August 19th, 2018, 04:09 AM | #1 |
ninjette.org member
Name: Mark
Location: La crosse
Join Date: Jun 2018 Motorcycle(s): 06 ninja 250r, 82 yamaha xj750 Posts: 37
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exhaust fabrication for 06 250r
looking for advice on possibly either fabricating a new set of mufflers, or a friend had said that I should gut the stock mufflers. but would that cause me to lose ot on horse power?
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August 19th, 2018, 03:30 PM | #2 |
ninjette.org certified postwhore
Name: Roger
Location: Mitchell, South Dakota
Join Date: Apr 2014 Motorcycle(s): 1978 Z1R, 1999 EX250 Posts: A lot.
MOTY - 2018, MOTM - Oct '16
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In my quest to lose weight on the bike and not in my wallet I experimented with making a 2 into one using stock head pipes and stock mufflers.
DSCF0003.jpg this didn't turn out to well...lost 6 mph on my test acceleration strip, so next I ran a long drill bit down the exhaust exit, it made a little more noise but didn't pick up any mph on the test course. Next I cut the muffler apart at the front weld of the muffler (where the muffler and head pipe meet) and used a big punch to curve back the center hole I had drilled out, and removed the "screen" on the inside pipe. DSCF0001.jpg before DSCF0002.jpg and after. this did pick up a couple of mph (and a little more noise) on the test course, but was still 4 mph slower than stock pipes and mufflers. After that I put on another set of stock head pipes and gutted another muffler (so it was dual pipes again) and walla, it was now 2 mph faster than it had been stock with a little more noise again, but easily streetable without getting the neighbors up in arms. So this gained a couple mph but didn't loose more than a few ozs. My next step was to find a used Muzzy header. It was then 2 mph faster than my gutted mufflers and 4 mph faster than stock. All jetting is stock, I know everybody says you need to rejet, and we did the rejetting thing on two different pregens and they both are fastest with stock jetting. Jetting is still a tiny bit rich at wide open throttle but close enough. BTW we are at 1300 ft. above sea level. ps: also running stock airbox and stock air filter
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1 out of 1 members found this post helpful. |
August 20th, 2018, 07:37 AM | #3 |
ninjette.org certified postwhore
Name: Eric
Location: Iowa City
Join Date: May 2009 Motorcycle(s): 2008 Kawmeracchi 350 2010 Project X Posts: A lot.
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MOTM - Sep '18, Feb '16
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What you loose is torque . I found that short open exhaust cost about one or two ft lb of torque. Plus added noise.
Long pipes seem to be the best for scavaging. The best system I ever made was 57 inch primary pipes and long cones. Then a reverse cone at the end. I kept open I g the outlet until the power stopped going up. About an inch and a half .
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Top speed 123.369mph. Ohio mile Worlds fastest 250 ninja |
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August 24th, 2018, 09:52 PM | #4 | |
ninjette.org member
Name: Mark
Location: La crosse
Join Date: Jun 2018 Motorcycle(s): 06 ninja 250r, 82 yamaha xj750 Posts: 37
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Quote:
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August 25th, 2018, 07:32 AM | #5 |
ninjette.org certified postwhore
Name: Eric
Location: Iowa City
Join Date: May 2009 Motorcycle(s): 2008 Kawmeracchi 350 2010 Project X Posts: A lot.
Blog Entries: 54
MOTM - Sep '18, Feb '16
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This is the exhaust
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Top speed 123.369mph. Ohio mile Worlds fastest 250 ninja |
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August 26th, 2018, 01:39 PM | #6 | |
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
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Quote:
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August 26th, 2018, 03:02 PM | #7 |
ninjette.org certified postwhore
Name: Eric
Location: Iowa City
Join Date: May 2009 Motorcycle(s): 2008 Kawmeracchi 350 2010 Project X Posts: A lot.
Blog Entries: 54
MOTM - Sep '18, Feb '16
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It is a twin exhaust system. 57 inch from the valve to the end of the cone. Then a four inch cone.
It is copied from a 500cc MV Augusta system in the Barber museum. Same bore and stroke. I figured they knew what the are doing since I don’t.
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Top speed 123.369mph. Ohio mile Worlds fastest 250 ninja |
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August 26th, 2018, 08:02 PM | #8 |
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
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I'm designing 2-1 for pre-gen now. From what I can gather on various published studies out there, I want header pipes to be between 18-22". Then critical diameter and flow-rates of pipe and muffler after that. What failed on Z1R's experiment was he stuffed 2-cylinder's worth of volume & flow after merge into pipe and muffler designed for 1.
Going to use Tyga's new-gen design for diameters after merge. Appears to work well and better than some other systems on market with pipes that are way, way too large. Large enough for 150-bhp engines! |
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September 11th, 2018, 07:16 AM | #9 | |
ninjette.org member
Name: Ney
Location: Connecticut
Join Date: Jun 2015 Motorcycle(s): 2006 Ninja 250, 1999 Aprilia RS50 Posts: 18
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September 12th, 2018, 08:13 PM | #10 |
ninjette.org certified postwhore
Name: Roger
Location: Mitchell, South Dakota
Join Date: Apr 2014 Motorcycle(s): 1978 Z1R, 1999 EX250 Posts: A lot.
MOTY - 2018, MOTM - Oct '16
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no, I bought a complete system with the aluminum muffler
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October 6th, 2018, 09:57 AM | #11 |
gokartmozart
Name: randy
Location: land of corrupt govt-illinois
Join Date: Nov 2015 Motorcycle(s): 250 ninja ,it's realy a ninja motor on a scratch built alum chassis (avatar is my old kart) Posts: 22
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did you keep the OEM crossover on your head pipe?
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