Exhaust? Who needs one of those?

[Magua]

I was out riding my bike today when I heard a strange noise, like I ran over something small and metalic, when I pulled over my exhaust fell off completely. Sounds pretty cool but I don't think I'd get far without taking out my ear drums.

http://frankeh.orcon.net.nz/Duncans/wah%20where%20da%20xhaust%20bo/1.jpg
http://frankeh.orcon.net.nz/Duncans/wah%20where%20da%20xhaust%20bo/2.jpg
http://frankeh.orcon.net.nz/Duncans/wah%20where%20da%20xhaust%20bo/4.jpg
http://frankeh.orcon.net.nz/Duncans/wah%20where%20da%20xhaust%20bo/5.jpg
http://frankeh.orcon.net.nz/Duncans/wah%20where%20da%20xhaust%20bo/6.jpg
http://frankeh.orcon.net.nz/Duncans/wah%20where%20da%20xhaust%20bo/7.jpg

[thehollowmen]

spot the picture that doesn't belong?

We'll give ya time to remove it :-P

Did you manage to find the other bit that fell off?
If it was just the bolt missing from the bracket, that shouldn't be too hard to fix back on.

uh

I'm really curious... exactly how loud is it?
I'd also get out some earmuffs and try to work out how many extra horsies I got from that super-free-flow exhast system .. but that's me

Good luck with fixing it.

[aff-man]

:eek: :buggerd: :killingme :killingme :killingme :killingme :killingme

Shit that is funny and i just read your signiture. Hmmm i was wondering the same thing :killingme :killingme :killingme .

[Two Smoker]

MotoGP styles aye????

[Hitcher]

It may be a bit louder but at least your L plate won't melt...

[Mr Skid]

Nothing a length of string and some double sided tape can't fix. :niceone:

[Frankie]

yeah i took the third photo... pretty random

we have a video of him reving it to about 5-6k pretty loud... its pretty late so yeah maybe tomorrow give it hell :D

oh yeah i was the one actually riding not him... :Oops:

incase u missed the third photo

http://frankeh.orcon.net.nz/Duncans/wah%20where%20da%20xhaust%20bo/3.jpg

[Magua]

Get your own bike, Russian!

[Frankie]

swap for my prelude + cash :P

you know u wana

[Antallica]

keep the poo-lude.

That shit is classic Magua. Good effort :niceone:

[Frankie]

the poolude is a tad faster than that bike

[Frankie]

i might take it off his hands onces hes had enuff of that bike though...

atleast im a little better funded then duncan and a bit more mechanicaly minded :shake:

[StoneChucker]

You were practicing stoppies, I even have the proof. A friend of mine caught you on tape, check it out buddy :killingme

Anyway, regardless of what you were doing, it's good to see the natural progression of loosing side mounted exhausts. Either underseat, or none, thats the way to go :msn-wink:

[Frankie]

rofl nice :laugh:

[Mr Skid]

the poolude is a tad faster than that bike

Really?

I thought the boxed warehouse six by nines in the boot and the skanky 14 year old girls in the back seat drinking cheap vodka from plastic bottles would slow it down a bit. :spudwhat:

Anyway, after Magua's mods to the fizzer you wont know which way he went. Sure, you'll be able to hear him 1km away, but that's not the point.

Magua, now that you've got rid of that silly (and heavy) fun dampener that your bike came with, the next step is to start cutting/drilling the subframe to reduce weight. After you've finished that, remove the pillion foot pegs, and replace the seat with a lightweight foam squab. Take out one of the headlights too, they're heavy buggers. (I'm sure KK'll help ya out.)

Poolude? Bah, give me a 250 with open headers anyday.

[aff-man]

Really?

I thought the boxed warehouse six by nines in the boot and the skanky 14 year old girls in the back seat drinking cheap vodka from plastic bottles would slow it down a bit. :spudwhat:

Anyway, after Magua's mods to the fizzer you wont know which way he went. Sure, you'll be able to hear him 1km away, but that's not the point.

Magua, now that you've got rid of that silly (and heavy) fun dampener that your bike came with, the next step is to start cutting/drilling the subframe to reduce weight. After you've finished that, remove the pillion foot pegs, and replace the seat with a lightweight foam squab. Take out one of the headlights too, they're heavy buggers. (I'm sure KK'll help ya out.)

Poolude? Bah, give me a 250 with open headers anyday.

:niceone: :niceone: :laugh: . But seriously man time for major mods. Do you know why it fell off in the first place????

[Frankie]

its a pos... everything is falling off

even the mudguard broke into 2 pieces for no reason...

on a side note the front guard is fixed n the paint is dry so when u get some money come over with a bita clearcote :)

[Magua]

:niceone: :niceone: :laugh: . But seriously man time for major mods. Do you know why it fell off in the first place????

Absolutely no idea. I removed it with the help of a friend a month or two ago and retached it firmly, maybe we stuffed up somewhere?

[aff-man]

Absolutely no idea. I removed it with the help of a friend a month or two ago and retached it firmly, maybe we stuffed up somewhere?

Sounds highly likly. You really gotta tighten them on because they can come loose due to vibrations. :bash: :doh:

[Mr Skid]

even the mudguard broke into 2 pieces for no reason...

Nothing that can't be fixed, cable ties make great plastic welding rods. If you don't believe me, check out my top fairing..

[Posh Tourer :P]

You wont get any more power out of it with no muffler - back pressure is important....

Oh and when you (re-)mount it, use rubber washers, or at least spring washers if you weren't already...

[Madmax]

plus you risk burning valves

[Magua]

You wont get any more power out of it with no muffler - back pressure is important....

Oh and when you (re-)mount it, use rubber washers, or at least spring washers if you weren't already...

What is a spring washer?

[Darryboy]

What is a spring washer?

At a guess I'd say a split washer.

[The Pastor]

Just duct tape it on. Works well and is cheep..... :D

[Frankie]

You really have no idea duncan do ya?

just get that bracket and bring it over to my place or ill come to u with some tools

[Jackrat]

:Oi: I's seen that flash seat somewhere before.
2-3 weeks ago out side Glenfield college???

Oh yeah,running it without a muffler will cook the exhaust valves.

[Magua]

:Oi: I's seen that flash seat somewhere before.
2-3 weeks ago out side Glenfield college???

Oh yeah,running it without a muffler will cook the exhaust valves.

That be my beast parked outside the bottom of the school. What were you doing prowling around a high school anyway? :D

[Jackrat]

That be my beast parked outside the bottom of the school. What were you doing prowling around a high school anyway? :D

Pickin' up yet another dumped car an havin' a look at me last school.
1972.

[Frankie]

that or u were perving at the 3rd former skanks... you pervert

[Magua]

Pickin' up yet another dumped car an havin' a look at me last school.
1972.

The school has gone down hill man, "tough stance on drugs" so they kick out the users but then let in the Westlake rejects who are known to do exactly the same.

[Frankie]

blame it on ian and louis lol...

recon it started going down hill since i left.. :shake:

[thehollowmen]

You wont get any more power out of it with no muffler - back pressure is important....

Oh and when you (re-)mount it, use rubber washers, or at least spring washers if you weren't already...

I know this is gonna open up a can of worms, get called a troll, but *WHY* is back pressure important?

People often say 'to stop damaging the valves' but there isn't any backpressure in the intake of a engine, and those valves seem fine... or do they require more frequent replacement?

I'm not trying to be smart, I'm just really curious. A lot of performance car / racers seem to try and reduce back pressure to a minimum with the exhasts...

[Blakamin]

I know this is gonna open up a can of worms, get called a troll, but *WHY* is back pressure important?

People often say 'to stop damaging the valves' but there isn't any backpressure in the intake of a engine, and those valves seem fine... or do they require more frequent replacement?

I'm not trying to be smart, I'm just really curious. A lot of performance car / racers seem to try and reduce back pressure to a minimum with the exhasts...
The pulsations and back-pressure create a scavenging effect on the exhaust gasses and help remove them from the combustion chamber quicker.....
but i could be wrong.... i usually am

[Mr Skid]

The pulsations and back-pressure create a scavenging effect on the exhaust gasses and help remove them from the combustion chamber quicker.....
but i could be wrong.... i usually am
Yeah, what that guy said.

I had a notion that the exhaust gasses also serve to cool the valves, and if the flow rate is too high, then there won't be time to absorb the heat from the valves, thus cooking the valves.

[thehollowmen]

We also say that back pressure slows the piston, robbing the engine of precious horsepower at high RPM... so if we remove back pressure we won't need any scavanging of exhast gasses. There seems to be a lot of missinformation about the subject and maybe some field trials are needed to help us investigate :cool2:

And my question stands about valve damage: if they stop the valves from cooking, then why don't the intake valves cook too?

[Madmax]

the intake valves are cooled by the incoming fuel are mix

[Madmax]

some info
http://www.enginehistory.org/air-cooled_cylinders_3.htm

[thehollowmen]

some info
http://www.enginehistory.org/air-cooled_cylinders_3.htm

As much as I hate to say it that article didn't even mention back pressure.

I keep seeing articles like this around:
http://www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.htm
and
http://www.miata.net/garage/KnowYourCar/S4_Back.html

Then again I also find this article:
http://web.tampabay.rr.com/redroby/3liter/exhaust.html
but a correctly tuned engine won't need back pressure to allow scavanging, correctly setting an overlap in the valve timing would do it just the same...

[Magua]

Well either way my exhaust has been retached, I went out during lunch and bought a bolt. Reattached it myself after school :first: . Went for a ride, seems to be holding. I'll buy some washers tommorow and I'll keep an eye on it for a while.

[Mongoose]

Just remembered this story while I read the thread.
Mate decided his Ducati just NEEDED new cans, so off with the old ones, "Hmmmm, hang on, forgot to pick up the new ones from the shop" First :doh:
Simple solution, ride bike as is to the shop. Second :doh:
Arrive at shop AFTER finding out the zorst finished exactly where max noise will travel up-inside helmet. Complaints of blurred vision not to mention impaired hearing on removing helmet.

[Blakamin]

Just remembered this story while I read the thread.
Mate decided his Ducati just NEEDED new cans, so off with the old ones, "Hmmmm, hang on, forgot to pick up the new ones from the shop" First :doh:
Simple solution, ride bike as is to the shop. Second :doh:
Arrive at shop AFTER finding out the zorst finished exactly where max noise will travel up-inside helmet. Complaints of blurred vision not to mention impaired hearing on removing helmet.
jeeebus... i'd hate to hear that!..

[Mongoose]

WHAT??? :thud: :killingme

[thehollowmen]

Many thanks for the backpressure help guys, understand it it a bit more, and can now understand how it could be detrimental to a bike that isn't tuned for it


:niceone:

[Posh Tourer :P]

I know this is gonna open up a can of worms, get called a troll, but *WHY* is back pressure important?

People often say 'to stop damaging the valves' but there isn't any backpressure in the intake of a engine, and those valves seem fine... or do they require more frequent replacement?

I'm not trying to be smart, I'm just really curious. A lot of performance car / racers seem to try and reduce back pressure to a minimum with the exhasts...

A couple of things. Firstly is the valve issue... Dont know the mechanics of that one sorry...

Paparazzi - it wont be speed of air, unless there is a finite volume of air - speed over the same time increases volume therefore equal cooling power.

Secondly, at a certain amount of revs, you get the muffler/exhaust system working for you. If it is the right size etc, it will start to pull the air through the engine as there is a vacuum after each output of exhaust gas. This creates some of your power peaks (horsepower).

Yes, many people put on "free-flowing" exhausts, and they are quite correct, as most factory systems are too restrictive, in the interests of long term reliability and noise reduction. However, you can go overboard. Milky's exhaust mods are a case in point (do a search for it). Put in a washer to restrict it, and it eliminated a power flat spot at about mid-range.

Dont really know if it reduced top end power, but it may have.

My theory tends to suggest that the less restrictive your exhaust/muffler, the higher your revs have to be to get the use of the vacuum effect I referred to above. Sometimes it just sounds cooler/faster, but really isnt.