Straight pipes

[ital916]

Hey dudes,

Listened to a guy talking about "straight pipes/ straight cut" pipes in a bike dealership the other day for his cruiser. Now on a two stroke I know the exhaust is designed to utilise the back pressure from combustion in the engines cycle, but on cruisers and other bikes for that matter is there a certain advantage many custom bikes have straight pipes, basically just metal tubing. Does the bike breath more thus increasing horsepower. Just wondering, cos aesthetically they look pretty darn cool. Sorry if i got the terminology incorrect. Noise wise he pipes were real loud when he rode it to the bike parking, like thunder on wheels lol

Drider

[Headbanger]

Hell no.

Straight pipes turn em into a gutless whale, with 5 times the noise.

Im fuckin slow, But god fuckin damn, IM FUCKIN LOUD.


Poser city.

[outlawtorn]

Hey dudes,

Listened to a guy talking about "straight pipes/ straight cut" pipes in a bike dealership the other day for his cruiser. Now on a two stroke I know the exhaust is designed to utilise the back pressure from combustion in the engines cycle, but on cruisers and other bikes for that matter is there a certain advantage many custom bikes have straight pipes, basically just metal tubing. Does the bike breath more thus increasing horsepower. Just wondering, cos aesthetically they look pretty darn cool. Sorry if i got the terminology incorrect. Noise wise he pipes were real loud when he rode it to the bike parking, like thunder on wheels lol

Drider

Hi dude, when I put on my V&H straightshots and got rid of the stock pipes I noticed more power in the bottom end but noticed a loss of power in the top end. But I didn't really put them on for the whole power thing, I enjoy waking up people! :niceone:

[FilthyLuka]

Hell no.

Straight pipes turn em into a gutless whale, with 5 times the noise.

Im fuckin slow, But god fuckin damn, IM FUCKIN LOUD.


Poser city.

i call bullshit

Engines don't need, nor do they LIKE back pressure. However they do need a carburettor jet/fuel map to fully utilize the derestriction of the exhaust

[FilthyLuka]

Hi dude, when I put on my V&H straightshots and got rid of the stock pipes I noticed more power in the bottom end but noticed a loss of power in the top end. But I didn't really put them on for the whole power thing, I enjoy waking up people! :niceone:

Go get your carbs sorted out, i know a guy in auckland who is very good with carb tuning, drop me a PM if you wanna get in touch with him

[James Deuce]

i call bullshit

Engines don't need, nor do they LIKE back pressure. However they do need a carburettor jet/fuel map to fully utilize the derestriction of the exhaust
Two strokes are totally different to 4 strokes and a tuned length cone, which is essentially what an expansion chamber is, improves exhaust scavenging, so there's less spent charge left behind, creating volumetric efficiencies over a two stroke without an expansion chamber. Change the length of the cone and it changes where the exhaust is scavenged best within the RPM range.

[Headbanger]

i call bullshit

Engines don't need, nor do they LIKE back pressure. However they do need a carburettor jet/fuel map to fully utilize the derestriction of the exhaust

Well then, we need to hear from a professional bike tuner.

I have known plenty of talented men to not be able to tune a bike to run as well with straight pipes as they did with a real exhaust system.

And at times the best people have been able to get is a gutless wonder that makes plenty of noise.

So...bullshit to you, Sir.

[skidz]

My 2 into 1 pipe has only the end cap and nothing else inside it. When the cap blows off, it just becomes a gutless piece of shit. It's loud, but when the cap is off it's sure a cop attractor as the whole town can get woken up at 4 in the morning on my way home from work.

[ital916]

Yeah, I was told that two strokes have a very finely tuned exhaust system which can be easily dinged out of balance, but with cruisers was just wondering how people change exhausts so often without changing performance, but as luka and co have said I guess to does change it. Was watching biker build off on discovery and they just use steel tubing? Guess hand built customs have a weaker top end then?

[Ixion]

i call bullshit

Engines don't need, nor do they LIKE back pressure. However they do need a carburettor jet/fuel map to fully utilize the derestriction of the exhaust

Two strokes most certainly do need back pressure. And even tuned four strokes may.Have you never heard a big single come up on the mega ?

[FilthyLuka]

Two strokes most certainly do need back pressure. And even tuned four strokes may.Have you never heard a big single come up on the mega ?

I thought we were talking about understressed 4 stroke cruisers?

As for the singlle, yeah :love:

[Ixion]

Two strokes are totally different to 4 strokes and a tuned length cone, which is essentially what an expansion chamber is, improves exhaust scavenging, so there's less spent charge left behind, creating volumetric efficiencies over a two stroke without an expansion chamber. Change the length of the cone and it changes where the exhaust is scavenged best within the RPM range.

As well as the negative pressure scavenging, a good two smoker chamber will also send a positive pressure pulse back up the pipe, which 'blocks' the exhaust port and prevents loss of charge. The positive/negative pressure wave is why two stroke pipes need to be a tuned length. And why straight pipes won't work, because it is the pressure pulse hitting the chamber open space that causes the required resonance.

[AllanB]

A well designed four stroke system for the road will benefit from a bit of back-pressure. You will get a better spread of power across the entire rev range.

Straight pipes without any form of baffle (even a straight through core baffle offers a bit of pressure) are only going to preform their best in a very narrow rev range (as you find in drag racing - flat out!).

Anyone running unbaffled pipes on the road is a ignorant wanker and spoiling it for the rest of motorcycledom.

Unbaffled pipes also sound like shit on the road banging and roaring popping and farting about pissing off everyone.

Get yourself a nice name brand aftermarket pipe with baffles and it will produce a clean, deep sound that should not offend too much but put a big smile on your face.

As for the biker build off chaps - absolutely no concern at all regarding tuning or baffling goes into the pipes they put on - its all about looks only- and big noise.

[GaZBur]

...Anyone running unbaffled pipes on the road is a ignorant wanker and spoiling it for the rest of motorcycledom.

Unbaffled pipes also sound like shit on the road banging and roaring popping and farting about pissing off everyone...

Hear hear!!!
If you run a cruiser with straight pipes - you are not cool and loud. You are a noisy wanker and just telling everone who can hear the bike - "Hey everybody - look at me I am a noisy self centred WANKER" who thinks he is soooo cool and has no consideration for anybody else. If you are considering putting on louder pipes for performance reasons as I am looking at doing right now myself, at least consider the noise that will result and think about others and what they are also going to think of you!

[dmouse]

i have a 100 cube in my fattie and i blew out a baffle from the shotgun pipes these are vance & hines pipes 2 and a 1/4 inch bore just try and get a replacement localy or even in NZ so if im noisey its not my fault im waiting for a replacement baffle, also i have starting probs with only one baffle maybe back pressure or the lack of it i duno !!!

[AllanB]

i have a 100 cube in my fattie and i blew out a baffle from the shotgun pipes these are vance & hines pipes 2 and a 1/4 inch bore just try and get a replacement localy or even in NZ so if im noisey its not my fault im waiting for a replacement baffle, also i have starting probs with only one baffle maybe back pressure or the lack of it i duno !!!

He he he love it - I've sent you a PM with a link to a US site than should have a replacement baffle. If I hear a HD around CHCH sounding odd, I'll stop and introduce myself :Punk:

:niceone::niceone::niceone:

[scumdog]

Hell no.

Straight pipes turn em into a gutless whale, with 5 times the noise.

Im fuckin slow, But god fuckin damn, IM FUCKIN LOUD.


Poser city.

Lucky the guys that drive the A/A Fuelers don't know that...

[Headbanger]

Lucky the guys that drive the A/A Fuelers don't know that...

You want to draw parallels between our gear and purpose built drag cars?

No you don't, You just slipped up, But I won't hold it against you.

Besides, I'm a liar.

Though you should fee free to get your bike dyno'd, then hack off the pipes, then get her back on the dyno.

Be sure to come back fully armed with references to drag cars running $100 000 engines, hell, we might as well talk jets, Have't seen a muffler on one of them babies.

[Headbanger]

And just for the record, If I'm gong to dig myself a hole, Then Its going to be deep, and its going to be wide.


Muhahahahaha

[scumdog]

Ahhhh, little thing called context.... :bash:

This IS KB.

Context here means jack-shit.

[outlawtorn]

hmmmmm

Hear hear!!!
If you run a cruiser with straight pipes - you are not cool and loud. You are a noisy wanker and just telling everone who can hear the bike - "Hey everybody - look at me I am a noisy self centred WANKER" who thinks he is soooo cool and has no consideration for anybody else.
and

Anyone running unbaffled pipes on the road is a ignorant wanker and spoiling it for the rest of motorcycledom.

Unbaffled pipes also sound like shit on the road banging and roaring popping and farting about pissing off everyone.
If you two fucktards are an example of what riders are like down on the mainland then I don't want to be visiting there. You two sound like a grumpy bunch of old men. I'm not a self centered wanker, I'm actually quite a courteous rider and considerate for many other riders and drivers on the road, yet you call me a wanker for having loud pipes? So tell me what other articles do you guys read in your local newspaper called the "Gross Generalisation"?

[GaZBur]

hmmmmm

and

If you two fucktards are an example of what riders are like down on the mainland then I don't want to be visiting there. You two sound like a grumpy bunch of old men. I'm not a self centered wanker, I'm actually quite a courteous rider and considerate for many other riders and drivers on the road, yet you call me a wanker for having loud pipes? So tell me what other articles do you guys read in your local newspaper called the "Gross Generalisation"?


Oh dear it seems I have upset someone. Never mind. I don't mind a little noise but some Harleys and others with performance pipes do seem to be making a point of noise to the ridiculous level. I am funnily enough a quite friendly guy but if you are putting out over 96 decebels then you are indeed a self centred wanker no matter how courteous you are to others as you deafen them. If not then my comments weren't aimed at you and you should stop being so precious. Even the MNZ are having to address noise issues for race meetings this year and you will have to admit it is only a matter of time before loud pipes are illegal because some people are ruining it for all of us by making extreme noise.
Please don't judge all people down here by the comments of a couple of grumpy old men or you will be accused of "Gross Generalisation" as some people do that you know!!!

[DEATH_INC.]

Pipes are all about pressure waves and gas velocity, it IS possible to make good power on an open header, if it's designed properly. But you will also make good power with a 2 into one (or 4 into one, or 4 into 2 into 1 etc) as you can utilize the pulses from both (or all four) cylinders to your advantage.
Backpressure will enhance the pulses (that's why 2 strokes have a tiny stinger) but only to a point. It also takes a bit of power to pressurize the pipe, so when this equals the amount gained from the pressurized pipe enhancing the pulses you'll start loosing power again. This also makes the pipe even louder....
A straight through muffler won't affect the power much, but must be tuned to work with the rest of the system. A megaphone is the best option, it gives the best power, but also the most noise, and again must be designed to work with the rest of the system....
Soooo drag pipes can work, but you probably are better off with a nice 2 into one with a megaphone on the end......hopefully the custom boys don't figure this out because there'll be some damn loud bikes around....

[motorbyclist]

my understanding of the 4-stroke muffler and exhaust is that it is generally a trade off (and alot is due to the engine design) between good low end and good high end - high backpressure and high flow respectively

my motox bike is "excessively" loud, around the 116 decibel mark at quarter throttle - and i love it. it also puts out more power than others of the same model, but that could be due to other go faster bits too

i only have that pipe/muffler cause it came on the bike. frankly i find it perfectly reasonable that an event organiser can refuse my entry due to noise as i may ruin the event for others and contribute to the loss of a venue. if i ever have the cash to upgrade i'd definetly leave the new bike stock, just i can't bring myself to "downgrade" (and i don't think it can go on the student loan either, so buggered as to how i'd afford it)

likewise i'm not about to blow money on a new pipe for my nc30 unless there is a proven power gain to be expected without making it offensively loud

as for two strokes, as ixion has said, the shape of the chamber ands backpressure is important in achieving max power at a narrow rpm range, and any modification must be reflected in the carby settings.... actually, any 4 stroke should be tuned for a new pipe anyway, ands you can get resonance chambers for four strokes too - my mate got one ("powerbomb") on his yz426f and noticed a definite improvement of engine response across the board and more power in the top end



but, ultimately, provided that their bike isn't doing any permanent damage to the hearing of others, it's entirely their choice and their money.

just remember that the aftermarket pipe isn't the only way to a more powerful engine

[GaZBur]

...my motox bike is "excessively" loud, around the 116 decibel mark at quarter throttle - and i love it. it also puts out more power than others of the same model, but that could be due to other go faster bits too

i only have that pipe/muffler cause it came on the bike. frankly i find it perfectly reasonable that an event organiser can refuse my entry due to noise as i may ruin the event for others and contribute to the loss of a venue. if i ever have the cash to upgrade i'd definetly leave the new bike stock, just i can't bring myself to "downgrade" (and i don't think it can go on the student loan either, so buggered as to how i'd afford it)

likewise i'm not about to blow money on a new pipe for my nc30 unless there is a proven power gain to be expected without making it offensively loud
....just remember that the aftermarket pipe isn't the only way to a more powerful engine
Unfortunatley you will need to buy a new pipe for your MX bike sometime this year if you want to race. Check out the MNZ notice here (http://www.motorcyclingnz.co.nz/results.aspx)(you will need to scroll to the bottom of the page) Not sure exactly what date the new regs are expected to start.

There is also a discussion on noise in the Dirt Bike forum (http://www.kiwibiker.co.nz/forums/showthread.php?t=66164)
I am actually trying to sort a higher flow muffler for my bike to get more power for Motards but its hard to know what decebels any particular pipe actually really puts out until fitted and measured.
Any prolonged noise over 85 decebels damages hearing.

[motorbyclist]

Unfortunatley you will need to buy a new pipe for your MX bike sometime this year if you want to race.

Any prolonged noise over 85 decebels damages hearing.

yeah i'm aware of both those facts, that's why i got it tested at my last race to see how bad it really was.... but currently all i can afford to do is maybe nick some aluminium from a bin somewhere and modify the muffler to take a bit more packing, and buy earplugs


i really prefer the trail rides/bike parks to racing anyway. last time i did well in a motox race the leader fell off his kx250 infront of me, buckling my front brake disc on impact, putting me out of racing for the rest of the day... it really requires commitment and money i don't have right now, so occasional trips for a fun "go nuts" day with mates works out funner ands cheaper

plus with a bit of consideration to my few neighbours who don't ride, my/neighbouring farm is always a good venue for a saturday blat:2thumbsup

[dmouse]

it has just cost me $221 for new baffles im considerate i have shotgun pipes but i do not think they will really be much quieter for the baffles i just hate the poping when slowing down so if i stop that then im sorry ive done my bit i am looking into new tailpipes but i cant see them making a great difference in the overall noise sound ratio

[AllanB]

hmmmmm

and

If you two fucktards are an example of what riders are like down on the mainland then I don't want to be visiting there. You two sound like a grumpy bunch of old men. I'm not a self centered wanker, I'm actually quite a courteous rider and considerate for many other riders and drivers on the road, yet you call me a wanker for having loud pipes? So tell me what other articles do you guys read in your local newspaper called the "Gross Generalisation"?


Oh dear it seems I have upset someone as well!

Do you have open un baffled drag pipes as I referred too?????

I've said it before - a Harley with say a set of screaming eagle pipes (BAFFLED) sound mellow and deep NICE - open un-baffled drag pipes - sound like an untuned piece of farm machinery.

The thing with the obnoxiously loud is they don't tend to give a f about anyone else in the community - until it affects them. I'd suspect it would be a different story if they had a RX7 with out baffles living next to them.

As for gross generalisation - my last bike had a full Yoshi system on it - baffled of course, and rated at a LEGAL 94db. Frankly that was loud enough.

I stand by my statement - UNBAFFLED drag pipes = wankers. Boy racers with no mufflers = more wankers. The community has pressured the government so much due to this that new noise levels are being introduced soon. Again a very small number of wankers are spoiling it for everyone.

Just listen to a stock Triumph bonnie - a sparrow can fart louder!

Old man - is 43 old? I've been riding since I was 16.

Of interest I was looking at a new Ducati Hyper-Motard yesterday - the factory frame stamp rates them at 97db @3500rpm. This will soon be illegal as the new level is 95 (the 1098 was 96db).

[dmouse]

my bike blew the bafflw out not easy to replace as they have to be orderd from the usa i dont intend to carry a spare for the likes of you, yes my pipes are drag pipes but the tail section alone is 27 inches thats not counting the headers if passed warrent and VTNZ with these pipes baffled of course if you dont like it treat yourself to some earplugs and get a life, there are far more noisier cars on the road than me maybe you should try following them and giving them your advice on sound and see how they react, you are not exactly a bike friendly person are you ?? i had a triumph tr6r with standard pipes very simular to the bonnie and it was louder than my harley so i do not see where the sparrow fart came from !!!!!

[GaZBur]

Unfortunately as dmouse sort of suggests it probably won't be about bikes at all that stuffs us in the end as far as noise goes but cars. The will be another boy racer crack down and the Govt will bring in new legislation about vehicle modifications and noise and we will end up as a by-catch of that legislation.
So us bike riders probably won't get an opinion or say in the matter in the end. I will be keeping my stock pipe in the garage for when that happens as it surely will.

[dmouse]

Unfortunately as dmouse sort of suggests it probably won't be about bikes at all that stuffs us in the end as far as noise goes but cars. The will be another boy racer crack down and the Govt will bring in new legislation about vehicle modifications and noise and we will end up as a by-catch of that legislation.
So us bike riders probably won't get an opinion or say in the matter in the end. I will be keeping my stock pipe in the garage for when that happens as it surely will.

exactly right mate we are only the small fry in this green eco forced world, where the thinking of so few is thrust down our throats, and without conclusive prrof to boot.

its a known fact that every few 1000 years or so the ice caps melt co2 levels rise and the greenhouse effect happens its documented from soil records, but it only now that humans think that they can change nature at the cost of so many, rising co2 also means rising costs for us all for a so called better world.

[Headbanger]

Unfortunately as dmouse sort of suggests it probably won't be about bikes at all that stuffs us in the end as far as noise goes but cars. The will be another boy racer crack down and the Govt will bring in new legislation about vehicle modifications and noise and we will end up as a by-catch of that legislation.
So us bike riders probably won't get an opinion or say in the matter in the end. I will be keeping my stock pipe in the garage for when that happens as it surely will.

If the noise levels are comparable then why should we be exempt?

[GaZBur]

If the noise levels are comparable then why should we be exempt?

I don't think we should be exempt, I am only pointing out that we aren't going to have any say or option in the matter in the end. I agree with what MNZ are doing in setting a maximum noise level of 96 decebels and think it is reasonable all vehicles should be under this level - road or race. I am sure my hearing suffers at Motards and MX riders are subject to the same levels as are many road riders(usually by thier own bike though). It well known that hearing damage starts as low as 85 so I am for reduction in noise levels for that reason and also for the annoyance loud vehicles make.

[motorbyclist]

exactly right mate we are only the small fry in this green eco forced world, where the thinking of so few is thrust down our throats, and without conclusive prrof to boot.

its a known fact that every few 1000 years or so the ice caps melt co2 levels rise and the greenhouse effect happens its documented from soil records, but it only now that humans think that they can change nature at the cost of so many, rising co2 also means rising costs for us all for a so called better world.

every few thousand years?

you may want to check that one:laugh:

picking and choosing numbers you like won't change the fact that loud machinery annoys the general public. it's a democracy so you'll just have to put up with it or, unfortunately, emmigrate

[Subike]

Today I let a friend take my bike for a ride,
The first time I had heard it on the road, whilst I was within earshot.
It is loud, not in a deffening way, but it groweling tone carrys for streets.
I have a 4 -1 with a harris muffler.
This week I will be buying a Dunstal trumpet to replace the Harris.
I wand to change the sound so that it is not so over whelming,
It was given a WOF like this, but sonetines the tone is worse than than the volume

[AllanB]

i had a triumph tr6r with standard pipes very simular to the bonnie and it was louder than my harley so i do not see where the sparrow fart came from !!!!!

Brand new Bonnie that is! :yes: Heck i read recently that in the 60's on some bonnie models mufflers were an optional extra!

Times are a changing..........

[dmouse]

every few thousand years?

you may want to check that one:laugh:

picking and choosing numbers you like won't change the fact that loud machinery annoys the general public. it's a democracy so you'll just have to put up with it or, unfortunately, emmigrate

nit picking we wont be around to see the end of this one and we wont be around for the next one, that is if anyone is.

you could allways sell your bike and get a scooter that makes that horrable whine noise, also maybe the police and other emergency services will have to turn down there sirens as they are over the legal 96db limit as are most house/car/bike alarms where do you finish !!!!!!