This article was in the March issue of the 1998 Motocross Action Magazine. “About 5pm yesterday, I was out at the HPCC track when I got the call to drive down to Glen Helen to meet the MXA test crew,” said Scott Sheak’s mechanic Tom Watson. HPCC is Honda’s top secret test facility, located out in the middle of nowhere (actually ten miles beyond the middle of nowhere). No one in a sound frame of mind would want to be at HPCC in the dead of the winter (even if Honda is paying him to be there). So the smile on Tom’s face couldn’t have been broader as he pulled into Glen Helen (which is not only warmer, but 100 miles closer to civilization). Why had the MXA test crew summoned Tom from the desert? To bring Scott Sheak’s new Team FMF/Honda CR125 to us. WHAT’S THE FMF ENGINE LIKE? With factory support from Honda, you would think that Honda’s resident engine builder Cliff White would have had his hands all over the FMF team’s engines. Well, you’d be wrong. Starting with Cliff’s best engines from ’97, FMF’s Terry Varner dove into the CR125 mill headfirst and came out with a engine that oozes usable horsepower. “Last year, Reynard’s CR125 engine produced a lot of horsepower, but it wasn’t easy to ride. It was all peak. Terry Varner came up with a engine that makes incredible numbers on the dyno and delivers usable power on the track,” explained Tom–who should know since he was Robbie Reynard’s mechanic before moving to Sheak in ’98. The worst part about the stock 1998 CR125 is it was a disappointing engine. The best part of the Honda/FMF bike was its impressive engine. This was the first Honda that had some bottom (albeit very little), tons of midrange and enough top end to get to the next corner. What else can we say, we liked it. On the racetrack, it was clear that Sheak’s bike wasn’t a stock ’98 CR125. The stocker is all midrange, with no top end and no bottom. Sheak’s bike was what every CR125 should be. The FMF bike had just enough bottom to get the engine into the midrange, where it makes the meat of its horsepower (by meat we’re talking T-bone not dog food). Then once into the middle, the FMF CR125 did something that the ’98 stocker doesn’t want to do–rev. It doesn’t rev to the moon like older CR125’s, but with the amount and quality of midrange the bike has, catching gears will have you going faster than you ever wanted to go. The stock CR125 falls off the pipe at least twice a lap, which requires a hardcore rider to fan the clutch to keep the bike going forward. Not Sheak’s CR125. It has enough midrange and top-end to pull every gear in the five-speed box. Equally noteworthy was that Sheak was not going for a hard hitting-style of power. His CR125 delivered its power in a very controlled, well-timed and manageable manner. Can you buy the same motor that Scott Sheak uses? Yes. FMF plans to sell the engines right out from under their team riders. However, each of Team FMF/Honda’s four riders has his own unique likes and dislikes when it comes to power delivery. FMF plans to advertise what each of their riders likes and sell it to the consumer as a Pingree, Sheak, Sellards or McCormick model. WHAT’S THE FMF SUSPENSION LIKE? Surprise, the CR125’s stock Kayaba parts magically turned into Showa pieces. The stock Kayaba units are missing on Sheak’s FMF CR125 and in their place are Showa Kit components. These are the same forks that Factory Connection sells to the general public (only Sheak’s forks have been slightly altered by FMF’s suspension guru Rob Hendrickson). The forks start as stock ’98 CR250 forks, but the internals (cartridge rods and all) are replaced with the Showa aftermarket kits. How do the Showa kit forks work? Superbly. They are plush, not only on the big landings that supercross delivers, but also over little bumps. The MXA test crew tested the Factory Connection kit last year and raved about its overall performance. They are stiff (because they have Supercross valving in them), but even then they still move. Some things that factory teams do they do just because they can. Take for example the stock 1998 CR125 shock. Sure stock its to soft for Supercross but with a revalve by FMF’s Rob Hendrickson it would work just fine. Then why switch to a Showa shock? Because they could, nothing else. Stock Honda CR125 forks suffer from a mild case of midstroke harshness, which rears its ugly head in the form of headshake (and at fourth gear wide open, no case of headshake is mild). With the Showa forks, the CR125’s headshake disappeared. Maybe it was better valving or the correct spring rates, but whatever it was we liked it. These are the best Honda forks made. Why did FMF switch from Kayaba to Showa? FMF said they asked the same question of Honda team manager Wes McCoy and he replied, “Factory support”. Can you do it? Yes, but it’s hard to imagine your average 125 pilot ripping his Kayaba’s off and replacing them with a set of ’98 Showa kitted forks. What would the forks cost? About $1500. That’s why you sign up with a factory team. For riders on a budget, FMF will offer Kayaba fork and shock mods priced for the average consumer. What about the shock? It too was a Showa kit shock. Sheak’s shock was valved on the stiff end, but surprisingly not enough so that you couldn’t ride around a normal motocross track on it. WHAT’S IT LIKE TO RIDE SHEAK’S CR125 Factory-backed bikes really shine (especially for the rider they are hand-built to suit). Scott Sheak’s personal set-up isn’t as off-the-beaten path as many big name rider’s bikes, but he does have his peccadilloes. FMF took the flaws out of the stock 1998 CR125, improved all the pluses threefold without creating any new flaws, pretty impressive. Bars: The first thing you notice when you sit on Sheak’s bike is that his handlebar position has more in common with a stock pair of 1973 Elsinore 125 handlebars than with anything current. They are swept back on the ends, rotated back in the clamps and downright different from what most people are used to. Besides moving his handlebars 5mm back in the clamps, Sheak runs a set of cast works footpegs that move his footpeg position back 5 mm. It’s common for the factory boys to move their handlebar position and footpeg to fit their stature. What’s uncommon is that Sheak didn’t move his shifter back to compensate for the new footpeg position. The setup may work for Sheak but for us the new peg/shifter position made the Honda into the worst shifting 125 of the year. Levers: Despite the fact that the clutch and brake levers are stock, the extra care Sheak’s mechanic Tom puts into them is evident in how strong the front brake is and how easy the clutch pull is. These things may not seem like much, but after pulling in the clutch lever and using the front brake during a thirty minute moto, every little bit helps. Scott runs his levers fairly high up on the bars. We had to reach up to grab them. Shifting: The big shocker was that none of the test riders could get Scott Sheak’s bike to shift very well. After scratching our heads wondering how the best shifting 125 could become so bad, we noticed something amiss. Sure enough, Sheak doesn’t run stock footpegs (although he does run a stock shift lever). Scott’s 5mm wider works footpegs are moved back on the chassis. Why would Sheak want to move the footpegs back? That’s easy. Since Sheak isn’t the tallest rider on the planet, he has trouble getting back on the bike when going through whoops. Honda built special footpegs and works triple clamps that mount the bars five millimeters back (without changing the steering angle) to ease his transition to the back of the bike. It didn’t work for our feet, but it must for Scott’s. Handling: The new CR125 alloy frame has a considerable amount of understeer, but Scott’s bike didn’t. It tracked straight, turned on a dime and didn’t have an iota of headshake. Most of these benefits come from the superior suspension components. CAN YOU HAVE SCOTT SHEAK’S BIKE? Want to make your bike a Sheak replica? Here’s what you’ll need: (1) Start with N-Style team graphics. The quickest way to have a Team FMF/Honda bike is to make your bike look like one. (2) After you ride with your new-looking FMF/Honda team bike, you will realize your gearing is all wrong. Time to buy that FMF Cobalt sprocket in the 52-tooth variety. (3) With that new big rear sprocket, it’s best you get a new chain–FMF opts for EK Chain. (4) After your first crash and bent set of handlebars, you’re ready for your next piece of the FMF/Honda puzzle–a set of FMF’s 909 handlebars. Most of the team uses #1966 (McGrath) or #1971 (Lammy) bends. (5) Now you’re ready to dive into the pipe and silencer department. Pick up an FMF Fatty pipe and a “Bad News Barker” carbon fiber Power Core II. (6) Next, have FMF tackle your forks. Sorry, they won’t be Showa’s (you’ll have to call Factory Connection for that), but the stock Kayabas can be made to work very well. (7) Last, but not least, pick the engine tuning of your favorite FMF/Honda rider’s engine. If you follow these seven steps, you can own a Scott Sheak replica. The post TWO-STROKE TUESDAY | SCOTT SHEAK’S 1998 HONDA CR125 appeared first on Motocross Action Magazine.
Every line on the deeply prepped Glen Helen National track is ours and made by our TM MX300 two-stroke project bike. TM’s Ralf Schmidt wanted to built a TM that addressed everything the MXA wrecking crew had ever complained about on the exotic Italian-built smokers. That included Pro X pistons, Faster USA wheels,VHM heads, GPM suspension, Ohlins shock, Brembo brakes, Excell rims, TM Designworks chain guide, Renthal bars, VP gas, Galfer brake hoses, Pro Circuit pipes and much more. To read the full story head over to motocrossactionmag.com The post MXA FIRST RIDE VIDEO: THE ULTIMATE TM MX300 TWO-STROKE PROJECT BIKE appeared first on Motocross Action Magazine.
MXA took all the talk and the music out of this 2014 KTM 125SX video so that nothing was left by the blaring sound and the blazing laps. This video is for two-stroke fans who hate music videos and only want to hear the bike in all it’s glory. That’s why we label these videos “Raw.” Enjoy. The post NO MUSIC EXCEPT THAT TWO-STROKE SOUND THAT PASSES FOR VIOLINS TO AN MX MAESTRO appeared first on Motocross Action Magazine.
This test of the 1999 TM 125 MX is from the May 1999 issue of Motocross Action Magazine. Interested in buying a new TM 125? Don’t know anything about it? Here are a few facts: Engine: Water-cooled, 123.5cc two-stroke, reed-valved engine. Bore and Stroke: 54mm by 54.4mm. Transmission: Six-speed, wet clutch. Suspension: 12.1 inch Paioli 46mm upside-down and 12.6 Ohlins shock. Wheelbase: N/A. Claimed weight: 94 kg. Price: $6000. Those are the tech specs, but these are the questions that most riders want answered. QUESTION ONE: IS THE ‘99 TM 125 FAST? Yes. Think of it as a ‘99 Suzuki without the over-rev. The real question is, is it so fast that you should sell your current 125 and plunk down 60 Benjamin Franklins on Italian machinery? No, but if you laid down $1201 more than you would for a ‘99 YZ125, you wouldn’t be embarrassed on the track. QUESTION TWO: WHAT DID TM CHANGE ON THE ‘99? What didn’t they change would be a better question. Being a small factory has perks that the big manufacturers, for all of their “economy of scale,” just can’t compete with. Since TM doesn’t make thousands of 125’s at one time, they have the ability to make creative changes when the mood strikes them. They can take what they’ve learned from racing or testing and apply it to the next bike on the production line. Perhaps they don’t implement changes this rapidly, but they aren’t bound by a surplus of parts that must be used before they can make a change. The list of goodies that made their way from the ‘98 GP effort to the ‘99 production bike is impressive. New Paioli forks, aluminum fuel tank, steel perimeter frame, redesigned saddle, alloy steering stem, revised shock linkage, updated shock valving, 270mm front brake rotor, several different pipes, more efficient silencer, bigger radiator and a new Keihin carb were all incorporated into the ‘99 parts book. QUESTION FOUR: WHAT DO ALL THE CHANGES MEAN? In truth, they mean that racing a TM125 is as close as the average rider will ever get to riding a full-on works bike. The production TM shares more components with TM’s GP bikes than any bike from the Big Four. The changes also produced a TM that is appreciably better than the last one we tested. MXA’s last TM experience was bad for us and bad for TM. After we wrote a scathing review of their bike, they didn’t want us to test any more of their bikes and we didn’t want to be forced to ride any of them. The ‘99 model bike increased their confidence and succeeded in changing our previously negative opinion. QUESTION FIVE: WHAT’S IT LIKE TO RIDE A TM 125? A learning experience. The TM125 has three educational quirks. (1) Test riders had to come to terms with the Euro handling. Although the TM turned light years better than its predecessor, it still had a tendency to push on flat turns. Additionally, the front fork deflected with alarming ease off of rocks, ridges and rills. The front wheel would snap to full lock for no obvious reason. This got our attention. (2) The power comes on in RM-like bursts–sort of. Blessed with a stout midrange powerband, the TM churns out a healthy chunk of the thunder. However, there is no low-end and, unlike the RM125 that its midrange emulates, no over-rev. We tested two TM125 pipes. The stock pipe produced lots of top-end rev, but less low and mid. The aftermarket pipe (that TM advised we use) was considerably stronger in the middle, but signed off sooner. Of the two choices, every test rider preferred the harder hitting midrange pipe. (3) With a jumbo-sized front brake rotor, test riders thought the TM would stop on a lira. It didn’t. The problem is brake pad related. KTM uses the same basic brake set-up, and after switching to the new green pads, their braking stepped up to the plate. TM should steal KTM’s brake pads. The rear brake is very touchy. You have two choices: on or off. QUESTION FOUR: WHAT ABOUT THE SHIFTING? Midrange engines depend on slick-shifting trannies to make the bark work. TM needs to spend more R&D dollars on their gearbox. It misses a lot of shifts, especially when you are trying to rush them (and that pretty much defines racing). The shifter shape is atrocious. It looks like a pretzel. The only way to guarantee a shift was to shift early and back off a notch. QUESTION FIVE: HOW GOOD IS THE HYDRAULIC CLUTCH? Let it be known that TM was the first to equip their bikes with a Magura hydraulic clutch–KTM copied them. The bad news is that although TM was first, they aren’t the best. The TM’s clutch actuation is more of a light switch than KTM’s. This problem is caused by a combination of plates, springs and leverage ratios more than simple hydraulics. Just like the shift lever, the clutch lever was also a test rider complaint. It was described as a Chinese torture mechanism. The quick fix? Use a grinder to smooth off the square edges and the clutch lever will be bearable. QUESTION SIX: WHAT ABOUT THE JETTING? Surprise! No Dellorto carb. TM spec’ed a 38mm Keihin PWM. We dropped the stock 7.0 slide for a richer 6.0 slide and felt that the TM was in the ballpark for our sea level SoCal racetracks. What was our best jetting? Mainjet: 175 Pilot jet: 52 Needle: N1EC Slide: 6.0 (7.0 stock) Air screw: 1 1/2 turns Clip: Groove number 3 Notes: Be sure to change the slide. The bike is ridable with the stock 7.0 slide, but the motor will have a lethargic feel in the midrange. QUESTION SEVEN: HOW GOOD ARE THE PAIOLI FORKS? A better question might be what are Paioli forks? They are the Italian forks normally seen on mopeds, scooters and small Italian street bikes. Mechanically, they have Kayaba-style internals and Paioli externals. Consumers get a choice of 46mm upside-down Paioli forks or 50mm conventional Marzocchi’s. MXA’s test bike came with Paioli’s, but we wish it had the ‘Zokes instead. We complained about the forks loudly enough that TM made a fork upgrade midway through our test period. We looked forward to the Fed-Ex shipment from Italy. Unfortunately, the updated ‘99 valving performed with the same low amplitude harshness, deflection and spikes as the first set. We have had great luck with the new 50mm Marzocchi fork. We can’t recommend the Paiolis. QUESTION EIGHT: WHAT ARE THE BEST FORK SETTINGS? The best fork setting is to spec Marzocchi forks, but this is what we ran (and disliked) in the Paioli upside-down forks. Spring rate: .40 kg/mm (5mm preload) Oil height: 95mm Compression: 17 clicks out Rebound: 12 clicks out Fork leg height: 8mm above the top of the triple clamp Notes: MXA’s criticism of the TM forks has to be counter balanced by the fact that the buyer doesn’t have to run Paioli forks. QUESTION NINE: WHAT ABOUT THE REAR SUSPENSION? Good news! The Ohlins shock was significantly better than the Paioli forks. Given the fact that the shock had to do double duty–to make up for the fork’s inability to absorb any bump smaller than a jump–the Ohlins could only work better if mated to the Marzocchi forks. QUESTION TEN: WHAT WAS OUR SHOCK SET-UP? This was our best shock set-up. Spring rate: 5.0 kg/mm Race sag: 100mm Compression: 18 clicks out Rebound: 14 clicks out Notes: The TM likes to have the rear end set up with 100mm of sag or less. QUESTION ELEVEN: WHAT DID WE HATE? The hate list: (1) The forks. Paioli versus Marzocchi is no-contest. (2) The brakes. There’s nothing worse than a bike that goes faster than it can stop. TM took the right step with an oversized front rotor, they just need to find the right pads to go with it. (3) Rear brake pedal. It is tucked in so far that you have to train yourself to find it (and to use it gently). (4) The levers. They’re square edged, uncomfortable and located a little too far away from the handlebar for small-handed 125 pilots. (5) Shifting. Worse than even the least accurate Japanese 125. QUESTION TWELVE: WHAT DID WE LIKE? The like list: (1) Ergonomics. The TM has a roomy feel to it. You won’t be cramped by the layout. (2) Aluminum tank. You don’t see alloy tanks anymore. It was nostalgic to ride a bike with an aluminum tank again. (3) Perimeter frame. Unfortunately, TM painted the ovalized, steel, perimeter frame black. It’s a clean design that would stand out more in a brighter color. (4) Brake pedal. We hate how far the brake pedal is tucked in, but this is the kind of workmanship we wish we’d see more of. (5) Plastic. You won’t break the bank buying special TM plastic. Most of the plastic has been borrowed from competing Japanese builders. QUESTION THIRTEEN: WHAT DO WE REALLY THINK? Let’s review. Engine: The power is significant, but its breadth is not. This is a gun-and-run motor that demands that the rider stir the gearbox and wring out the throttle. Handling: Not as bad as most Italian bikes, but it still has a hitch in its get-along. Not a quick turner, it has superb straight-line stability (until the front wheel hits a pebble) Suspension: Once you have a good set of forks on the front, the rear will be even better. Plus, more absorptive forks might help the cornering and deflection problems. Overall rating: Even with the litany of complaints, the MXA wrecking crew would choose to race the TM 125 before we’d volunteer for several Japanese brands. Choosing to ride a TM carries with it all the risks of small, cottage industry, works-style production. This is not a mass-produced machine. It’s very much a work in progress. The post TWO-STROKE TUESDAY | WE TEST THE 1999 TM 125MX appeared first on Motocross Action Magazine.
Being the first rider out on a freshly ripped and watered track means that you are going to have to really hammer your bike to keep it moving. Dennis Stapleton proves how hard you have to go in deep loam to keep from falling off the pipe. Note, how much faster he goes with each passing lap. When you throw in big hills, deep loam is a major test for the power of a KTM 250SX two-stroke. We think Stapo’s 250SX passed the test with flying colors. The post NO TALK, NO MUSIC, JUST THE RAW SOUND OF DENNIS STAPLETON’S KTM 250SX TWO-STROKE appeared first on Motocross Action Magazine.
document.createElement('video'); https://motocrossactionmag.com/wp-content/uploads/2018/06/Rad_Valve_Main_.mp4 Believe it our not, this is a factory Honda CR125 from Great Britain. Up close this bike is super trick. Photos by Daryl Ecklund The fifth round of the 2018 125cc All-Star Race is in Washougal, Washington this weekend. Friday was amateur day as well as the 125cc All-Star qualifier. There were 56 riders that signed up to qualify to race during the Washougal National’s intermission on Saturday. It is awesome to see how many smokers were in attendance. The top 18 in each class qualify to be in tomorrows 125cc All-Star race. We took a walk around the Washougal pits and found many other two-stokes that were being raced in the amateur races. WASHOUGAL 125 ALL-STAR RESULTS 1. Ryan Villopoto…Yam 2. Mike Brown…Hus 3. Wil Hahn…Yam 4. Brad Nauditt…Hus 5. Robbie Wageman…KTM 6. Chris Johnson…KTM 7. Braden O’Neal…Yam 8. Harris Hulzenga…Hus 9. David Pingree…Hus 10. Tyler Ducray…KTM 11. Layton Small…Yam 12. Nathan Barnes…Hon 13. Talon Gorman…Hon 14. Zach Redding…Yam 15. Maston Holt…Hon 16. Bryan O’Neil…Hon 17. Neal Allen…Yam 18. Preston Dickinson…Hus 19. Bradley Olsen…Yam 20. Randal Skillman…KTM 2018 WASHOUGAL NATIONAL | FULL COVERAGE Nathan Barnes was the one riding the factory CR125. Ryan Villopoto is in Washougal to race his YZ125. Ryan in action on the smoker. Suzuki RM125. Jason Jerk’s Honda CR125 that has been restyled to look like the new Honda’s. Jason also has a restyled Honda CR250. Old Honda CR500s were hiding in the pits. Honda CR500 that was raced on amateur day. Make America Great Again. KX250 smoker. It is not a two-stroke race without Uncle Ronnie. Nothing sounds as good as a shorty. Garhett Carter’s KTM 125SX. Garhett in action. Yamaha YZ125. Braden O’Neal’s YZ125. Robbie Wageman’s KTM 125SX. Robbie went on to win the 125cc All-Star division two qualifier. Factory pipe or stock pipe? Thomas Caldwell striped the paint off the stock 2001 CR125 pipe to get this look. Thomas ripping. 2001 Honda CR125 powerplant. Ain’t she pretty. Chris Johnson’s KTM 125SX that got all rusted up after practice. Chris placed second behind Mike Brown in the first 125cc All-Star race. Cody Buyas turned his Husky TC125 pink. Mike Brown pulled a big lead and won his 125cc All-Star qualifier. Brandon Hoff. Ryliie Dickinson’s YZ125. Brad Nauditt placed second behind Robbie Wageman. Tyler Towles Kawasaki KX125. Harris Huizenga’s 2019 Husky TC125. Tyler Ducray’s KTM 125SX going up Horsepower Hill. A trick CR125 getting roosted. Mason Holt jumping the triple on his CR125. Tanner Paulsen pulling a tear off. TWO-STROKE ALL-STAR RACES | FULL COVERAGE The post 2018 WASHOUGAL NATIONAL | TWO-STROKE PARADISE (UPDATED) appeared first on Motocross Action Magazine.
In the action-packed thriller “Top Gun,” based on a brash Navy pilot trying to prove himself, the main character Maverick (played by Tom Cruise) poses a statement that all adrenaline junkies can relate to. Cruise boldly proclaims, “I feel the need…the need for speed!” And so it goes with all gearheads who relish the thought of going fast. That sensation wasn’t lost on John Garde, the 63-year-old dirt track kart racer from Connecticut. At one time ranked fifth in the highly competitive Unlimited All-Stars series, Garde is still taking chances in a never-ending search for glory. However, unlike the one-track-minded Maverick, John has enjoyed the many stops along the way. Garde has lost track of all the races that he has won through the years, but he still remembers the first time he worked on a two-stroke engine at 14 years old. Age isn’t the only indicator that John Garde isn’t exactly your garden variety kart racer. He, along with his brother and a friend, masterminded their own 250cc two-stroke kart engine. Crafted out of billet cases, mated with a production top-end, fit with a specialized Wiseco piston and tuned to the Moon, Garde’s creation pumps out more than 80 horsepower. This is no ordinary 250 two-stroke engine. Fitted with billet cases and custom components, this is a work of performance art. Meet John Garde, the world’s fastest 63-year-old kart racer. John, how many years have you spent behind the wheel of a kart? I actually got out of car racing and switched to karts, which I have been racing since 1976. In reality, I started messing around with karts when I was four years old. That was back in 1958! My dad built me a dragster kart that had pedals. I have been hooked ever since. I always liked motors and became fascinated by two-stroke engines. I also like four-strokes, but I’m really into the two-strokes. John has been working on karts since he was four, and racing them since 1976. That’s a kart racing veteran if you ask us. Speaking of four-strokes, looking at the results sheets of the Unlimited All-Stars, it seems that four-strokes are generally more popular than two-stroke engines. Is that true? The majority of kart engines are Honda CRF450R four-strokes. There are also quite a few Jawas and GMs. Those motors come out of Speedway motorcycles, which are really big in Europe. That type of motor is easily attainable, and it goes fast without much modification. Regarding 450cc four-strokes, the rulebook allows up to 500cc displacement. Most guys punch their CRF450Rs out to 488cc. Those engines are highly modified and push out 80 horsepower. How does a two-stroke compare to a four-stroke? The two-stroke is a little bit more work. It has been a long learning curve with these two-strokes, but I like the challenge. I actually just had several custom pistons made by Wiseco. I used some of my own ideas and went through a few design changes. So far, the pistons are working really well. Believe it or not, two-strokes usually win the majority of the races, even when 250cc two-strokes are up against the 500cc four-strokes. I do think the two-stroke is a little harder to drive, but they can hang on a competitive level. John runs custom Wiseco pistons in his 2-stroke kart engine builds. Can you please explain the rules behind Unlimited All-Star dirt track kart racing? The whole intent was to provide a class for true open karts with very few rules. There are obviously rules regarding safety, but the class was built for guys who wanted to run unlimited displacement motors. The motors are at different weights for the various sizes, but you can have someone running anywhere from a 100cc two-stroke up to a 500cc four-stroke. Somewhat surprising is that it works out pretty evenly. The Unlimited All-Stars is an interesting class. I have been running karts forever, and I always ran the Open classes. The Stock classes didn’t appeal to me. Unlimited All-Stars keeps true unlimited class kart racing alive. Racers have a lot of freedom to run what they want, which is what has always appealed to John. We have never heard of your kart engine before. What exactly is a PK 250? The PK 250 was an idea that a friend of mine, Rory West, came up with. He owns a kart shop, called Prokart Racing Karts, where I live in Connecticut. He always wanted to build a crazy two-stroke. About six years ago, the Unlimited All-Star rules were opened up to allow motorcycle engines, whereas before you had to a run a kart-specific engine. Most of those were two-stroke Italian motors. Rory decided that he was going to make his own engine. He’s a very good fabricator. Rory came up with a design for billet cases. The reason behind that was because most two-stroke kart racers don’t use transmissions. Rory built billet cases that would work with a Honda CR250 cylinder. He intended to sell that motor as a package. Rory made some design changes, and we got to talking about it. I told him that I was on board. It has been a learning curve. This is one of John’s PK 250s, which features custom billet cases by Rory West of Prokart Racing Karts and a Honda CR250 cylinder. The billet cases allow for use in the karts, as they don’t utilize transmissions. How does a kart engine setup differ from a motorcycle-specific configuration? A kart engine has to make really good power from about 5,500 rpm to 10,000 rpm. It has to have a very fat torque curve and smooth transition. I can’t have a light-switch powerband. You have to remember that I’m trying to get the power to the ground on tires that are only 11 inches in diameter. We’re able to pump out 80 horsepower on a machine that weighs 400, and that includes the driver’s weight. You’re talking about a pretty serious machine. Has the billet engine case concept caught on? Yes. A few people are making billet bottom-ends that mate up with Yamaha or Honda top-ends. There are even guys who are building billet lower ends for the four-strokes, because they don’t want to run the transmissions. The racing structure has evolved into mostly motorcycle engines being used in the Unlimited All-Stars. There are still some guys that use older kart engines, where they’re running a twin-engine configuration. That setup is very fast. We were producing close to 50 horsepower out of a 130cc single cylinder on a kart engine. If you get two of those on the same machine, then you’re talking about pushing 100 horsepower. It’s crazy [laughter]. We had my 250cc two-stroke on a chassis dyno a few years ago. It was making 72 horsepower at the rear wheel. If you put in that 12- to 15-percent factor, it meant that my engine was producing over 80 horsepower. On the dyno, John’s 250cc kart made 72 HP to the wheels, translating to over 80 HP at the crank. Better hold on. What torque numbers does your PK 250 two-stroke make? It’s right in the 35- to 38 foot-pounds area. Now I have a 275cc two-stroke put together. That’s the maximum size two-stroke displacement that you can run. The engine has been a struggle. We broke a lot of pistons with that, but then we tried different wrist pin offsets. It fixed the problem. My plan is to dial in the engine on the track. I have no idea how much power that engine will make. It would not be crazy to think that the engine will be pushing 90 horsepower. I’m anxious to find out. How many laps do you get out of an engine before having to do a rebuild? We just ran three of the engines a couple of weeks ago. After pulling the cylinders off we noticed that the pistons looked brand new. The races are really short. A 20-lap race doesn’t take long at all. You have heat races and practices, so you’re logging 50-60 laps a night. I don’t think there’s a track that takes longer than 16 seconds to complete one lap. I can go quite some time before needing to do an engine overhaul. What’s the story behind your kart chassis? Most of the chassis’ being used these days are manufactured around the Charlotte, North Carolina area. I run a chassis that’s made by Rory West here in Connecticut. He came up with a unique front-end design way back in the late 1980s. It was a heim joint design, where you could adjust the caster and camber. He took that a step farther. Rory used a jacket bolt through the spindle, allowing a racer to adjust his cross-weight in less than a minute. Conventional karts use washers, spacers and cams to change the chassis balance. Rory’s design fascinated me. I have stuck with his chassis ever since then. With that said, the big-track kart uses a basic chassis. My brother and I changed a whole lot of things on that chassis to accommodate for what we needed. The nose came from a 250cc super kart that we had to cut in all kinds of pieces to fit on an oval kart. The same goes with the body. How important is chassis setup to success on the racetrack? The chassis is a big part of racing. There’s no suspension on a kart, but the chassis works as a big torsion bar. It still matters how the chassis is put together. Some handle better on hard-pack tracks, while others seem to excel on soft-dirt tracks. You have to account for all conditions. It really is a science. I play around with tenths of a percentage point when changing cross weight. Racing has evolved into a high-tech game. The only thing is that we don’t have shocks and springs like cars do. I don’t care how fast your motor is; if you can’t get around the corners, then you’re not going to win the race. Handling is so important. My brother always says, “There are four corners and only two straightaways. What do you think you should worry about?” He’s exactly right [laughter]. How much does your race kart cost? I can’t even imagine how much money I have spent on my race karts! With the work my brother put into, and the time I have invested in the motor, it would probably be about $25,000. There was a lot of time spent on research and development, and then there are the parts to think about. My karts aren’t cheap, that’s for sure. How taxing is kart racing on the body, and at 63 years of age, how much longer are you going to race? It’s hard to do, regardless of age. People don’t think of kart racing as being a physical activity. There’s a lot of upper body strength that’s required, and you need to have good cardio conditioning. These 250cc two-strokes feel like someone is trying to rip your head off when you’re going down the straightaways, and then like someone is trying to pull you out of the kart when you get to the corners. I race against most guys who are young enough that they could be my kids. I have to be in shape to stay with these guys. I’m okay with that. I’ll keep doing it for as long as I feel I can win, and I also have fun. The post TWO-STROKE TUESDAY | 80 HORSEPOWER SMOKER ENGINES appeared first on Motocross Action Magazine.
document.createElement('video'); https://motocrossactionmag.com/wp-content/uploads/2018/06/Rad_Valve_Main_.mp4 Believe it our not, this is a factory Honda CR125 from Great Britain. Up close this bike is super trick. Photos by Daryl Ecklund The fifth round of the 2018 125cc All-Star Race is in Washougal, Washington this weekend. Friday was amateur day as well as the 125cc All-Star qualifier. There were 56 riders that signed up to qualify to race during the Washougal National’s intermission on Saturday. It is awesome to see how many smokers were in attendance. The top 18 in each class qualify to be in tomorrows 125cc All-Star race. We took a walk around the Washougal pits and found many other two-stokes that were being raced in the amateur races. 2018 WASHOUGAL NATIONAL | FULL COVERAGE Nathan Barnes was the one riding the factory CR125. Ryan Villopoto is in Washougal to race his YZ125. Ryan in action on the smoker. Suzuki RM125. Jason Jerk’s Honda CR125 that has been restyled to look like the new Honda’s. Jason also has a restyled Honda CR250. Old Honda CR500s were hiding in the pits. Honda CR500 that was raced on amateur day. Make America Great Again. KX250 smoker. It is not a two-stroke race without Uncle Ronnie. Nothing sounds as good as a shorty. Garhett Carter’s KTM 125SX. Garhett in action. Yamaha YZ125. Braden O’Neal’s YZ125. Ronnie Wageman’s KTM 125SX. Robbie went on to win the 125cc All-Star division two qualifier. Factory pipe or stock pipe? Thomas Caldwell striped the paint off the stock 2001 CR125 pipe to get this look. Thomas ripping. 2001 Honda CR125 powerplant. Ain’t she pretty. Chris Johnson’s KTM 125SX that got all rusted up after practice. Chris placed second behind Mike Brown in the first 125cc All-Star race. Cody Buyas turned his Husky TC125 pink. Mike Brown pulled a big lead and won his 125cc All-Star qualifier. Brandon Hoff. Ryliie Dickinson’s YZ125. Brad Nauditt placed second behind Robbie Wageman. Tyler Towles Kawasaki KX125. Harris Huizenga’s 2019 Husky TC125. Tyler Ducray’s KTM 125SX going up Horsepower Hill. A trick CR125 getting roosted. Mason Holt jumping the triple on his CR125. Tanner Paulsen pulling a tear off. TWO-STROKE ALL-STAR RACES | FULL COVERAGE The post 2018 WASHOUGAL NATIONAL | TWO-STROKE PARADISE appeared first on Motocross Action Magazine.
MXA PRODUCT SPOTLIGHT: ONE SHOT DEAL! This is a cool idea. Pro Circuit plans to built a special limited-edition run of 1986 Honda CR250 Works Pipe and 304 silencers for bike builder and vintage racers. Just like back in the day, Pro Circuit’s Works Pipe increases horsepower and torque, while the unplated, oiled metal finish gives your bike that “works look.” Completing the special throwback kit is a 304 Factory Sound Silencer that has a slightly longer body to add top-end performance while reducing noise output. The brushed aluminum silencer body and stainless steel inlet tube and end-cap make the 1986 CR250 silencer look as good as it performs. It brings back memories of Ricky Johnson in his Team Honda days. Pro Circuit is accepting orders for the $425.00 1986 Honda CR250 kit now and fulfill them when they reach the required production number. Order now if you want to be included in this special offer. For more info go to www.procircuit.com The post PRO CIRCUIT TO MAKE SPECIAL RUN OF 1986 HONDA CR250 TWO-STROKE PIPES appeared first on Motocross Action Magazine.
The 2019 KTM four-stroke exhaust pipes have absolutely nothing in common with two-stroke expansion chambers. The bulge is a resonance chamber. Dear MXA, I was shocked to see the photos of the 2019 KTM 450SXF. I thought it was strange a couple years ago when their four-stroke pipes began to resemble two-stroke pipes, but now they are two-stroke pipes. I don’t understand how KTM can put a two-stroke pipe on their four-strokes and get it to work. What’s the deal? We’ve been over this a million times, but people don’t always catch it the first 999,999 times. No surprise we probably answered questions about 2007 Honda CRF250 jetting specs every day (and we still get letters about how to jet one 11 years later). The 2019 KTM four-stroke pipes are not two-stroke pipes, nor would a two-stroke pipe work on a four-stroke. The actual KTM four-stroke pipe is a normal-looking, constant-diameter tube. The part that reminds you of a two-stroke expansion chamber is a resonance chamber. It is stamped just like an expansion chamber and then welded over the four-stroke exhaust pipe (after a hole is drilled in the four-stroke pipe to allow excess exhaust to be sucked into the empty space of the resonance chamber). We find it hard to believe that you never noticed this before; although, on the 2018 450SXF Factory Edition and 2019 KTM four-strokes, the resonance chambers aremuch larger than it was in the past. The post ASK THE MXPERTS: IT’S NOT A TWO-STROKE PIPE, IT’S A TUMOR appeared first on Motocross Action Magazine.