RS250 NF5 - - 96hp & 50lbft - too good to be true? Videos.

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Questo vecchio rz
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Re: RS250 - Onboard 360* Panorama video & photos.

#16 Post by Questo vecchio rz » Wed Mar 08, 2017 5:04 am

RC45 wrote: 49ftlb and 95hp & 50ftlb and 96hp. This appears to be one very healthy RS250. ALmost too healthy :oops: And without getting too caught up in the numbers.
No doubt about it, that is a well tuned RS, did she come w any factory kit options? It matters little what some internet tuners/heros may say about diffrent dynos and their generous results , that is still one machine that deserves accolades & much respect.

One must admit the factory bikes were impressive. Think about it..from only a.diminutive 250cc thats 40-45 h.p. more that a average RZ 350 and a easy 25 h.p. more than a average RG500 Gamma!
If youve ridden a Gamma and felt the power delivery when it comes on song...just think what that lil 250cc bike thats 100lbs lighter and with that explosive top end windup of power, it is going to feel like...quite exciting.
Yes cranks and pistion life is measured in minitues...lol :grin: but its gonna be worth every penny.

The bike found a good home and caretaker with you.
Enjoy.
Banshee (Baja) race bike, Lonestar A-Arms, dual 9" L.E.Ds, FMF, Toomey,19cc domes, IMS tank, run flats.
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85 custom Tri-Z
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podman
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Re: RS250 - Onboard 360* Panorama video & photos.

#17 Post by podman » Wed Mar 08, 2017 6:27 am

RC45 wrote:Finally got around to doing some controlled plug chops and AFR checks on the dyno.

Picked up the bike form the local Honda dealership where it is on display...
Image

Took the bike for the dyno runs down to a local bloke that builds and tune some crazy Banshees and other 4 wheelers
Image

Warm-up video..
https://youtu.be/en6SUsyoaMM" onclick="window.open(this.href);return false;

The Dyno Run video
https://youtu.be/FKuBEVP7jjs" onclick="window.open(this.href);return false;

That was great viewing, what a bike...look forward to seeing some shots of it on the track..

begbie
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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#18 Post by begbie » Wed Mar 08, 2017 1:49 pm

Your right not to get hung up on the numbers, that is one really, really happy Dyno, or it's not reading the rpm accurately. peak power is way beyond 10k on an NF5.
For a 250cc engine to make 50 ft/lb at 10,000 rpm it would have to have a BMEP of 246 psi ! to put that into perspective a new stock 94 tz making 94 hp has a BMEP of 192 psi.

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#19 Post by RC45 » Wed Mar 08, 2017 2:27 pm

Well, the dyno posted numbers well within expected ranges for a number of other quads and bikes over the last 2 weeks - nothing out of bounds by a percent or 2.

We had the dyno vendor on the phone as I was very surprised by the numbers. But all indications are the numbers are where they ought to be.

The exact history of the bike is unknown other than it was raced competively up through 1991 - which for an 88 bike may mean various internal upgrades, perhaps a kit barrel here or there - who knows.

But as I have taken it apart or catalogued or verified various bits it seems to be very well put together and very specifically setup vizaviz jetting, exhaust chamber spacers power valve lash etc.

I am also running leaded oxygenated 110 octane gas.

As for the pull showing power at 10,000rpm, that's jus the screen I snapped. That was a run cut short. Other runs all the way to 11,500 showed power peaking a bit higher :)

The point of the excercise was never the numbers, it was to get a jetting baseline as tuned.

I am not interested in changing tune other than using bigger or smaller mains based on weather.

Who knows, this bike may have a set of hand me down ported HRC NSR barrels and secret sauce milled heads ;)

As it is, the left carb was out of sync to keep the right cylinder radiator hose from being cooked as it passes by the left exhaust.

Sync carbs overheat bike - unsync carbs pull 95hp ;)

This bike is a 30 year old treasure chest I tell you and on face value even if it is only making 65hp as it stands untouched as it came off the boat I am pleased as punch :)
CBR1000RR SP2 HRC WSBK
TZ500V/OW53 Track bike
YZR500 OW81 Clone
OW69 Daytona 200 Replica - 784cc Monster
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RS250R NF5
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begbie
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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#20 Post by begbie » Wed Mar 08, 2017 3:18 pm

RC45 wrote:
This bike is a 30 year old treasure chest I tell you and on face value even if it is only making 65hp as it stands untouched as it came off the boat I am pleased as punch :)

I should have added that, they are beautiful things built to go fast and I want one :-)

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#21 Post by pstamper » Wed Mar 08, 2017 8:37 pm

Nice numbers and good to see it running. There is a guy that has an NSR that just rebuilt it with a 300CC kit and a bunch of ceramic bearings. He says it hauls ass. Always rode in the group below him and will be fun to ride with him Sunday. He about blew the bike up last year with the oxegenated fuel. I gave him some MS98 and he finished the day out. He went back to the oxegenated fuel again so we will see how it does on the back straight. Hopefully he will not have two expensive ash trays.

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#22 Post by RC45 » Thu Mar 09, 2017 1:52 am

I believe that 300cc TYGA kit is good for about 75bhp. It is supposed to be a blast to ride - makes the already nimble NSR250 into a cruise missile. :)

How long are you at full throttle down the back straight?
CBR1000RR SP2 HRC WSBK
TZ500V/OW53 Track bike
YZR500 OW81 Clone
OW69 Daytona 200 Replica - 784cc Monster
NS400 Track Bike
RS250R NF5
TZ250T 2KM
TZ250B 3YL
TZR250 3MA Track Bike
427ci C5 Z07

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#23 Post by pstamper » Thu Mar 09, 2017 10:10 am

About 7/10 mile.

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#24 Post by RC45 » Thu Mar 09, 2017 3:22 pm

Whats that equate to time-wise on the RZ? About 20 seconds at WOT?
CBR1000RR SP2 HRC WSBK
TZ500V/OW53 Track bike
YZR500 OW81 Clone
OW69 Daytona 200 Replica - 784cc Monster
NS400 Track Bike
RS250R NF5
TZ250T 2KM
TZ250B 3YL
TZR250 3MA Track Bike
427ci C5 Z07

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#25 Post by pstamper » Fri Mar 10, 2017 12:03 pm

All I know is it is too long. Added the 17 tooth sprocket. When I had my bike dynoed the guy asked if I trusted the engine. I said I would rather have it blow here. Several base runs. 4 plug chops. Two max runs with the 47x ignition curve and two with the1ge curve. The dump room was miserable. Hdyocarbon level was over 6,000.

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#26 Post by RC45 » Fri Mar 10, 2017 4:04 pm

So you are out of gear before the turn? What are your current sprockets? Are you running stock RZ500 gear ratios on gears 1 through 6?

What redline are you pulling at WOT?
CBR1000RR SP2 HRC WSBK
TZ500V/OW53 Track bike
YZR500 OW81 Clone
OW69 Daytona 200 Replica - 784cc Monster
NS400 Track Bike
RS250R NF5
TZ250T 2KM
TZ250B 3YL
TZR250 3MA Track Bike
427ci C5 Z07

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#27 Post by pstamper » Fri Mar 10, 2017 11:43 pm

Not sure on rear. 10 to 10.5 because I am cruising. Saturday rain. Can not wait. Started bike and float stuck open. Got thru tech and noticed. Think I got it settled. Will find out in the morn during storm.

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Re: RS250 NF5 - - 96hp & 50lbft - too good to be true? Video

#28 Post by pstamper » Mon Mar 13, 2017 4:12 pm

Managed an estimated 138 with my instructor behind me on a KTM super duke. Was just shifting into 6th right before end of back straight at
the overhead sign before braking zone.

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