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Hey Rich - Traction Control
(Click here to view the original thread with full colors/images)

Posted by: MikeeeP

Remember the debate we did on traction control devices on bikes - well recently I've been thinking about that.

If FMF has the AOF ignition, what would be wrong with an AOD Traction Control that allows riders to use it during starts, along straights etc...

Of course, there would have to be something that would allow for the bike to rev when in the air for attitude adjustment of the bike - how about this - Corvettes have an air pressure sensor in their tires. What if when the bike had no extra pressure ie: weight on the rear tire, the traction control would kick off so that when the rider was in the air he'd have full control of his bike.

Things that make you go Hummmm?

BTW the "Pro" of the debate was your side, but the more I think about it the more I like the idea. This traction is what is making thumpers move to the front so quickly in racing - if 2 strokes could hook up a bit better, no telling what could happen - not to mention that even thumpers could benefit from better traction control.

MP

Posted by: MikeeeP

Oops that was supposed to be an AOF traction control (adjust on the fly)

MP

Posted by: Rich Rohrich

Sure I remember that Mikeee.

I think we are talking along the same lines now. My thought at the time was more of a torque control feedback system, and clearly the ignition timing is a simple effective way to accomplish this.

For some reason the rebuttal link disappeared from the original article but I'll dig it up and repost our discussion in this thread.

Posted by: cujet

Traction control seems like a great idea with little added weight. Kevin Cameron wrote a piece on declining torque curves and how that aids traction. Very interesting.

One thing I find is that if a bike has enough power to spin the tire rapidly in sand, that bike is more able to climb sand hills. So, in certain situations traction control may be undesireable.

Chris

Posted by: bclapham

i was of the opinion (well maybe i just made the assumption

) that the FMF AOF ignition simply comprised of two separate ignition maps, and that one was advanced and the other retarded and the torque and rev settings were simply a matter of ignition timing. Well thats the way i would try and do a setup like that anyway.

as for traction control, i suppose one way to do it might be the old fashioned way of clutch slippage controlled with the left hand?

back to my off topic waffle, it seems the FMF AOF never caught on, i just got a new one on ebay for $87 shipped and i know FMF have got them on sale for similar....i will report back in due course, if it dont work i suppose its a cheap spare black (or orange) box! (now you see why i was asking about precise TDC measurements Rich)

ps. mikeee, dont forget to give us more info on that iCAT, i am assuming again but does it go inbetween the coil and plug and provide a hotter spark or something at the lower RPM to give the improvedd throttle responce?

applogies in advance for my digresions and assumptions!

Posted by: viking20

FWIW,the Aprilia RS Cube road racer uses both launch and traction control.
The engine is designed by Cosworth,wonder who gave them that idea?

Posted by: dklink2000

I have a basic question along this same line, so I'll ask it here.  Why is it that the thumpers hook up better than a two stroke?

Posted by: Rich Rohrich

For those of you who don't know what Mikeee is talking about...

In early 1998 I wrote a little piece for Eric's website called Future Tech Thumpers about some of the technology that might eventually find it's way into dirt bikes. It's pretty fun to look back on this 5 years later and see where the technology has advanced, and where it has lagged. Plus it's even more fun to see where we completely missed the boat on predicting stuff. It's amazing how much smarter you become in hindsight

Below is the original text as it appeared in Jan/1998 . The post that follows is a rebuttal of sorts from MikeeeP

Future Tech Thumpers
By Rich Rohrich

Techno-Bigot - A person who regards his own faith and views in matters of technology as unquestionably right, and any belief or opinion opposed to or differing from them as unreasonable or wicked. In an extended sense, a person who is intolerant of opinions which conflict with his own, as in engine type or morals; one obstinately and blindly devoted to his own belief, opinion or style of engine.

I've known Eric Gorr (AKA: Dr.Dirt) for close to 20 years now, and in most respects he is an open-minded, forward thinking person with great vision. But when it comes to Two-stroke engines (his first love), he is a card carrying TECHNO-BIGOT.

This is from Eric's article "Future Dirt Bike Technology".

"I think its a cop-out for the manufacturers to wedge a four-stroke engine in a modern dirt bike chassis and try to convince us that its going to be lightweight, faster than a two-stroke, and as easy to start. Those benefits will never happen. Yamaha's prototype YZM400 relies on an abundance of titanium and carbon fiber just to be light enough to be competitive. Yamaha's claims of 57HP are greatly exaggerated. A number like 48HP is more believable, and that is the average power of a production 250cc two-stroke. A two-stroke engine is always going to be better than a four-stroke, for an off-road motorcycle. Riders may have their preference, but a two-stroke has far more potential than a four-stroke engine. Four-stroke engine technology has received a great share of R&D money, and has evolved to the limit."

I guess we all have our blind spots!

YAMAHA SETS THE PACE

Regardless of what you think about four-stroke dirt bikes, or for that matter even if you're a die-hard two-stroke zealot like the good Doctor. You should thank Yamaha for legitimizing in one fell swoop the whole concept of affordable, competitive four stroke MX bikes. We've seen competitive four-stroke Open bikes on the European GP circuit for years now, but they've been powered by the cubic money that is typical of factory backed works bikes. What trickled down to the average MX racer was a far cry from those race winners we drooled over in the magazines. So basically all the MX thumper faithful had to choose from were great trail bikes like the KLX300 & the XR400; slow but stone reliable bikes with low tech running gear that proved easy prey for any Two-stroke built in the last ten years. Then along comes Yamaha who took the bold approach of using 1998 YZ250 chassis parts and wrapped them around a brand new purpose built engine that lends a good deal of it's design to Yamaha's involvement as an engine supplier to the Arrows Formula 1 team.

There was a time in the not too distant past when the automotive racing industry looked to motorcycles for ideas and inspiration. As hard as it might be to believe, GP engine designers tried and failed miserably with their first attempts at using 4-valve heads. Auto racing had to wait till Honda came along in the early '60s and made 4 valve designs work on motorcycle engines before they could come to grips with the concept. Racing lore is filled with similar cross breading stories.

As so often happens in life, TIMES CHANGE. Formula 1 cars have been the leaders of the technology parade for some time now. Most of the latest advances in engine and suspension technology start in F1 and trickle down to other industries. Yamaha's 1994 3.5litre V10 is estimated to have achieved a specific power output of 205bhp/litre on unleaded pump gas. Slice off one of those cylinders and you have a 72hp 350cc engine. You could roost the entire Vet class with this much power. Obviously this power output is fairly unlikely but the upside to all this is the fact that all of the major motorcycle manufacturers have a direct link to this technology. Honda and Yamaha both build successful F1 engines. Suzuki is heavily involved in various forms of auto racing, and Cagiva/Husky has an extremely close working relationship with Ferrari. You can bet Kawasaki, KTM and Rotax keep a close eye on what everyone is doing. This allows new F1 technology to be used in production engines very quickly. So anyone who thinks that Yamaha can't squeeze 57hp out of Doug Henry's $400K handmade hot rod is kidding himself. The evolution of the Four-stroke single is FAR from over.

TRICKLE-DOWN F1 TECHNOLOGY

Lets take a look at some of the current F1 technology that may into find it's way into production thumpers in the near future.

Engine designers have always had the problem of deciding whether to use a carb and intake ports biased toward high rpm horsepower or low speed torque. No matter what they decide it's always a compromise. In the past Yamaha has used two carbs on some of their singles to balance low speed torque and high RPM breathing requirements. One very small carb was used for low speed torque with a second larger carb kicking in at a specific throttle opening to allow the engine to breath on the big end. It was a reasonable solution to a tough problem. Dual-purpose bikes have used Constant Velocity (CV) carbs for years to provide throttle response without resorting to a tiny carb. CV carbs have both a slide and a throttle plate, with the throttle plate being the only thing connected directly to the throttle cable. The cable does not directly control the slide and needle, instead they react to changes in Manifold Absolute Pressure (MAP). This helps provide a constant velocity, stronger signal to the jets. Which ultimately leads to more controlled throttle response. Honda has gone them one better in F1 with a variable length intake tract. Using a combination of electronic solenoids and hydraulic actuators Honda was able to build an induction system that varies the length of it's intake stack from very short for high RPM use to very long to optimize low speed torque.

An onboard-computerized engine management system senses an assortment of engine parameters to determine the optimum intake tuned length during the course of a race. Combining this system with electronic fuel injection enabled Honda to make gains in low speed torque while improving overall horsepower by about 10%.

Along the same lines F1 engines use a type of fly-by-wire throttle control taken from advanced aviation. When you stomp on the gas in an F1 car a signal is sent to a computer, from there the computer decides how much to open the throttle. Now this seems like a really complex way to accomplish a very simple job, but think about this. What if before the computer told the throttle how far to open it checked to see if there was excessive rear wheel spin, or it checked to see if the engine was being over revved and changed the throttle opening to correct the problem. The car guys call it traction control, and it's already being used in various forms of racing and even some production cars. The YZ400F has a throttle position sensor on it's flat slide Keihn FCR carb. It's likely being used to optimize the ignition timing to a Minimum for Best Torque (MBT) setting, but that may be just the beginning.

PVS FAST RESPONSE VALVE MECHANISM

One of the real advances from F1 that will have far reaching effects for all new engine designs, is the Pneumatic Valve Spring (PVS). One of the ongoing problems that plagues designers in the search for higher RPM is valve control. As RPM rises it becomes increasingly difficult to keep the valves from bouncing off their seats as they close. The standard fix is to increase the valve spring pressure. In some cases the spring pressure will need to increase at the cube of the speed. In other words a 5% increase in RPM could translate to a 125% increase in spring pressure. All this spring pressure translates to increased heat, increased cam wear, but more importantly increased friction which eats up some of the horsepower that we have worked so hard to get. Renault and Honda have replaced the standard steel valve springs in their F1 engines with a nitrogen filled chamber to decrease valve-train weight by 20%, increase safe operating speed to nearly 16,000 RPM and minimizing frictional losses at high speeds. Working in conjunction with high tech valve gear is variable valve timing (VVT), which enables engines to be optimized for greater torque and much wider powerbands. The cam duration and lift can be varied to better match the torque requirements to engine speed. It's like having a low RPM torque cam and a high RPM screamer cam in the same engine. Toyota working in conjunction with Yamaha as well as Honda has been using this technology in production cars for quite some time. Expect to see this on your dirt bike SOON!

THE NEW TUNED PIPES

An area that is ripe for change is the exhaust system. On the surface it seems fairly simple, one or two straight primary header pipes leading to some sort of collector/muffler setup. What else is there to do? How about a stepped variable length header pipe leading to a variable area collector that adjusts itself to the optimum tuned length for the situation. It's already being done. Everyone is familiar with the fact that two-stroke engines extract huge power from the use of exhaust systems made up of multiple cone sizes. By varying the size and length of the cones they can take advantage of the high-energy waves exiting from their exhaust ports to help scavenge the combustion chamber and draw in a fresh charge. Ferrari took a page from the go-kart tuners handbook and used a variable length exhaust system on their V12 F1 engines. By varying the pipes' tuned length during engine operation it's possible to extend the RPM range in which the scavenging effect will be most effective. The kart guys were doing this with a series of springs and cables operated by the driver nearly 30 years ago, Ferrari took this idea one step further and used solenoids and computer control to adapt it to high RPM Four-strokes. Given the simplicity of the exhaust system on a single cylinder engine it opens up a lot of possibilities for us. It's a lot cheaper to experiment on a single than it is to try things on a V12, not to mention a lot simpler.

Continuing on the exhaust side of things, comes an idea from the world of drag racing. Jack Davis of Davis Step Headers designs exhaust systems for Chevrolets that use primary header pipes built up from 3-4 individual pipe sections that get progressively larger in small steps. Each step section is made with a three-degree internal taper. These pipes are all the rage in drag racing and Nascar. Sounds an awful lot like a two-stroke expansion chamber doesn't it? They are using the same basic principles. Scott Summer's GNCC XR600 uses a tapered head pipe design built by Yoshimura. This is an instance where the after market beat the factories to the punch. Look for the major manufacturers to follow suit.

CERAMIC MATERIALS

Ceramics offer some interesting possibilities for lightweight engine components. On their own ceramics offer tremendous properties like very light weight and incredible heat resistance, but when they are combined with certain metals the results are mind boggling. A company in Southern California has developed a way to combine ceramics and aluminum to form a metal matrix composite with incredible strength that is lighter than the high tech aluminum alloys that are currently being used in racing. Magnesium has also been formed into a composite for an even lighter end product, and a titanium composite can't be far behind. With materials like this we can expect to see super strong, ultra-light connecting rods, valves, and pistons. Not to mention the possibilities for frame and swing arm use. Pure ceramic valves are already available from American Ceramic Engine Co. for racing engine use. So production use could be closer than you think.

NEW LUBRICANTS

Synthetic engine oils have evolved to the point that it would be difficult to find a major team in any type of racing that doesn't use synthetic oil exclusively. Chevrolet ships their ZR model Corvette from the factory with synthetic oil. So it stands to reason that you should be using synthetic oil in your engine. No reason to wait around for manufacturers on this one. Synthetics offer viscosity stability over a wide temperature range, and reduced friction. This adds up to longer engine life and best of all MORE HORSEPOWER! Many race teams have shown power increases of 1-2 percent and up, just from the addition of the right synthetic oil. Synthetic oil may seem expensive at first glance, but it's probably the cheapest horsepower you'll ever see.

ENGINE CONFIGURATIONS

Current engines are already becoming extremely over-square, with stroke to bore ratios in the 0.73 to 0.85 range. It's likely that they will continue in this direction till we get something in the range of 0.53 to 0.58 which is standard in the high RPM world of F1. The YZ400F has a 92mm bore and a 60.1mm stroke for a stroke to bore ratio of .0.65. So the trend has already begun. The shorter strokes will allow these engines to operate at significantly higher RPM. As the strokes get shorter and the bores get larger look for dual plug heads to become standard equipment, along with very steep port angles to maximize flow.

EPILOGUE

Yamaha has raised the bar, and the rumors of hard core four-stroke MX bikes from Honda and Suzuki, prove that things are about to get VERY interesting for thumper fans. In the coming weeks we will dive further into the YZ400F as well as taking a look at the rumored thumpers from Honda, and the rest of the players. But unlike the overpriced catalogs masquerading as MX magazines, we're going to take a hard, in-depth look at the technical side of the production YZ400F and the current state of the art in four-stroke engine design. Looks like things are really getting interesting around here. Stay tuned!

(Link to the original article with pictures on Eric's website )

Posted by: Rich Rohrich

... and here's the rebuttal e-mail sent by noted Internet wag and consumate wise-ass Mike Patrick (aka MikeeeP of Fresh Dirt fame)

my responses to MikeeeP are in bold text below

From: "MICHAEL J PATRICK" <MX-MIKEEEP@prodigy.net>

Interesting article on the YZM400F yet the writer sort of shot himself squarely (oversquare?) in the foot when he said that it wasn't inconceivable that Yamaha could develop 57hp from Doug Henry's $400,000 YZM. Oww, if that much monies were placed into a 400cc two stroke... oh
yeah, the two stroke would have to be only 250cc to compete in that class and Yamaha got a variance from the AMA to experiment.

RR - Granted $400,000 SEEMS like a lot of money, but 20 years ago they were quoting the same amounts for 250 works bikes. I think that the Cali mags might only know how to quote 1 figure for a works bike .

Hmm okay, we have a 250cc two stroke, it is box stock and it can and has pulled the exotic $400,000 dollar Yamaha to the first turn (take note of any privateer that beat the YZM to the first turn), now, what can be done to that little 1/4 litre bike to make it more competitive with the exotic hardware that is wearing sheeps clothing?

RR - Given the fact that the current production 250s have a 20 year development head start, it doesn’t seem unreasonable to think that they might have some advantages here and there. It cost a hell of a lot more than $400K to get to the point that we are now with production bikes. R&D NEVER SLEEPS, or stops spending.

First off the traction control spoken of for Formula racing, would literally put every motocrosser in the planet in a wheelchair. I know that when I need to powerslide that if the rear tire suddenly slowed due to timing, carb etc. I would highside instantly. It wouldn't be a pretty site on a 4th gear sweeper to say the least. Lets take that same traction control and put it two stories in the
air with Guy Cooper on it and his rear wheel is extremely high. Will the Cooper rev be available to us, because trust me we are going to over rev the motor at this point, and pray to _______ (<--add your favorite deity here).

RR - Mikeee is right. In an effort to keep it simple I failed to explain things properly.

Let’s think of this not so much as traction control but as TORQUE control. Every rider shifts and slips the clutch in an effort to match the available torque to the traction in the corner, or the acceleration and speed needed to clear a jump. Think about what happens when you go hammering into a turn. You brake (maybe?) to modulate the speed you carry into the turn. At the same time you’ll shift into a gear that seems appropriate for the drive through the apex and out of the turn. BUT WHY SHIFT? Why not just leave it in the gear you were in ? Simple, you’ll likely be outside the usable portion of the powerband and kill your drive. So the rider picks a gear and tries to keep the rpm in the fat part of the powerband, but if the traction is poor he may be forced to overrev the engine to get it to stay slightly above the torque peak and limit the wheel spin, while still keeping the engine responsive for the next corner. Or the same rider may come in at an engine speed below the torque peak , and use the clutch to control the torque& engine speed on the drive out. Not exactly news, but it takes a lot of skill to get it right on a high strung engine. Four strokes, by virtue of wider powerbands and increased engine braking just widen the window for the rider. You just don’t have to be as precise. Most of the development work done on 500cc GP Roadrace bikes over the last few years has concentrated on making them more rideable rather than more powerful. So by adding some computer control to the clutch and building a semi-automatic gearbox, you could keep the engine at it’s torque peak and lessen the load on the rider. It would be a simple matter to override the system with a switch built into the clutch lever, to allow the rider to have full control. The possibility also exists to use a Continuously Variable Transmission (CVT) similar to what snowmobiles call “clutches”, to keep the engine at it’s torque peak at all times and let the rider use the throttle and brakes to control speed and acceleration, most non-expert riders would likely see quicker lap times, even if it didn’t FEEL like they were going faster if you took away the need to shift and control the clutch. Olav Aaen of CVT Research has been doing development work on racing CVTs for automotive (SCCA D-Sports class) racing applications. There are a number of other companies involved in on going CVT racing research. So this isn’t as far fetched as it may first seem. (For more info see references at the end of this post)

I'm not saying that these things won't work, but to get them TO work in motocross is going to at least double the price of those exotica known as the YZM. Not to mention that the guys at the Ti shop will be working overtime because the now reasonable weight of the factory YZM will be growing by leaps and bounds as we add solenoids and the like.

Variable length exhausts on a motocross bike. Great idea... until the first whoop section when the vibration and impacts totally destroys it.

RR - They said the same thing about Aluminum frames a few years ago. NUFF SAID!

Ceramic... wonderful stuff, I dig this technology, but how well are they going to last when the bike has to be over revved 15 times every lap because this is the norm in motocross (coming into turns, or approaching a large jump just out of a turn etc...). They may work fine, I don't know...this one was just me pondering.

RR - Overrev on a Japanese MX bike may see MAYBE 12,000 rpm. This technology is being developed for the 17,000+ rpm world of F1. At some point it may be cost effective enough to see limited production on small runs like MX bikes.

Pull one circlip, slide the wrist pin out, take piston off. Slide new piston into place, add one circlip. You have just completed a top end job on a two stroke engine. Even Bubba can do it in between moto's.
Pull... one... "Man anyone know about valves, cams, cam chains, this variable intake with solenoid etc. guess we're going home son, daddy just can't figure this one out. Yeah I know you wanna ride your new YZM 50, but I just can't figure it out, I'll call the bank tomorrow and see if I can get a mortgage and we'll take it over to the Yamaha shop okay?"

RR - I’ll give you this one. All those hamfisted losers that have been tearing up two strokes all these years and pretending to be tuners/mechanics will be screwed. WAWAWA
Anyone doing quality maintenance on a racing two stroke will be able to handle a four stroke single.

Will 4 stroke pee-wee's be 125cc's to make them competitive with a Cobra 50?

RR - It’s pretty difficult to beat the power/weight ratio of a small well designed two stroke. I wouldn’t want to be the guy that has to design the four stroke to take on the likes of the little KTM or Cobra.

I know this note is comparing much of todays technology with technology not yet seen in the four stroke world. Thing is, if Honda, Yamaha, Kawasaki, Suzuki, KTM, ATK and the rest of the crew have to spend 10 million dollars (not inconceivable) on R&D what will our new wonder techno thumpers cost us, 'John Q. Public' ?

RR - R&D is simply a cost of doing business. If you want to be in the motorcycle business you spend the money to be competitive. If you want to sell product, you find a way to produce your product at a price that the market will bear.

My “REAL” job is in engineering with a company that is ranked in the top 100 in the country on the basis of R&D dollars spent versus sales dollars. Yet we are in a business that is ULTRA price conscious at the end-user level. So we can’t just pass the costs of advancing technology along to the customer, we have learned how to produce product more efficiently to protect our profit margins.

I can't listen to anymore B.S. about the dollar/yen relationship. That relationship changed between 1989, 1990, 1991 and if I'm not mistaken the price of CR250's stayed the same for three years. Honda might have hurt themselves when they allowed this to happen, as I'll never forget all the people that purchased 1990 CR250's late in the year that were quite ticked that they could have purchased a 91 for the same price!

Technology... I think it's great and I hope that the four stroke revolution (evolution?) continues full force. Thing is, I'm in my early (mid?) 30's and I fear that I'll never truly see a production 125cc four stroke that will ever run with a two stroke. I may be wrong... but then I won't be able to ride one, because a man on Medicare shouldn't be riding a dirtbike... should he?

RR - Making four strokes competitive on a 1:1 displacement basis , especially in the smaller classes, is a HUGE task. You may be right, it may NEVER happen, but modifying the rules to make 2 & 4 stroke bikes competitive can only be a good thing for racers. Having more competitive choices when you decide what you want to ride sounds pretty good to me.

Then again, wasn't Hondas 'original' motto something along the lines of "We are a four stroke company." ??? If someone with the horsepower behind them (read monies) ever decided to take this really seriously, we could have that techno-marvel as a late release 1998 model!

RR - Based on their recent announcements (Honda to Switch to Four-Strokes by 2002 - Motorcycle Online 12/24/97), it looks like it could happen sooner than we thought.

Eric a bigot... when we are talking two and four stroke engines, lets call it biased. I'm sure that Eric will readily admit that the world champ in past years rode an open four stroke. As mentioned in the story he (they) had cubic YARDS of monies behind him to make that a reality. Lets put them on a 250cc four stroke and a 125cc four stroke and check back...

RR - It was Eric’s idea to call him a bigot, he’s always stirring up trouble. You should have been there when we first showed up at a local race in the early 80’s with an MX bike with wheel covers, full body work, and a gas tank below the bike’s center of gravity. The protests were flying hot & heavy Hehehehe He’s been a troublemaker as long as I’ve known him (I just hope he never stops).

BTW, haven't all the R&D monies been spent on four strokes over the years? I mean walk into any shop and you will see streetbikes, streetbikes, streetbikes... if all the R&D money that was spent just since the first DOHC engine had been spent on two stroke technology I would venture to say that we would all be riding 50hp 125's, 75hp 250's and Ralph Nader (spelling?)
would most certainly have gotten those nasty 100+ hp Open Bikes outlawed!!!

RR - Actually I’d say No, the R&D money hasn’t really been spent there for motorcycles. There is little doubt that Honda, and Yamaha have spent HUGE dollars on four stroke automotive development, but outside of repackaging engines to make them lighter and smaller, street bike engines were pretty much status quo until someone in Japan figured out that Ducati was ass whipping there high strung four cylinders with an ancient twin. One the other hand, all the manufacturers have spent huge dollars on things like power valves, Active Radical Combustion, Direct & Indirect fuel injection, and countless other less publicized schemes to get two strokes through the ever increasing emission regulations. With Honda’s recent announcement that they are going to four strokes corporate wide, it looks like they might be looking to cut there losses. It’s a pity really. I for one will miss the sounds and smells of two strokes when they are gone. Looks like I’ll be keeping all 3 of my RD350s and my 1972 Hodaka Wombat. They may actually end up with some collector value to someone other than me!

References for further reading:

Guebeli, M., Micklem, J.D., Burrows, C.R.
Maximum Transmission Efficiency of a Steel Belt Continuously Variable Transmission
6th International Power Transmission and Gearing Conference (PTG 92), Phoenix, Arizona, 1992 (ASME)

Van Valkenburgh, Paul
Constantly Variable Racing Transmissions
Racecar Engineering Vol 3 No 5

Aaen, Olav
Where CVT Thrives
Racecar Engineering Vol 5 No 2

Ribbens, William B.
Understanding Automotive Electronics
Fourth Edition

Posted by: IrishEKU

Vote #1 for the Archive. Great read Rich and Mike.

Posted by: Kav

cool to see were we are at now with all of this

Posted by: techman

Here's a twist on the traction control idea. It is an observation that the riding technique and handling for the 2WD Yamaha (and soon I suppose KTM too) is different enough that it bugs very good, experienced riders used to rear wheel slide, spin, etc combined with traditional front end handling. The 2WD is somewhat of a traction-control scenario, because front wheel drive increases with rear wheel spin (loss of traction), in action both giving drive to the front and re-apportioning engine power so less goes to the back wheel too. Aha, torque reduction as a result of traction loss...

So - very good riders will think the new handling is weird/sucks, as compared to their finely tuned capabilities with finely tuned existing bikes - even if it works just fine. And, as people can illustrate, there are times when rear wheel spin is your friend. So the real issue would probably morph more into an attitude or state control issue rather than just wheel spin, as sometimes wheel spin helps you and other times it puts you on your butt. Good luck to the guys trying to identify that mess (when spin is good or ok vs when it is bad) and practical-ize it into a working system. Therefore the crux would not be implementing a control loop on the torque, but rather operating the loop at appropriate times in a manner that suits offroad conditions.

Posted by: Daniniowa

Couldn't you just use suspension sensors? When both the front and rear suspensions were extended, then the rider has control.

Posted by: shed

Moto GP use wheelie control based on front fork extension. Great thread. Rich / Eric, have you got a picture of that MX bike with wheel covers etc?

So whats the bottom line with 4 Strokes vs 2 Strokes when getting the power down? I saw mention of decaying torque curve being advantageous, but why are 4Ts better?

Shed

ps thinking of returning to a 2 stroke for enduros on a weight basis, but prefer a 4T power delivery. 2 smokes scare me.

Posted by: Rich Rohrich

Quote:

Originally Posted by shed

Moto GP use wheelie control based on front fork extension. Great thread. Rich / Eric, have you got a picture of that MX bike with wheel covers etc?

Eric unearthed a bunch of old pictures from the original build up of the bike when we were still in the old shop in Elk Grove. Eric is working on an article about the bike that will be posted in the DRN Knowledgebase section. But we'll post a couple of teasers pics this weekend just for fun.

Posted by: shed

So whats the skinny in the 2 vs 4 stroke traction debate. Why does a 4 stroke seem to hook up better?

Posted by: Rich Rohrich

Quote:

Originally Posted by shed

So whats the skinny in the 2 vs 4 stroke traction debate. Why does a 4 stroke seem to hook up better?

The spacing of the power pulses and having the torque spread over a greater area are a big part of the four-stroke traction difference.

Posted by: olderndirtmom

Quote:

Originally Posted by IrishEKU

Vote #1 for the Archive. Great read Rich and Mike.

Never made archives, near as I can tell. I'd be interested to learn what happened to these concepts since this thread first posted.

Historians?

Posted by: 76GMC1500

I've heard little tidbits of some kind of traction control or acceleration rate control on 97 and 98 CR's. Is there any validity to these bits of information or am I just hearing things?

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Hey Rich - Traction Control

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