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Harley Pipes

07/22/2011 3:09 PM

Why do the pipes of a Harley make popping noises upon deceleration when the fuel mixture is lean, but they don't pop if the mixture is rich?

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#1

Re: Harley Pipes

07/22/2011 4:01 PM

Spark generated 'flame' speed is directly related to mixture ratio. At very lean mixture it's so slow that it's still 'burning' when exaust valve opens, or worse a missfired mixture amount is burned after geting to exaust by the next (randomly not missfiring) exiting flame. S.M.

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#8
In reply to #1

Re: Harley Pipes

07/23/2011 11:51 AM

Thanks, that explains it.

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#2

Re: Harley Pipes

07/22/2011 4:08 PM

A weak mixture burns slower than a rich mixture;

So with the lean mixture, the mixture is still burning and expanding by the time the exhaust valve opens after power stroke.

On cars with a vacuum advance on the distributor, the ignition timing is advanced when the engine is on light load to compensate for a longer time it takes for the mixture to burn out.....in this instance the advanced timing is necessary because on light load less air filled the combustion camber.....thus less heat from compression and molecules of mixture is further apart.

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#3

Re: Harley Pipes

07/22/2011 9:12 PM

I don't want a pickle, I just wonna ride my motorcycle.

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#9
In reply to #3

Re: Harley Pipes

07/23/2011 11:52 AM

Nice Arlo Guthrie reference, thanks for the laugh Lyn.

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#10
In reply to #9

Re: Harley Pipes

07/23/2011 12:00 PM

"Alice's Restaurant" is one of my all time favorites. "Group W" was my group.

I'm getting us OT.

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#12
In reply to #10

Re: Harley Pipes

07/23/2011 12:04 PM

Not much point in staying on topic, my question was answered by the first response.

Have a great weekend!

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#13
In reply to #12

Re: Harley Pipes

07/23/2011 12:10 PM

Thanks. You too.

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#4

Re: Harley Pipes

07/23/2011 12:04 AM

Because they are not stock pipes

tomorrow morning [saturday] there will be the usual parade of HD riders who feel it is their right to run loud pipes & spread the hearing loss around

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#11
In reply to #4

Re: Harley Pipes

07/23/2011 12:00 PM

The combination of decibles and duration is not likely to damage your hearing. Too bad you posted anonymously or I could avoid your neighborhood.

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#14
In reply to #11

Re: Harley Pipes

07/23/2011 12:16 PM

it's annoying, just like booming stereos

loud pipes belong on the track, not on the street

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#15
In reply to #14

Re: Harley Pipes

07/23/2011 4:39 PM

Ill bet you annoy me with your anonymous posts more than I annoy you with my bike.

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Anonymous Poster #1
#17
In reply to #15

Re: Harley Pipes

07/23/2011 8:57 PM

There's a big difference

you can ignore my posts

your loud pipes annoy everyone in the area

Typical Hardly rider, no manners or consideration..

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#18
In reply to #17

Re: Harley Pipes

07/24/2011 4:48 AM

Please keep it a secret but this noise has saved their lives more times than you (or they) think, from considerate drivers. S.M.

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#20
In reply to #18

Re: Harley Pipes

07/24/2011 8:50 AM

Old bikers tail

or should everyone run open headers?

most of the noise is behind, since the pipes face that way

your freedom does not extend to infinity

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#21
In reply to #18

Re: Harley Pipes

07/24/2011 9:14 AM

That's a lame and definitely unprovable bikers justification for the machismo feeling brought on by running too loud pipes.

Would you also have us believe that the jerks who have 10,000 watt sound systems in their cars are doing it to be safe on the streets?

I just don't buy it.

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#22
In reply to #21

Re: Harley Pipes

07/24/2011 9:33 AM

Illegal loud pipes and illegally loud music are not acceptable, but I never saw that anyone here had them here at least.

Anon 1 just assumed that someones accessory pipes were illegal, that started the hacking!!!

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#24
In reply to #22

Re: Harley Pipes

07/24/2011 10:12 PM

Stock HD's running around sea level don't generally pop

Ace admitted his bike is loud (#15)

in other words I just stepped in some duck crap....

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#25
In reply to #24

Re: Harley Pipes

07/24/2011 11:36 PM

Q. What is the difference between a Hoover and a Harley?

A. A Harley has the dirtbag on the top!

I am not sure why AP#1 fasely states that I confessed to my bike being loud in #15. I guess if he cannot be identified there is no motivation for him to be honest. Oh well.

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#26
In reply to #25

Re: Harley Pipes

07/24/2011 11:47 PM

Well, are you running stock pipes?

I'm not the one with a HD that pops

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#27
In reply to #26

Re: Harley Pipes

07/25/2011 2:55 AM

In Europe we are hard on loud bikes, but there are plenty of after market accessories, including exhaust pipes, that are good looking and totally legal.

Is the US different then? Do you imply that the after market pipes in the US are ALWAYS loud?

Sounds strange to me....and you must have a VAST knowledge of ALL HD Pipes....

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#28
In reply to #27

Re: Harley Pipes

07/25/2011 4:40 PM

"and you must have a VAST knowledge of ALL HD Pipes...."

More like half-VAST knowledge of some pipes.

(Giggles like a little kid with hand over mouth)

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#30
In reply to #28

Re: Harley Pipes

07/25/2011 5:15 PM

LOL!!

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#29
In reply to #27

Re: Harley Pipes

07/25/2011 5:10 PM

Is the US different then? Do you imply that the after market pipes in the US are ALWAYS loud?
yes
In almost every case after market pipes are louder than stock
It's even less likely that A HD with aftermarket exhaust is quieter than stock
Ace's reaction reinforces the impression that he rides a loud HD

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#31
In reply to #29

Re: Harley Pipes

07/25/2011 5:18 PM

To answer your last sentence, I did not get that impression at all.......

You are pushing the envelope on "reading in between the lines" dramatically......

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#32
In reply to #31

Re: Harley Pipes

07/25/2011 5:46 PM

not even close

see lyn's post #21

HD's without loud pipes are in the minority by a large margin in every area I've ever been in...

BMW's on the other hand would be the opposite, much more interested in covering miles than looking like a 1%er

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#61
In reply to #32

Re: Harley Pipes

08/09/2011 11:06 PM

Do you know the difference between a BMW owner and a porcupine?

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#62
In reply to #61

Re: Harley Pipes

08/10/2011 12:20 AM

I'll bite.

What is the difference between a BMW owner and a porcupine?

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#63
In reply to #62

Re: Harley Pipes

08/10/2011 12:35 AM
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#37
In reply to #21

Re: Harley Pipes

07/26/2011 12:45 PM

I want to chime in here as a long time motorcycle rider..and yes....same thing on both the Harley Davidson as I experienced with the two previous Yamaha bikes.

Even in the days before cell phones "cage" drivers routinely failed to see motorcyclists...even when in the lane next to them....its far worse these days.

Either that or they specifically TRY to kill people on motorcycles by either running them over or forcing them off the road at speed.

I've had people look right past me like I was invisible then turn into my lane without any hesitance. And do this in the middle of the afternoon.

It slowed down a lot when I started running drag pipes. I started carrying a handful of large nuts or bearings in my pocket for those that still pulled that stunt. And I didn't hesitate to use them.

One night about midnight I had a run-in with ca car full of college punks....who apparently thought it would be funny to see how close they could get to my back tire.

Being we were the only ones on the road and they continued to do this up to 70 mph....way above the 55 mph limit of the time.... That is until I unfastened my helmet and threw it over my shoulder. And it center-punched their windshield. I saw headlight, taillight, headlight, taillight, headlight, taillight, as they soiled their shorts collectively as they spun their car out after slamming on the brakes.

It really IS a matter of life and death when you are on a motorcycle or bicycle and have a run-in with a car. I have had too many friends die from inattentive, or drunk drivers that hit them.

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#39
In reply to #37

Re: Harley Pipes

07/26/2011 2:59 PM

Hmm you may be on the wrong thread

http://cr4.globalspec.com/thread/70678

you probably feel safer with drag pipes

I've had more than a few incidents on bikes [& cars] myself, I think visibility is more important.

without looking which view do you think the research & data supports?

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#40
In reply to #39

Re: Harley Pipes

07/26/2011 3:43 PM

This is the right thread....I have a Harely, it has loud pipes.

I don't THINK I am.....I KNOW I am Definately safer with them. Huge difference between those two. Particularly since so many people refuse to put their cell phones down to pay attention to other vehicles around them.

They may not care to see anything smaller than a car.....but they WILL hear me if they get too close. Or is their right to run me over greater than my right to be safe by making it hard to yap on their cell phones when in close proximity to me.

And I have kicked in a couple drivers doors and left nice dents as well...and a lug nut will do a job to any part of the front of a car except the bumper.

I consider it payment for putting my life at risk due to their inattention.

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#41
In reply to #40

Re: Harley Pipes

07/26/2011 3:55 PM

Sorry, I don't buy your loud is safer arguement.

Maybe sitting next to someone at a red light gets you noticed, but if you are going down the highway, either behind me or approaching me, and we are both doing 70MPH, you're dreaming if you think I can hear you until you're within about 20 feet of me.

In town, in slow moving traffic, guys like you just piss me off!

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#43
In reply to #41

Re: Harley Pipes

07/26/2011 4:10 PM

Maybe if YOU was the guy on the bike nearly getting run over and killed by oblivious car drivers...you would understand. There are plenty of blind drivers....not as many deaf and blind drivers.

If you are in front of me....its not an issue. If you are behind me..you will hear me....the biggest issue is in the lane next to me since the average car driver doesn't see anything smaller than a Kenworth next to them. THAT is the most dangerous situation and the one I was specifically addressing. Because peripheral vision only goes so far. If you wear glasses its far less. And I've had more issues with Idiots to my left or right than I ever had with people behind me....or in front of me.

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#45
In reply to #43

Re: Harley Pipes

07/26/2011 4:24 PM

I've been that guy. I owned morotcycles for 20 years. I'm not disputing the fact that there are a bunch of idiots driving cars out there, but I don't think loud pipes save lives.

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#46
In reply to #43

Re: Harley Pipes

07/26/2011 4:38 PM

My bike is not loud, even if it was I would still make it a point to never linger in anyones blind spot. I am vigilant about maintaining situational awareness and presume that every cage is trying to kill me. I don't antagonize cage drivers as they could easily run my little butt over and the best I could do is run away, if they cut me off I try to respond with a smile and a wave.

I do my best to avoid unhappy cowards like anonymous poser #1 in all aspects of my life.

And somehow I still manage to have fun.

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#51
In reply to #46

Re: Harley Pipes

07/26/2011 10:33 PM

I lost my patience to smile and wave after the first six or 7 times some idiot almost squeezed me into the guard rails. And I have NEVER ridden in someones blind spot (which you should always be aware of)....I've nearly always almost been at the front tire or front door in the cases I previously mentioned.Never the rear quarter panel.

I started getting even after some idiot driver flipped me the bird after she got so close I kicked her door. After that I was convinced they did it on purpose not by accident.

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#42
In reply to #40

Re: Harley Pipes

07/26/2011 3:55 PM

a classic

the ends justify the means...

there is also a huge difference between what you think you know & what you can prove with data, science. We are after all on a engineering site

if you ride in harms way, it will find you

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#44
In reply to #42

Re: Harley Pipes

07/26/2011 4:11 PM

So how many people have you run off the road while on your cell phone......or haven't you noticed yet? Or is it really about disturbing your phone call when you are driving?

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#16
In reply to #4

Re: Harley Pipes

07/23/2011 5:06 PM

Please repeat louder, I simply could not hear you at all !

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#5

Re: Harley Pipes

07/23/2011 12:42 AM

try some Ethanol FREE gasoline that stopped the poppin in my Goldwing.

Or some seafoam to get the water out.\

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#6

Re: Harley Pipes

07/23/2011 6:18 AM

Its not just Harley's that do that, in my limited experience it happens with carburetted motors mostly, as many have said, when the mixture is lean, or when an exhaust is added/replaced that allows less back pressure, which also "leans" the mixture....

I have personally never see it on an injected engine, but it is still theoretically possible even then.....

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#7
In reply to #6

Re: Harley Pipes

07/23/2011 10:24 AM

I got the poppin when I started up a van I had bought to give my son when he turned 18. It has been setting almost a year i only put 5 gal of new gas in it and 2 of the injectors soon got clogged so I added sea foam and then filled it up and drove is agressively and unclogged them. it smoked some but the poppin went away as the water was cleaned out of the system .

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#19
In reply to #7

Re: Harley Pipes

07/24/2011 4:49 AM

Burnt exhaust valves will also cause this "popping " sound when going downhill with the throttle closed but this will then happen with a rich or lean mixture. So this would not be the Harley's trouble.

With ethanol added to gasoline the carburettor jets will be too small and the float level too low, also causing a too lean mixture [That is if the carburettor was set up for only petrol].........popping sound! Feul injection would probably solve this.

jurie

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#23

Re: Harley Pipes

07/24/2011 9:57 PM

Beware. Maybe head oriented exhaust is on drawboard for next FatBoy. (LOL) S.M.

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#33

Re: Harley Pipes

07/25/2011 6:27 PM

simple mind is correct.

Ace-Pull in your clutch and use the brakes to slow down and save your exhaust valves and stop the popping. Running a flame past the valves is not that good for them. You are running a little on the lean side unless your are at altitude which is only about 1/3 of Washington. If you are running a CV card and 2 into ones there are tricks to stop this.

to anon#1 stock pipes do this when tuned up at a place with a higher altitude and then you drive to lower altitude like the coast. I used to live in Santa Fe New Mexico (7000+ feet). when I got down to Galveston TX I had to retune just to keep it running and then re-tune again when most of the way home. More air same amount of fuel. You also probably have hearing loss at higher frequencies so you hear the Harley better than all the other stuff on the road. your prejudice is showing.

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#34
In reply to #33

Re: Harley Pipes

07/25/2011 6:43 PM

oh yeah

I don't like jake brakes or loud hotrods either

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#35
In reply to #34

Re: Harley Pipes

07/26/2011 12:14 PM

It sounds like a lot of things in your environment bother you. There are places to go to avoid these things.

The EPA has mandated cleaner burning engines. Air cooled engines have a problem with efficiency and cleanliness so HD had to do something. They leaned out my engine to the point that right out of the box these things can approach 300 degree F oil temperatures. Of course, this would destroy my $25,000 machine in a hurry. So the first thing you must do with a new bike is put about $1000 worth if items on it so it will run cooler and last. Stage 1 consists of free flowing air cleaner and mufflers and a fuel management system capable of richening up the mixture. These 3 modifications can make a bike louder than stock although it does not have to. Most of the offensive noise comes from the operator and not the bike. They can be driven quietly but it sounds so good to hear my pipes.

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#36
In reply to #35

Re: Harley Pipes

07/26/2011 12:34 PM

I don't share the joy [nor should I have to] in your loud pipes

Bad engineering, isn't a justification to infringe on my pursuit of happiness

It's not the EPA's fault HD sells an unusable as delivered product, things change...

You can buy several ready to use Motorcycles for $25k

when you choose style over substance, you pay a premimum

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#38
In reply to #36

Re: Harley Pipes

07/26/2011 2:34 PM

As long as there are other poeple in your environment there will always be something you don't like. Maybe you can get a law passed so I no longer have a right to do as I please. That should make you happy. Maybe we can all be like you. The world would be great then! I can't wait. Oh, and I am sure you don't do anything that anyone else would take offense to.

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#47

Re: Harley Pipes

07/26/2011 5:08 PM

I saw an ad in a motorhead mag at one point that made me laugh...

It was for a DIY HD kit... "TURN YOUR KAWASAKI INTO A HARLEY" ...

As I recall it was only $20 too... the ad continued... "Includes a metal punch, hammer, and directions on where to place holes in your muffler."

Completely off topic but the banter going on reminded me of it...

(I learned alot reading this thread. Thanks to all who contributed!)

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#48
In reply to #47

Re: Harley Pipes

07/26/2011 5:31 PM

Where do you punch the holes to make it leak oil?

Now I've done it!

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#49

Re: Harley Pipes

07/26/2011 8:51 PM

Me and my "pipes".

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#50
In reply to #49

Re: Harley Pipes

07/26/2011 10:28 PM

Nice ride Fredski....mine is an old school chopper. Real old school. Stretched and raked Santee frame...8" over forks. Running Antique tags on mine.

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#52
In reply to #50

Re: Harley Pipes

07/27/2011 9:25 AM

Throw a picture up!

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#53
In reply to #52

Re: Harley Pipes

07/27/2011 9:45 AM
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#54
In reply to #52

Re: Harley Pipes

07/27/2011 9:48 AM

Its not much....but I've been riding it for 30 years. and I got it used. I built it...was stock and 7 years old when I got it.

Right side shift...left side brake. A 1975 retrofitted to pre-1974 specs to remove the federally mandated left had shift cobble that AMF threw together.

This bike has been ridden all over the USA...and France, Italy, Belgium, Germany, Austria, Switzerland, Monaco and a few other small Principalities few have heard of.

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#55
In reply to #54

Re: Harley Pipes

07/27/2011 2:35 PM

Looking at the picture makes my lower back ache.

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#56
In reply to #55

Re: Harley Pipes

07/27/2011 2:52 PM

Suprisingly enough...with a hardtail the rear axle is further back than a swingarm axle is. You actually don't get the full impact of bumps etc because your butt isn't over it...or close to it. Like sitting near the center of a See-saw. A hardtail isn't nearly as bad as you might think if you have never ridden one. And I've ridden this up to 16 hours straight.

I have had rather interesting conversations with an upset border guard in Europe over the Support you local Hells Angels decal on the handlebar clamp.

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#57

Re: Harley Pipes

07/27/2011 9:28 PM

The popping happens when fresh air enters the exhaust and ignites unburned hydrocarbons. My Vulcan has reed valves that facilitate this for emission control. They are opened by the increased vacuum created when the throttle is closed. It is hardly noticable with factory pipes.

Pipes leaking around the crush gaskets do a lot of popping. I would imagine rolling off the throttle leaving the clutch engaged would pull enough fresh air through the engine to cause this. Personally, I like loud pipes but can't afford them so I ride when it's really quiet.

Just to clarify, are you saying lean as in throttle closed or are you seeing this effect after adjusting the fuel/air mixture?

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#58
In reply to #57

Re: Harley Pipes

07/28/2011 9:03 AM

I am pretty sure that simple mind provided the correct explanation in post #1.

But to clarify for your amusement the popping occurs at closed throttle such as riding down a steep hill at 35 mph in third gear, however if the enrichener (like a choke) is pulled out slightly the popping quits.

I am refering here to a FLHT touring bike with stock evolution engine and factory pipes with aftermarket slip on performance full legnth mufflers.

The carb jetting is original which due to the reduced backpressure of the aftermarket mufflers causes the mixture to be slightly lean for an air cooled engine in hot weather. Idle is set at 800 rpm , and I am confident that the crush gaskets are in excellent condition.

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#59
In reply to #58

Re: Harley Pipes

07/28/2011 10:58 AM

Post #1 is an excellent explanation. This is one of the few times I have commented without reading the other comments, and I apologize for that. It sounds like you have a nice bike and I did not mean to infer there was anything wrong with your crush gaskets.

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Guru

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#60

Re: Harley Pipes

07/29/2011 8:32 AM

When that happens to my 2009 BMW (r 1200GS) I take it to the service, the guys do something on the bikeĀ“s computer, and no popping any more!

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