what happened to my mid range power?

[freak_leg]

Ok guys. So untill today i had no mufflers, just open 4-2s so obviously i had now low end power. (or ear drums) Today I installed a nice set of harley mufflers, did a new by ear tune, and took her for a short ride. Now the low end power startled me a little bit. and i liked it. However i hit 4k and it started to studder and stamer like it either had too much fuel or not enough. then once i hit 5.5-6k she took off again to red line. I freely admit before this bike i knew very little about carbs, that said i ask you this... could the lack of mid range power be the float bowl related? would some one clue me in on how to adjust them if it is?

Thanks again guys, without this forum and my stupid questions my bike would be another $500 craigs list special.

Tony

[3Phase]

Ok guys. So untill today i had no mufflers, just open 4-2s so obviously i had now low end power. (or ear drums)

Tony, did you have any mid-range power before you put on the mufflers?

Today I installed a nice set of harley mufflers, did a new by ear tune

What did you tune by ear?

i hit 4k and it started to studder and stamer like it either had too much fuel or not enough. then once i hit 5.5-6k she took off again to red line.

Again, what did you change when you tuned it?

could the lack of mid range power be the float bowl related? would some one clue me in on how to adjust them if it is?

Have you already cleaned the carburetors and set the floats before putting on the mufflers or?

[WMarshy]

Did you check you plug color since you made the change, what jets are you running? Its probably running richer now and you might benefit from moving your needles up one adjustment (clip down one)... This vid will help you learn how to read plugs.

[freak_leg]

phase--

I had mid and high range power before. with no mufflers it would stumble up to 3-4k then take off like a bat. The carbs are in good shape. completely gone threw 2 summers ago. I ran a about half a can of seafoam threw the fuel this spring just to be sure. about a month ago i did a bench sync. All i did today when i re-tuned today is adjust the mixture screws. She purrs like a kitten and runs like a raped ape. Aside from the 4k-6k range.

[freak_leg]

p.s. I'm not sure what jets are in the carbs, I would assume stock or a step up. when i got the bike it had a set of aftermarket 4-2s with a slightly larger pipe diameter. (collector measures 2inches O.D) and the set up links #1-#4 and #2-#3. And the plugs look alright, they need to be replaced but from what i've read the look alright, they were running rich last time i checked them (all black) now they are starting to whiten.

[3Phase]

p.s. I'm not sure what jets are in the carbs, I would assume stock or a step up ... And the plugs look alright, they need to be replaced ...

Planedick and I think Geezer have put Harley pipes on their bikes. You might send them a PM if they don't drop in this thread. Ask them what if anything they changed and how they tuned.

Whatever you do, start with simple things and only make one change at a time!

Before you get too involved, do you remember if you have genuine Mikuni jets or has someone put in aftermarket jets? All jets are not the same so any recommendations (use genuine Mikuni jets!) really depend on what you actually have in your carburetors.

The spark plugs may need to be replaced? Replace them and see if it makes a difference. Do some throttle chops with the new plugs to see if you're running rich or lean. Start with a high speed chop to check the main jets first, then check the mid-range, then low speed. Take your time.

Do you remember where the carburetor slide needle clips are set? You can pull the tops off the carburetors while they're on the bike to check the needle clip position. Look and see if they're set in the middle notch.

Do you have the stock air box or pod filters? It's relatively easy to check the floats if you have pod filters, not so easy if you have the stock air box. You can try raising the floats (okay, lower them if you have them out on the bench upside down) a millimeter or two and see how it runs before you go out and spend money on new jets.

[petejw]

hey freak,
if the engines braking down at 5000rpm
under throttle it usually indicates that the main jet
is to large and it was recommended to reduce the
mainjet by 2 - 3 sizes, i read this a while ago on
a tec bulliten from yamaha, and from my own experience with my carbs
the info worked well, as stated before by adding mufflers
your now going to have a richer mixture.

[petejw]

found the page i was referring too,

[3Phase]

Thanks, Pete! Snnnagged and archived!

[petejw]

no worries scott,
the above relates to a race engine hence the high standard idle setting
but checking the main jet is still the same.
i was probably a bit to specific when i said 5000rpm
but between 5 - 6000rpm its been a pretty accurate
way of setting the main jet.

[3Phase]

Pete, I knew everything when I was a teenager and it's been all downhill since then!

[freak_leg]

Hey just a thought here, Assuming that my jets were "upgraded" at some point to make up for the bigger pipes, could i switch from a stock air box to pods or possibly give the mufflers a bit of the broom stick and hammer treatment to make the mid range to lean out a bit?

[clcorbin]

Good grief! Where am I supposed to do this test at??? What is this bikes speed in 5th gear at 8,000 rpm???

I really need to pull my header off and have an O2 sensor bung welded in so I can just hook up my wideband and be done with it. 30 years ago, they did not have the ability to actually measure A/F. We can today and it is a WHOLE lot clearer than reading spark plugs or color tune.

[freak_leg]

Good grief! Where am I supposed to do this test at??? What is this bikes speed in 5th gear at 8,000 rpm???

I really need to pull my header off and have an O2 sensor bung welded in so I can just hook up my wideband and be done with it. 30 years ago, they did not have the ability to actually measure A/F. We can today and it is a WHOLE lot clearer than reading spark plugs or color tune.

Thats the best idea i've heard yet!!

[Incubus]

Bogging down in the midrange is often an indication that the bike is running too rich. The fact that you are going from open pipes to muffled pipes would buttress this. You can check this my putting in new plugs, running the bike for a couple miles at the range where the bike is bogging and then hitting the kill switch. Pull a plug and see what color it is.

The midrange is controlled by the carb needles. If your needles are adjustable then you should try raising the clip one notch so the needle goes deeper into the main jet and restricts flow a little more. if your needles are not the adjustable type, check to see if the person you put ion the straight pipes also shimmed the needles to make the bike run a littler richer.

Carbs are fun - if you like tinkering with your ride.

Patrick