Motorcycle Engines

[Henrik]

I know I have talked about this topic in the past, but I can't recall under what thread, and seeing this new tech area I thought it a good place to take the discussion up again.

Having always been fascinated by the technology that goes in to motorcycle engines, it is probably the engined produced by Honda in the 60's that I am most impressed with. Considering the level of technology that existed back then compared to what is available today, they produced some amazing things. Take this as an example:

Difference between the RC115 and the RC116 is a new bore and stroke, now being 35.5 x 25.14 mm. Power output is 16 bhp at 21,500 rpm. This means 320 bhp per litre and a Pme of nearly 16 kg/cm2 ! As regards bhp per litre, this is a figure that has never been surpassed by any naturally aspirated four stroke engine, and even today's formula 1 cars with their special fuel brews cannot hold a candle to it. I know this is not a totally fair comparison, but it gives an idea of the level of four stroke technology nearly 40 years ago. This engine is the most advanced of all the Honda engines. Red line at 22,500 rpm. Carburettors have flat slides. The gearbox contains a nine speed cluster. Dry weight of the bike is 58 kg. The piston pin has a diameter of 9 mm and weighs 6 g. The inlet valve head is 13 mm, the exhaust valve head is 11.5 mm, and the stems are 3.5 mm diameter. Weight of the exhaust valve: 6 g.

Think about it for a second (even though as the article says it is not really comparable to today's F1 engines) a theoretical 320 bhp per litre at 22'500 rpms!!!

It boggles the mind....

[El Sid]

Henrik,

You are so right ....

but it gives an idea of the level of four stroke technology nearly 40 years ago.

40 years ago!

It is mind-boggling

[rick1776]

Henrik,

If we are to believe the 900 odd HP that some of the F1 engnes are developing now, we are getting close to that 320Hp/litre limit. Given that the frictional as well as thermal losses would be a lot higher for a 3 L engine and the fact that they only rev to 19000RPm I think that they are nearly there!!

cheers
rick1776

[Henrik]

Rick,

For sure they are getting there, but that Honda engine was made 38 years ago!! Given the incredible advances technology has made since then, I still think we should be way ahead of those figures.

Maybe Honda received some help from aliens......

Never mind, we still have

[daSilva]

I think if they were to redesign an engine of that size you would find that we are much further ahead than 38yrs ago. That engine is tiny and we know that weight is the biggest factor in an engines ability to rev.

I still think Honda's oval piston bike is one of their greatest design achievements.

[raptor22]

yes the silver one is right, the small size of that engine helped it produce it's power. What was it's torque like? I imagine It can't have been very useful for a car.
It's very difficult to read across similarities between a motobike engine and a passenger car, weight reliability, cooling, drivability all play a significant role in how an engine needs to perform for a car. For a bike revs is all that matters.

with advances in lubrication technology as well it will be possible to increase teh output of that honda engine.

And that oval engine os by far their best design yet , although I believe the patent belonged to an Italian....

Let me check on that

[raptor22]

seems those pistons are an original Honda idea.

[daSilva]

Have any of you guys ever read any of Kevin Cameron's articles. He's a great tech head and writer.

Kevin Cameron
by dean adams
(1994)
In the realm of motorcycle journalists there is an entire gamut of persons and personalities, a tiny microcosm of society as we know it. From shameless egotistical posers interested in only printing stories about themselves and their supposedly fascinating lives and surreptitious word spinners twisting the truth to suit their own predicament, to arrow straight scribes who sleep like babes with an unburdned concinse, to glorified pr men with blinders so huge its a wonder they can see to walk, in bike writing we all survive in a enviorment of hybrid bottomfeeding.

And then there is Kevin Cameron. Not fitting easily into any catagory or lable, Cameron the near twenty-year contributing editor of the now defunct Cycle magazine is easily one of the most well read and well known motojourno scribes on the planet. His column--TDC--is read with interest each month by everyone who fancies himself a serious mover or shaker or even serious enthusiast. From Marlboro Roberts mechanics in Europe to a quiet woodworker in LaCrosse Wisconsin all read his columns in Cycle World and Motorcycle International.