, or if you wish you could taper the AFR in and out but the most important point is to make sure you are operating in the 14.2 during cruise, your cruise/speed.
Don't over think this and don't worry if your engine ends up running at 14.2 most of the time, even under substantial loads. Remember the stock engine is tuned to 14.6-15.2 most of the time.
There is way too much concern that 14.0-14.2 is lean and will harm engines. Quite to the contrary IMO running too rich does more damage over time, not to mention the absolute waste of fuel and dirty air to boot.
Anyway off my soapbox, sorry for the run-on, and as always JMHO, Bob

Vic,
From my POV, there is really no reason for AFR to be any richer than 14.0 @ idle. There is absolutely no load, and no rpms to create heat.
I find bikes tuned to 14.0-14.2 @ idle as well as all light loads/lower rpm run very well and get great mileage.
I know there are those who say they set their idle to 12.8-13.2 to cool their engine, but I believe there must be something else causing the heat if it has to be that rich @ idle.
Hope this helps, Bob

[FLTRI]

OK sonny,
I think I see where the confusion lies. With EFI we can get the AFR perfect everywhere, however with a carb there is always fluctuation in what the AFR does @ different rpms/tp. I try for best compromise to the target but sometimes the build/exhaust will only allow a mean average, with up to 1.5-2 AFR from leanest to richest readings. This applies to part throttle as well as WOT.

I find Mikunis are the best for holding AFT to target and the CV next, followed by S&S carbs.

I always start with whatever the carb comes with and work from there. Most of the time folks try to second guess what the jetting "should" be just to find out the stock jetting was closer than the guess. This is especially true with Mikunis and CVs. S&S carbs usually come with too big a main jet.
Hope this helps,
Bob

[Sonny S.]

I always start with whatever the carb comes with and work from there. Most of the time folks try to second guess what the jetting "should" be just to find out the stock jetting was closer than the guess. This is especially true with Mikunis and CVs. S&S carbs usually come with too big a main jet.
Hope this helps,
Bob

Bob,
I really hate even keep this going but....

I'm no tuner but I'm also not a dumbass. I know EFI is different and more accurate.
I'm not sure why my WEGO III or my CV40 would hold steady a perfect # at WOT but it does. That is of coarse after an initial rich dip when the throttle is cracked. Limiting accelerator pump squirt of course lessens that.
Even at cruise and idle when the bike was warmed up the #'s would NEVER vary .5, unless of coarse road conditions, throttle position, wind, a passing vehicle, a low flying duck..etc.
If you want to blame the WEGO, well, Iv'e seen others post the same results with an LM-1 and other AFR " meters " not LED gauges. PHR is using a RSR gauge that only shows colored lights for AFR #'s and nothing specific other than I believe 17.1,13.2,12.2....something like that. Either way, you could not read a true 13.5:1 if you wanted to.I know, those are the only numbers that matter so it is perfect 
Yes it will keep you in the " safe " range

Now for starter jetting. You're going to tell me that if you installed a street legal CV44 on a motor that from your previous experience would require more fuel, that you would still start with stock needle / jet ?  WHY ?
If you knew for a fact that the leanest needle available was in that carb, you would run it anyway, knowing you would have to swap needles, even if it meant pulling the carb ?  WHY ? ......
or would you say....hmmm , the last few times I've tuned a CV44 on a motor like this, the " L " " M " ( whatever ) needle is what I used so I think I'll just start with that ?

Look, I know you don't even like carbs, so I find it hard to believe that you're going to dick around with one any longer than you have to.


Edit :

I forgot to mention the 12.25-13.5 idle that you agreed with PHR on. IMHO 13.5 yes.
I realize that EFI and carbs are different but don't the same idle AFR's apply but what about this statement.
From my POV, there is really no reason for AFR to be any richer than 14.0 @ idle. There is absolutely no load, and no rpms to create heat.
I find bikes tuned to 14.0-14.2 @ idle as well as all light loads/lower rpm run very well and get great mileage.
I know there are those who say they set their idle to 12.8-13.2 to cool their engine, but I believe there must be something else causing the heat if it has to be that rich @ idle.
Hope this helps, Bob


Also, PHR,  how are you getting 17.1 decel with the CV ? Are you blocking off the decel enrichener ?

[FLTRI]

Sonny,
I guess I should have qualified my statements by saying if it is a repetitive build that I know based on history requires different jetting, yes I will make changes prior to tuning.

Also, since the CV40 is a smog carb there are known low speed and needle changes that are well documented, but that only applies to the EPA carbs, not aftermarket, performance carbs such as Mikuni, S&S, CV44, CV51, Edelbrock, PSI, etc. These carbs come with jetting based not on EPA, but on mfg testing and development, so prejetting may not even be in the right direction.

A little suspect that your AFR "NEVER" varies more the .5 afr, unless you are referring to static rpm/tp, or have a stock cam and good back-pressure exhaust. Usually with high overlap cams, 2into2 exhaust, goofy air cleaners, etc, will affect the way the engine breathes varying AFR readings. Unlike EFI with well over a 100 rpm/tp cells for each cylinder, there are only at most, 3 normally adjustable circuits in a carb that feeds both cylinders.

PS- It's not that I don't like carbs, it's that they are such a compromise compared to EFI, I can't make the tune perfect for all rpm/tp. Hard to be perfectionist with carb tuning, even after spending 3-4 hrs modifying circuits, adjusting float levels, changing jets, modifying air bleeds, changing CV slides and springs, adding/jetting Thunderjets, and adjusting accellerator pump output.

HTH,
Bob

[Sonny S.]

A little suspect that your AFR "NEVER" varies more the .5 afr, unless you are referring to static rpm/tp, or have a stock cam and good back-pressure exhaust. Usually with high overlap cams, 2into2 exhaust, goofy air cleaners, etc, will affect the way the engine breathes varying AFR readings.

The one I was refering to was..
95"
06 Heads
TW37's @ 9.5
SuperMeg 20 discs closed cap
Zippers filter with SE backing plate

I was testing on a nice flat road it was very consistant. I looked at a data log and did see spots where is would very more than others but there are several places where it stayed .4-.7. So, NEVER should have been left out 

Look's like we are winding down to a nice place to put this conversation to rest    

[FLTRI]

Sorry I got involved. Didn't realize it was pissing match. I thought there was a bit of good info for someone with a CV44 that wanted to know how they react and what was usable jetting, and how to compromise.
Let's play nice, boys

[Fxstchewy]

Leave the thread........I can read thru the bs... good info on the CV44, Thank's for all who put in their .02 

[Sonny S.]

Chewy,

I went through and just deleted a bunch of the totally unnecessary BS that you had to read through...well, all I could anyway 

[mayor]

well 'ol Red finally bolted on a CV44 carb to his RK, now he has actual data to contribute ( ).  He sent me his run files, so I figure I'll update this thread with some more data points.  Here's his afr:

Build details:
2000 RK
95"
9.3:1 (180 ccp)
Crane 300 (gear)
D&D Fat Cat (quiet baffle)
SE CV 44 (50 pilot /M- needle /200 main)
Syke Performance Ported Heads (1.9"/1.61")
Stk ignition
SE Stage I A/C

I believe he told me his cruise afr checked out to be around 14.1-14.4. 

[FLTRI]

Hmmmm. Wonder why the AFR isn't very straight?
Does the torque graph have a corresponding dip to the AFR?
Bob

[mayor]

yep there's a tq dip, but not so much of one.  More like a "tell-tail" sign of a fatcat. My guess is any other pipe, and more of a dip would be present in the tq curve. here's his chart:
http://www.harleytechtalk.com/htt/index.php/topic,17237.0.html


looks like all three afr charts I posted of the CV44 has an over active accelerator pump.   

[Sonny S.]

yep there's a tq dip, but not so much of one.  More like a "tell-tail" sign of a fatcat. My guess is any other pipe, and more of a dip would be present in the tq curve. here's his chart:
http://www.harleytechtalk.com/htt/index.php/topic,17237.0.html


looks like all three afr charts I posted of the CV44 has an over active accelerator pump.   

really ?
whatcha thinking ?
something wrong with the carb ?

[mayor]

really ?
whatcha thinking ?
something wrong with the carb ?

 

just saying.