Header pipe mods

[marlbororman]

Just found this article on the oz firestorm site by barrenvonrotter

Apparently it makes a big difference, loads on there have done the mod and posted positive results
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I dont know if you guys have done this yet or not but I highly recommend it after just sorting it out.

The right hand side exhaust has a lip that restricts flow out to the end can. If you take your right hand side exhaust can off you will immediately see what I mean.

A standard one inch header pipe is restricted to about half an inch round in standard form.

File the bitch back and open up the hole fully. You dont have to go nuts and make it flush unless you really want to.

The result is AMAZING.

Sound: silky smooth
Idle: improved
Low down response: significantly improved
High end response: breaths better - approached redline fast

Drawbacks: it will take you about an hour of sustained hard filing

During the test ride I noticed that on full throttle - besides going faster in general - it had a slight dip in performance around 5000rpm. It only happend once - so its probably an anomoly.

Even if it is a constant thing now - I dont care - cant turn back anyway - and for the extra crispy response low down - including an ability to cruise in first in much lower rpm.

ITS WELL WORTH IT

Before




After




Original thread here (but you need to register) http://ozfirestorm.proboards.com/index. ... 929&page=1

[tony.mon]

Tried this, and used a ball grindstone on a drill- much quicker than filing, and you get a clean transition.

There's been several threads about this in the past, to my knowledge no-one's done a before and after dyno to show what, if any, difference it makes.
It's supposed to be there to aid mid-range due to reflected exhaust pulses helping to scavenge the cylinders.

Personal seat-of-the pants opinion when I did mine?
Yes, it helps to give a punchier bottom end, couldn't tell if there's a top end payback, though.

[marlbororman]

hmmmm dunno wether to do it or not. off to garage in a minute to get a nipple for front vac take off point,as one i had was too big. will then be balancing carbs this afty. was thinking , maybe to do this before balancing as it may effect the balance...Whats your thoughts???

[tony.mon]

Shouldn't affect balance, because this part is after the pipes join into a single one, but if you're going to do it anyway, then do it before.

[kevg]

i might be wrong, but i'm sure in one of the threads about this Rodger said to leave it as is, it will make things worse...i can't be arsed looking through all the old threads to find it...i'm sure someone will though, lol

[marlbororman]

Well couldnt get the nipple anyway, and only just got in and cant br rsd to strip bike so staying as is for now, gunna hunt online for a nipple

[tony.mon]

You need a 5mm one.
If you can't find it then look on http://www.carbtune.co.uk/carbaccs.html

[marlbororman]

I only need one not 4 I`ll have to give em a ring, pointless paying 8 quid for 4 Plus postage probs lol

[MacV2]

Ahh but if you can only buy 4 bung the spares on sales or wants! Pleanty of folk on here will snap 'em up off you, play ya cards right & nmake a small profit!

[warby221]

i might be wrong, but i'm sure in one of the threads about this Rodger said to leave it as is, it will make things worse...i can't be arsed looking through all the old threads to find it...i'm sure someone will though, lol

Ditto
same thing said to me it’s to do with the balance of gas leaving the exhaust cans remove it and it flows more gas out of one can cutting down the overall flow rate if I remember right

[sirch345]

Ian,
If it were me I'd leave it as standard too. Another member on here ages ago also read that on the Oz site, he tried it but wished he hadn't.

It came back to what Roger said, the restriction is there for a reason, not shoddy workmanship.

Chris.

[marlbororman]

Ok, will leave alone then, pleased i asked about first There is allways more to the story than meets the eye

[tony.mon]

Seems to me it depends on what you've done in the way of mods.
If you've already messed with the flow characteristics of the engine with a K&N, cans etc you've already made enough changes that the original careful exhaust pipe header design isn't working as it was meant to anyway.
So once you've gone that far I'm all for losing as much back pressure as possible and letting it breath.

So I've done mine, twice.
Once from standard, and once with a replacement set of headers after the first ones cracked.

Sounds better, seems to go ok, feels like better low end, but could easily just be more noise

Each to his/her own...

[marlbororman]

but could easily just be more noise

Dont we all want more More is never enough though

[benny hedges]

was always fkin about with pipes in my seedy past - trial & error cutting the downpipes down 1/4" at a time to get the perfect length - you can finely tune your powerband to cooperate with your exhaust cams if you got the time to play about.
thing is the storm is a mass produced bike and was meant to be tractable from tickover to redline with no real surge & peak, no flat spots...
to do that you have to compromise, same as when you're tuning for power. there isn't much extra power to be had - all you are doing is moving what you already have further up the rev range rather than it being spread out.

you might gain power up top but if it makes it less friendly round town the bike will be a lot less rideable.
don't see the point in giving it a narrow power band unless you have a close ratio box (mmmh wonder if you could fit a varadero box???)

i don't think that lip in the collector is there for a reason apart from that's how theyre made. they just slip the pressing over the tubes and weld it. you get what you're given.
theyre not going to spend hours grinding and polishing to match everything up, just make em & bang em out.
imo all the bs about resonance and reflection is bs for bs sake, like finding a reason why men have nipples.