Best engine design for a motorcycle?

[boraticus]

" B&S..."undoubtabley" great for canadian motorcyclists. Is that what Yamaha used in those RD's?"


Bombardier, the Canadian manufacturer of various recreational products (ATVs, snowmobiles, Seadoos, Spyder etc.) build Rotax engines for applications in a few "high end" motorcycles and other forms of motor sports. Rotax are built in Austria and are famous for their leading edge design, engineering, build quality and above all, performance.

Yamaha obviously use Yamaha engines. Even in the old RDs.

The Briggs and Stratton Vanguard although built in Japan, was never used in a production motorcycle. I'm certain that it would have been a better choice than similarly designed engines presently being used in some models.

 

[SWSportsman]

Originally Posted By: boraticus

" B&S..."undoubtabley" great for canadian motorcyclists. Is that what Yamaha used in those RD's?"


Bombardier, the Canadian manufacturer of various recreational products (ATVs, snowmobiles, Seadoos, Spyder etc.) build Rotax engines for applications in a few "high end" motorcycles and other forms of motor sports. Rotax are built in Austria and are famous for their leading edge design, engineering, build quality and above all, performance.

Yamaha obviously use Yamaha engines. Even in the old RDs.

The Briggs and Stratton Vanguard although built in Japan, was never used in a production motorcycle. I'm certain that it would have been a better choice than similarly designed engines presently being used in some models.


Thanks for the update! You're a real treasure trove of previously unheard-of information.

 

[boraticus]

Originally Posted By: SWSportsman
Originally Posted By: boraticus

" B&S..."undoubtabley" great for canadian motorcyclists. Is that what Yamaha used in those RD's?"


Bombardier, the Canadian manufacturer of various recreational products (ATVs, snowmobiles, Seadoos, Spyder etc.) build Rotax engines for applications in a few "high end" motorcycles and other forms of motor sports. Rotax are built in Austria and are famous for their leading edge design, engineering, build quality and above all, performance.

Yamaha obviously use Yamaha engines. Even in the old RDs.

The Briggs and Stratton Vanguard although built in Japan, was never used in a production motorcycle. I'm certain that it would have been a better choice than similarly designed engines presently being used in some models.


Thanks for the update! You're a real treasure trove of previously unheard-of information.


Always a pleasure to help!

 

[Jeff_D]

I worked for 6 1/2 years as a small engine/snowmobile mechanic from '84-'91. Rotax was hardly a name synomymous with dependability in those times, which were mainly on the 70's/early '80's sleds.

'70's Rotax engines made 70's Harley shovelheads look like marvels of mechanization. Truly!! Early '70's Rotax's were absolute junk.

An '80's Ski-Doo Blizzard 9500+ would be doing absolutely great if it live to 2500 miles without a top end. Their rotor gear train wasn't exactly the toughest thing around either. Broken piston skirts would lodge in the intake rotor and ruin the crankshaft worm gear that drove their rotor induction.

Rotax's were on par with JLO/Rockwell & Hirth, regarding their dependability, in those days. Hardley a bragging right.

Now, certainly Rotax has come along ways, but certainly many other manufacturer's have too.

To bad every manufacturer, today, wasn't given the same benifit of the doubt, regarding their history??

 

[boraticus]

Not to question your mechanical history nor recollections thereof JeffD but, I see plenty of old Skidoo snow machines around here with the orginal 1960's single cylinder Rotax engines in them, still running strong. Most of them never opened up. Could be that some people know how to properly maintain and operate their machines while others obviously don't.

I'm certain that if we dig far enough back into any manufacturer's history, we'll find examples that they would not be too proud of. However, progress is progress. Look at BRP's Rotax engines of today and compare them with what was being offered thirty years ago. You'll see NO resemblance other than basic engine operating principles. The same cannot be said for all manufacturers. Most but not all.

Change is inevitable. Change for the purpose of progress is essential. If it wasn't, we'd still be riding horses.

 

[Jeff_D]

Quote:
Not to question your mechanical history nor recollections thereof JeffD but, I see plenty of old Skidoo snow machines around here with the orginal 1960's single cylinder Rotax engines in them, still running strong. Most of them never opened up. Could be that some people know how to properly maintain and operate their machines while others obviously don't.
I don't believe it came down to how those early Ski-Doo Rotax's were maintained. If they haven't been opened up it's more likely due to lack of use. I'm betting very few, % wise, have not been opened up by now. As for their singles, even running 20/1 oil/gas mix they still had main cranksaft bearing problems. This was due to their poor balancing and the loads those bearings had to try and endure. Often those mains became so sloppy that the crank seals would fail to do their job, the engine draw excess air (lean out), and the engine would burn up.

They shook so bad their solid mounted exhaust's had a short lifespan due to cracking. Their excessive vibration often took it's toll on many other parts, including the motor and handlebar mounts. There was other issues, too, like their horrible pull starter design, and the need to carry a 6 pack of sparkplugs just to go on a full day ride, due to fouling.

Now, I can't say Rotax was any worse than most other engine manufacturers used on snowmobiles of that era. Snowmobiles in general were crazy undependable compared to todays sleds.

The point I was geting at is Rotax has evolved from their early, undependable, beginning, to be what they are now. HD has done the same.

I also would go so far as to say, that in their respective worst years, HD's engines were much more dependable than those Rotax's, if measured on hours of engine use/major repair.

I'll conceed that the Rotax 2 strokes were being run closer to their max output, for a greater % of that time, but you can get the drift of what I'm getting at.

Someone here in this forum (not you) made a comment something to the effect "If Harley Davidson made airplanes, would you fly in one?"

My thought was, yes, if the HD of today was building them.

-Or- conversely, If '70's Rotax's were used in planes would you want to fly in one?

 

[SWSportsman]

Jeff, if you haven't figured it out yet, there are folks on this forum (and many others) who are just going to pretend to not get your point. They apparently have an uncompromisable agenda to propagate negative comments about one particular brand of motorcycle...facts be [censored]. Although they frequently deny it, my theory is that most of it is the result of either ignorance or envy.

BTW, my well-maintained 1998 Sea-Doo's twin-cylinder Rotax engine is still going strong after more than 500 hours. Never been opened up. Anecdotal, but at least by 1998, Rotax could do it right also.

 

[boraticus]

" -Or- conversely, If '70's Rotax's were used in planes would you want to fly in one?"

Funny you would mention that. Rotax engines are the number one choice for powering ultralights and home built aircraft and have been for close to thirty years. I believe they began production of small two stroke aircraft engines in 1982.

For the purpose of this discussion, I'm not contesting HD engine reliability. After all, in over 107 years of producing basically the same design, one would hope that they have that aspect dialed in by now.

 

[Jeff_D]

Originally Posted By: SWSportsman
BTW, my well-maintained 1998 Sea-Doo's twin-cylinder Rotax engine is still going strong after more than 500 hours. Never been opened up. Anecdotal, but at least by 1998, Rotax could do it right also.
I don't doubt that at all, SW. I personally like and respect Rotax.

Gotcha on the rest of what ou said too.

Quote:
For the purpose of this discussion, I'm not contesting HD engine reliability. After all, in over 107 years of producing basically the same design, one would hope that they have that aspect dialed in by now.
You mean the 4 stroke piston powered v-twin?

Is that notably any different than Rotax continuing to build 2 cycle parallel twins?

 

[Zedhed]

Comparing the life-span of a multi-cylinder 2-stroke snowmobile engine to a 4-stroke, air-cooled, push-rod V-twin is like comparing apples to coconuts.

2-strokes by their very nature were temperamental, and relatively unreliable for daily use BECAUSE they are high-output, light-weight designs. Reliability is sacrificed for high power and light weight.

Shovel-head engines while not as reliable as other 4-strokes designs of their day, were certainly more reliable, and longer-lived than most 2-strokes of that time. BUT, they were not designed to be light-weight or high power output engines

 

[SWSportsman]

Originally Posted By: Zedhed
Comparing the life-span of a multi-cylinder 2-stroke snowmobile engine to a 4-stroke, air-cooled, push-rod V-twin is like comparing apples to coconuts.

2-strokes by their very nature were temperamental, and relatively unreliable for daily use BECAUSE they are high-output, light-weight designs. Reliability is sacrificed for high power and light weight.

Shovel-head engines while not as reliable as other 4-strokes designs of their day, were certainly more reliable, and longer-lived than most 2-strokes of that time. BUT, they were not designed to be light-weight or high power output engines


Good points!

 

[boraticus]

Originally Posted By: Zedhed
Comparing the life-span of a multi-cylinder 2-stroke snowmobile engine to a 4-stroke, air-cooled, push-rod V-twin is like comparing apples to coconuts.

2-strokes by their very nature were temperamental, and relatively unreliable for daily use BECAUSE they are high-output, light-weight designs. Reliability is sacrificed for high power and light weight.

Shovel-head engines while not as reliable as other 4-strokes designs of their day, were certainly more reliable, and longer-lived than most 2-strokes of that time. BUT, they were not designed to be light-weight or high power output engines


Not necessarily true.

The old Japanese two strokes of the late '60s to the late '70s were more reliable than most four stroke motorcycle engines of the time. The only mass produced four stroke of the era that wasn't prone to frequent failure was BMW. The old air cooled two strokes of the day were not only outperforming competing brands of two, three, four times the displacement, they were also infinitely more reliable.

Do you think that the Japanese would have achieved world wide motorcycle dominance in the late '70s by building unreliable bikes? They had the motorcycle world by the bells forty years ago. I wouldn't be pounding my chest too hard because a motorcycle company who's been making bikes for over 100 years has finally accomplished something the Japanese had achieved decades ago.

By the way, if you were to take a look at the BRP web site, you'll see that they make much more than parallel twin two stroke engines. They make liquid cooled singles and V-twins with specific horsepower output that rival the best in the world. They also make a couple variations of three cylinder two stroke snow machine engines that are marvels of modern technology. Take a look at their two stroke outboard marine engines. To even allude to suggesting that BRP/Rotax is complacent is ludicrous.

I applaud HD's attempt at true evolution by producing the V-Rod engine. It's too bad that most Harley-philes do not appreciate technological advancement. Without it, the future of Harley's fate is certain. Look at any other historical industry that failed to progress with the times. The future will not be too bright for any company that chooses to remain producing primarily mechanical anachronisms.

 

[Jeff_D]

Originally Posted By: Zedhed
Comparing the life-span of a multi-cylinder 2-stroke snowmobile engine to a 4-stroke, air-cooled, push-rod V-twin is like comparing apples to coconuts.

2-strokes by their very nature were temperamental, and relatively unreliable for daily use BECAUSE they are high-output, light-weight designs. Reliability is sacrificed for high power and light weight.

Shovel-head engines while not as reliable as other 4-strokes designs of their day, were certainly more reliable, and longer-lived than most 2-strokes of that time. BUT, they were not designed to be light-weight or high power output engines
I can't disagree with any of that. I did eluded to part of that in my earlier post.

Here's what I'm trying to dispell, though.

Rotax as being famous for quality and dependability, but HD, in comparable years, as not.

Why are some manufacturers past overlooked while others are often held in judgement for their worst years.

HD's were indeed more problematic in the 70's than other bike manufacturers.

-But- In the 70's Rotax was not the best engines built, used in snowmobiles, either, IMO. They may have built more engines than anyone else, but if I had a choice I'd have picked a Suzuki, Fugi, Yamaha, Kohler, possibly a CCW, and maybe a couple others that I can't recall off the top of my head over a Rotax.

In the 80's Rotax started building better engines. An example is given of an aircraft engine being introduced by them in 1982. I don't know if that's fact, as I never worked on ultralights, but it could be. I'm doubtful it was considered a dependable aircraft engine by Aircraft standards, though.

In 1984 Harley came ot with their Evolution motor. It was a giant step for them in dependability, and could be considered as dependable as the other manufacturers at the time.

Also, FWIW, Harley has been noted as using an engine originally designed for some other purpose. Rotax engines were not origianlly designed for snowmobiles, either, but were also used for other purposes and made to fit.

IMO, Rotax cannot be touted as "famously dependable" while HD is panted as being a company building rolling rubbish with a B&S engine looked at as being a viable, improved, replacement.

 

[Jeff_D]

Quote:
I applaud HD's attempt at true evolution by producing the V-Rod engine. It's too bad that most Harley-philes do not appreciate technological advancement. Without it, the future of Harley's fate is certain. Look at any other historical industry that failed to progress with the times. The future will not be too bright for any company that chooses to remain producing primarily mechanical anachronisms.
Funny, others don't see things quite the same as you, regarding these thoughts.

http://www.motorcyclecruiser.com/roadtests/touring_motorcycles_comparison/index.html

These people feel HD Electra Glide is the winner in this touring motorcycle comparison.

 

[Zedhed]

boraticus:

I'm the last guy that would defend AMF HD products, but I gotta call BBS on some of the things you said:

First of all, Kawasaki only made the 2-stroke triples as a temporary measure until they could produce the mighty Z1. If you think that a Mach III was even half as reliable as a Z1 then you didn't ride motorcycles back then. I owned both bikes and my Mach III seized with alarming regularity as did many of my co-riders who owned them. That bike would never even approach 20K miles without a top-end rebuild. While the Z1 could easily reach 100k miles without a problem. Even the venerated RD350 (400) was no match for a Honda CB750 on reliability.

That said, 2-strokes were a quick way to performance without all the investment it took (by Honda) to achieve high performance with a 4-stroke engine. I can't tell you the number of Kawasaki crankshafts Mach III & VIs I had to rebuild during that time.

And although a Shovelhead could certainly not be compared to a CB750 or a Z1, it had all the reliability attributes of a 4-stroke. It was just such a poorly produced example, much was lost in the translation. I rode Bultaco 2-stroke dirtbikes in the early 70's and we used to measure the time between rebuilds in hours not days, weeks or years.

If you want to go back to the 60s. just remember what Honda was producing before the CB750 --- all their 4-stroke singles and twins set the bar for reliability and quality. There is a good reason that nearly all the Japanese switched over to 4-stroke street bikes in the 70's long before they were forced to by EPA Regs in 1980 -- it was a more reliable design philosophy.

Remember, only Yamaha was still producing a 2-stroke street bike in 1980 when the EPA regs took effect (excluding the RG500, and NS400 which were limited production street-racers)

BTW, we should all know how awesome Rotax 4-strokes are, I would never say otherwise. KTM, BMW, Buell, Aprilia and other manufactures know too.

 

[Jeff_D]

Originally Posted By: Zedhed
BTW, we should all know how awesome Rotax 4-strokes are, I would never say otherwise. KTM, BMW, Buell, Aprilia and other manufactures know too.
I seem to recall Can-Am also using a 4stroke Rotax in one model, instead of a 2 stroke, shortly before they quit making dirt bikes.

Always would've like to try out one of them Can-Am's.

 

[boraticus]

Originally Posted By: Zedhed
boraticus:

I'm the last guy that would defend AMF HD products, but I gotta call BBS on some of the things you said:

First of all, Kawasaki only made the 2-stroke triples as a temporary measure until they could produce the mighty Z1. If you think that a Mach III was even half as reliable as a Z1 then you didn't ride motorcycles back then. I owned both bikes and my Mach III seized with alarming regularity as did many of my co-riders who owned them. That bike would never even approach 20K miles without a top-end rebuild. While the Z1 could easily reach 100k miles without a problem. Even the venerated RD350 (400) was no match for a Honda CB750 on reliability.

Reference the above. I suggest you re-read my previous post. I was not including Japanese four strokes. They were just about as reliable then as they are now. My references to four strokes of the day were BSA, Triumph, Norton and HD. None of which were blessed with reliability unless meticulously maintained and gently ridden.



That said, 2-strokes were a quick way to performance without all the investment it took (by Honda) to achieve high performance with a 4-stroke engine. I can't tell you the number of Kawasaki crankshafts Mach III & VIs I had to rebuild during that time.

I agree with the above comments. However, a reasonably ridden air cooled two stroke will achieve 50K miles before major work is required. Problem is that due to their nature and performance capabilities, they were usually flogged pretty hard. Thus reducing their reliability. Nonetheless, they could take much more abuse than other non-Japanese brands of the day.



And although a Shovelhead could certainly not be compared to a CB750 or a Z1, it had all the reliability attributes of a 4-stroke. It was just such a poorly produced example, much was lost in the translation. I rode Bultaco 2-stroke dirtbikes in the early 70's and we used to measure the time between rebuilds in hours not days, weeks or years.

Bultacos aren't Japanese and I'm aware of their fragility. I had friends who owned and occasionally rode them.




If you want to go back to the 60s. just remember what Honda was producing before the CB750 --- all their 4-stroke singles and twins set the bar for reliability and quality. There is a good reason that nearly all the Japanese switched over to 4-stroke street bikes in the 70's long before they were forced to by EPA Regs in 1980 -- it was a more reliable design philosophy.

Agree with the above. Progress marches on. However, modern two stroke machines are equal to the task. If there was more demand for them, they'd probably be back in production.



Remember, only Yamaha was still producing a 2-stroke street bike in 1980 when the EPA regs took effect (excluding the RG500, and NS400 which were limited production street-racers)

Agree with the above however, liquid cooled RZ-350s were produced in Brazil right up until 1995. Air cooled RD350 (1973 technology) was built and marketed in India as a Rajdoot right up until 1990. They were built for a couple simple reasons. They were cheap to manufacture, easily maintained and very reliable.

BTW, we should all know how awesome Rotax 4-strokes are, I would never say otherwise. KTM, BMW, Buell, Aprilia and other manufactures know too.


I see you mentioned Buell in the above list of Rotax powered motorcycles. It's a tragedy that HD shut them down. They were a breath of fresh air that many had hoped would breath some life into North American produced motorcycles. Eric had all the right ideas. It's unfortunate that he partnered with a retro thinking manufacturer to supply him with engines and support.

One has to wonder if HD shut Buell down due to Buell's preference for the Rotax engine.

Shutting Buell down was truly a sad day for North American motorcycle manufacturing.

So, Zedhed, I call BBS to your BBS.

 

[boraticus]

Originally Posted By: Zedhed
boraticus:

I'm the last guy that would defend AMF HD products, but I gotta call BBS on some of the things you said:

First of all, Kawasaki only made the 2-stroke triples as a temporary measure until they could produce the mighty Z1. If you think that a Mach III was even half as reliable as a Z1 then you didn't ride motorcycles back then. I owned both bikes and my Mach III seized with alarming regularity as did many of my co-riders who owned them. That bike would never even approach 20K miles without a top-end rebuild. While the Z1 could easily reach 100k miles without a problem. Even the venerated RD350 (400) was no match for a Honda CB750 on reliability.

Reference the above. I suggest you re-read my previous post. I was not including Japanese four strokes. They were just about as reliable then as they are now. My references to four strokes of the day were BSA, Triumph, Norton and HD. None of which were blessed with reliability unless meticulously maintained and gently ridden.



That said, 2-strokes were a quick way to performance without all the investment it took (by Honda) to achieve high performance with a 4-stroke engine. I can't tell you the number of Kawasaki crankshafts Mach III & VIs I had to rebuild during that time.

I agree with the above comments. However, a reasonably ridden air cooled two stroke will achieve 50K miles before major work is required. Problem is that due to their nature and performance capabilities, they were usually flogged pretty hard. Thus reducing their reliability. Nonetheless, they could take much more abuse than other non-Japanese brands of the day.



And although a Shovelhead could certainly not be compared to a CB750 or a Z1, it had all the reliability attributes of a 4-stroke. It was just such a poorly produced example, much was lost in the translation. I rode Bultaco 2-stroke dirtbikes in the early 70's and we used to measure the time between rebuilds in hours not days, weeks or years.

Bultacos aren't Japanese and I'm aware of their fragility. I had friends who owned and occasionally rode them.




If you want to go back to the 60s. just remember what Honda was producing before the CB750 --- all their 4-stroke singles and twins set the bar for reliability and quality. There is a good reason that nearly all the Japanese switched over to 4-stroke street bikes in the 70's long before they were forced to by EPA Regs in 1980 -- it was a more reliable design philosophy.

Agree with the above. Progress marches on. However, modern two stroke machines are equal to the task. If there was more demand for them, they'd probably be back in production.



Remember, only Yamaha was still producing a 2-stroke street bike in 1980 when the EPA regs took effect (excluding the RG500, and NS400 which were limited production street-racers)

Agree with the above however, liquid cooled RZ-350s were produced in Brazil right up until 1995. Air cooled RD350 (1973 technology) was built and marketed in India as a Rajdoot right up until 1990. They were continued to be built for a couple simple reasons. They were cheap to manufacture, easily maintained and very reliable.

BTW, we should all know how awesome Rotax 4-strokes are, I would never say otherwise. KTM, BMW, Buell, Aprilia and other manufactures know too.


See my comments to your previous post above.

I see you mentioned Buell in the above list of Rotax powered motorcycles. It's a tragedy that HD shut them down. They were a breath of fresh air that many had hoped would breath some life into North American produced motorcycles. Eric had all the right ideas. It's unfortunate that he partnered with a retro thinking manufacturer to supply him with engines and support.

One has to wonder if HD shut Buell down due to Buell's preference for the Rotax engine.

Shutting Buell down was truly a sad day for North American motorcycle manufacturing.

So, Zedhed, I call BBS to your BBS.

 

[Zedhed]

OK, points well put. I'm not a 2-stroke hater as I cut my motorcycling teeth on them, and I agree that technology has marched on, but R&D on 2-strokes has not kept pace with R&D for 4-strokes.

Every major racing venue has adopted 4-strokes. Even the long-time 2-stroke dominated motocross, enduro, outboard, PWC and snowmobile markets are dominated by 4-strokes now. I think that many Trials bikes are still 2-stroke however.

BUT, with the EPA putting 2-strokes directly in their "bulls-eye" I think the 2-stroke's day is done.

Sadly, for Buell and 2-strokes, all things must have an end.

 

[boraticus]

"I agree that technology has marched on, but R&D on 2-strokes has not kept pace with R&D for 4-strokes."

Not sure if that's the case. In the respect that fewer manufacturers are dabbling with two stroke is absolutely correct.

If you're talking about revolutionary changes in technology, I think modern Rotax two cycle engines have made substantial strides and huge changes.

Four stroke operation principles haven't changed a great deal. Valves controlling fuel/exhaust gas movement through the engine, some changes in crankshaft geometry/timing, EFI, variable valve control. Maybe there's a few things I've missed.

Take a good look at the latest Rotax E-Tec engine.

http://www.ski-doo.com/brphtml/skidooenginetech/en/Index.htm

The technological sophistication leaves little resemblance to the engines of ten to fifteen years ago.

I'm a motor head, I like all engines. I prefer the old two strokes because they're simple, easy to work on, light, powerful, reasonably reliable (even by today's standards) and they're different.

As time marches on, two stroke engine/motorcycle scarcity will make them even more desirable for anyone interested in motorcycle history.