What Was The Reason

[retroman]

Hey Folks:

Since the Japanese entered the motorcycle market they limited their offerings to bikes with short strokes and relatively large pistons ( oversquare engines) and larger valves (a larger piston allows more room for larger valves). These bikes showed up as high revving, high horsepower, overhead cam models that easily out performed the long stroke bikes from America and Britain. It seems as tho the Asian engineers just couldn't justify producing inefficient bikes when they knew how to make them perform better. However, here comes the NC (New Concept) bikes from the Asians with an under square engine (stroke longer than the piston is wide), overhead cams, and a high compression package. My question is: Why did they finally make a bike that doesn't "buzz"like their bikes of the past. My take on it is that they mastered the engineering of the 270 degree engine. That is that both pistons on the NC are moving at each ignition point. A standard engine has a piston set to change direction when the opposing piston is firing. Could I be correct on this OR, is there another reason?

 

[670cc]

Well, one could read the NC700 press release papers and learn about the variety of features Honda touted, and try to form a composite picture of the whole New Concept. I think the 270 order is just one of many aspects of the concept, although not in itself unique ( https://motofomo.com/motorcycles-27...torcycles-with-parallel-twin-270degree-cranks ). For me, the NC is about efficiency, and a broad, usable powerband that mimics an automobile engine more so than a high strung motorcycle engine. I like the NC engine, but frankly, I can do without the 270 crank thing as I do find it somewhat annoying.

As for your question, “Why did they finally make a bike that doesn't "buzz" like their bikes of the past”, well Honda has been building the Goldwing engines for a long time, and I wouldn’t say that mine buzzes. It’s smoother than the NC.

 

[the Ferret]

I agree on the 270 degree crank being annoying. I'd rather have a 360 degree crank with counter balancers.

 

[750dct]

Hey Folks:

Since the Japanese entered the motorcycle market they limited their offerings to bikes with short strokes and relatively large pistons ( oversquare engines) and larger valves (a larger piston allows more room for larger valves). These bikes showed up as high revving, high horsepower, overhead cam models that easily out performed the long stroke bikes from America and Britain. It seems as tho the Asian engineers just couldn't justify producing inefficient bikes when they knew how to make them perform better. However, here comes the NC (New Concept) bikes from the Asians with an under square engine (stroke longer than the piston is wide), overhead cams, and a high compression package. My question is: Why did they finally make a bike that doesn't "buzz"like their bikes of the past. My take on it is that they mastered the engineering of the 270 degree engine. That is that both pistons on the NC are moving at each ignition point. A standard engine has a piston set to change direction when the opposing piston is firing. Could I be correct on this OR, is there another reason?

What do you mean by buzz? It sounds different but does anybody know the real reason they went to the 270* crank? I see where they went to undersquare for the lower end torque, which I like but was sound the only reason for the 270* crank? Maybe it's all about balancing, IDK.

 

[670cc]

ffffff

What do you mean by buzz? It sounds different but does anybody know the real reason they went to the 270* crank? I see where they went to undersquare for the lower end torque, which I like but was sound the only reason for the 270* crank? Maybe it's all about balancing, IDK.

We may never know the why on the 270 crank, but Honda has justified the unsmoothness of the NC engine by stating or suggesting that it gives the bike “character”.

 

[the Ferret]

The 270 degree crank is the latest "hot thing" in parallel twin motors because it supposedly sounds and feels like a V Twin (giving it "charachter" as 670 said). Triumph started using it in 2016 I believe in their Bonneville line after running a 360 with balancer shaft on previous models, Honda in their NC, AT/NT, and Rebel lines, Yamaha in their MT 07/R7 line, and Super Tenere', Kawasaki in their Versys 650 line, Aprilia 660, BMW F 750-800-900, Royal Enfield 650, and Suzuki's new GSX8 and 800 V Stom. (after running a V Twin in their previous V strom line)

My 2003 Bonneville T100 with 360 crank and balancer was a lot smoother than my brothers 2016 Bonnie T120 with 270 degree crank. However, the manufacturers don't want to appear to make smooth bland motors. They want them all to shake like a Harley. They think that's what we want. I'd take a smooth engine like a Goldwing's vs a V Twin shake any day. But that's just me.

If you want a P Twin, these days it's going to be a 270, and you are going to have to put up with the throb (some actually like it)

 

[Rabbit]

I like some vibrations in my bike. My Royal Enfield shook enough you needed blue loctite for everything!

 

[670cc]

I have heard track riders claim the 270’s periodic slightly longer spacing between power pulses gives the rear tire a chance to “hook up” and maintain traction. I don’t think the NC will see much benefit there.

 

[670cc]

While certainly not a 270 degree twin, my CRF250 single is the noisiest, shakiest bike I own and for those reasons it may be sold before too many more seasons go by. Besides the 250, the NC vibrates the most of the other 4 machines. Wish it was smoother.

 

[750dct]

While certainly not a 270 degree twin, my CRF250 single is the noisiest, shakiest bike I own and for those reasons it may be sold before too many more seasons go by. Besides the 250, the NC vibrates the most of the other 4 machines. Wish it was smoother.

I'm wondering if the newer NC's are any smoother. The YouTube videos I have seen claim them to be smooth. I haven't ridden my '23 model yet (after waiting 1 year and 3 months to get it) but I hope it is smooth. Liking a little shake sounds like liking a little pain, it makes no sense to me.

 

[the Ferret]

I'm wondering if the newer NC's are any smoother. The YouTube videos I have seen claim them to be smooth. I haven't ridden my '23 model yet (after waiting 1 year and 3 months to get it) but I hope it is smooth. Liking a little shake sounds like liking a little pain, it makes no sense to me.

Your 23 will be no different than my 21, and like 670 said it was designed into the bike. It's inherent in the motor design. It's not a buzz, so there is no tingle in the tank, grips or footpegs to annoy you, but there is a throb or thump you feel on every stroke. RPM's do help diminish the throb, so it you are a revver, it is less likely to bother you, but if you like riding around at lower revs using the torque of the bike to propel you, you will definitely feel it. In a non DCT you can downshift and get the revs up and hold it in the higher rev zone to diminish the feeling, but on a DCT you are sort of at the mercy of the shifting algorithm, unless you put it in manual mode to control the rpms.

 

[dduelin]

Your 23 will be no different than my 21, and like 670 said it was designed into the bike. It's inherent in the motor design. It's not a buzz, so there is no tingle in the tank, grips or footpegs to annoy you, but there is a throb or thump you feel on every stroke. RPM's do help diminish the throb, so it you are a revver, it is less likely to bother you, but if you like riding around at lower revs using the torque of the bike to propel you, you will definitely feel it. In a non DCT you can downshift and get the revs up and hold it in the higher rev zone to diminish the feeling, but on a DCT you are sort of at the mercy of the shifting algorithm, unless you put it in manual mode to control the rpms.

Doesn’t your 2021 have four modes in Auto? Each more aggressive in upshift and downshift points?

 

[the Ferret]

Well yes, standard, sport, rain and a user mode you can set up, with rain being the least aggressive and sport being the most aggressive ( you cant set up user mode any more aggressive than sport I dont believe) but in any of those modes, the algorithms that Honda wrote decides when its going to shift, up or down. Only in manual mode can it hold a gear indefinitely whether accelerating, decelerating or going up or down a hill.

 

[dduelin]

Well yes, standard, sport, rain and a user mode you can set up, with rain being the least aggressive and sport being the most aggressive ( you cant set up user mode any more aggressive than sport I dont believe) but in any of those modes, the algorithms that Honda wrote decides when its going to shift, up or down. Only in manual mode can it hold a gear indefinitely whether accelerating, decelerating or going up or down a hill.

I guess I when I read the original comment I focused on the use of singular for shifting algorithm meaning the different modes [algorithms] don't really affect the shift points.

 

[dduelin]

Hey Folks:

Since the Japanese entered the motorcycle market they limited their offerings to bikes with short strokes and relatively large pistons ( oversquare engines) and larger valves (a larger piston allows more room for larger valves). These bikes showed up as high revving, high horsepower, overhead cam models that easily out performed the long stroke bikes from America and Britain. It seems as tho the Asian engineers just couldn't justify producing inefficient bikes when they knew how to make them perform better. However, here comes the NC (New Concept) bikes from the Asians with an under square engine (stroke longer than the piston is wide), overhead cams, and a high compression package. My question is: Why did they finally make a bike that doesn't "buzz"like their bikes of the past. My take on it is that they mastered the engineering of the 270 degree engine. That is that both pistons on the NC are moving at each ignition point. A standard engine has a piston set to change direction when the opposing piston is firing. Could I be correct on this OR, is there another reason?

I don't fully agree with the supposition that Asian bikes are/were limited to high revving OHC oversquare engine designs prior to the New Concept platform. The Big Four all produced undersquare V twins to appeal to American buyers and have for over 40 years. This genre we loosely know as metric cruisers. High tech features are not of value in this genre powered by essentially modern versions of antique engine designs. Even water cooling systems which were almost universal in mid and large displacement motorcycles by the turn of the last century had to be hidden as best as possible so as to appear to be an air-cooled long stroke undersquare V twin. When Harley modernized these functional antiques with the help of Porsche the HD faithful wouldn't buy the result - the V Rod.

I believe there were multiple reasons for the relatively low rpm long stroke NC engine. The world's economy had been in free fall for several years, energy costs were rising and expected to continue to rise in in the long term, credit costs spiked and credit for recreational toys in first world economies dried up. Consumers were holding on to their toy money but in European and UK economies where motorcycles are seen as transportation not just toys Honda saw opportunity for a inexpensive middleweight that returned very high fuel economy. The world was in the Great Recession when the New Concept was berthed. Motorcycle designers had been chasing 2 kg weight reductions and 2 hp increases for years but this motorcycle engine was going to be different, times were different. Honda started this project with a clean hard drive and reputedly prioritized efficiency and value in the initial design phases. Use of existing technology and R & D from the automobile side provided the basis for the engine's architecture. Limiting engine rpm to the low and mid range limited friction losses in internal bearings and bushings, a twin is optimal for reducing piston ring swept area & resulting friction, if rpm is limited then a long stroke 4 valve fills and exhausts the cylinders most efficiently and Honda had patents on manufacturing 270 degree cranks that saved both material and machining costs. Like 670cc said, the technical briefs and press packages Honda released with the NC700 platform claimed that the feel or character of a 270 crank was the primary reason for the choice. They also mentioned that Honda held a 1985 patent on a lower cost method of manufacturing 270 degree forged cranks that start as 360 degree cranks which are easier to machine thus using less metal and wasting less in the machining process. When the machined 360 crank is nearly done it's heated to the plastic stage and the crank is twisted 90 degrees then allowed to cool. Honda included a single counter balance shaft to reduce engine vibration but not eliminate it as the uneven firing interval throb was part of the design from the beginning. There might have been "too much" character with a single balance shaft so Honda engineers added the second balance shaft to the 745cc NC750 successor to the original 670cc engine.

 

[the Ferret]

Some very interesting info in there dduelin.

Amazing how all the other P Twin manufacturers fell in line and adopted the design as well.

 

[670cc]

I was hoping dduelin would contribute to this conversation. He always provides us the best hows and whys on the New Concept’s original design and development.

 

[dduelin]

I was hoping dduelin would contribute to this conversation. He always provides us the best hows and whys on the New Concept’s original design and development.

Thanks 670cc. I am grateful you did not use pedantic & dduelin in your reply haha.