A little help please

[BigAlsRK]

Every once in a while, when idling and I blip the throttle I get a backfire thru the carb.......and suggestions.....REAL suggestions.:coffee:

[MegaGlide]

Richen up your idle screw a smidge. Stock CV or Mikuni Carb? One turns out, the other in to richen. Ever happen w/ a slow, low RPM roll-on?

[BigAlsRK]

Richen up your idle screw a smidge. Stock CV or Mikuni Carb? One turns out, the other in to richen. Ever happen w/ a slow, low RPM roll-on?
Stock CV........and no never happens with a slow roll on. Richen the idle by the mixture adjustment and not the speed.....right? I think I am already 3 turns out.

[captainlee]

you blip !!!!!!:roflback: :roflback: :roflback: :roflback: :roflback:

[BigAlsRK]

you blip !!!!!!:roflback: :roflback: :roflback: :roflback: :roflback:
AND Trailer.......

[MegaGlide]

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

3 turns is the recommended max, so I'm out of ideas. W/ the Mikuni, I adjusted the accelerator pump as well to eliminate it on my FXDWG, but I'm not sure if it's adjustable on the CV.

[BigAlsRK]

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

3 turns is the recommended max, so I'm out of ideas. W/ the Mikuni, I adjusted the accelerator pump as well to eliminate it on my FXDWG, but I'm not sure if it's adjustable on the CV.
Reckon it's time to take her in and get someone to take a look at her....Thanks!

[MegaGlide]

Wait for somebody smart to come by...

[GrayRider]

Do you have a SE air filter?

[LittleBear]

On the CV the idle mixture screw is a fuel screw. Out more, more fuel. You might need to go up one size on your pilot jet and readjust that screw. It should be in another turn with a larger pilot jet. Mega is right, you are out the max on that screw.

How is your warm up time on a 70 degree day. Do you have to have the enricher out for more than 1/4 mile of riding if you just start it up and ride off, with only about 30 seconds of idle warm up. If so, you are too lean down low.

Second suggestion, stop blipping the throttle at stops.

And, no Mega, the accelerator pump is not adjustable on a CV unless you change pump nozzle size or cut the rod down.

[dynageno]

Could be an intake leak like my bike had before the build! The rubber O ring was tweaked!

[BigAlsRK]

On the CV the idle mixture screw is a fuel screw. Out more, more fuel. You might need to go up one size on your pilot jet and readjust that screw. It should be in another turn with a larger pilot jet. Mega is right, you are out the max on that screw.

How is your warm up time on a 70 degree day. Do you have to have the enricher out for more than 1/4 mile of riding if you just start it up and ride off, with only about 30 seconds of idle warm up. If so, you are too lean down low.

Second suggestion, stop blipping the throttle at stops.

And, no Mega, the accelerator pump is not adjustable on a CV unless you change pump nozzle size or cut the rod down.
It does take it a while to warm-up with the enricher out. I don't usually blip at stops....I was listening to it run last night while parked at home...sounded a bit rough so I gave it a little blip and she farted thru the carb....I will try the jets....and I am replacing the intake gaskets and possibly the manifold this weekend.

[LittleBear]

One of the most common problems people create with a CV is to only change out the main jet. A stage 1 build only requires the pilot jet to be upped one size. Most people just do the main, which is already large enough for a stage 1 build which still leaves the bike lean down low and rich at the top.
Not sure of your build.

A rough idle is one of the indications of an intake leak. I would do that first before changing anything on the carb.
If you spray WD40 on the intake seals while it is idling and the idle increases, it has a leak. A little messy, but does not hurt paint like starter fluid or carb cleaner will.

[BigAlsRK]

One of the most common problems people create with a CV is to only change out the main jet. A stage 1 build only requires the pilot jet to be upped one size. Most people just do the main, which is already large enough for a stage 1 build which still leaves the bike lean down low and rich at the top.
Not sure of your build.

A rough idle is one of the indications of an intake leak. I would do that first before changing anything on the carb.
If you spray WD40 on the intake seals while it is idling and the idle increases, it has a leak. A little messy, but does not hurt paint like starter fluid or carb cleaner will.
And also an idle that increases as well....right?

[LittleBear]

And also an idle that increases as well....right?

I said rough, but I really meant an idle that goes up and down in rpm. Usually increases over normal idle and then drops back down, up and down. Really inconsistent would have been a better word. Sorry for the wrong use of the word rough.
I should reserve rough for the way a big block V-8 sounds with a high lift cam, but that would be more of a lope.

[BigAlsRK]

I said rough, but I really meant an idle that goes up and down in rpm. Usually increases over normal idle and then drops back down, up and down. Really inconsistent would have been a better word. Sorry for the wrong use of the word rough.
I should reserve rough for the way a big block V-8 sounds with a high lift cam, but that would be more of a lope.
It does lope a bit like my old 69 Chev pickup with a 396 and 3/4 cam....

[BigAlsRK]

So....I go with the pilot jet up one size...replace the manifold gaskets ( possible manifold as well)....and see what happens....right?

[rk custom]

are you finished yet?

[BigAlsRK]

are you finished yet?
Uh....no......gonna have to wait til Saturday....

[TalonChief]

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

3 turns is the recommended max, so I'm out of ideas. W/ the Mikuni, I adjusted the accelerator pump as well to eliminate it on my FXDWG, but I'm not sure if it's adjustable on the CV.

You could step your pilot jet up 1 size and readjust the mixture screw from there.

Edit: Duh, yah, what Littlebear said a few replies back.....

[Nowhereman]

If your using a Mik, just tweek your accelerator pump to come on sooner.
Somewhere between 1 and 2 mm gap should do it.
Your low speed mix should be between 1.5 and 2 turns open.:coffee:

[genoway]

If your using a Mik, just tweek your accelerator pump to come on sooner.
Somewhere between 1 and 2 mm gap should do it.
Your low speed mix should be between 1.5 and 2 turns open.:coffee:

That was almost 2 years ago. He has a different bike now.

just sayin'

[Scabbydoo]

Yep, he does have a bagger now but the extra input is always a good thing.

[BillyB]

Yep, he does have a bagger now but the extra input is always a good thing.

BigAl got a bagger?!?!?!?! :woohoo:

[Scabbydoo]

Can you believe it...

[genoway]

Yep, he does have a bagger now but the extra input is always a good thing.

True, might help someone else.

I used to could strip and rebuild a carb with my eyes closed. Now I'm an EFI guy. I love the ability to adjust everything with an EFI. SO, much better.

[fxr4mikey]

If your using a Mik, just tweek your accelerator pump to come on sooner.
Somewhere between 1 and 2 mm gap should do it.
Your low speed mix should be between 1.5 and 2 turns open.:coffee:

So, I just finished my build last week. Installed a HSR42 as part of it .... currently my bike idles best when the screw is only one turn out .... is it your opinion that I should put in a pilot jet that provides more fuel, and re-adjust the air screw ?

I will also adjust the accelerator pump to come on sooner. I checked the current setting .. it's a 8mm
I'll go down to 4mm and see how it comes off idle then.

The idle is pretty good, and here's the only things that I've noticed

the plugs look like it's well on the lean side
occasionaly when making a turn from one street onto another, at very low throttle, when opening the throttle to get gas for making the turn, she spits back through the breather ....

are these two items indication that I should move up to a richer jet needle... the manual says that the carb comes std with a -97 jet needle, so move to a -96 ?

again, do you think that I should also change the pilot jet ? the manual says it comes std with a 25, what size would I move to ?

Thanks !!


That was almost 2 years ago. He has a different bike now.

just sayin'
time sure goes by fast ... but I still have the same bike :whistling:

Yep, he does have a bagger now but the extra input is always a good thing.
it is, otherwise I wouldn't have seen this, and this is a CURRENT thing for me ..... :d good to have new people come along sometimes and dig up some old stuff :DD

BigAl got a bagger?!?!?!?! :woohoo:
Can you believe that ..... WOW

Can you believe it...
Oh, that's where I head that :whistling:

True, might help someone else.

I'm hoping that it's gonna be helping me

I used to could strip and rebuild a carb with my eyes closed. Now I'm an EFI guy. I love the ability to adjust everything with an EFI. SO, much better.
RIGHT, RIGHT, RIGHT !!!

EVO's and Carbs FOREVER !!!!!!!!!!!!!!!

[Highmiles]

occasionally when making a turn from one street onto another, at very low throttle, when opening the throttle to get gas for making the turn, she spits back through the breather ....


Stop turning at very low throttle, or don't change streets. :whistling:

[fxr4mikey]

Stop turning at very low throttle, or don't change streets. :whistling:

Thank you Jim, for those wise tips !!
I'm sure I'll find them very useful .... and I can tell the officer that I had been advised


:roflback::roflback: