ESE's works engine tuner

[Frits Overmars]

The V4 engine employed a single crankshaft, instead of the dual-crankshaft arrangement of the three-cylinder unit in the previous NS500.

To take the greatest possible advantage of the four-cylinder engine's increased power over its three-cylinder predecessor, the V4 was fitted with a single crankshaft instead of dual counter-rotating crankshafts which minimised losses due to friction. Another innovation was the engine's reed valve input system which was introduced to replace the rotary valves that had been used up until then.

An Auto-controlled Torque Amplification Chamber (ATAC), which is a valve system in the exhaust designed to optimise gas flow, was also introduced to further improve the engine's performance.

In 1990, engineers went yet another step further by deciding to change the engine's ignition timing to allow the pistons to deliver power all at once or in a distributed manner. They achieved this by coming up with an engine design where the two sets of two pistons were at 180-degree angles, and because of the unique sound it made, this engine became known as the "Screamer."

I read this today on Hondas own page. Now I never worked at HRC but I do know the RS500 never had two cranks or Disc valves.

Yep, it's an incredibly ill-informed article. BS about dual crankshafts, rotary valves, ATAC (introduced years before on the NS500 triple but never used on the NSR500), 180°-firing screamer (the real screamer had 90°-firing), and so on; hard to believe that Honda published it on their own pages.

[katinas]

Indeed very strange, but except about rotary rotary valve, maybe it could be explained by wrong translation.

NS500 engine, like first 1984 "bottom tank" NSR500, was counter rotating, with additional shaft between crank and clutch basket "instead of the dual-crankshaft arrangement of the three-cylinder unit in the previous NS500",

With new 1985 1986 NSR 500 under engine exhaust concept, that required more space under engine for four exhaust, intermediate shaft was removed . Because of that, forward rotating crank connected directly to clutch gear and looks like this was widest NSR engine "the V4 was fitted with a single crankshaft instead of dual counter-rotating crankshafts which minimized losses due to friction".

ATAC was used on NSR500 until 1986.

From 1987 intermediate shaft again was added, because rear cylinders exhaust arranged under seat and more free space under engine was available.

Inline double crankshaft was used from 1992 to the end, together with shorter intermediate shaft, with gears positioned in the center. This reduce crankshaft twisting angle, with more accurate ignition timing for 1 and 2 cylinders in comparisons to previous single peace crank

[Peter1962]

It's here, just waiting on a suitable gearbox.
Wayne Blackwood has an R1 gearbox lined up.
A 700 twin, start looking for R1 gearboxes, if you want one.

Neil, i suppose this is your homemade twin 700 that you made for the autogyro ? For that specific usage, do you still think that a 2 stroke is a viable option for a gyro or an ULM, or would you also opt in for the 4 stroke subaru or the inevitablel rotax 912-914 ?

Back over here in Belgium, it is all Rotax... I live at a couple of kilometers of the Airport-Amougies ULM base. Every ULM has a Rotax 4 stroke... Not one 582 or 503 has lasted. All gone.

[F5 Dave]

It's here, just waiting on a suitable gearbox.
Wayne Blackwood has an R1 gearbox lined up.
A 700 twin, start looking for R1 gearboxes, if you want one.

R1 gearbox are known to be a bit fragile in 2nd at least.

[Ns1Montesa]

Always thought a 500VTwin would make a cracking roadbike in the 90s. . . . If only someone made one. . . .

https://en.m.wikipedia.org/wiki/Bimota_V_Due

The Bimota V due is a 500V Roadbike. Dont know the whole story, but seems like they had some problems with fuel injection and reliability.

[Flettner]

Neil, i suppose this is your homemade twin 700 that you made for the autogyro ? For that specific usage, do you still think that a 2 stroke is a viable option for a gyro or an ULM, or would you also opt in for the 4 stroke subaru or the inevitablel rotax 912-914 ?

Back over here in Belgium, it is all Rotax... I live at a couple of kilometers of the Airport-Amougies ULM base. Every ULM has a Rotax 4 stroke... Not one 582 or 503 has lasted. All gone.

Rotax dont support the twostroke now. 503 gone, 582 shortly.
My 700 twin I think is a great engine (I would say that) smooth with the balance shaft and powerful.
Reliable? In 30 flying hours its stopped three times with three different pilot's, me being one of them. These problems all solved now. Its an ideal gyro engine, light, powerful, smooth and compact with a built in pre rotator output, in my small single seater its a rocket.
Yet all I hear is 'it sounds like a scooter'. Aviation people are not engine people, they tend to have deep Rotax pockets also. The Rotax fourstroke is not a particularly good engine but it has millons of flight hours history.

Ive had zero interest in the 700 twin but then I havent really advertised it. Im just happy burning off some hours myself, it needs more flight time before Im comfortable to let anyone else have one. Its a circuits only or at least only fly over what you can land on engine still at the moment.

[Peter1962]

Rotax dont support the twostroke now. 503 gone, 582 shortly.
My 700 twin I think is a great engine (I would say that) smooth with the balance shaft and powerful.
Reliable? In 30 flying hours its stopped three times with three different pilot's, me being one of them. These problems all solved now. Its an ideal gyro engine, light, powerful, smooth and compact with a built in pre rotator output, in my small single seater its a rocket.
Yet all I hear is 'it sounds like a scooter'. Aviation people are not engine people, they tend to have deep Rotax pockets also. The Rotax fourstroke is not a particularly good engine but it has millons of flight hours history.

Yes, all that matters is Rotax...
But it is also very sad that the few two stroke engine builders for the aero market did not innovate more.

Take Hirth for example, they are still producing the same engines like 20 years ago.

Not one brand ever made a twin with a counter balancer...

I would say that 'the competition' made it verry easy for Rotax to dominate the market with their overpriced 912-914's...

[Peter1962]

Rotax dont support the twostroke now. 503 gone, 582 shortly.
My 700 twin I think is a great engine (I would say that) smooth with the balance shaft and powerful.
Reliable? In 30 flying hours its stopped three times with three different pilot's, me being one of them. These problems all solved now. Its an ideal gyro engine, light, powerful, smooth and compact with a built in pre rotator output, in my small single seater its a rocket.
Yet all I hear is 'it sounds like a scooter'. Aviation people are not engine people, they tend to have deep Rotax pockets also. The Rotax fourstroke is not a particularly good engine but it has millons of flight hours history.

Ive had zero interest in the 700 twin but then I havent really advertised it. Im just happy burning off some hours myself, it needs more flight time before Im comfortable to let anyone else have one. Its a circuits only or at least only fly over what you can land on engine still at the moment.

My favorite of all times : the Monarch butterfly
https://www.youtube.com/watch?v=k7A3pobLMfU

[Flettner]

Yes, all that matters is Rotax...
But it is also very sad that the few two stroke engine builders for the aero market did not innovate more.

Take Hirth for example, they are still producing the same engines like 20 years ago.

Not one brand ever made a twin with a counter balancer...

I would say that 'the competition' made it verry easy for Rotax to dominate the market with their overpriced 912-914's...

I would say you are totally on the money.

I fly my two seat a lot, with the Subaru EA81 engine. Its got the SUB4 four port heads, turbocharged. The SUB4 heads are no longer availabe so Im re making the molds now. NA these engines with the four port heads will produce 130HP at the prop flange for 90kg dry, including reduction gearbox. Not to shabby in my book.
But once again a small market. In saying that I have a number pre sold aready (with a camshaft). These engines/heads have a long history now and finally are seen as desirable and dont sound like a scooter.
https://youtu.be/6Az42nw0Hx8

[Flettner]

R1 gearbox are known to be a bit fragile in 2nd at least.

I don't think we will be pushing ithe gearbox as hard as an R1.

[F5 Dave]

Yeah but 2nd hand ones may be hard to find as a result.

[F5 Dave]

https://en.m.wikipedia.org/wiki/Bimota_V_Due

The Bimota V due is a 500V Roadbike. Dont know the whole story, but seems like they had some problems with fuel injection and reliability.

That bike was really the subject of my slightly surreptitious post
Or was I being forseafish?

[Flettner]

My favorite of all times : the Monarch butterfly
https://www.youtube.com/watch?v=k7A3pobLMfU

Imagine it with a decient engine.

[Flettner]

Yeah but 2nd hand ones may be hard to find as a result.

Or easier, lots of broken R1's about. Second gear is easy enough to get, for Blackwood Yamaha.
Or probably even easy enough to manufacture a new second gear set if I have to.
If Wayne turns up with an R1 gearbox, it will have an R1 gearbox.

[Grumph]

Remember I've got a heap of Z1 gearbox bits here that apparently no-one wants. Reasonably close ratio 5 speed - and rugged.
Drag guys have put huge HP through these boxes.
Pay freight and they're all yours. One complete and one with no selector drum.