Author Topic: what does a cb 650 sound like with straight pipes?  (Read 4999 times)

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Offline cormier1989

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what does a cb 650 sound like with straight pipes?
« on: June 24, 2009, 12:53:02 PM »
i want to know what one of these four cylinder animals sounds like when they have straight pipes but cant seem to find anything? help?

Offline mlinder

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Re: what does a cb 650 sound like with straight pipes?
« Reply #1 on: June 24, 2009, 01:16:11 PM »
Anything with straight pipes is loud as hell, and you'll give yourself a headache within an hour of riding.
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Offline cormier1989

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Re: what does a cb 650 sound like with straight pipes?
« Reply #2 on: June 24, 2009, 08:53:04 PM »
im bobbin my bike and once im done with the rear fender and tail light the pipes are going to look weird. i dont want my bike rediculously loud i am planning on putting a baffle in the pipes, that is whenever i can jet the carbs. im not sure what jet size to use. anyone know what size to use for straight pipes?

Offline mlinder

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Re: what does a cb 650 sound like with straight pipes?
« Reply #3 on: June 24, 2009, 09:19:54 PM »
Depends on the pipes. baffles, and intake. And altitude. And humidity.
You'll ahve to run the thing, check plugs, and rejet accordingly.
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Offline MJL

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Re: what does a cb 650 sound like with straight pipes?
« Reply #4 on: June 24, 2009, 09:29:02 PM »
I don't know how people ride with straight pipes. I pulled the muffler off my 650 once and replaced it with a straight pipe (4-1) and it sounded great at idle, and good through town, but get on a long stretch and it just drones. Ugh, not for me.
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Offline Pinhead

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Re: what does a cb 650 sound like with straight pipes?
« Reply #5 on: June 24, 2009, 10:42:35 PM »
IMO it sounds good. :) I've got 4-2's with straights on my '79 CB650 and it's not really loud unless you're either cramming WOT or are above 6000 rpm. Going down the highway on the bike and the wind is much louder than the pipes, enough to drown them out...
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Offline mlinder

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Re: what does a cb 650 sound like with straight pipes?
« Reply #6 on: June 25, 2009, 02:47:08 AM »
IMO it sounds good. :) I've got 4-2's with straights on my '79 CB650 and it's not really loud unless you're either cramming WOT or are above 6000 rpm. Going down the highway on the bike and the wind is much louder than the pipes, enough to drown them out...

Do you have baffles? Because real straight pipes will NOT be drowned out by wind, unless your ears are 4 feet across and shaped like a horn-o-plenty.
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Offline Pinhead

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Re: what does a cb 650 sound like with straight pipes?
« Reply #7 on: June 25, 2009, 10:28:11 AM »
IMO it sounds good. :) I've got 4-2's with straights on my '79 CB650 and it's not really loud unless you're either cramming WOT or are above 6000 rpm. Going down the highway on the bike and the wind is much louder than the pipes, enough to drown them out...

Do you have baffles? Because real straight pipes will NOT be drowned out by wind, unless your ears are 4 feet across and shaped like a horn-o-plenty.

I cut the pipes right behind the collectors and installed a 2 inch ID, 24 inch long galvanized pipe on each of them.
Doug

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Offline mlinder

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Re: what does a cb 650 sound like with straight pipes?
« Reply #8 on: June 25, 2009, 10:38:27 AM »
Ah. That length of pipe at that diameter for all 4 cylinders will, in itself, be a bit of a muffler. A fair amount of back pressure there. (looks lik4 4 into 1, anyway, maybe it's not.)

/edit: on 4th look, I guess you have 4 into 2. Maybe. Can you make a recording?
« Last Edit: June 25, 2009, 10:45:38 AM by mlinder »
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Offline Pinhead

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Re: what does a cb 650 sound like with straight pipes?
« Reply #9 on: June 25, 2009, 11:16:19 AM »
Ah. That length of pipe at that diameter for all 4 cylinders will, in itself, be a bit of a muffler. A fair amount of back pressure there. (looks lik4 4 into 1, anyway, maybe it's not.)

/edit: on 4th look, I guess you have 4 into 2. Maybe. Can you make a recording?

Yep, it's got 4 into 2. I've been trying to figure out how to get a good recording because the only camera/voice recorder I have is on my phone which is extremely low quality; the audio overloads very easily. I'll see what I can do, though.
Doug

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Offline cormier1989

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Re: what does a cb 650 sound like with straight pipes?
« Reply #10 on: June 25, 2009, 11:20:31 AM »
 i would like to hear how those four cyclinders sound with no baffle. Also, what size jet did you go up to?

Offline Pinhead

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Re: what does a cb 650 sound like with straight pipes?
« Reply #11 on: June 25, 2009, 11:32:54 AM »
Remember that the 650 is a different beast than any of the other SOHC4's.

Main jet is 102.5. Idle jet is stock. Emulsion tubes were modified as per Hondaman's write-up. I removed the stock "airbox lid" that always seems to choke the 650s. Ignition coils are "relayed" to get power straight from the battery (not through the wiring harness). Charging voltage is steady at 14.5v above 1500 or so RPM (using the R/R in my sig).

I did all of these changes before I cut the stock pipes off, though, or rather before they fell off due to rust.

When it's good and hot out (today it's going to be 98°F) I only choke it for the first 20 seconds or so, then the choke is completely off and I'm on my way. Most 650s need to stay choked for quite a while before they'll run right, even when it's hot out. In the winter time I only have to choke it for a few minutes (or at least until I'm confident I won't have to sit at any stop lights for a while). I believe my idle circuit is a bit lean but it's not bad enough to effect performance too much.
Doug

Click --> Cheap Regulator/Rectifier for any of Honda's 3-phase charging systems (all SOHC4's).

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By the way, I'm going for the tinfoil pants...so they can't read my private thoughts.
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Offline Pinhead

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Re: what does a cb 650 sound like with straight pipes?
« Reply #12 on: June 25, 2009, 05:58:54 PM »
This is a really crappy video of my bike after a cold start. It's about 95°F out so I didn't even need the choke. The revs only barely tapped 3k on the tach.

http://www.facebook.com/v/106378586973

I'll try to get a better video, probably from further away so the microphone doesn't overload.
« Last Edit: June 25, 2009, 06:00:50 PM by Pinhead »
Doug

Click --> Cheap Regulator/Rectifier for any of Honda's 3-phase charging systems (all SOHC4's).

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By the way, I'm going for the tinfoil pants...so they can't read my private thoughts.
:D

Offline myhondas

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Re: what does a cb 650 sound like with straight pipes?
« Reply #13 on: June 25, 2009, 06:01:35 PM »
sounds like a cop giving you a ticket for excessive noise ;D ;D ;D
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1974 CB 750 K4 IN PART-OUT PROCESS (my original bike)
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SOHC# 5105 11228

Offline Pinhead

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Re: what does a cb 650 sound like with straight pipes?
« Reply #14 on: June 25, 2009, 06:08:04 PM »
In "normal driving conditions" the bike isn't really all that loud. It does make a ruckus when accelerating hard, though. However, in those situations the cop will pull you over for exhibition of speed, speeding, excessive acceleration, reckless driving, etc and in which case the pipes probably won't help or hurt your case any.

Edit: Coincidentally we have an off-duty police officer working security here tonight. I brought him out back and asked if he thought it was loud enough to get pulled over. At first I revved the engine like I did in the video. He said if I was sitting at a stop light revving it like that I could possibly get pulled over, mostly because it sounds like I'm showing off/getting ready to race. I said OK, what about when I'm driving like normal? I jumped on and pulled out of the parking lot, cruised around the block and came back. He said, and I quote, "It's not nearly as loud as any of the thousand Harleys driving all over town."
« Last Edit: June 25, 2009, 06:19:09 PM by Pinhead »
Doug

Click --> Cheap Regulator/Rectifier for any of Honda's 3-phase charging systems (all SOHC4's).

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Offline myhondas

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Re: what does a cb 650 sound like with straight pipes?
« Reply #15 on: June 25, 2009, 06:16:26 PM »
Different State....different laws.  run straight pipes around here and odds are you will get a sound ticket before long.
1974 CB 750 K4 SHOWROOM
1974 CB 750 K4 IN PART-OUT PROCESS (my original bike)
1965 C100 CUB 50 (PIT BIKE)
1996 VF 750 CD daily rider
1983 VF 1100 V65 Magna in restoration process
SOHC# 5105 11228

Offline cormier1989

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Re: what does a cb 650 sound like with straight pipes?
« Reply #16 on: June 25, 2009, 09:27:29 PM »
so if i change my main jet to 102.5 I should be alright to chop my pipes?

Offline Pinhead

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Re: what does a cb 650 sound like with straight pipes?
« Reply #17 on: June 25, 2009, 09:36:54 PM »
I can't say yes or no... Everything I've read points to my bike being "different" somehow. Most people jet up to 98's without modifying anything else.

I will say, however, that with the jetting/intake/pipes combination that I have, the ignition system is much more critical than if everything was in the stock condition. A low charging voltage, especially when the bike is cold, causes stumble and misfire. This points to my A/F ratio being a bit on the lean side, even though plug chops look normal.

If I were you, I'd get 98's, 102's, 105's, and 110's and see how the bike performs as-is wit the new jetting. Then if you want, chop the pipes (if they're in like-new condition or usable, put them up for sale/trade so someone that's looking for an original set can find them) and do it all over again. You'll likely get the best performance with the next step up in jet size.

Like I said before, though, you have to make sure your ignition is up to spec or better.

Also, look up Hondaman's emulsion tube modification, as I've done that to my bike as well. I'm can't be certain if you'll need to do it also but you'll have to keep it in mind.
Doug

Click --> Cheap Regulator/Rectifier for any of Honda's 3-phase charging systems (all SOHC4's).

GM HEI Ignition Conversion

Quote from: TwoTired
By the way, I'm going for the tinfoil pants...so they can't read my private thoughts.
:D

Offline cb650 bobber

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Re: what does a cb 650 sound like with straight pipes?
« Reply #18 on: June 26, 2009, 04:56:40 AM »
like a lawn mower on crack
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