Archive for Two-Stroke – Page 2

CanAm MX3

1977_mx3_250This article went up on the Canadian Design Resource blog today. It’s a little historical retrospective on the 1977 Can-Am MX3 250. The article notes the passing of Can-Am, as Bombardier moved away from recreational vehicles to transit equipment and later into aircraft manufacturing. In 1983, Bombardier licensed the brand and outsourced development and production to Armstrong / CCM of Lancashire, England. 1987 was the final year for Can-Am.

Long live the two-stroke Part Deaux: FUD in the marketplace

Editor’s note: You may want to read Long live the two-stroke: Part 1 and FIM to put 2-strokes on even footing in 2010 for more background.

Recently a vintage racing/CZ friend posted the following query here:

Hey Terry, Correct me if I’m wrong because I’m not totally sure, but hasn’t Calif banned 2 stroke sales there or Read More…

FIM to put two-strokes on even footing in 2010

According to this Dec 21, 2007 press release (pdf) from the Federation Internationale de Motorcyclisme, the Permanent Bureau has decreed the following:

2) Motocross Classes: as of 2010, single cylinder engines will be used in MX1 and MX2 and multicylinder in MX3, whether 2 or 4-stroke (open concept). The cubic capacity will be 250cc in MX2, and up to 650cc in MX3. Discussions are currently being held about the cubic capacity in MX1. A decision should be taken in the next three months. Concerning the MX2 class, a maximum age limit of 23 years will be introduced. Moreover, a World Champion will be allowed to defend his title only one time (in the following year).

3) The FIM Junior World Championship will have an additional class as of 1.1.2010: 65cc. All the classes (65cc, 85cc, 125cc) will be exclusively 2-stroke.

I think this is a move that’s long overdue. I’d prefer that there not be a specific technology decreed, even for the tiddler classes, but I’m glad to see this happening. For far too long MX has been run as a corporate organ for the Big 4 Japanese mfgs. We can only hope that AMA/DMG/NPG follow suit.

A rule whose time has passed

The idea of granting 4-strokes a 2:1 displacement advantage (30% in MX3) was fine 20+ years ago, and was intended to prompt the development of competitive 4-stroke engines. That purpose has been served. But for at least the last 10 years the net effect has been to kill all 2-stroke technical development. This, I have been told, was at the behest of Honda, who have been dedicated to eliminating 2-strokes from the market since shortly after Soichiro’s death in 1991.

The end result has been a very cloistered, cozy, little world of coopetition for the Big 4 in MX. They leisurely roll out technology as it suits their budgets, without fear that anyone new will come along and rock their boat. Now that may change. We have long needed technical rules that foster innovation and invite new players into the sport. One of the reasons so many of us are not interested in modern bikes is they are so damn boring – not an ounce of personality amongst a warehouse full of them.

The myths of modern marketing

We have all heard the anti-2-stroke arguments — 2-strokes can’t compete anymore, 2-strokes can’t meet emissions standards, 2-strokes are too hard to ride, etc. Many of these “everyone knows…” comments started in a Honda marketing department and their pervasiveness should serve as a lesson to us that just because a major motorcycle manufacturer says a thing is true, doesn’t mean it is. Thanks to Honda and their motorcycle keiretsu we are well past the point where even general comparisons between 2-stroke and 4-stroke MX motors are valid. You simply can’t compare a technology that hasn’t been developed for a decade in any meaningful way to the state-of-the-art in another technology. It’s nonsense.

In conversations with a well-placed industry engineer I was told that the real issue for Honda (who, ironically, have declared they will produce no 2-strokes after 2010) is intellectual property – they don’t own any patents on two-stroke technology. So, like any big, market-dominating company, they attempted to kill off what they could not control. It appears they have failed.

Which is better?

This does not mean that the different designs don’t have relative advantages and disadvantages. In a Cycle News editorial titled “R.I.P. Two-Strokes? Not So Fast” (Cycle News issue #26, July 2, 2008, pg 60) Michael Scott discusses the 2-stroke situation in the context of the dissolution of the 250GP road race class. He lists a number of the well-documented, legitimate differences in the 2-stroke vs 4-stroke debate — simplicity via fewer moving parts, lighter weight for a given displacement and, typically, better power/performance at the smaller displacements. Scott interviews Aprilia two-stroke engine designer Jan Witteveen and notes that modern technologies have brought two-stroke fuel efficiency, emissions, and performance well into the modern era. Modern direct injection significantly lowers the amount of oil needed in the cylinder, and there are already 2-stroke engines which meet stringent Euro-3 emissions standards. With newer materials like ceramics and carbon fiber the need for oil injection may soon be completely eliminated.

Witteveen is, understandably, a 2-stroke advocate and insists, “There is definitely a need for the two-stroke motorcycle engine, particularly in small capacities.” He recently designed the innovative Maxtra 125 for Chinese company Haojue and is currently working on a rather secretive project for the future of the 2-stroke engine. It is likely the emerging markets (like China) that have driven the realization that 2-strokes are not only viable, but necessary. Cost matters in these markets and 2-strokes have, historically, been cheaper to design and manufacture.

No favorites

It will be very interesting to see how this all plays out. I’m curious why this rule change hasn’t seen more conversation on this side of the pond. It has to be pissing the Big 4 off, having spent millions developing, marketing, and selling the mythical advantages of their 4-stroke race bikes. Don’t get me wrong. I don’t favor 2-stroke over 4-stroke. What I favor is choice, free market policy, innovation, competition, and variety. MX has been the cozy playground of the Big 4 for nearly 30 years. It is the role of the FIM/AMA to safeguard the future of motorcycling for all of us, not just for a handful a big corporations. It’s high time they gave us an environment that encourages new players to get in the game. This is an important step in the right direction.

I look forward to the new discussions that should come out of this change. For the first time in a long time we might actually get new blood into the MX marketplace. At the very least we can begin to have productive discussions about engine technology and what the future might hold. It’s great to throw off the stifling blanket of corporate market speak that has controlled our choices for decades. We can only hope the US sanctioning bodies follow the FIM’s lead.

Long Live the two-stroke

Michael Scott’s “In The Paddock” column in the new Cycle News, (pg 60, July 2, 2008) is all about the two-stroke motorcycle engine, its past, present, and future. Some interesting stuff there. Mostly Scott talks about road racing and the death of the 250 GP class, which DORNA has killed effective 2010. But he also interviews Jan Witteveen, legendary Aprilia two-stroke engine designer and gets his views on the state of the two-stroke, plus discusses possible changes at the FIM to bring the two-stroke back to MX.

According to Scott, Witteveen recently designed an innovative two-stroke 125 for Chinese company Haojue and is “working on a project for the future of the two-stroke engine.” Scott goes on to discuss the “death” of the two-stroke and, like others with whom I’ve spoken, lays the blame at the doorstep of Honda, who were the first of the Jap conglomerates to declare a moratorium on two-stroke production.

In fact, I’ve been told by one well-placed industry engineer that the entire affair at Honda has little or nothing to do with emissions, performance, or cost but rather with patents. He claims that Honda has no patentable two-stroke technology and, therefore, no way to control that segment of the industry. So they declared it a “very bad idea”, Yamaha meekly followed, and voila! the two-stroke is dead.

Or is it? According to Scott the FIM is now proposing a return to two-stroke racing in MX:

Over on the mud, they’ve already made the switch from two-stroke to four-stroke, and now there is a significant backlash. Four-stroke racing dirt bikes are expensive to buy, and virtually impossible for an amateur mechanic to maintain. Engine blowups can be financially crippling. They also have a strictly limited service life, making them lose value rapidly. And two-strokes are lighter and more fun. In response to these problems, which afflict all but factory riders, the FIM are now proposing a switch back to an all two-stroke formula, with the plonkers actually banned.

Now don’t go blaming me for the problems Scott attributes to four-bangers. I was actually told by one fellow that anyone who can read a manual can do a proper job servicing a modern four-stroke MX race motor. But then, I also know that people as well respected as Stu Peters (CMC founder) and Tim Cotter ( and promoter of Loretta Lynn’s) feel that the maintenance cost and complexity of the modern four-stroke are serious problems for the long-term health of the sport. So it’s not just me, folks.

On the other hand, I’d hate to see four-strokes banned in MX, and I think that unlikely. After all, I’m sure Honda are dead serious about not making them anymore. But there should be displacement parity such that the two technologies can compete on more-or-less equal terms. Then the racers can choose. And that would be good for everyone. What we have now is an arbitrary policy imposed, essentially, by one big Jap conglomerate. It’s not to the racers’ benefit, it’s not to the fans’ benefit, it’s not even to the environment’s benefit. It’s mostly just to Honda’s benefit. And I’m getting tired of that.

Update: You may be interested in reading this article posted on July 10, 2008 which goes into more detail on this topic.

Two-stroke championship video

Short video of Round 3 of the DEP British Two-stroke Championship. Pretty cool. This makes a hell of a lot more sense than the 4-stroke MX championships now that two-strokes have been all but outlawed from all national and international MX competition.

Project Big-bore lives

Got a call from old-school CZ builder Gary Davis today. A little over a year ago I visited Gary up at his home/shop in North Carolina. I left him several boxes that constituted my CZ380 motor. Back in the day Gary was known for his over-bored, reed-valved CZ motors and his inverted stinger expansion chambers.

Back in ’06 I contacted Gary to see if he was interested in building such a motor for me. I drove up and we did an initial tear-down and inspection on my motor, which had cratered a transmission earlier in the year. I left there around mid-December of ’06 with a list of stuff I needed to source for the rebuild. I went to work on it but weeks turned into months and before I knew it a year had passed. I have all the needed parts now. I Just need to get them together.

But as I said earlier, I think 2008 is going to be a CZ year. So over the holiday I started trying to get in touch with Gary. Finally heard from him today and we’re going to get together in Feb. to start the rebuild.

The motor will cc out at about 408 cc displacement, running a Yamaha 400 piston (I think). Gary also has a dyno in his shop so when we get it together we’ll dyno it and see what it does. Should be fun.

It’s a drain hole, Dummy

Turns out the hole in the bottom of the TM motor is supposed to be there. It’s a drain hole of some sort. Right there in the bottom of the motor. Whod’a thunk? Glad to hear that. Now it’s off to the post office.

There’s a hole in my bucket

tm100_crankcase_hole_smallI had a bit of a disappointment tonight as I was cleaning up the little Suzuki motor to ship off to the engine builder. Upon turning it upside down to clean the gunk I discovered a hole along the centerline of the engine cases. “Uh oh, this can’t be good.” It’s an odd little hole, sort of square. It’s located in a place where someone may have tried to pry the cases apart with a screw driver, but it’s not broken like that would be. There’s a bigger picture here. The bike wasn’t leaking gear oil, and it wasn’t empty because I drained several hundred CCs out of it before I pulled it from the frame. That means it must be under the crankshaft – which could explain why the engine ran so poorly, but the cylinder shows no sign of sucking dirt. It’s weird. But anytime there is a hole in the motor it means my repair bill could be significantly higher. We’ll just have to see.