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!

[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!

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

[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 !!!