Removing limiter on CBRXX Blackbird (04 plate)

[getyerkneedow...]

Hi folks,

Got a technical issue for ya.

My friend and i are trying to make my friends 04 plate Blackbird clear the 200mph mark (true speed as measured on a GPS not clocks).

So far we've got a 17tooth front, and a 42tooth back and by the book that should be good for about 201.9mph.

However, its still reving out at 10k in top gear. So we're wanting to remove the limiter to let it rev all the way around to its 12500 mark.

Anyone got any knowledge of derestricting blackbirds?

Any knowledge, do's and dont's greatly appreciated.

GYKD.

NB: The book suggests with 12500 and the set up we've got, we should see a true speed of 210mph ish. So once thats acheived, its time to get all the engine reworked, gas flowed heads etc. and im trying to persuade my friend that NOS is a sound investment.

[finpos]

Are you sure the bike can actually develop enough power to do that? i.e. is the engine simply running out of steam as opposed to actually being limited by something??

I don't know, I'm just asking.

finpos.

[getyerkneedow...]

Its being limited at 10k rpm. The research ive done suggests it should be able to run around to 12500.

[finpos]

Well, if that's the case, it would suggest that somehow the ecu knows it's in top gear...?

finpos.

[stevo as b4]

The engine's red line is 10800rpm. The engine should not be revved past this point anyway, as peak power is at 10000rpm, so there is nothing to gain. Being a Honda id expect the rev limiter to cut in at or only very slightly past the 10800rpm red line. Id find a way of getting the engine to pull that speed with taller gearing, which of course means more power!
What modifications have you made so far, and what is the bike making bhp wise?

[finpos]

Ahh right, You're talking about bypassing the normal rev limiter...

good luck with that!

finpos.

[jamieclayton9]

correct me if i am wrong but hasent that model got the 186mph limiter on it the same as the zx12r and the busa. cheers. jamie
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all my previous rides, c50 steppie, h100s, cb250n superdream, gpz500s, gsf600s bandit, gsf1200s bandit, zx6r, thunderace, dr350, sv650s, cb600f hornet ooohhhhh and the mrs

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Limiter or not, as you say, you're going to need quite a lot more power to get that sorta speeds out of it - so reckon NOS is probably needed at least, though apparantly this often isn't great for top speed runs?

Got a feeling as standard they make a tad under 140hp rear wheel hp - think Mr C needed a bit over 175hp to just touch over 200mph on a GPS (not on the timing system though).

As for taking the rev limiter out, I would be talking to the place doing your tuning - you want to be in the right part of the power at the right time, so may need to change the gearing to be a bit higher so that 200mph comes just as the power is trailing off, or whatever.

[Dark]

[stevo as b4]

I don't think any Bird's had a 186mph speed limiter fitted. This is because they don't have the power to reach 186mph in std form! I've seen several tested top speed figures of 178mph, which is faster than a ZZR1100, but only by around 3-4mph. I heard that they tested a Blackbird in Italy at a large speed bowl circuit, and they found removing the mirrors got them to a fraction over 180mph, so that's something you could do if you havn't already.

A good injected Bird makes 137bhp at the rear tyre, and a Full race system+filter+Power commander takes that to closer to 150bhp. This still probably isn't enough for a true 200mph, but then there are so many factors to consider, and gearing, weather conditions, temperature, etc all make small but important differences to speed you can achieve.

Good luck anyway!

[Black Knight]

I've a Bird with over 150 at the wheel and it's nowhere near 200mph.

It would cost a silly amount of money to attain 200 on a Blackbird.

I remember once seeing 165, maybe a little more. Don't think I hit 170 though. Probably could with the right conditions on a clear road.
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Where does a turn end? 'Where you can do anything with the gas you want to, where you are brave again, where your attention is free from the turn, where you are sure you can do it better next time; that's the end' - Keith Code.

[Kickstart]

Hi

Mr C had 187hp on his ZX12R, which was just about enough to hit 200mph on a bike with the mirrors off, strapped down at the front, lowered at the back, etc.

Don't think without major engine work the Blackbird makes anything like enough power to hit 200mph.

Bike magazine list it as 136hp at 9800hp, in which case there is no point to revving round to 12500rpm (even if you bypassed the rev limiter it is so far past peak power it is probably going to be producing a lot less than 136hp).

All the best

Keith
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[Rockhopper]

Wasn't one of the mags trying to do this with a GSXR1300? I think they gave up in the end after turboing it and spending loads of cash.

[stevo as b4]

You need to find alot more power thats for sure! The BlackBird makes 162bhp at the crank in std form, and loses maybe 15-16% in transmission losses. Assuming that 180bhp at the rear tyre is enough, with the right gearing, then you need at least 210bhp at the Crank. That's a massive increase that will simply not be possible to achieve without either more capacity+tuning work, and or Nitrous.

I know that in an artical about the 200mph+ club in PB magazine a couple of years ago, most of the bikes that clocked over 200mph, were turbocharged Busa's, all with around 320bhp. TTS's Richard Albans had clocked over 200mph, but his bike being naturally aspirated had a 1600cc conversion, and lots of other expensive internal mods! He made 223bhp without Nitrous, and 240bhp with the gas.

I won't say getting a blackbird to make that power is impossible, but it won't come cheap, and im not sure there's enough scope in the Bird's engine to make that kind of power without Gas or a blower fitted.

[edd]

PB are trying to get to 250 mph with the aptly named "project 250" and no they havent given up, they are taking it to bruntingthorpe in next months issue.
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Bluespark Automotive - Diesel Tuning for Performance and Economy

[Kickstart]

Hi

200mph is certainly fairly possible with a stock engine out of a 'busa. However that is with careful setting up and using a decent exhaust.

With decent aerodynamics then 180hp should be enough for 200mph, but the Blackbird is not as good as a 'busa (but then the Blackbird looks better) so say 190~200hp at the back wheel. Even rounding a stock Blackbirds rear wheel hp up to 150hp then that is 30% more power required. Holeshot Racing would charge your £1765 for doing that work to your engine.

All the best

Keith
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[divuk83]

Never heard of a 200mph Blackbird. Its gonna take more than just changing sprockets and upping the revs to get it there.

Try 200mph.org there are a few guys who race Blackbirds at Straightliners and I think they post on there.

Dave

[getyerkneedow...]

Smashing. Cheers for the help guys.

I dont really buy PB, but ill grab a copy and check out that Project 250 see what kinda work they're doing.

Certainly food for thought. Thanks once again for the help and ill let you know how we're getting along.

[edd]

I can roughly remember all the things they have done to the busa, but 250 mph is a hell of a lot more difficult than 200. Project 250 has had A huge garrett turbo, an intercooler, JE forged turbo pistons, carrillo rods, specifically turbo profiled cams, an e-boost boost controller £2.5k of MoTec ECU, Dymag wheels, an extended swingarm, a huge (50mm i think) external wastegate.

You wont need all of this for the blackbird, but you will need to work hard. You need a greater increase in power for every extra mph you gain. I think a nitrous oxide system is a good place to start, im not sure how much gas you can feed a blackbird motor, but id have thought you could manage 60-70bhp (maybe) www.nitrous.info has some good jetting charts which should help you set your system up. For bringing in big boost you will want a wet nitrous oxide system (much better than a dry kit) and a progressive controller to bring in the power more steadily. Nitrous oxide kits can be built very cheaply nowadays, if you are interested how, ask me.
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Bluespark Automotive - Diesel Tuning for Performance and Economy

[Kickstart]

Hi

Having seen the 200mph events, nitrous is not that useful on its own. A 'busa with nitrous and little else will struggle to hit 200mph . One guy managed 194.1mph with nitrous (recently fitted, so still learning to use it although very experienced at fliers) on a 'busa at USBC2, about the same as he managed without nitrous. For comparison there were 5 people with the same or higher top speeds with just pipe and filter type mods

Trouble is that tanking along a runway a nitrous bottle sticking out has a large effect on aerodynamics. Also it gets colder with speed, dropping the pressure in the bottle and reducing the amount of nitrous that can be squirted in.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[edd]

I was going to mention that sticking the bottle in the airstream would seriously hinder progress. Other than that its a power gain the same as any other. How much underseat storge is there on a blackbird? could you not fit one, or several smaller bottles under the fairing somewhere? EDIT: as for the coldness issue, bottle heaters are available, and although temperature is relatively significant you can always upjet to account for this.
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Bluespark Automotive - Diesel Tuning for Performance and Economy

[Kickstart]

Hi

Bottle heaters draw a fair amount of current (ones I have seen have all been plugged into an external battery pack).

Yes it is extra power, but to be honest I take the nitrous power claims (the "use a xxHP nozzle") with a large pinch of salt. Think too few people really understand setting them up, and plenty of people get convinced by the results obtained by a few people who do know what they are doing.

While you can use larger nitrous nozzles you also need all the rest of the system to be able to flow that much gas (eg, the lines from the bottle).

Personally I would say to stick with conventional tuning as long as you can. At least that can be used when you want it, without expensive refills and purging the system before use.

All the best

Keith
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[edd]

Surely if you check your system's max flow rate, which anyone can do with a fuel pump and regulator connected to each solenoid in turn into a measuring container, jet out of the solenoid/line and timed with a stopwatch. Then you know how high you can go.

I agree with you Keith I think a lot of people dont understand N2O systems but i genuinely dont understand why (probably because people talk utter bollocks about it all the time, misleading anyone who is interested).

Id be keen to use it for their purpose, mostly because I think that even with a serious amount of money spent, they wont beat 200mph on conventional tuning alone. Theoretically (obviously depending on max flow rate) they can inject as much gas as they need until the engine fails. The system I built will flow 175bhp (on paper) of N2O at 800psi bottle pressure and the same with fuel at 45psi. I just feel that for the money they will spend on nitrous oxide they will get a much greater gain than with conventional tuning, though i think they will probably need to tune the bike conventionally as well.
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Bluespark Automotive - Diesel Tuning for Performance and Economy

[Kickstart]

Hi

Not sure on your method. Would depend on exactly where the restriction occurs (eg, 4 cylinder engine it could be earlier in the system), but should be easy enough to addapt running all 4 at once.

To be honest I suspect they are going to really struggle with anything under 200hp. 'busa does work well, but that is because when it was hit in the face with the ugly stick they also made it very aerodynamic.

Not sure how much the Blackbird could take (eg, 'busa engines are pretty tough, but the ZX12R makes similar stock power but doesn't take so well to tuning). I believe the Big CC tuned 'busa was running on stock rods until it was producing well over 500hp.

Other problem with nitrous is that it is rather too obvious .

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

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