DIY tuned induction & exhaust, take 2

Nate888

Member
Joined
Aug 12, 2016
Messages
178
Shoutout to Steve Best for the resonant filter box idea.

Undermeath all the Bondo & bullsh*t, that exhaust is pretty well tuned now too ;)

seriously, it's almost scary fast now. most of 18-40 mph seems to be something of a power band, & I would be surprised if I'm getting less than 5-7 HP out of my motor now!
20161014_110554.jpg
20161014_110545.jpg
 


Nate888

Member
Joined
Aug 12, 2016
Messages
178
14765323127581500076685.jpg
update. desert camo paint job. (hey it's a work in progress & at least I'm not afraid to experiment!)

riding it a little more, the power band really starts to take hold at 24 mph up thru something probably in the low 40s

also, if I cock my knee out to the side, it seems to get a better boost. you can hear the noise from the filter box change a bit & get maybe 5-8% more power. at that level I can't quite rule out that it could be an illusion, but it also seems like it might work by creating a vortex of air that helps the filterbox, or by creating a zone with either more or less turbulence
 

Nate888

Member
Joined
Aug 12, 2016
Messages
178
I tried to set up the angles in the expansion chamber to spread the Power Band, at the expense of max boost at any given rpm.

my choice of sh**ty materials ensured some rough edges on its inner surface, which is the opposite of what you generally want when tuning a hi performance 2 stroke because it means more turbulence, which dilutes the reflected waves & slows the overall exhaust flow. however, I think a certain amount of turbulence helps spread the band & dampen noise, though obviously at the price of overall peak efficacy
 
Last edited:

Steve Best

Well-Known Member
Joined
Sep 22, 2012
Messages
1,236
Hey Nate, congrates for trying.
Did you try different intake shapes?

That exhaust wrap looks like a wasp's nest.
Could be a stealth camo tactic with a forestland paint job!
 

Nate888

Member
Joined
Aug 12, 2016
Messages
178
the expansion chamber ends about 2" before the end of the wasp nest/elephant trunk part. I'll try drawing a rudimentary schematic to give a sense of its actual shape

Steve, this is the first test. I read your post on resonant filter boxes & most of one of the links i think you shared to an old 2 stroke tuner guide, & I just thought about it & picked the bottle & how to cut it based on my intuition based on that. I bet it can be dialed in better when I get a chance. it feels like it's tuned for higher rpm then I'd actually intended, but I kind of like it that way
 
Last edited:

Nate888

Member
Joined
Aug 12, 2016
Messages
178
20161015_162527.jpg
well, it ain't pretty, but I hope my sketches give a sense of what's underneath the 'mud wrap'
 

jaguar

Well-Known Member
Joined
Nov 25, 2010
Messages
3,476
with a header that short I'll bet your engine can't rev high enough to get into the pipe powerband
 
Thread Status: Hello , this thread is over 3 years old. You can still reply if relevant, but sometimes it's better to create a new thread to get more replies!
Top