Hi there,

I have moded my mc21 with early mc18 electrics and pgm1.I disconnected the black blue wire and run my bike in a dyno.With some jetting and stock exhausts my bike measured 62.3 hps at the back wheel.I placed a set of old jha exhausts rejetted my bike in the dyno and it gained 1 hp at the high rpms and it losted about 6 hps at the midrange.What I want to say is that with the delimited pgm3 and stock exhausts the mc21s gain about 5 hps and adding a pair of aftermarket exhaust like tygas the bike gains with proper jetting and a few airbox mods another 7 to 10 hps!!Is there a set of aftermarket exhausts that will give my moded bike more horse power????Until now i have done some mods to the crancases, matched the cylinders to the crancases,rear head conversion,R cylinders with sp heads,reed spacers and placed early mc18 delimited electrics.What else can i do to gain more hps???????

Thanks in advance
Padelis

The MC21 only makes those kinda gains as it's starting from 45hp - it's restricted.

We're all aiming for about 62hp no matter what model NSR (maybe less from an MC28). It's possible to get over 70 if you are prepared to fit RS250 parts and do frequent rebuilds, but really, it's not worth it. You have enough power there to beat much bigger bikes on a twisty road, so concentrate on your suspension instead!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Dear Dave,

My suspension is nearly perfect, a have recently bought a RVF front end but haven't placed yet on my bike.Right now my bike is equiped with a 5 inches real wheel and a 165/55/17 Dunlop and a 3.5 front wheel with 120/60/17 dunlop and sp suspensions.In the near future i plan to fit the RVF front end and, maybe, I will mod a Suzuki Srad 750 swingarm to fit the nsr with magnesium 5.5 or 6 inches rear wheel for that killer 190/55/17 look, lots of cutting and soldering.We will see.Now for the power output of my bike.I want a set of exhausts to give me a few more hps all over.Will a set of a rs 250 work, i think nf5?????I also have a pair of keihin pwk38 to fit the bike.

P.S.:I am a co-owner in company here in Greece named Suzukomania.We do all the kind of bike mods that someone can imagine and we are the only company that does that job here in Greece.

Ah, you lucky man!

I'm not sure that change to the rear will improve the handling any, as a 190 is way too big for a little 250, but I'm sure it'd look awesome!

I don't know that the RS pipes will fit on an NSR, and most NSR pipes are based on the RS pipes anyway. Have your ports altered to match the RS, and swap to the RS single ring pistons. Ditch the airbox and you'll be good for a heap of top end power...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Lucky????Why?????

By changing the rear you have a completely different bike.I don't know about that mod and i am trying to find a nsr proarm swingarm.This swingarm fits a nice 5.5 inches wheel with a 180/55/17 tyre.I was wondering what rims and tyre sizes are fitted on the 2001 rs250.The Rs exhausts need a set of custom made manifolds to fit the nsr cylinders.

P.S.:Dave check your inbox.

Dave you have no email address????Oh I just wanted to send you a picture of a bike that we have moded here in Greece.

Dave@nsr-world.com!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

I suspect that the reason you have lost hp. in the midrange is that you have the wrong ignition advance curve for MC 21 barrels and pipes with a PGM 1. The MC 18`s porting is much better on top. With the 21`s, honda changed the porting and ignition curve for more midrange due to the 45 hp. restrictions.

Mike
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Mike

Should I try to put back the mc21 flywheel?????I haven't thought that before maybe the 2 flywheels have different advance curve.I will try that and post later.

so whats the best bang for your buck pipe out there?

for mc 21 sp

Koren

TYGA... simple!

Jap style and performance at sensible prices!

Andy.
NSR-WORLD.COM

Where do you like your bang? Some pipes give you more over-rev than others. I find the TYGA pipes on pipe peaked at 11,800 - which is absolutely fine by me, the redline is there for a reason!

Other pipes will peak at a higher rpm, but then engine life will suffer as (generally) will midrange.

For the money, TYGA stuff really is hard to beat.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Errrrr, where to start?

The MC18 flywheel is more retarded than the MC21, so by fitting the MC21 flywheel, it should beef up the upper mid range and peak power, but at the expense of over rev. You'll also need to watch for detonation.

NSR pipes are not based on RS pipes. Well, ours aren't anyway. The RS pipe is designed to peak at 12,250~12,500 rpm, where as the NSR porting is aimed more towards the upper end of 11,000. this mismatch makes for a seemingly powerful engine, but in reality it just makes it peaky, with a major drop in bottom end power.

If you want to fit RS pipes then you'll be needing to get in the engine with the dremel and give it a good whizz. ven then you won't exploit the full potential of the pipes because of the RS's ignition and carbs. for your info, NF5 pipes are the closest fit, although not perfect as the engine position in the NF frame is different to that of the NSR.

The RS piston doesn't go straight into the NSR (unfortunately). It's shorter than an NSR piston and used a different size gudgeon pin, so the standard gasket must be replaced with a thinner one to bring the timing back in to spec and you must use special piston pin bearings.

Blah blah blah.........

HARC PRO pipes and the new JHA's are the top pipes in Japan. I have a set of Tyga's, and they are just as good, if not better in performance. You cant find a better deal for your performance with the Tyga's. (maybe because Matt used to work for HARC PRO?)

As for pistons, the older RM125 piston will fit perfect in the NSR barrels (what I used for my overbore). The RM piston is 1mm shorter between the pin and piston crown, though, so you will need to machine the cylinder base down 1mm to get everything to work the same as stock. And if you get the Wiseco pistons, they are DRAMATICALLY lighter than the stock NSR units.
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Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS

So apart from being wrong about the pistons and pipes I got it just about right then!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball