Stutter attempting go over 3k rpm and tachometer all over the place (may be related?)

[No H2O]

Everything is good getting up to 3000 RPMs. However once at 3000 RPMs, when I twist the throttle more to try and get it to 3500 RPMs I'll usually get one or two stutters and I can get it to 3500 but it takes some doing and is very slow to get there.
On a possibly related note the tachometer often times just flashes all over the map sometimes all the way in the red when I know the RPMs aren't nearly that high and other times it'll display just at 1,000 when I know it's more than that.
I'm hoping the EHC isn't limiting the rpms and sending incorrect signals to the tachometer

 

[Jersey Big Mike]

EFI or Carb?

 

[No H2O]

EFI or Carb?

Carb, S&S Super G (upgraded from stock S&S E), matching S&S intake for Super G. Stock air cleaner, recently cleaned (less than 1k miles ago)
2005 Chopper DT

 

[Mastiff Rider64]

Carb, S&S Super G (upgraded from stock S&S E), matching S&S intake for Super G. Stock air cleaner, recently cleaned (less than 1k miles ago)
2005 Chopper DT

Could it be the ignition coil or wires? I know a while back one of my wires came off the coil and it would make some and miss others. Made my tach jump all over the place and the loss in power made me so worried that i pulled over and had it towed home. Felt like an idiot taking it to the shop only to get called back up there the next day to show me what happened.

 

[HMAN]

Replace the small black rubber caps on the top of the carb. They dry rot. Use silicon caps from auto parts store.

 

[awg]

When it shutters, could it be the plugs fouling?

 

[No H2O]

Could it be the ignition coil or wires? I know a while back one of my wires came off the coil and it would make some and miss others. Made my tach jump all over the place and the loss in power made me so worried that i pulled over and had it towed home. Felt like an idiot taking it to the shop only to get called back up there the next day to show me what happened.

I feel if that were the case then the issue would be random and not reproducible like mine is at a specific RPM.

Replace the small black rubber caps on the top of the carb. They dry rot. Use silicon caps from auto parts store.

I'll try that, thanks.

When it shutters, could it be the plugs fouling?

If the plugs were fouled I think that too would cause random stutters as opposed to a predictable one

 

[mleach72]

Everything is good getting up to 3000 RPMs. However once at 3000 RPMs, when I twist the throttle more to try and get it to 3500 RPMs I'll usually get one or two stutters and I can get it to 3500 but it takes some doing and is very slow to get there.
On a possibly related note the tachometer often times just flashes all over the map sometimes all the way in the red when I know the RPMs aren't nearly that high and other times it'll display just at 1,000 when I know it's more than that.
I'm hoping the EHC isn't limiting the rpms and sending incorrect signals to the tachometer

It could be just the temperature. Your carb was probably tuned in the summer. Carbs don't self adjust for temperature. A carb that is in tune at 80 degrees will be out of tune with a drastic temperature change. We are in the 30's in the northeast. That's pretty drastic. 50 degree cooler air is much more dense, leading to a leaner air/fuel mixture.
The tach issue is a pretty common problem. My tach and speedo are all over the place, especially right after start up. After running a while, they seem to settle in.

 

[No H2O]

The tach issue is a pretty common problem. My tach and speedo are all over the place, especially right after start up. After running a while, they seem to settle in.

That's what I'm thinking it's unrelated. Moisture in the air exacerbates it.

My carb was indeed tuned in late summer /early fall. Should I just adjust the carb screw to be a richer mixture?

 

[mleach72]

That's what I'm thinking it's unrelated. Moisture in the air exacerbates it.

My carb was indeed tuned in late summer /early fall. Should I just adjust the carb screw to be a richer mixture?

If it runs fine below 3k rpms, I'd leave it alone. 3k rpms is right about when the main jet comes in. It might be too small for the colder temperatures. Try bumping up the main jet and see if it helps. That is easy to change. It's under the float bowl drain plug.

 

[Sven]

Just a quick think-out... can't be the carb, it idles, reaches 3k, but struggles and eventually heads up the rpm range, then no, not fuel. Bouncing tach could be more spark related. Plugs/wires/coil. So it doesn't backfire, misfire, so say it's not the plugs. Tach signal is losing that wave before it reaches the plug, so wires to coil is the next test.

Wires off, do the resistances equal out? Does the coil match resistance between a good known coil?

 

[mleach72]

Cooler temperatures will lean your afr. If he has a spot that is slightly lean, it may not be noticeable in warmer weather. In much colder temperatures, that spot will become very lean, leading to sputtering.

 

[awg]

When I bought my 04 Chopper from Texas, I had to rejet the carb. Wouldn't run unless I used the enricher. I thought you bought this bike not to long ago.

 

[No H2O]

When I bought my 04 Chopper from Texas, I had to rejet the carb. Wouldn't run unless I used the enricher. I thought you bought this bike not to long ago.

Correct, bought it in mid to late summer.
Given that it's a 2005, and this typically happens most noticeably around 75 mph, I have to ask if BDM had placed any restrictions on the speed that year?

 

[mleach72]

Correct, bought it in mid to late summer.
Given that it's a 2005, and this typically happens most noticeably around 75 mph, I have to ask if BDM had placed any restrictions on the speed that year?

Has this sputtering always been there since you've owned it? I was under the impression that it just started.

 

[No H2O]

Has this sputtering always been there since you've owned it? I was under the impression that it just started.

The sputtering has always been there.
bear in mind the carb is only a couple months old (went from E carb to G carb) so I'm thinking that likely rules out the jetting possibility.
also the plugs were changed around that time as well.
I doubt it's a limitation on speed since this happens around 60 mph, I'll shift up and go to 75 mph and it'll happen again.
the only thing that would make sense is some sort of RPM limiter, they do that on cars.

 

[mleach72]

The sputtering has always been there.
bear in mind the carb is only a couple months old (went from E carb to G carb) so I'm thinking that likely rules out the jetting possibility.
also the plugs were changed around that time as well.
I doubt it's a limitation on speed since this happens around 60 mph, I'll shift up and go to 75 mph and it'll happen again.
the only thing that would make sense is some sort of RPM limiter, they do that on cars.

That kinda sounds like a jetting problem, as the main jet comes in around 3k. The s&s carbs have a common problem at the transition between intermediate and main. A lot of guys have a thunderjet installed, which is supposed to fix it. Yes, it could be other things, but happening at the same spot is usually an air/fuel problem. IMHO, a mikuni cures all of the problems. What kind of pipes are you running? Open pipes will cause problems like this sometimes.

 

[No H2O]

That kinda sounds like a jetting problem, as the main jet comes in around 3k. The s&s carbs have a common problem at the transition between intermediate and main. A lot of guys have a thunderjet installed, which is supposed to fix it. Yes, it could be other things, but happening at the same spot is usually an air/fuel problem. IMHO, a mikuni cures all of the problems. What kind of pipes are you running? Open pipes will cause problems like this sometimes.

Supertrapp stock 2->2.
Lots of popping on deceleration both with the e-carb and the g-carb

 

[mleach72]

Supertrapp stock 2->2.
Lots of popping on deceleration both with the e-carb and the g-carb

Those pipes shouldn't be causing the problem. It may be something you will have to live with, unless you want spend more money on a thunderjet. The s&s carbs are good carbs, but they do have their shortcomings.

 

[Sven]

Back in the day of drag racing, It is my understanding about adjusting the jetting via temp/wet/pressure; is how you tune throughout the day watching those 3 gauges under the race trailer awning. Since FI has all those parameters wired up with sensors, it's an auto-set kind of tune no matter the hour or time of season. Apply the theory... solid/liquid/gas kind of theory and see if that helps the theory of jet tuning. So to tune, cold, condense air is packed tight with oxygen. You jet up to match the air. Humidity is wet and has water in it so that too is condensed oxygen to compensate for rejetting in the rain. Heat expands, so the domino effect is saying; a molecule is farther away for a smooth flamefront, so you jet down so as not to waste gas that won't fire for lack of air. Sea level I'm rich with air and this is one jet tune. Denver mile, I have less air so I jet down for this tune.

Prophylactic my air cleaner cone. The more I roll it back out and close off the pleats, the more fuel pulled. It is displacing the air's speed going in; to balance the pressured event. The intake valve closes at atmosphere, but the air to fuel ratio changed. No jets were molested during this seat of the pants rich running roll out.

If I test condomless, then I'm at my bog rpm range, I pull the choke, it stops nosing over and takes off like a race horse out of the gate = Too lean. If it bogs out even more and noses over = Too rich.

That's the science and I'm sticking to it.