Ducati Monster Forum

<yawn> Meh, just another Honda part.  [coffee]

(http://farm3.static.flickr.com/2752/4185784693_b816db03a5_o.jpg)












Well, *that's* a bit out of the ordinary.  ;D

(http://farm3.static.flickr.com/2541/4185785501_669e9808f5_o.jpg)

(http://farm3.static.flickr.com/2637/4185785663_fc420bb4cc_o.jpg)

(http://farm3.static.flickr.com/2487/4186543548_3737ce22ff_o.jpg)

(http://farm3.static.flickr.com/2689/4185785121_878fa0f89c_o.jpg)

(http://farm3.static.flickr.com/2533/4186543144_689c59c4b1_o.jpg)

Who can identify the make, model and year of production bike it fits?

http://en.wikipedia.org/wiki/Honda_NR (http://en.wikipedia.org/wiki/Honda_NR) (1992)

(http://upload.wikimedia.org/wikipedia/commons/thumb/0/06/Honda750NR.jpg/644px-Honda750NR.jpg)

(http://upload.wikimedia.org/wikipedia/commons/thumb/1/18/Ovalpiston.jpg/800px-Ovalpiston.jpg)

Ahem, nr750 1992?

Edit: damn

Based on the cost of the bike..what's a piston like that cost?

I remember when that came out. It was so cool, now the rear looks fat as hell. I wanted to answer your triv but those guys beat me.

Instantly recognized!

Do I get any bonus points for actually having ridden a NR750 in the USA?

Note: so what are you doing with this piston? (and how much for one?)

Note 2: if you don't want the piston, I'll gladly take it for free!

hate to phrase it this way....but sweet package.

 ;D

I remember the cycle world with that bike and the "future super Hawk" (that never came out!) That bike is still bad ass!

Wow, for possibly the first time in my life, I want a Honda.

That f'n cool, Nick.   Good post.  [thumbsup] 

Two conrods per piston?  Mebbe I haven't looked at the guts of enough engines, but that really doesn't seem normal.  And it seems like it's a recipe for your engine to get out of balance.  And what is up with the firing order?  I assume there are journals/bearing between the conrods on that go to the opposing piston.  

Think that's wierd? The Neander has two cranksafts and four rods to promote balance.

http://www.neander-motorcycles.com/shortversion-neu/main_en.html (http://www.neander-motorcycles.com/shortversion-neu/main_en.html)

Turbo-diesel, two crank, four rod engine in a motorcycle. Not sure you can get more unique than that!

Except the price. It's like 95k euros :o ???

and the NR worked.


Nice post Nick.  Now, what is the rest of the story...

mitt

maybe not more unique but the motoczysz c1 motor is pretty out there

The story isn't much, the piston was just passing through, on it's way to a new home.
Only stopped long enough to get photographed.

Not mine, not for sale, and certainly wouldn't leave my possession if it was free.  [laugh]

Technically....

Piston too heavy and too wide for a single rod.

The crank/rods/pistons assembly shown in Derby's pic are from the NR500 GP race engine.
Pistons are significantly different, flat on the sides.
The production piston in my pics has sides that are significantly curved.
In either case, machining the bores, pistons and rings was quite an effort I'm sure.

Both motors were essentially V-8's, just the pistons and cylinders were a bit different.
GP rules at the time (late 70's) didn't allow more than 4 cylinders, and all the bikes were 2-strokes.
Honda wanted to re-enter GP racing with a 4-stroke, but needed a V-8 to hope to be competitive with the 2-strokes.
Honda's solution was the NR.
IIRC, fundamentally all for naught; too heavy, thirsty, and maintenance intensive.
Honda caved and built 2-strokes.

Honda NR750 sound (http://www.youtube.com/watch?v=UNFmCnlXhPk#normal)

Cool thread!!

What was the redline on the 750? 

What made them maintenance intensive?  Nevermind, I just counted the valves on the 500 motor!!   :o   :o   :o   [laugh] 

Plus almost every racing santioning body in the world added a few additions to the rules book -- ie: pistons must be round in shape.  Reason being that Honda held almost all the patents for these pistons and getting the compression / oil rings to work! (which was the most difficult part of the equation) 

Too bad unfortunately -- the NR750 I rode had the most incredible powerband of any motorcycle that I've ever ridden. 

Here's a pretty good road test, combined with a 'sedici:

http://www.visordown.com/road-tests/bloodlust---honda-nr750-vs-ducati-desmosedici/7049.html (http://www.visordown.com/road-tests/bloodlust---honda-nr750-vs-ducati-desmosedici/7049.html)

"The first NR, the NR500 0X, combined an oval-pistoned engine with a monocoque frame. By the end of its development it was reckoned that the NR produced around 130bhp and revved to over 20,000rpm, but despite all their best efforts Honda couldn’t make it competitive."

 :o

I think based on the picture - about 10 bucks  ;D

Cool pic(s) Thanks!

If you have to ask, you can't afford it.  [laugh]

I've no idea what $ the piston traded hands for.

A friend of mine has one actually, very cool bike, I probably wouldn't ride it even if he did offer.

man. talk about needing crazy tight tolerances when running multiple con-rods per piston. hope the metal doesn't expand and contract at different rates or in different places on the rods to the same piston.

I was going to Honda Tech school at the time they were developing the oval piston concept, the theory and R&D behind it was discussed at length, when a corporation like Honda launches a project like that they have no limit to engineering,only the best were employed to the cause. Honda really thought their idea would revolutionize the internal combustion engine, and spent a lot of coin trying,They had not figured out how to seal the rings on the piston flat sides yet, and also production machines for the boring / honing process. It was a very exciting time though, and as young students it was huge, too bad it didn't work out, but it opened a lot of minds and brought a lot of knowledge to light.