cv carb vs mikuni

[4speed]

i just finished my build 01 heritage,went to 95" 10.3to 1 comp screamin eagle heads s&s 510 gear drive cams ,daytona twin tec ignition.i have a cv carb with a thunder slide and jet kit .bike runs great i just keep hearing put a mikuni on it and it will run better what are your thoughts
thanks

[ANNIVERSARY DEUCE]

The CV works well and adjusts to changes in altitude. I live in hills and mountains so I have a CV done by Bob Wood. Works perfectly regardless of altitude. Other carbs are very sensitive to altitude changes so it partly depends on where you live and ride.

[05FLHTC]

I run mikuns on both my EVO & TC. No carb that I have used provides the tune ability of the mikuni.

How ever it will not make any additional power, the short throttle throw accompanied by the mechanical slide will make it feel faster.

[BUBBIE]

 

The Biggest improvement for me when I used a 42 mikuni and matching intake manifold on my 00 FXDS Built big , was the excellerator pump on the mikuni... SLICK and really adjustable..  Just for that reason I would have changed.

A GOOD blueprinted cv carb is Hard to beat though.

signed....BUBBIE

[koko3052]

 The Miks are easier to tune...but, when you have that CV tuned, you have the best! JMHO     

[hogdoctor]

It mostly comes to your own personality.   If you're the type of person who just wants to make it right to begin with and not have to worry about it  ever for years to come, then stick with the CV.  If you're the type that doesn't mind tweaking your carburetor frequently to compensate for the changing seasons and fuel quality, then the Mikuni will not disappoint you.   It will likely also puke gas all over the ground if your bike leans over too far on the sidestand.   Don't put a breather system on it that obstructs access to the top of the carb, as you will get handy pulling the top off the carb to change the clip position on the needle.   Get the instruction tuning sheet for the carb and get familiar with all the different things you can tweak on it.  If it makes your brain swim circles in your skull, maybe the CV would be a better choice.   http://www.mikuni.com/FS carburetor.html

[Rusty Steel]

It mostly comes to your own personality.   If you're the type of person who just wants to make it right to begin with and not have to worry about it  ever for years to come, then stick with the CV.  If you're the type that doesn't mind tweaking your carburetor frequently to compensate for the changing seasons and fuel quality, then the Mikuni will not disappoint you.   It will likely also puke gas all over the ground if your bike leans over too far on the sidestand.   Don't put a breather system on it that obstructs access to the top of the carb, as you will get handy pulling the top off the carb to change the clip position on the needle.   Get the instruction tuning sheet for the carb and get familiar with all the different things you can tweak on it.  If it makes your brain swim circles in your skull, maybe the CV would be a better choice.   http://www.mikuni.com/FS carburetor.html

Wow, thanks for the information. I've been running Muikuni's for 25+ years and never experienced any of  the problems you speak of and I am very satisfied. Once it gets dialed in it stays dialed in. (for me anyway)CV is a good carb as well, no need for the Mikuni. Unless you want the best.. 

[speedzter]

I had the CV running pretty well on my mild 95", but when I fitted the 42 Mik' I probably didn't gain a lot
of power, but enjoyed the better throttle respone, and found it far more tunable due to plenty of tuning parts available.
I find it uses more fuel, I think due to the pumper and my throttle addiction, but I haven't tried changing pump jet size.
I even enjoy the sound of the slide rattle at idle !!

[05FLHTC]

I have never experienced any of what is stated below   

It mostly comes to your own personality.   If you're the type of person who just wants to make it right to begin with and not have to worry about it  ever for years to come, then stick with the CV.  If you're the type that doesn't mind tweaking your carburetor frequently to compensate for the changing seasons and fuel quality, then the Mikuni will not disappoint you.   It will likely also puke gas all over the ground if your bike leans over too far on the sidestand.   Don't put a breather system on it that obstructs access to the top of the carb, as you will get handy pulling the top off the carb to change the clip position on the needle.   Get the instruction tuning sheet for the carb and get familiar with all the different things you can tweak on it.  If it makes your brain swim circles in your skull, maybe the CV would be a better choice.   http://www.mikuni.com/FS carburetor.html

[Max Headflow]

Unless you are getting above about 8000-10000 feet a mik is fine.. I'd bet the CV might be questionable.. WOT it would still be way rich.. Simple putting it might be better..

The heads you have could support more flow over the CV making the Mik an option..

http://harleytechtalk.org/htt/index.php/topic,1238.0.html

http://harleytechtalk.org/htt/index.php/topic,8966.0.html

Max

[HD/WRENCH]

cv has its place as well does the MIK.. If the CV will work for your engine size I would keep it. A 40 CV will support a 100 hp but thats about it , with out boring etc.

[HILLSIDECYCLE]

i just finished my build 01 heritage,went to 95" 10.3to 1 comp screamin eagle heads s&s 510 gear drive cams ,daytona twin tec ignition.i have a cv carb with a thunder slide and jet kit .bike runs great i just keep hearing put a mikuni on it and it will run better what are your thoughts
thanks

A CV will have more coming up thru to torque peak than a Mikuni, where the Mikuni will show a couple more hp on the other side.
We did back/back testing in regards about a dozen years ago.
Both carbs work/tune well.
Scott

[Northside]

I run a 45 Mikuni on my 95" with Mackie heads, pistons and cam.  I live in Colorado so altitude changes are a fact of life.  I find the Mikuni works amazingly well from 4000 to 12000 ft. altitudes.  I have run CVs and they are great carbs, just not as tunable as the Mik.  In the seventies I used to run SU carbs on Harleys, same constant velocity principle, and I love that big ol' dome sticking out there.  Personally I like the Mik best and wouldn't worry about altitude changes on rides.

[OldBogie]

i just finished my build 01 heritage,went to 95" 10.3to 1 comp screamin eagle heads s&s 510 gear drive cams ,daytona twin tec ignition.i have a cv carb with a thunder slide and jet kit .bike runs great i just keep hearing put a mikuni on it and it will run better what are your thoughts
thanks

This set up sounds good to me. I've got an 00 Heritage almost the same except I stayed with ported and revalved stock heads and a Screaming Eagle ignition with a 45 Mikuni. Like life in Colorado here in Washington State everything is way up or way down from where every your at. It took a little time to tease out the compromises that work in Seattle (more or less sea level) to Sunrise on Mt. Rainer (6400 ft) which is the highest paved road in the state, the Chrome Show does not do dirt and gravel roads as I'm the bike's cleaner and don't like that much nor that kind of work.

I'd say if the CV is dialed in leave it alone, there isn't that much more power out there with the Mikuni without more and deeper engine mods to take advantage of the Mikuni's potential.

Bogie

[4speed]

thanks for the help, the cv is dialed in perfect soon as i am done breaking it in will put on a dyno

[dunbarton]

It mostly comes to your own personality.   If you're the type of person who just wants to make it right to begin with and not have to worry about it  ever for years to come, then stick with the CV.  If you're the type that doesn't mind tweaking your carburetor frequently to compensate for the changing seasons and fuel quality, then the Mikuni will not disappoint you.   It will likely also puke gas all over the ground if your bike leans over too far on the sidestand.   Don't put a breather system on it that obstructs access to the top of the carb, as you will get handy pulling the top off the carb to change the clip position on the needle.   Get the instruction tuning sheet for the carb and get familiar with all the different things you can tweak on it.  If it makes your brain swim circles in your skull, maybe the CV would be a better choice.   http://www.mikuni.com/FS carburetor.html

Wow, thanks for the information. I've been running Muikuni's for 25+ years and never experienced any of  the problems you speak of and I am very satisfied. Once it gets dialed in it stays dialed in. (for me anyway)CV is a good carb as well, no need for the Mikuni. Unless you want the best..

I heard they give one away with a case of Amsoil but that's only rumor mind you. ...LOL.
My experience is that either will get the job done and so will S&S.

[Winston Wolf]

It mostly comes to your own personality.   If you're the type of person who just wants to make it right to begin with and not have to worry about it  ever for years to come, then stick with the CV.  If you're the type that doesn't mind tweaking your carburetor frequently to compensate for the changing seasons and fuel quality, then the Mikuni will not disappoint you.   It will likely also puke gas all over the ground if your bike leans over too far on the sidestand.   Don't put a breather system on it that obstructs access to the top of the carb, as you will get handy pulling the top off the carb to change the clip position on the needle.   Get the instruction tuning sheet for the carb and get familiar with all the different things you can tweak on it.  If it makes your brain swim circles in your skull, maybe the CV would be a better choice.   http://www.mikuni.com/FS carburetor.html

This is not accurate advice in my experience in regards to the HSR.  I've yet to have to readjust for altitude or season. From 45 degrees to 105 nor from sea level to 14144 feet   

Of the 3 bikes I have Hsr 42's on, never has one leaked gas on the side stand.

Best carb out there. Try it and you will see....

[koko3052]

 

[Shooter1]

I've had a Mik HS40 on my '89 FXRS-Sp for the last 22 years. I have the stock CV on my '00 FXDX and i've re-jetted it. I've also messed around with a number of CV's on imports bikes over the years. The Mik slide carb will get you the most crisp, sharp throttle response you can get. My HS-40 replicates the throttle response I get from my KTM 300XCW two stroke race bike. Although the CV will get you close to that, it will always have a softer initial hit due to the vacuum slide. In terms of how much power they both produce, they are pretty similar in my opinion. If you are looking for the ultimate in throttle response for a racing or hot street application on a lighter bike such as a Sporty or FXR, maybe a Dyna I suppose, the Mik gets the nod. For everyday use, the CV is hard to beat. I was having some problems with the idle hanging up recently on the Mik but traced it to a cable issue and have since fixed it. Other than that, it's been bulletproof. All the CV's I've had have been solid too. Both my FXDX and FXRS get low 40's mpg. If you're not racing, the CV will probably suit you just fine. My .02 cents.

-Harvey
'89 FXRS-Sp
'00 FXDX
'06 300 XCW
'07 EXC450

[bobrk1]

guy with dyno told me the cv is good up to about 90hp but you can have it bored out to 42mm, but if you got a lot of inches and looking for hp the mik is the way to go.

[nhrider]

A dialed-in CV is all you really need, but if you're like me you will really appreciate the crisper throttle response of a mechanically actuated throttle  as in the Mikuni or S&S carbs.   I've had all 3 and really  like the S&S.   Many people think they are hard to tune, but I never had any problems.   I think those people just don't understand carbs.   I had one on a 94 FXDL that has been passed on to 3 different nephews, and it still runs strong...hasn't been re-tuned since about 1996.

The mikuni is also a great carb, and very tunable.   I don't think you will be dissappointed with it if you decide to go that way. 

[Ohio HD]

A dialed-in CV is all you really need, but if you're like me you will really appreciate the crisper throttle response of a mechanically actuated throttle  as in the Mikuni or S&S carbs.   I've had all 3 and really  like the S&S.   Many people think they are hard to tune, but I never had any problems.   I think those people just don't understand carbs.   I had one on a 94 FXDL that has been passed on to 3 different nephews, and it still runs strong...hasn't been re-tuned since about 1996.

The mikuni is also a great carb, and very tunable.   I don't think you will be dissappointed with it if you decide to go that way.

   Always did prefer the Super E & G carbs.

[05FLHTC]

A dialed-in CV is all you really need, but if you're like me you will really appreciate the crisper throttle response of a mechanically actuated throttle  as in the Mikuni or S&S carbs.   I've had all 3 and really  like the S&S.   Many people think they are hard to tune, but I never had any problems.   I think those people just don't understand carbs.   I had one on a 94 FXDL that has been passed on to 3 different nephews, and it still runs strong...hasn't been re-tuned since about 1996.

Have yea ever tried to tune an S&S carb for a desired AFR at cruise?  I have and it didn't respond well.  If yr willing to live with what it gives ya, then yea the S&S works fine, just don't get to picky.   BTWTFDIN 

[Max Headflow]

A dialed-in CV is all you really need, but if you're like me you will really appreciate the crisper throttle response of a mechanically actuated throttle  as in the Mikuni or S&S carbs.   I've had all 3 and really  like the S&S.   Many people think they are hard to tune, but I never had any problems.   I think those people just don't understand carbs.   I had one on a 94 FXDL that has been passed on to 3 different nephews, and it still runs strong...hasn't been re-tuned since about 1996.

Have yea ever tried to tune an S&S carb for a desired AFR at cruise?  I have and it didn't respond well.  If yr willing to live with what it gives ya, then yea the S&S works fine, just don't get to picky.   BTWTFDIN 

The problem is that you need to ignore what the AFR meter is telling you and tune "seat of the pants".. The bike will run good but the AFR will be all over the place and mileage will suffer compared to variable Venturi or constant velocity carbs.. The problem is the transition between low speed and high speed circuits is not as smooth as the other 2 mentioned carbs.. Even if you add a toilet seat or play with the air bleed..

Max