Hi all
I have MC28 with HRC card, but the engine RPM can not rev over 12000(red line). On the other hand. Two of my friends' MC21 with HRC wire harness moded, they can go up over red line to 13000 RPM. what's the problem is MC28? Do I have problem with my NSR MC28? or MC28 need HRC wire harness to support its PGM?

anyone having the same problem as I have???

Hung
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

have you done the wire splice to coincide with the HRC card.
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MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold

I'm guessing that the splice has been done or you wouldn't see any HRC action.

You'll need to be a tad more specific in telling the crew what else you've done if you want the answers

Pipes?
Airbox?
Carb setting?

etc etc.

I have done the wire splice and the HRC appeared in 1 min, TSR chambers, mod MJ and JHA air box. But still I have turning light and horn, brake light... Did I do something wrong with wiring harness?
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

MJ size?

Some people would say that you just want to keep leaning it off til it revs to the moon.

I wouldn't though

Or would I?

Have you plug chopped it? Chances are that it's a size of two rich, which is why it doesn't rev.

My dyno trace dies a death at 12000ish anyway, the change there is one needle clip, it was a little better when I went a size leaner but then it seized up in the cold, you play with fire........

I've never seen one rev up to 13000 really anyway, the rev counter may say so but it lies.

See all the ones from the 1st dyno day here - not one making power past 12000

Even the Apex/Frank Wrathall 74 bhp monster makes peak power about 11000 and is dead by 12.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

Fontyyy's right of course. The MC28 tach is a bloody liar! They seem to be at least 500rpm optimistic, so if it's hitting 12,000 on the tach then it's probably only 11,500 in real numbers.

We used to gear our race 28's used to hit about 12,600 on the tach. This was in SP spec, so no mods to the cylinders. Then we read the rules again....and again....and then tickled the exhaust and transfers to errrr NSR spec and we'd see a healthy 12,800 on the tach. Good job that the guv'na of Harc-Pro was on our team and he was best of pals with the MFJ scrotum'neer.

If a stock mota 28's hitting 12,500 on the tach then it's doing ok, but I'm talking a racer here, so it won't stay together if you hold it full volume for any serious length of time.

SS (Super Sprint) spec 28's will see 13,000+. But that's with a lot of engine work. Piston changes every race. Cranks every 2000kms etc etc.

My MJ is 145..only hits 12000, could not go over ..then my engine slow down. But MC21 does....what if I had engine mod with cylinder intake,RS250 crank, MiKuni 38, Could it go up over 12000?? here are some links about NSR mod which can make your NSR250 become unbeatable monster.

http://www.hm3.aitai.ne.jp/%7Eaichi/kaizou2.htm
http://www.hm3.aitai.ne.jp/%7Eaichi/kaizou4.htm
http://www.hm3.aitai.ne.jp/%7Eaichi/kaizou5.htm
http://www.hm3.aitai.ne.jp/%7Eaichi/kaizou6.htm
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

It seems geared so that it runs out of puff at the redline. A number set by Honda to stop you blowing the engine up.

Why the desperate urge to get it over 12000? If that's all you want, then lower the gearing and it'll rev until it goes pop.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Dave
Lower the gear is a good idea, I already have MC21 trany on MC28, Stock front 15T and 45T on the rear. only up to top speed at 178 on speed sensor(NO speed on my tach) at 12000RPM. What if I put 36T at rear, but acceation would be lower at beginning. Any suggestion for me?
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

A 36 tooth rear? You'd never pull away before the clutch burned out!

What are you trying to achieve, a high top speed?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

YES...The top speed is what I want..about 230km,,,is it possible?
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1996 HONDA RS250
1995 MC28 NSR250 SE red/white/green
1994 MC28 NSR250 sp W/ RS250 engine

The Apex Wrathall tuned bike is my old race bike and still sitting in the garage HLB Racing owned the bike and l raced it for a number of years with 62bhp with never an on track breakdown with a good over rev facility into the red .Wrathall then did the engine work and Jo and l set it up on Wrathalls dyno with one of Franks operators the 74bhp was achieved after inserting the HRC card and losing the over rev .After a number of early season heavy crashes l retired after 27 years racing and the the bike has never been raced with its full potential explored .If you read this Jo thanks for all the help .Keith Butcher

Hung wrote:YES...The top speed is what I want..about 230km,,,is it possible?

How heavy are you? haha. I'd be willing to bet if you stopped eating all those hot dogs and big macs, you could increase your top speed
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'87 MC16

230km, 140mph? No, probably not, you're going to need 70ish bhp to get there, your 36 tooth rear and you'd best weigh about 50kg.

No roadbike at the Brutingthorpe RGV bash thingie was that fast.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread