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Old October 14th, 2017, 09:13 PM   #41
DannoXYZ
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Quote:
Originally Posted by Triple Jim View Post
That's either a 250 or 350
Nope, it's a 3-cyl 750 2-stroke. 250 per cylinder qualifies for ninjette status?
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Old October 14th, 2017, 09:16 PM   #42
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That's either a 250 or 350, and appears to be built for its look, rather than performance. Things like Emgo pod filters, tires chosen for their vintage appearance, and low-end expansion chambers give it away. I like the one I had the opportunity to do the exhaust system for a lot better. It's an S3 with a highly modified H1 engine and a lot of real performance mods. Admittedly the airbox wasn't back on yet, and I've probably posted it before, but:
Have you ever read "Two Stroke Tuners Handbook" by Gordon Jennings? He does a mind-blowing dissertation on expansion chamber design. I fool around with model airplane engines and they sell after market chambers for these little engines. I just smile and shake my head. Ain't no way they put any of Jennings theory to work. I'm sure they just make them to look cool. By the way after Gordon's fist ride on an H1 he said "He had to beat-down the goose bumps with a hammer"

That gas tank on the Jac Ryan photo looks a-lot like a 73' 500 tank.

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Old October 14th, 2017, 09:21 PM   #43
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Originally Posted by JacRyann View Post
Nope, it's a 3-cyl 750 2-stroke. 250 per cylinder qualifies for ninjette status?
I note the owner has a solid functioning brain. No 5 1/2" rear tire. I used to run 4.10's front and back on my 500. He needs Uni air filters. Nice bike and a-lot of work.

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Old October 14th, 2017, 09:30 PM   #44
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Quote:
Originally Posted by JacRyann View Post
Nope, it's a 3-cyl 750 2-stroke. 250 per cylinder qualifies for ninjette status?
I've owned an H2 since 1978, and trust me, that's not a 750 and it's not a 500. They have nine horizontal fins on their cylinders. The 250s, 350s, and 400s have seven fins on their cylinders, although the bottom one is hidden in your photo. A 400 has very square looking heads. The photo below is of me on my H2 a couple years ago. You can count fins if you like.

Ramjet, yes, the Jennings and Bell books are old staples of tuning.

Correction: I don't have any S1 cylinders here, but I thought they were externally the same as S2 cylinders. They're not, S1 cylinders have six fins, and other photos of that triple, like the one on the right below, on http://notyouraveragebikes.com/ clearly show six fins, so that's definitely a 250 triple. I guess that might qualify it as a Ninjette, but it was rated only 28 hp at the crank, so somewhat less power than our 4-stroke 250s.

At about $7,300 US, I doubt if it will sell very soon: http://notyouraveragebikes.com/our-b...h250caferacer/
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File Type: jpg jims_h2_killboy_gamma_800.jpg (93.5 KB, 7 views)
File Type: jpg not_your_average_bikes_s1_engine.jpg (195.6 KB, 1 views)

Last futzed with by Triple Jim; October 15th, 2017 at 07:11 AM.
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Old October 27th, 2017, 04:49 AM   #45
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ok guys, here is the end result. if anybody wants all the details let me know. thanx member jacryann for the help. long stacks is what i wanted but you loser your taper. here is the final price quote from steel dragon

Hi Michael,

Price for a set of (2) aluminum stacks, 2.5" long, machine finish, is $60.00 + $25.00 programming fee = $85.00. Shipping is additional; if you're in the US, it would be between $6.65 and $8.35, USPS Priority Mail. Polished finish would be an additional $2.50/stack.

Just let us know if you're good with everything- if so, we would need your shipping address and which finish you would prefer. For payment, we send a PayPal invoice to your email.
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Old October 27th, 2017, 07:59 AM   #46
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I users the stacks for a long time. They look cool but don’t really help topend power. I got the best power from just using nothing. But that was on the dyno. I am not sure but I think the right side will go lean with stacks or open carbs when traveling at speed. I use pods on the street to keep dirt out. But for the track I take them off.
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Old October 27th, 2017, 08:05 AM   #47
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Quote:
Originally Posted by Racer x View Post
I users the stacks for a long time. They look cool but don’t really help topend power. I got the best power from just using nothing. But that was on the dyno. I am not sure but I think the right side will go lean with stacks or open carbs when traveling at speed. I use pods on the street to keep dirt out. But for the track I take them off.
thanx for sharing mr. X. i will try them with ram air socks. still going to get innner screen installed too. some say don’t might upset air but if i run them naked it will have some protection. here is my zrx stack screen
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Old October 27th, 2017, 10:47 AM   #48
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That's gonna kill the flow...
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Old October 27th, 2017, 06:24 PM   #49
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It might actually cause the airflow to straighten out. Less volume but better flow caricteistics. It would be fun to see a color computer program of pressure with different screen size.

I love the look of the stacks and have used them. But don’t have any real information or knowledge that can add to the conversation. What I have read is the original intention of a big long funnel comes from dragsters. Now I could be and probably am wrong but what I read was the high over lap camshafts caused pressure to go the wrong way and fuel was splashing back out of the intake track. The long tubes coughs the fuel droplets and when the throttle was whacked open all the fuel that was splashing out of the intak went into the engine. Call the myth busters
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Old October 27th, 2017, 06:57 PM   #50
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Quote:
Originally Posted by Racer x View Post
It might actually cause the airflow to straighten out. Less volume but better flow caricteistics. It would be fun to see a color computer program of pressure with different screen size.

I love the look of the stacks and have used them. But don’t have any real information or knowledge that can add to the conversation. What I have read is the original intention of a big long funnel comes from dragsters. Now I could be and probably am wrong but what I read was the high over lap camshafts caused pressure to go the wrong way and fuel was splashing back out of the intake track. The long tubes coughs the fuel droplets and when the throttle was whacked open all the fuel that was splashing out of the intak went into the engine. Call the myth busters
Like this?

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Old October 27th, 2017, 07:20 PM   #51
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Yup, Is that an old Hilborn system?
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Old October 27th, 2017, 07:30 PM   #52
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With two different lengths to make up for the two different intake runner lengths of a big block Chevy. (although this set looks a little on the overly different side)
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Old October 27th, 2017, 08:19 PM   #53
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Like this?

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Most likely. It's just a photo I pulled searching "fuel injected small block Chevy photos". Many "roundy round" oval track cars ran very long velocity stacks for probably a good reason. Formula 1 cars have/had an affinity for velocity stacks also. According to Gordon Jennings "Two Stroke Tuner's Handbook" the long velocity stacks tend to eliminate secondary intake tract resonances that upset proper fuel metering. Short velocity stacks may look cool but may in fact interfere with proper fuel metering. Bottom line is you are hard pressed to beat the O.E.M airbox/air filter set-up.

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Old October 27th, 2017, 08:49 PM   #54
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Right Bill. Tony Nicosia told me that for the H1 and H2, you can't beat the stock airbox setup if you're using anything close to the stock carb size.
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Old October 28th, 2017, 01:08 AM   #55
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Every engine has an ideal stack length for maximum torque=power at X rpm. Shorter stacks move power up the rpm range & longer ones move it down. You need to tune the intake pulse for your required use. This can be done with intake length & exhaust primary length.

The Ninja 300 & Versys-X 300, share the same engine, but the versys makes more torque lower in the rpm range & overall but loses out on max hp to the ninja. All achieved with intake & exhaust header lengths.

For maximum power you need an airbox & velocity stacks, plus ramair if you can get it. My 800 gained 5hp with no other mods other than moving the same filter to the top of the airbox, rather than sandwiched in the middle, so the volume never changed, but the still air area above the v-stacks doubled !!! 5hp from just moving the filter location ! You need as big an airbox as possible after the filter. Minimum size should be 10x the engine capacity, there do not appear to be any gains past 20x which is usually very hard to package on a bike. So a 250cc would need 2.5L minimum & 5L maximum. Obviously the larger the engine the harder it is to package the larger airbox.

YMMV
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Old October 28th, 2017, 02:03 AM   #56
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Every engine has an ideal stack length for maximum torque=power at X rpm. Shorter stacks move power up the rpm range & longer ones move it down. You need to tune the intake pulse for your required use. This can be done with intake length & exhaust primary length.

The Ninja 300 & Versys-X 300, share the same engine, but the versys makes more torque lower in the rpm range & overall but loses out on max hp to the ninja. All achieved with intake & exhaust header lengths.

For maximum power you need an airbox & velocity stacks, plus ramair if you can get it. My 800 gained 5hp with no other mods other than moving the same filter to the top of the airbox, rather than sandwiched in the middle, so the volume never changed, but the still air area above the v-stacks doubled !!! 5hp from just moving the filter location ! You need as big an airbox as possible after the filter. Minimum size should be 10x the engine capacity, there do not appear to be any gains past 20x which is usually very hard to package on a bike. So a 250cc would need 2.5L minimum & 5L maximum. Obviously the larger the engine the harder it is to package the larger airbox.

YMMV
Great perspective. Velocity stake length may be a-bit more complicated than you have described as cam timing and valve overlap are big players too. I have a Honda FT500 single and have kept the airbox intact. It's a wonderful design but the airbox takes up about as much space as the engine itself. The airbox on the Ninja and my Honda serve a multitude of purposes and I'll admit it's tempting to free-up a-lot of internal frame space but I think it's unwise to remove it. Don't anybody get mad. I'm just vomiting my opinion. I tend to trust Kawasaki engineers and if there was not a good reason for the design it probably wouldn't be there.

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Old October 28th, 2017, 04:55 AM   #57
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I have been modifying the 250 engine for almost ten years. I think the stock airbox has a lot of merrit. If it could be improved and I have not tested it but the metal flame guard and snorkel removed is about it.
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