Custom pregen exhaust options

Baby NinjaRR · August 4th, 2022, 02:32 PM

I'm trying to find a source for small diameter pipe, a 27mm-? universal 2-1 merger if such a thing exists. Everything else can probably be dealt with using thinwall emt, a wire feed, and maybe an apprentice with a hand bender but 2-1 collectors smaller than 2" don't seem to be a thing?
As much as I don't believe the stock twin exhaust on a pregen is much of a limiting factor in terms of flow/power potential the weight savings of a 2-1 has to be significant on such a small bike.

DannoXYZ · August 4th, 2022, 04:31 PM

Yes, HUGE weight-savings going to 2-1. Check out this Area P pre-gen exhaust thread:
https://www.ninjette.org/forums/showthread.php?t=13852

Since it's already tuned for max-power at high-RPMs, more gains can be had in mid-range. Which is what you want on street-bike anyway. Apparently really significant gains in mid-range.

Check this out for merge collectors: https://coneeng.com/collector_components.html
and this for tubing: https://burnsstainless.com/collectio...ends-304-steel

Baby NinjaRR · August 5th, 2022, 01:47 PM

Quote:

Originally Posted by DannoXYZ

Yes, HUGE weight-savings going to 2-1. Check out this Area P pre-gen exhaust thread:
https://www.ninjette.org/forums/showthread.php?t=13852

Since it's already tuned for max-power at high-RPMs, more gains can be had in mid-range. Which is what you want on street-bike anyway. Apparently really significant gains in mid-range.

Check this out for merge collectors: https://coneeng.com/collector_components.html
and this for tubing: https://burnsstainless.com/collectio...ends-304-steel

This is interesting, thanks. The actual ID where the stock header mounts to mufflers is 1 1'4" but starts at 1" out of the head, interestingly enough. I'm inclined to agree about the stock twin system- it's like shorty headers on an old Chevy, good for nothing but the dyno.

Ceeloo Yello · August 5th, 2022, 02:37 PM

Subscribing to this thread

Baby NinjaRR · August 5th, 2022, 03:15 PM

Quote:

Originally Posted by Ceeloo Yello

Subscribing to this thread

If I commit to this there will be awful flux core weld pics at some point...

Ceeloo Yello · August 5th, 2022, 05:11 PM

I can relate, I keep burning through when trying to weld thin sheet metal. Practice, practice, practice

Baby NinjaRR · August 5th, 2022, 07:31 PM

Quote:

Originally Posted by Ceeloo Yello

I can relate, I keep burning through when trying to weld thin sheet metal. Practice, practice, practice

The last exhaust I tried to weld up had an extra spool of flux core attached but looked less like crap after attacking it w a grinder.

August 4th, 2022, 02:32 PM	#1
Baby NinjaRR ninjette.org member Name: Ken Location: Portland Or Join Date: Jul 2022 Motorcycle(s): 2006 Ex250F-RR Posts: 18	Custom pregen exhaust options I'm trying to find a source for small diameter pipe, a 27mm-? universal 2-1 merger if such a thing exists. Everything else can probably be dealt with using thinwall emt, a wire feed, and maybe an apprentice with a hand bender but 2-1 collectors smaller than 2" don't seem to be a thing? As much as I don't believe the stock twin exhaust on a pregen is much of a limiting factor in terms of flow/power potential the weight savings of a 2-1 has to be significant on such a small bike.

August 5th, 2022, 02:37 PM	#4
Ceeloo Yello ninjette.org guru Name: C Location: Hawaii Join Date: May 2011 Motorcycle(s): 250 Posts: 472	Subscribing to this thread __________________________________________________ "It ended up being the loose nut behind the wheel"

August 5th, 2022, 05:11 PM	#6
Ceeloo Yello ninjette.org guru Name: C Location: Hawaii Join Date: May 2011 Motorcycle(s): 250 Posts: 472	I can relate, I keep burning through when trying to weld thin sheet metal. Practice, practice, practice __________________________________________________ "It ended up being the loose nut behind the wheel"

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August 4th, 2022, 04:31 PM	#2
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	Yes, HUGE weight-savings going to 2-1. Check out this Area P pre-gen exhaust thread: https://www.ninjette.org/forums/showthread.php?t=13852 Since it's already tuned for max-power at high-RPMs, more gains can be had in mid-range. Which is what you want on street-bike anyway. Apparently really significant gains in mid-range. Check this out for merge collectors: https://coneeng.com/collector_components.html and this for tubing: https://burnsstainless.com/collectio...ends-304-steel