If I were dumb enough ... nitrous oxide? - Honda Rebel Forum
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post #1 of 19 Old 11-01-2019, 11:24 AM Thread Starter
 
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If I were dumb enough ... nitrous oxide?

I'm not saying I'm gonna add nitrous. But I am saying I'm dumb enough. How much of a power boost would be safe on a stock engine Rebel?

With only 18 flywheel horsepower at most, I'm thinking +40% would be the max. And even at that, I would be concerned with blowing it up. However, since I can watch the AFRs, I believe I could keep the combustion safe.

40% is approximately 7 horsepower. I tend to believe the mechanical components of this engine could handle that. Imagine a Rebel with 20 - 25 hp versus 13 - 18 hp. I'm just dreaming here. I think it would be inconvenient to attach a bottle that keeps running out. And why would anyone ever need such nitrous power? Beating a Prius to the next traffic light? Almost keeping up with a Harley? The occasional roll down a quarter mile dragstrip?

I started designing a nitrous plate that would distribute nitrous nicely down the intake. So an opening in the intake casting wouldn't need to be drilled and this plate would be a simple install.. But I might as well quit wasting my time. I don't believe there'd be any real use for it.


7milesout

2016 Honda Rebel 250 - The "Piglet."
AFR sensor equipped and downsized to a 0.105" main jet.
The only changes so far.
Bought on 6/29/19 with 44 miles.
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post #2 of 19 Old 11-01-2019, 01:31 PM
 
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But it would be so much fun!


My absolute favourite 250 is the Suzuki GT, developed 27HP, 2-stroke, 6 gears.


It was my dad's bike, wasn't legal for me to ride it, but I used to cruise around when he was at work, after I got home from school.

1974 CB125S (purchased 1983, ate 2 crankshafts, sold 1984)
1986 Rebel 250 / N. California (purchased 2019)
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post #3 of 19 Old 11-03-2019, 05:17 PM
 
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If you want power from a 250, try finding an Aprilia RS250 (mid-90's to early aughts). It was a two stroke 90 V-twin that produced 60HP to the ground. Yes, you read that right: 60HP...almost as much as an SV650.

"Ride Safe, Chop Safer" Motorcycles are not unsafe. However; they are extremely unforgiving of inattention, incompetence, ignorance, and stupidity.
Dismantling, sawzalling, and rattle canning does not make a bobber.
Those are STEPS toward customizing, not customizing unto itself.
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post #4 of 19 Old 11-04-2019, 12:53 PM
 
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Try a turbocharger instead


Small Engine Turbo Charger - RHB31 VZ21
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2001 CMX250C Rebel
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post #5 of 19 Old 11-04-2019, 01:45 PM
 
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Wow, that is surprisingly cheap. I'd give that a go if I had a spare bike.

1974 CB125S (purchased 1983, ate 2 crankshafts, sold 1984)
1986 Rebel 250 / N. California (purchased 2019)
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post #6 of 19 Old 11-04-2019, 02:14 PM
 
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I was surprised at the cost also.


Might need to put one on my Kawasaki push mower.

2001 CMX250C Rebel
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post #7 of 19 Old 11-04-2019, 02:26 PM Thread Starter
 
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Yeah I've checked that turbo out already. I can get one for $249. Its a much better option because as much as I'm on the throttle stop I'd probably blow through a bottle every day. A turbo would be, the gift that keeps on giving.

I've checked out the capacity and boost maps of that turbo compared to the capability of the Rebel's engine. That turbo can crank out roughly twice what would be required by our 233.8 cc engine. Which if I understand the boost curves correctly would put that turbo right in its high efficiency zone when paired with our engine. Meaning it should work well for our engine. The problem is the plumbing, and maybe moreso the plumbing of oil to / from the turbo.

I'm considering this design though. Probably just a pipe dream though. I would love to put together a "kit." The mechanical design engineer in me.


7milesout

2016 Honda Rebel 250 - The "Piglet."
AFR sensor equipped and downsized to a 0.105" main jet.
The only changes so far.
Bought on 6/29/19 with 44 miles.
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post #8 of 19 Old 11-04-2019, 03:41 PM
 
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Plumbing of rubber hose from carb and to head is relatively simple.
Oil would be the challenge.


Oh that reminds me the FJ180v Kawasaki on my mower is full pressure lubrication with a spin on filter.
Adding this turbo would be easy on it.......

2001 CMX250C Rebel
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post #9 of 19 Old 11-04-2019, 10:38 PM
 
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If I had a small enough bottle I would blow some nitrous through my rebel. I would be the first to try it.


Only problem is momentarily dumping enough fuel to enrich the mixture during the nitrous blast.


The engine could easily handle 40% more power. I think the failures would begin occur in the clutch, gearbox, or output shaft. There would also be the possibility of valve float in the higher rpms.


If the clutch didn't slip first I would expect gear or bearing failures in the gear box.

1970 CT90
1986XL600R
2001 KE100
2002 Honda Rebel
I'll buy a Harley someday
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post #10 of 19 Old 11-05-2019, 02:34 PM
 
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In all my years on various Rebel boards (since Y2K) I have yet to see a single success story involving a turbo. Many have tried, so far only one "finished" and it didn't pan out well (that one is documented somewhere on this board). With that solitary event being the closest thing to a success story, I'd bet on the N2O to fare better.

"Ride Safe, Chop Safer" Motorcycles are not unsafe. However; they are extremely unforgiving of inattention, incompetence, ignorance, and stupidity.
Dismantling, sawzalling, and rattle canning does not make a bobber.
Those are STEPS toward customizing, not customizing unto itself.
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