I found this on sportbikeriders.com

[ThAzKat]

This is the NR750 from Honda. Leave it to Honda to do something like this. I really like the way they try to do something outside the BOX.

[md86]

Oh yeah , the oval-piston deal . I remember reading about that in some cycle mag a few months ago . I forget , why was that project scrapped ?

[ThAzKat]

They have had that design for years but this is the best pic's I have found

[ThAzKat]

Can you imagine trying to keep the flat edge of the piston from leaking.

[Black_peter]

For one thing Honda couldn't race it because the sanctioning body (I forget what class) deemed it a V8. I also remember they had issues with the rings. The NR750 was available to the public and though the road version is underwhelming it is a collectors item..

[ThAzKat]

That would be the only reason I would and might buy one in the future. Yeah, after I hit the lottery!

[The CyberPoet]

The reason for it made great sense at the time -- far better heat dissipation, far better fuel-air & exhaust venting -- while retaining the V-twin power-pulse that keeps the tires from losing traction as often (four cylinders cause more bangs, thus more times per RPM for the tires to lose a bit of traction from the bang). Due to uneven expansion rates, these engines were known to fail very quickly and seize. The next time around, they simply stuck to individual cylinders, but timed the crank so that the cylinders fired concurrently or just slightly off each other, mimicking the same firing effect as the oval-piston ones.
Yamaha did the same basic thing for Rossi's M1 this year by making the cylinders act as if they were effectively a close-firing V-twin instead of a straight-four. And, as we all saw, Rossi came and kicked Honda's butt this year on his (far less powerful) Yamaha, because that firing order kept the limits of adhesion far more usable (and he's a superior rider).

Cheers
=-= The CyberPoet

[ThAzKat]

More so Super rider, I was very surprised he came right back with the Yamaha. I do like the V-5 that Honda has built.

[The CyberPoet]

More so Super rider, I was very surprised he came right back with the Yamaha. I do like the V-5 that Honda has built.

You'll see it second half of next year in the new VFR/Blackbird follow-on (should be labeled a VFR). Of course it won't put out 230 HP, but it will be cam'd to produce a hellacious amount of torque and should put the bike up there in the 160 - 170 mph range... not bad for a sports-tourer

Cheers
=-= The CyberPoet

[ThAzKat]

I am patiently waiting to see it. I am expecting it to put out a comfortable 160 hp.

[The CyberPoet]

I am patiently waiting to see it. I am expecting it to put out a comfortable 160 hp.

Unfortunately, I just have this feeling to the core of my bones that Honda will insert their VTEC system into it, and that will make the valve adjustments a total nightmare (5 cylinders, 10 adjustments with the Vtec off, another 10 with the pins in for the VTec system -- 6 hours conservatively?). I wish they'd find a different solution...

Grumbling Cheers
=-= The CyberPoet

[Black_peter]

Am I missing something?
I thought the last "Blackbird" was knocking on 200mph's door??

[ThAzKat]

I think that is the idea they have, Cyber. The last talk I heard was VTEC and Direct injection system.
Another state of the art vehicle from Honda.

Mechanics Nightmare and Engineers dream, you know how it goes.

[The CyberPoet]

Am I missing something?
I thought the last "Blackbird" was knocking on 200mph's door??

The blackbird (CBR1300XX) tops out at a tested 172 according to most of the magazines, putting it at the back of the top-speed brat pack. On the other hand, it is the most comfy bike in that brat pack (IMHO), with ergo's almost identical to the 98+ Kats. The problem is that the platform hasn't been updated in five or six years now, and is lost in the shuffle with the new race 600's able to catch it and the 1 liter race bikes able to dust it. The VFR also hasn't had a major update since the engine went VTec in 2001 or 2002, and is also showing it's age (plus declining sales because of the service cost at the valve adjustment interval -- around $600 -- and the top speed).

Honda gets to capitizalize on the V5 engine they build for the race world by retasking it for a new high-displacement VFR which is slated to fill both the blackbird and VFR slots (no clue whether the existing VFR will remain, the current blackbird won't), while getting it into the hands of people who will provide the best field testers for the platform available -- long range sport-touring riders who tend to do their maintenance on time but value speed. It should also appeal on a marketing-basis to those who loved the ST1100 but didn't like the bloated ST1300.
From the release of the V5 VFR, it wouldn't be hard to refine the engine for race-rep use in some future (2007 model year?) race bikes.

Does that clear it up? Personally, I've been waiting with baited breath for the Blackbird update and was planning on getting one this past year if they had updated the platform as Honda's originally-announced intentions had been (before the V5 project became the new engine of choice). With the VTech connundrum, I'll have to take a very close look at the service procedure before I'd go down that road for the new one, because the procedure is complicated (and time-intensive) enough that I passed on the current VFR altogether... Special tools, double adjustment (first set the single valves, then insert the special tools and do the other valves, etc).

Cheers
=-= The CyberPoet

[ThAzKat]

I will do it for you Cyber. Just get the bike and I will do it.