Best engine design for a motorcycle?

[Zedhed]

Interesting twist on 2-strokes by Rotax, but the 2-stroke frailty remains -- lubricating the crank and the subsequent emissions caused by burning gas and OIL.

As you know, the EPA is NOT going to allow these burned and unburned hydrocarbons to be emitted in the US, so unless Rotax finds a way to clean up the exhaust, (like Yamaha tried in the early 80's) this technology is going nowhere in the US.

We all know, with the exception of a Rotary engine, no other engine produces more power per pound than a 2-stroke, and judging from the technical analysis of Rotax, that the reliability issues of 2-strokes seem to be resolved, but the 800 pound gorilla remains -- what to do with the dirty exhaust of the 2-stroke cycle? Maybe Rotax can find a way, maybe ceramic crank bearings, maybe sealed crank bearings, I don't know. But unless this can be resolved, 2-strokes are destined for the fringes and niches of the motorsport world.

I thought with direct injection that there would be no need for the fuel to pass into the crankcase and so the crank could be sealed (ala 4-strokes) and have permanent lubrication? Where has this idea gone?

 

[XS650]

Originally Posted By: Zedhed


I thought with direct injection that there would be no need for the fuel to pass into the crankcase and so the crank could be sealed (ala 4-strokes) and have permanent lubrication? Where has this idea gone?


For a simple engine, you still need crankcase compression to pump the air because there is no intake stroke like on a 4-stroke.

You can do it with a supercharger, Detroit diesel was building direct injection 2-stroke engines with "permanent" crankcase lubrication since well before WWII. In the pst 20 years, and maybe before DDC built versions of their 2-strokes to run on Ethanol (Coors brewed their own fuel), natural gas and propane. I would be surprised if they didn't also make them run on gasoline but have no knowledge of that.

Dr Gordon Blair, Queens university Belfast was responsible for some clean running two strokes that used a 2nd piston to compress a super rich mixture to inject into a 2-stroke engine sort of like a stratified charge. I saw one run nicely on diesel fuel. Piaggio worked with him on some engines. I decided to get out of the consulting business and retired completely before I got to meet him.
http://books.sae.org/author/1073416002

 

[Zedhed]

Originally Posted By: XS650
Originally Posted By: Zedhed


I thought with direct injection that there would be no need for the fuel to pass into the crankcase and so the crank could be sealed (ala 4-strokes) and have permanent lubrication? Where has this idea gone?


For a simple engine, you still need crankcase compression to pump the air because there is no intake stroke like on a 4-stroke.



OK, I guess I misunderstood that article.

 

[boraticus]

What about those rotary engines? I know that they were notoriously hard on fuel but the idea of a revolving engine vs. a reciprocating engine sounds too good to be left behind.

 

[Zedhed]

Originally Posted By: boraticus
What about those rotary engines? I know that they were notoriously hard on fuel but the idea of a revolving engine vs. a reciprocating engine sounds too good to be left behind.


Well, just think about an engine that can produce 3 power pulses per turn of the crank per rotor. Pound for pound, no engine is even close to a rotary for power to weight ratios. That's why they are heavily penalized in racing, too powerful compared to 4 or 2-strokes. A 4 rotor engine without turbo or supercharger could easily produce 500 HP and weight less than 200 lbs. No vibration and with direct injection very little emissions -- BUT they are gas hogs.

They are the ultimate performance engines. They are 2nd only to gas turbines for power. Buy a RX-8 if you want to mess with these engines. Only Hercules, Norton, and Suzuki ever put them in a motorcycle.

 

[rszappa1]

I had a 1973 BMW R90s that I purchased new. I loved that bike and the engine.....The color was daytona orange....

 

[SWSportsman]

Originally Posted By: rszappa1
I had a 1973 BMW R90s that I purchased new. I loved that bike and the engine.....The color was daytona orange....


I have a 1985 BMW R80RT that I purchased new. I love this bike and the engine.....The color is Yukon Blue Metallic....

 

[rszappa1]

I wish that I still HAD it....... I like the older BMW's....70s and 80s then the new ones.... Nice bike...

 

[boraticus]

I owned this 1982 R-100. Bought it brand new. Had hard panniers but no fairing. Good all round bike but not my cup of tea. It would often touch down the engine guards when cornering. By the time I sold it a couple years later, guards were close to wearing through. Here's a picture of it in the first month or so that I had it:

 

[rszappa1]

BMW's would just run forever...... and no chain....

 

[boraticus]

Originally Posted By: rszappa1
BMW's would just run forever...... and no chain....


Despite their archaic engine design and awkward packaging with the cylinders sticking out the sides, it was a very efficient way to keep the engine cool and center of gravity low. Engine maintenance was a piece of cake because everything was easy to get at. Carbs were out in the open as were the cylinder heads for quick valve adjustments.

From a utilitarian point of view, they were a do-it-yourselfers dream. If attention was paid to keeping the engine and drive train properly lubed, it was good for many a thousand miles.

One thing these old boxers didn't like was to be over-revved. A missed shift could mess up the valves in a hurry. Never happened to me but it did to others.

Overall, it was a decent handling bike. The problem was that the confidence one had in the handling would invite lean angles that used up cornering clearance pretty quick. Brembo brakes were excellent.

The ride was pretty good too even with the ironing board for a seat. I put many long hours on it with not too much discomfort.

Even though it was an excellent motorcycle, it just didn't do it for me. Compared to the hot rod Yamaha FJ750 that I had owned just before the BMW, it was a little too tame.

This was one exciting motorcycle in it's day. The 1981 Yamaha FJ750 Seca:

 

[Silk]

My R65 spins to 8,000rpm no problem....the problem is to stop doing it.I have to watch the tacho if I'm pushing it hard.I didn't like my first BMW 30 years ago,and I didn't like my 1987 R65 when I first got it...but a few changes to suit my likes has made it into a bike I really enjoy.

 

[SWSportsman]

Originally Posted By: boraticus
I owned this 1982 R-100. Bought it brand new. Had hard panniers but no fairing. Good all round bike but not my cup of tea. It would often touch down the engine guards when cornering. By the time I sold it a couple years later, guards were close to wearing through. Here's a picture of it in the first month or so that I had it:

I had no idea you ever owned a high-quality bike.

 

[boraticus]

"I had no idea you ever owned a high-quality bike."

The total sum of a motorcycle's parts does not necessarily equal it's quality. Despite the BWM's additional cost and few endearing qualities, it wasn't anything near what it's "reputation" had lead me to believe.

I sold the Seca and bought the BMW because the Seca attracted to many crotch rocket wannabe racers looking for a stop light challenge. Being young and always up for a rush, I didn't turn down too many. One day a guy on a new Kawasaki GPz 750 and I lit off from a red light down a long stretch of clear street with no lights or much traffic for close to half a mile. We were doing well over 100 mph and the next light was coming up pretty fast. I geared down and applied lots of brake stopping safely for the light. The GPz had been behind me all the way but not too far. He finally goes by me and stops 100 feet or so on the other side of the lights. The guy didn't seem to have the riding skills to stop the bike before the lights. Had someone been going through the green at that intersection at the time, the guy would have died. After that I figured I'd better get rid of the Seca and get something more sedate.

I had read a great deal about BMWs and saw the brand new R100 gathering dust on the dealership floor. Sitting on the floor with a big selection of flashy Japanese machines didn't make the BMW a really a big seller. With it's odd looks and muted paint scheme it didn't draw too much attention so I bargained for a pretty good price.

Having owned both the Yamaha 750 and BMW R100, I have to say this. From my experience, the Yamaha was a better machine in practically every way. It gave up nothing to the BMW.

It handled better, was quicker, faster, smoother, just as comfortable, obviously looked much better and was a couple grand cheaper.

Owning a BMW is a lot like owning any other obscure or expensive motorcycle. It's more of a state of mind than it is a mechanical achievement or superior product.

My present KLR650 is a better motorcycle for all riding purposes than the BMW was. Better suspension, better handling, better acceleration. The BMW did have better brakes. The KLR can go more places too and is famous for it's reliability and durability.

So "high quality" is relevant. Spending more money for the same class/size machine does not necessarily get you a better motorcycle by any means. People can feed the idea that it is, but those willing to accept the facts know otherwise.

 

[SWSportsman]

Apparently you have a hard time discerning between "quality" and "suitability for your requirements," as well as the difference in "facts" and your "opinion."

As the owner of an '06 KLR as well as an '85 BMW, I can assure you that calling a KLR "better" than a BMW is ludicrous. You may have been addressing the KLR's use as an off-road machine, but even there a nice '80s era GS would be far superior in most ways, including build quality and quality of materials.

My reference to "high quality" may have a lot or a little to do with the suitability to a specific use.

Of course, that's my opinion.

 

[RonH]

Everyones opinion varies of course. I had a 1991 or 92 R100RS I bought new and it was so forgettable I can't even remember the year for sure. Main gripe I had was dealer service. I looked in the manual and they had like 20 pages for dealer to stamp they did maintenence every 2 or 3 thousand miles clear up to 100,000 miles and beyond. I took it in for the 1st service with zero problems, picked it up $400 poorer and had valves clattering to beat heck, it wouldn't idle without holding the grip open, then to top it off I rode home 10 miles, find oil all over the rear and find the drain plug had fallen off the drive so I was running no oil in the gears. I'm sure glad I let "the experts" work on my new bike as I may have "goofed it up". On top of that when I got it new it had all these rivets with the center pins you press through to expand them to secure the windshield to the fairing. Well the iddiots did not know this "complicated system" and clipped off all the pins, so the windshield kept pulling loose of the fairing.. Soured me on BMW. I still look at them, like them, but would doubt owning one again would ever come. I'll stay Japanese. Sorry, rant over. Nothing to do with engines, they were a fine boxer engine, just did not have too much excitement on top of everything else.

 

[boraticus]

Originally Posted By: SWSportsman
Apparently you have a hard time discerning between "quality" and "suitability for your requirements," as well as the difference in "facts" and your "opinion."

As the owner of an '06 KLR as well as an '85 BMW, I can assure you that calling a KLR "better" than a BMW is ludicrous. You may have been addressing the KLR's use as an off-road machine, but even there a nice '80s era GS would be far superior in most ways, including build quality and quality of materials.

My reference to "high quality" may have a lot or a little to do with the suitability to a specific use.

Of course, that's my opinion.


You can say what you want. I know from my experience that there is nothing the my BMW offered that would cause me to trade the KLR for it.

Fiberglass body panels and Magura controls vs the inexpensive yet just as durable components on the Japanese bikes, do nothing to enhance the BMW abilities. That's fluff.

Compare the Bing carbs on the BMW to the excellent Keihin CVK on KLR. No comparison. That's the kind of quality that matters. I ride. I don't lick and polish.

It's abundantly clear in your posts that you are vehemently anti-Japanese. That venom is clouding your judgment. All you have to do is look around. The Japanese didn't take over the motorcycle industry by building junk. On the contrary.

You should be thankful that the Japanese have made such a positive impact on motorcycling. Otherwise Harley would still be making the unreliable, oil leaking slugs of years gone by.

I see things the way they are. Not the way I like to see them.

 

[Steve S]

Motorcycles are a vehicle of passion, what is your passion?

 

[dblshock]

 

[dblshock]

I'd like to post a pic of my Magna but when I put the photobucket hotlink in the box it doesn't work, WTH?