Screaming Eagle Kit installed, now new sound from Carb. - Harley Forum

skully · #1 10-21-2009, 02:16 PM

Just recently installed a Screaming Eagle Stage 3 kit. Everything went well and runs very well. I have sound coming from my Mikuni 42 carb. It's not a constant sucking sound. Its not the same sound as it was when it was stock. The sound has breaking points. It's hard to explain since I've not heard a Twin 88 motor that has had the bigger pistons and SE heads before.

coot · #2 10-21-2009, 08:15 PM

Is it a bad noise? Or is it the wonderful sound a big carb makes as the plate opens and you can hear the engine breathe? There will be an idle sound, a mid throttle sound (cruising speed), then a Roll-on throaty sound, and finally the full song of WOT.
Or is it a bad noise?

skully · #3 10-22-2009, 10:06 AM

At idle it's a chopping sound. I don't know if it's because of the longer duration of the cam. It's a SE 211 cam which has a much longer duration than the other cams we looked at. After idle it's a great throaty sound all the way through. My engine builder says it because of the cam and the intake valve cutting off the air to the cylinder. It's just a sound that I'm not familiar with.

coot · #4 10-22-2009, 07:06 PM

I am not familiar with the profile of that cam. But the description you are giving sounds like a longer duration and a mild overlap. If I make a guess about the cam, I'll bet that it starts pulling like mad at about 2500RPM and goes like crazy up to around 5500. Do you have a velocity stack intake, or a regular air cleaner body? A stack will make the intake very noisy.
My old Hot Rod 351W has a Comp Cam in it that won't let the engine even idle below 1200. Jeez I love that sound. But it is a very thirsty sound. Can't pass a gas station.

Sounds like you got a good running combination. Does it still start easy?

shovelmike · #5 10-22-2009, 07:27 PM

It doesn't sound like anything to worry about, Skully. A low restriction air cleaner will allow you to hear a lot of noises produced by the airflow, once you get used to it you will love it.
And Coot: Yeah I love that high ragged idle you described regarding the 351, I built a pretty radical 390 in my younger days...12.5 hi domes, 427 cam...a thirsty sound alright, I estimated 3 mpg.

coot · #6 10-22-2009, 07:43 PM

Cams are an intoxicating thing. They cause the adrenalin to flow at a very high rate. At my tender age, I plan to keep the scoot mild. And my Hot Rod Ford is gonna git another 351W installed shortly. As soon as I can get it finished. The cam will be just a bit lumpier than stock so I can afford to feed it regular pump gas at 87 octane. If I want to impress the crowd, I'll get louder mufflers like FlowMasters. They won't know the difference. But I will.
Shoot! I may even go a little crazy on an old 300 6cyl just to freak some kids out.

skully · #7 10-23-2009, 12:07 PM

I'm just like you guys. Nothing sounds better than a good cam rattle. I raced dirt track modifieds last year and had a 415 small block chevy with 680 horsepower. Nothing any better other than a good sound'n Harley. As far as my carb. sound, I'm sure I'll get used to it. I'll let you know if it's something different.

Skully

coot · #8 10-23-2009, 12:50 PM

In short Skully, you have just changed the way your engine breathes in a big way. The heads flow a lot better and the carb mouth and intake pathway are bigger and unrestricted.
So you're gonna hear every gasp & puff the monster makes. And you will grow to LOVE each sound it makes as you feed the throttle. If bad things were happening, you would be having trouble already. Be happy!

skully · #9 10-28-2009, 03:02 PM

Hey Coot. Your were right. Took the monster for a 150 mile ride this past Sunday and loved every minute of it. Man!! What a blast with all that torque. I didn't realize how much I would enjoy it. It was well worth the money. The gas mileage was great too. With just myself riding it got 48 mpg. I guess the torgue is what made that happen. I was expecting 35. Can't wait to get the wife on it. I think she will love it too. I'm sure I'll have this ride for a long time. Have a good one.

coot · #10 10-28-2009, 06:41 PM

Fantastic.
As soon as Thanksgiving is over, I'm gonna put gear cams in my Nelly Bell. And a real scary stereo system. I hope to be done for a New Years Day ride.
I'm gonna change needles in the Carb too.
Everybody be well.