Know a little something about maintaining, repairing, tuning, or modifying motorcycles, ATVs, UTVs, snowmobiles, or PWC? Or, maybe you have mad skills riding or racing them? Whatever the case, if you have valuable knowledge and experiences that relates to power sports, please help your fellow riders by sharing your best tips, tricks, and how-to.

Kevin from Wiseco
Freshening up the top end in your dirt bike or ATV is a critical part of preventative maintenance. However, it’s not as simple as purchasing a new piston kit and dropping it in. Properly preparing your cylinder is equally as important as installing a quality piston. Cylinder prep recommendations are always included with the piston when ordering from Wiseco. Depending on your application, it will either say “deglaze / hone” or “bore & hone” or “bore / replate.” We’ll take a look at exactly what these different terms mean and how to perform these steps.

Deglaze your Cylinder
A common question is “Do I need to deglaze my cylinder?” The answer is: yes, unless it’s time for a replate or resleeve. If you’re engine has any time on it, the glazing process has begun. The term ‘glazed’ in this context refers to the motion of the piston ring(s) flattening out and polishing the surface of the cylinder wall during normal operation. The more time on the engine, the more glazed the cylinder is going to be. However, depending on how much time is on your engine and what type of cylinder you have, you may need to replate or resleeve, which we’ll discuss next.
Notice the shiny surface of the cylinder wall. This cylinder has become glazed over time.
Plated vs. Sleeved Cylinders
If your Powersports engine was made in the last 2 decades or so, chances are it is plated with a Nikasil (Nickel Silicone Carbide), chrome, or electrofusion plating. Nikasil has been the latest and most commonly used cylinder coating due to its wear resistance qualities, but they do still wear out. We recommend checking your manual for normal top end rebuild times, but generally if your engine has long hours, the overall condition of your cylinder will need to be closely reviewed. This will include not only the bore size and plating condition, but also the cylinder roundness and taper in reference to OEM service specifications. There are a number of good companies that offer replating services, just do your research and choose a trusted company. Your cylinder should come back with fresh plating, honed, and ready to go after a quick cleaning.
This cylinder has been replated and prepped for the rebuild. The cylinder wall surface is no longer reflective and glazed-looking.
Other forms of cylinders that aren’t plated commonly have iron or steel/alloy sleeves. If your cylinder does have a sleeve, you should be able to see the seam between the sleeve and the actual cylinder. If you’re still not sure, check to see if a magnet sticks to the cylinder wall. If it sticks, it’s a sleeve, and if it doesn’t, it’s plated.
Much like replating a cylinder after normal top end rebuild time, your sleeved cylinder should have a new sleeve installed. The same cylinder shops that do replating should do resleeving as well, and it will come back honed and ready to go back together.
In short, if your engine has enough time on it to need a full top end rebuild, we recommend replating or resleeving your cylinder. Technically you can have your previously plated cylinder sleeved, but we recommend sticking with how it came from the OEM. If it is just freshening up with low hours on the engine, you should be able to just deglaze / hone.
What is Honing and Why do I Need It?
When your engine was made brand new in the factory, the cylinder was honed. Honing is a process of conditioning the surface of the cylinder wall to help with lubrication of the piston ring(s) during operation. Honing creates fine cross hatch imperfections on the surface of the cylinder bore. You can think of these imperfections as peaks and valleys in the surface of the metal. These are essential because it helps the cylinder wall retain oil to assist with piston ring lubrication. Theoretically, the idea is for there to be a very thin layer of oil between the edge of the piston rings and cylinder wall. If there was no oil to lubricate the constant contact with the cylinder wall, there would be too much friction and both the rings and cylinder would wear out quickly.
The term ‘deglazing’ simply refers to re-honing your cylinder to put those peaks and valleys back in your cylinder wall.
This crosshatch pattern on the wall of the cylinder is the goal of the honing.
How to Hone your Cylinder
The most common tools you’ll find for honing small engine applications are rigid or brush hones and ball hones. Hones can be ordered by size according to your cylinder bore, just cross reference your bore size with the information from the company you order your hone from.  The hone company should also have recommendations on grit and material type based on what type of rings you have.
After disassembling your top end, inspect your cylinder wall and ports for damage. If you had a piston seizure or something break, chances are the cylinder was damaged. Depending on how extensive the damage is, sometimes cylinder shops can repair them. If you see any questionable damage or deep scuffs, we recommend sending your cylinder to a trusted shop for their best recommendation.
If your cylinder is in normal condition with no damage, and you’re just changing rings between top ends, honing should be the only thing required. If the glazing is minimal and you can still see a fair amount of cross hatch marks, you should be able to get away with using a rigid or brush hone to just restore those cross hatch marks. You should only have to hone for about 10 – 15 seconds at a time until you can see consistent cross hatch marks.
A soft hone brush like this is one of the tools that may be used to prepare the interior surface of the cylinder.
The ball hone will be a little bit more abrasive, which is why we don’t recommend using a ball hone on plated cylinders unless they are specified to be safe. If you do need to use a ball hone for heavier glazing on your sleeved cylinder, attach it to your drill and lubricate it with a light coat of motor oil. Make sure the cylinder is secured and stationary, and the ball hone is spinning before entering the cylinder. Hone the cylinder back and forth for about 10 – 15 seconds, then switch to the opposite spinning direction and repeat. Check the cylinder for the desired cross hatch marks, and repeat if necessary.
After honing is complete, be sure to clean the cylinder thoroughly until there is no residual material.
When reassembling your top end, always be sure to double check your piston to wall clearance.
Do I Need to Bore my Cylinder?
If the instructions for your new piston say “bore & hone” or “bore / replate,” it’s because you ordered a piston that is larger than the stock bore size. Instructions to bore and hone your cylinder means your cylinder did not come plated from the OEM, and only requires to be machined out to the correct size for your piston. However, if it is a sleeved cylinder, consider having it resleeved depending on the time on the engine. Instructions to bore and replate your cylinder means your cylinder came plated from the OEM, so the only work required is to have the cylinder machined to the correct size for your piston, and then replated / honed.
We recommend having your local trusted cylinder shop do your boring and replating work.
In any case, we recommend having the cylinder bored by a professional machinist with the proper equipment. Cylinder shops that replate and resleeve usually have the capability to bore as well.
Don’t Forget to Chamfer and Clean Up
After any boring or honing work on a cylinder, it’s important to chamfer all ports and the bottom of the cylinder. Chamfering is smoothing out any sharp edge to leave a symmetrical sloping edge. Creating sloped edges on the bottom of the cylinder allows for easier piston and ring installation. You also want to make sure that the edges of the ports in the cylinder have a nice slope as well so the piston rings don’t get caught on any edges during engine operation.
If your cylinder has an exhaust bridge, be sure it is relieved .002” - .004” to allow for expansion.
Exhaust bridge relief is important in certain 2-stroke applications. Read more about exhaust bridge relief here.
Lastly, be sure to properly clean any parts that have been worked on. Cylinders that have been bored and/or honed will have residual honing grit. This must be removed by washing with warm soapy water until an oil dampened cloth does not show any grit after wiping the surface of the cylinder wall. Once clean, apply a thin coat of oil on the cylinder wall before proceeding with your rebuild.
Always be sure to cover all your bases when freshening up the top end in your machine. Giving the required attention to all areas will help you be sure you’re getting the smoothest performance and most reliability out of your engine.
2009 DRZ400sm I bought this bike with a little less then 600 miles.  I have since put down more 60000 miles on the bike.  I thought I would share a little about my bike and the modes i have been able to do.  
1. Gearing I Run a 16 tooth front sprocket and a 37 tooth rear.  And you can go all the way down to 35 tooth if you wanted to slightly modify the rear hub. I would advise against this.  My opinion, a with mildly modified DRZ(exhaust and 3x3 mod) I would not go with taller gearing than 16-39 or 15-37.
2. Rear Tire, You can run up to 160/60 R17,  My opinion 150/70 R17 is the best handling. 
3. Rewiring Charging cable, by shortening and using a thicker gauge wire that is routed from the battery over to the starter relay and then back into the loom.  As well as bringing down the Fuse AMP down to 15amp.  15amp is enough to operate 100 watts of light.
4. 4mm Stroker, Can be installed using the stalk piston and 91 pump gas.  5mm stroker needs to modify the crank case and replace the piston.
Bryan Bosch
Industry’s Most-Iconic Helmet Brand Continues Tradition of Partnering with Category Leaders for
Special-Edition Helmet Designs 
SCOTTS VALLEY, CA – February 23, 2018 – (Motor Sports Newswire) –  Bell Helmets, an industry leader since 1954 in helmet technology and innovation, today unveiled its latest moto graphics from its 2018 Season One line. Additions include collaborative designs with premium moto lifestyle brands Fasthouse and Seven MX across the Moto-9 FLEX and Moto-9 MIPS helmet lines, as well as an all-new MX-9 Adventure MIPS graphic. All of the 2018 seasonal one line helmets are equipped with Bell’s advanced, state-of-the-art protective MIPS and FLEX technologies.
Limited-Edition Fasthouse
Bell has a long history of offering riders helmets that combine state-of-the-art performance and protection technology with innovative graphic designs that continually raise the industry standard. The new collaborative graphics are the latest in Bell’s continued partnerships with Fasthouse and Seven MX that have previously produced limited-edition designs for Bell’s innovative Moto-9 FLEX and MX-9 MIPS helmet. Overwhelmingly positive response to previous collaborations demonstrated the significant power of these partnerships and paved the way for the new releases.

Limited-Edition Seven MX
“We understand that riders demand helmets that perform and protect at the highest level, while at the same time, look incredibly cool and command attention, and these collaborations allow us take that to another level,” said Chris Sackett, Bell Helmets Vice President. “Fasthouse and Seven MX are powerful brands that compliment Bell’s history and values. Like Bell, both brands represent the authentic moto lifestyle, and clearly that is incredibly appealing to riders.”

All-New MX-9 Adventure
In 2014, Bell set a new industry standard with the Moto-9 FLEX helmet. Moto-9 Flex features Bell’s exclusive “progressive layering” technology, composed of three different materials each designed to protect against specific impact velocities. Combining these three materials at varying densities creates an unparalleled energy management system that protects against low, mid and high-speed impacts.
The MX-9 features MIPS, Multi-Directional Impact Protection System, a technology that was first used by Bell in its bicycle helmets before being introduced to powersports helmets last fall. MIPS, which is designed to manage energy from rotational and angular impacts, uses a slip-plane system that moves inside the helmet, mimicking the brain’s own protection system. This system allows the head to slide independent of the helmet during the most critical milliseconds of impact, thus reducing the violence to the brain which significantly reduces the risk of a serious brain injury.

The entire seasonal one line is now available at select retailers and online while supplies last. For more information on the helmets please visit

Ride Engineering
At Ride Engineering, we pay close attention to handlebar position and bar mount height. You’d be surprised just how much a few millimeters from stock can make to improve your body position and overall control. Keeping the bars neutral is another important aspect. By this we mean keeping the bars parallel to the forks within a few degrees. Drastically changing them by raising the bars 25mm+ or moving them forward that much can have a totally adverse effect. This article’s main focus is to explain where the “sweet spot” is for maximum control reinforcing the proper riding position on track or trail. 

Handlebars that are rotated too far out of parallel alignment with the forks can create adverse handling issues
The first thing that you want to do is pick a handlebar bend that you are comfortable with. Typically, a lower bar will allow you to “muscle” the bike more, but it should still be relative to your height. For example, at my 5’6” stature I like the lowest bends. Currently, my favorite handlebar is the Husqvarna bend Pro Taper Evo. It's 80mm in height at the ends and a little less sweep that my old favorite, the Pro Taper Carmichael. If you’re a bit taller, you may like the SX Race bend with a height of 87mm. Those over 6’, may like the stock Honda bars at 97mm tall (Renthal 971).
Since each bike is different, your favorite bar may still need further adjustment. For example, I love the Husky bar on a Husky or KTM with the stock bar height, but on the 2017 CRF450R, I preferred it 5mm lower. On my current 2018 RM-Z450, I prefer them 5mm higher. I tried the SX Race bend with the stock bar mount height, but they felt too tall for me, even though the net difference was only 2mm more. Also, due to my short arms, in every case I run the bar mounts in the back position. This gives me a good head over the bars posture and maximum control of the bike. Incidentally, the forward holes that come on a stock KX-F and YZ-F triple clamps are too far forward for most riders.
Before you start shaking your head and tell me that the OEMs wouldn’t design it that way if that were true, let me explain further. Because they use a rubber mounting design, which I agree is way better than the old metal on metal system, they have no choice but to put the forward holes 25-30mm out. The rubber cones are over an inch in diameter, so it’s not physically possible to provide a second mounting position any closer than that. Remember, KTM used to have two positions. But back then it was only a 10mm bolt hole, so it was possible to add a second hole 15mm away. Then by using an offset bar mount you could make changes in 5mm increments. Now that they also offer a rubber cone system, they have eliminated the forward position all together.
Ride Engineering bar mounts are typically made the same height as stock (except YZ bar mounts which are the same as the 2017 & older stock mounts and 5mm lower than the 2018) with plus or minus 3mm of adjustability forward or back. We also offer 5mm and 10mm spacer kits to raise our mounts (Ride bar mounts come with posts that unscrew to allow for a height adjustment or to replace in the event they are bent in a crash). Aftermarket bar mounts that are 20 or more millimeters higher that stock are going to put the rider in a less than ideal riding position.

Neutrally mounted handlebars
Many steering dampers also have this adverse effect. They mount over the stem nut and under the handlebar, so often raising the bar is the only way to make clearance (Ride Eng. offers a damper kit that mounts behind the front number plate, allowing one to keep the bar height standard). Some riders like to go on mellow trail rides for a couple of hours and have found really tall handlebars add comfort. The problem lies when you come across a rider heading in your direction or an unforeseen obstacle that needs an instantaneous reaction. A poor riding posture can contribute to a crash and getting injured. If that happens, any added comfort will be the last thing on your mind.

Handlebar mounts w/ spacers

Here’s how a few fast guys with a lot of riding experience set up their riding position:
Sean Lipanovich Pro
5’5” - 150lb - 27 yrs old  Years riding from 12 yrs old to present Current ride: 2017 KTM450sxf Sean has raced professional supercross and motorcross, finished in the top 25 at the 2016 USGP, won the 25+ class at the 2017 Vet World championships and now trains young riders for SL MX School. He’s always couching riders to “put your head over the bars, squeeze the bike with your knees and be on the balls of your feet.”
“I run the stock KTM handlebars (78mm tall) in the back position (bar mounts rotated back) with the Ride Eng. bar mount that is the same height as stock with the bars neutral (not rotated forward or back) to the forks. I feel this gives me the most control of the bike to get on the gas harder.”
Kris Keefer Pro
6’ – 170lbs – 40 yrs old Years riding from 9 yrs old to present Favorite bike: 2018 YZ450F At 24 years old, Kris started his testing career with Yamaha Motor Corporation which led him to a position at Dirt Rider magazine as associate editor, then eventually to Senior Test editor. Today he’s doing his own testing and pod casts as a new business owner for Throughout his career he’s raced professional motocross and supercross, the Canadian nationals, Vet World and Loretta Lynn’s. 
“I use the SX Race bend on my YZ450F with last year’s bar mounts (5mm lower) in the back hole with the mounts rotated forward. I like to keep the bars fairly neutral and coach others to do the same. If you have your bars rotated too far back, it’s harder to get your weight forward on the bike when entering corners. If you have them rotated too far forward where the ends are pointing up, you don’t have the right leverage to initiate the turn.”  

Ted Campbell Pro
6’ – 210lbs – 42 yrs old Years riding from 12yrs old to present Current bike: 2017 CRF450R Ted has traveled the world racing professional supercross and motorcross and has made many lifelong friends because of dirt bikes. He obtained his first pro national number in 1999 and kept a top 100 number for 6-7 years of his professional racing career. 
“I use the Mika Metal’s RC bend (this is a tall bar at 105mm), and like to set up my bike with my bars just behind the forks (bar mounts rotated back) in the neutral position so I can get over the front of the bike. I feel I have more control turning and it puts me more in the attack position. I run my bars back further than most being 6’ tall but it gives me the ability to really feel comfortable turning and leaning the bike over as I’m on top of the bars more.” Ted added a set of Ride Eng. CRf triple clamps which did lower the bar position 5mm and moved it 3mm forward from stock.  
Cody Webb Pro
6’ 3” – 185lbs – 29 yrs old Years riding from 3yrs old to present Current bike: 2017 350EXC Cody is the 2010 AMA National Trials champion,  2014 and 2017 AMA Endurocross champion and has finished on the podium or won numerous other off-road races like the 2017 Erzberg Rodeo where he finished in 3rd place. 
“I run the PHDS bar mount system (these have +/- 5mm of adjustability) with the Renthal 996 handlebars (93mm tall) on Neken triple clamps with no added bar risers although sometimes I hit my knees on the bars. We place the bar mount in the forward hole (these have two 10mm holes for adjustment) with the bar mounts rotated back. If I have the stock clamps on my practice bike, I run the mounts in the forward position. I also like the bars just a hair rolled back from the neutral position.” Cody’s race results speak for themselves and his “average Joe” set up works great even for a guy 6’3” tall (he only raised his bars 15mm from the stock height).  

I hope this helps everyone understand regardless of your stature, you shouldn’t increase your bar height or move the bars forward too drastically. Small increments of 5mm is ideal. In many cases such as mine lowering the bars will be far more beneficial in reinforcing proper riding posture, getting your head over the bars and maintaining optimal control of your dirt bike. Happy riding.
Adrian Ciomo
Vet Int. 5’6” - 150lb - 53 yrs old Years riding from 14 yrs old to present Current ride: 2018 RMZ450  
About Ride Engineering
Ride Engineering Inc designs and manufactures the highest quality billet aluminum accessories to improve the performance of motocross and off-road motorcycles specializing in handling and braking components. The company combines hands on testing with feedback from past and present professional race teams to bring products to the average customer that are typically not available for sale. Located in Southern California, all Ride Engineering products are made in the USA. For more information on the company visit:


Bryan Bosch
We need your help to introduce families to the exciting world of motorcycles and ATVs through the MIC’s RiDE events.
RiDE is about getting new buyers interested, swinging their legs over seats, and getting behind the handlebars with professional guidance from RiderCoaches and Instructors. The MIC RiDE initiative is in partnership with Feld Entertainment®, the global live entertainment company. RiDE will take place at various Monster Jam® events that features giant, high-horsepower trucks and pro drivers.
We are looking for fun, energetic, and enthusiastic volunteers to show new riders the joy of riding motorcycles and ATVs. These new rider experiences include demo rides, virtual reality programs, photo-ops and more. Volunteer and be a part of this groundbreaking program that offers an immersive, hands-on powersports experience to families and young people.
You will receive a commemorative RiDE T-shirt to wear during the event, a FREE ticket to the Monster Jam, $50 and most rewarding, the opportunity to spread the joy of motorcycling and ATV riding to the next generation of enthusiasts!
For more information on dates, time, locations, and to submit a volunteer application, please click HERE.  
Check out this video of our inaugural event and be part of the fun!  If you have any questions, please contact us at 
Hi guys, i watched what Dave Simon from ktmhusky youtube site did to the Yamaha YZ250FX fuel injector to improve low rpm response, cure the lean out issue, and stop flame outs and stalling at low rpm. Very interesting I thought, so i pulled my 16 YZ450FX apart and checked out the fuel rail and i's exactly the same. It has a sharp as 90 degree bend right on top of the injector and another sharp as 90 bend about 4 inches upstream. Not cool at all.
I have done what Dave did by getting an engineer to make a new straight shot injector top, but I had a 8mm tail with a barb made on mine so That I can use a bit of 8mm fuel injection line to push onto it and use a hose clamp to secure it. Dave made his so he still clips onto the stock 90 degree fuel fitting. I have made mine better than that to get the best possible fuel flow. I found 8mm steel fuel line on an old wreck of a car I have, a z32 300ZX with almost the perfect bends for the job. So, the injector now has a stainless steel top made with a straight up 8mm tail with a barb. The steel fuel line joins there and it goes up and then curls over like an upside down U-shape with nice curved bends (no restrictions). It then turns 90 degrees nicely and goes towards the right side of the bike. From there it curves nicely 90 degrees again and goes towards back of bike with a barb on it joining it to the stock rubber fuel injection line that goes to the tank.
There's about 40 or 50mm clearance between top of injector and the bottom of the airbox, so just enough room to do it. My steel fuel line under the airbox is almost touching, but apart from that, it's an awesome install and i love it. My YZ450FX never stalls now! I was lucky enough to find the right shape fuel line, bending it slightly to make it perfect. Apart from finding a steel line off a car, I'm not sure if an Engineer could fabricate an 8mm steel line to do the job. Because it's a fairly tight upside down U shape that goes to the injector, rubber and braided lines likely won't be suitable. Dave Simon from ktmhusky is onto something big with fixing four-stroke fuel systems. The stalling and flameouts that I experience with my YZ450FX aren't something we have to live with. It wasn't bad, but now it's just perfect in the woods. This is a cheap and awesome mod!
Bryan Bosch
Kirsh Helmets Debuts With CHM-1, the Toughest, Lowest-profile, DOT-certified Half-shell Helmet on the Market
SCHENECTADY, NY – October 11, 2017 – (Motor Sports Newswire) – Kirsh Helmetsa member of the Impact Technologies family, both founded by Jason E. Kirshon, are poised to effect a sea of change in the motorsports and other helmet industries. For decades, legacy compression polystyrene technology (aka foam) has been the standard in helmets, from motorsports to football to snowboarding and any number of other impact sports and activities. No longer. “Has been” is the right way to frame it, because Kirsh Helmets, with its patented fluid-displacement-liner (FDL), is about to make foam to helmets what rotary phones are to cellular technology—obsolete.
“We see Kirsh’s fluid displacement liner as a game changer,” said Donnie DeVito, President and Chief Operating Officer of Kirsh Helmets. “It works better than foam, it’s safer and it’s adaptable to any number of sports and high-speed activities.”

Kirsh Helmets, Inc., a member of the Impact Technologies family, was formed in late January 2017 to take up the challenge of commercializing the innovative, patented technology invented by Jason Kirshon. Focusing first on solving the problem of unsafe—but popular—novelty half-shell motorcycle helmets, Kirsh’s CHM-1 outperforms “competing” helmets by orders of magnitude in independent testing.
At one half of an inch thick, the CHM-1 is the lowest-profile half-shell helmet on the market. Made from the highest-quality materials, coupled with the most-advanced impact technology available, it is also Department of Transportation–certified and entirely manufactured in the U.S.A.
Since their inception, the thinking on helmet design has been “more is better.” More foam equals more protection for the head in the event of impact trauma. The independent testing conducted on the Kirsh CHM-1 proves this is not the case. Foam does little to slow down or prevent the brain from slamming into the skull after impact. And the bulk necessary for foam helmets requires more mass, which, in turn, translates into more torque exerted upon the head and neck in the event of a crash.
The Kirsh FDL’s silicone and fluid construct mimics the body’s natural protective functions. The brain sits in fluid in the skull. With the FDL, the skull sits in fluid within the helmet. This allows for less mass, reducing impact torque, and a fluid buffer that more effectively protects the skull and brain. And the malleability of the liner ensures that it conforms uniquely to each user’s head, insuring better protection and a custom fit, which means much greater comfort.
Size and style are key components that influence consumers. Despite overwhelming evidence that helmet use reduces the likelihood of injury for motorcycle riders, many go without. Kirsh is looking to help change that and reduce traumatic brain injury across the board by offering stylish, low-profile helmets that are safer and work better than their larger, bulkier predecessors. Another compelling feature separating the CHM-1 from all other helmets on the market is its ability to sustain multiple impacts without compromising the helmet’s integrity. And the versatility of the FDL allows for application in half-shell and full-shell helmet designs for any sport or activity that requires the use of head protection, meaning its potential goes far beyond motorsports.
So, a question: What do rotary phones, the Ford Edsel, the answering machine, and the foam helmet have in common? Answer: They’re all obsolete relics. Kirsh Helmets is offering the next generation of helmet technology, today, and, for the motorcycle rider, the world is a safer place because of it.
About Kirsh Helmets
Kirsh Helmets, a member of the Impact Technologies family of companies, is an All-American-Made Helmet Company. Our unique technology brings together style, safety, comfort, and improved performance.
Source: Impact Technologies

Coach Robb
Dating back to 1775 and the research completed by a biochemist by the name of Joseph Priestly, it was discovered the importance of oxygen associated with sustaining life.  Ironically, he also discovered the dangers associated with the utilization of oxygen as it related to health and wellness.  As you breathe and your body utilizes stable oxygen (O2) molecules, and converts them to a free radical molecule.  Scientists now associate oxygen free radicals with every major chronic disease, including heart disease and even cancer.  Free radicals play a major role in the gaining process.  It is important to become aware of these potentially harmful substances, what increases their production and how to control them in order to reduce the negative effects on your health, performance and the aging process.  Increases in oxidative stress, whether from too much free-radical production, too little antioxidant activity, or both, speeds up the aging process. 
According to Dr. Maffetone, different levels of exercise intensity can produce varying amounts of free radicals.  Low intensity aerobic training (according to your personal heart rate zones), produce little or insignificant amounts of free radicals, and the smaller amount is more than likely well controlled through the body’s natural defense system, especially if enough antioxidants are present.  A well-developed aerobic system has its own antioxidant effect.  Fat burning and free radical breakdown occur in the mitochondria contained within aerobic muscle fibers.  With this in mind, people in better aerobic shape are more capable of controlling free radicals compared to those who are out of shape.  Research validates that individuals with a higher percentage of aerobic muscle fibers have more antioxidant production and therefore more antioxidant capabilities.
However, exercising at high intensity levels (above HR Z4) and lifting weights can have the opposite effect.  Such intense activity produces more oxidative stress – some research indicate as high as 120% over resting levels.  This is the result of physical damage to muscles, lactic-acid production and highter oxygen uptake, which may increase tenfold during activity.  Higher injury rates are also associated with increased free radical production.  Additionally, the development of more anaerobic muscle fibers means less aerobic mitochondria for free radical elimination.
This is (amongst others) why you will see the majority of your weekly volume based on aerobic effort.  Understanding intensity levels and their influence on your health, wellness and ultimately performance is another tool for Working Smart, Not Hard!
Yours in sport and health,
-Coach Robb 


Photo: KTM 300 EXC TPI - Six Days ISDE Edition 
Two-strokes are still a hot button when it comes to talking about dirt bikes these days. The old "two-stroke vs. four-stroke" debate has been beat to death and many of us are sick of it, but it rages on regardless. 
OK!! So four-strokes won, the Japanese factories, AMA and EPA got what they wanted and it's over...two-strokes, once the powerhouses of motocross, have now been relegated to the shed, gone out of fashion and not used by any top racing team in MX or SX. 
But the two-stroke is still gasping for air thanks to KTM and maybe even Honda... who officially stated they'd converted to a four-stroke company years ago, so that's a surprise! 
Why is it still here?  
Because it's awesome that's why...two-stroke engines pack more horsepower per pound than four-stroke engines, and even if that statistic was equal, the number of complicated, fragile and expensive parts in a modern four-stroke will always cost more to replace. 
Granted the replacement interval for four-stroke motorcycle engines has gotten longer and longer but you'll always have the complication and expense factors to think about...and that's good for the manufacturers...a nice balance between reliability and the need to replace worn parts makes for a good bottom line, but that's another discussion. Obviously less moving parts and making more HP/lb are excellent attributes that appeal to motorcyclists and maybe not so much to the manufacturers at large. 
Three years ago, I wrote an article that talked about advances in two-stroke technologies and the possibility that these technologies (EFI, DFI, TPI) could help the two-stroke gain more market share. One of the conclusions was that EFI using DFI was too expensive, bulky and heavy to be a reality on off-road motorcycles and that has turned out to be the case when looking at how the technology is presenting itself in production form. 
KTM have been the leaders in two-stroke motorcycle engine design and accompanying technologies so it was only natural that KTM would be the first major motorcycle manufacturer to provide a viable cleaner-burning technology to the two-stroke arena. The first bikes to display this technology are the KTM 250 EXC TPI and the KTM 300 EXC TPI. Honda also has filed a similar patent but has not put any examples into production and looking at the patent drawings, it appears to be an industrial design featuring a pushrod, not suited for high-performance applications.  
What does this advancement mean, and is this the saving grace technology that two-stroke fans have been waiting for? 
No. But OK, it's a great advancement in terms of the accomplishment - but how does it impact the market as a whole? It's great if you ride enduro bikes in the EU...but will TPI bring two-strokes back to off-road bikes?  
Maybe, but motocross only bikes won't be included. Why not?  
Because the Japanese factories have a lot of time and effort invested in four-stroke technology and it's not going away. They influenced the sanctioning bodies and promoters to implement unfair displacement rules that favor four-strokes. 
So why did KTM do it? 
Because a lot of folks ride two-stroke enduro bikes and KTM sells a lot of them both in Europe and here in the USA! Although KTM doesn't make two-stroke streetbikes per se, they do have two-stroke enduros with plates and lights and these enduro models are homologated for use on EU public roads, which means they have to adhere to tough new Euro4 emissions limits, as well as be prepared for the upcoming Euro5 restrictions. 
I've spent a lot of time in the EU and small bikes fact small motorcycles are the norm not the exception. You see lots of small two-stroke bikes and scooters...but the EU impose restrictions on emissions so these bikes need to have some kind of emissions/clean air technology if they are to survive and prosper.  

Photo: New for 2018 KTM TPI Unit
KTM has come to the conclusion that Transfer Port Injection (TPI) is the EFI delivery system that has won the war against its Direct Fuel Injection (DFI) rival which was the technology explored earlier by KTM. Why? 
DFI seemed good and had been proven on the street in a few smaller two-stroke applications and a bunch of four-strokes but when all the support hardware and electronics were installed on an off-road machine, things didn't play as well. Weight, expense and complexity all played into KTM abandoning the DFI technology. But they didn't stop looking for a cleaner burning two-stroke solution. TPI wins that war until something better comes along. 
TPI wins for now because of its unique new design which according to KTM features "two lateral domes, holding the fuel injectors supplying fuel into the rear transfer ports. Thus the loss of unburnt fuel is reduced for less emissions, a more efficient combustion and reduced fuel consumption. A little tube in the back of the cylinder is connected with an intake pressure sensor, which supplies pressure data to the control unit."  
KTM continued: "The TPI engine is fitted with a newly developed throttle body made by Dell`Orto. It features a diameter of 39mm. The airflow is regulated by a butterfly connected with a twin-cable throttle cam, which is operated by a new handlebar throttle assembly.  A throttle position sensor provides airflow data to the control unit, while a bypass screw allows the regulation of the idle speed. The cold start device also opens a bypass supplying more air. Via an oil intake tube oil supplied from the oil pump is mixed with the incoming air to lubricate crankshaft bearings and cylinder/piston etc." 
Another great advantage is no more pre-mixing the fuel with oil, there is now an oil tank and metering system controlled by the ECU and this allows a very precise, variable and minimal mixture of oil to be burnt resulting in lower emissions.  

Photo: KTM 2-Stroke TPI Engine for 2018
Smaller niche companies that make two-stroke off-road machines in the same niche could be expected to follow this trend, possibly by licensing the technology from KTM or creating their own variants. This could include brands like Sherco, Ossa, Beta, TM, Gas Gas and the KTM-owned Husqvarna brand. 
So more cool bikes in Europe but what does it mean for riders in the USA? 
It could mean a little or a lot. Could this mean that KTM will be able to certify two-strokes with an emissions label indicating for "on-highway use"? This would be the hurdle to cross...once they've passed emission in places like Californis, the whole pie is up for grabs – here is what the California regulation says now: 
"Off-highway motorcycles must have an emission label affixed to the vehicle indicating certification by the manufacturer for on-highway use when converting to on-highway or dual registration. Registration guidelines for off-highway motorcycles converting to on-highway or dual registration require verification of the emission label." 
For KTM two-stroke riders, this technology would make sense to scale to the whole two-stroke lineup from EXC to SX. Imagine a version of the 250 EXC with lights that's legal for the streets here...and you ride it to work like the ultimate hooligan, or just be able to get a street plate to ride to your favorite riding destination. 
In conclusion, most people thought two-stroke was dead but maybe, just maybe, technology like TPI will make it feasable for KTM to expand their offerings using this technology. The first step it seems would be the ability to pass emissions both in the EU and USA, then maybe apply it to US market machines.  
If that happens we'll be first in line to try them. 
ThumperTalk wants Your Comments On This Article:
Is this a stopgap or a technological step forward?
Would you ride a two-stroke street bike?
Aren't those Six Day graphics awesome?
Tell us what you think below!!
Bryan Bosch

Always following his heart, never having the desire to repeat accomplishments, constantly looking for new, seemingly impossible challenges…few racing careers compare to the epic moto journey of Danny Laporte. Danny is and will always be part of our FMF family. Take a dive into the life of one of the most interesting personalities ever to race on two wheels.

Video courtesy of FMF Racing - Uncle Donnie's Flying Machine Stories

Bryan Bosch

September 20, 2017 Motor Sports Newswire

PICKERINGTON, OH – September 20, 2017 – (Motor Sports Newswire) –  The American Motorcyclist Association has announced the professional competition numbers for pro-licensed riders competing in Monster Energy AMA Supercross, an FIM World Championship, and the Lucas Oil AMA Pro Motocross Championship for the 2018 season.
All riders use the assigned professional number for competition. In addition, the current champion runs the No. 1 plate instead of an assigned professional number when competing in the class or region in which the No. 1 plate was earned. When competing in a class other than the class where the championship was earned, the rider must use the assigned professional number.
2018 Top 100 and Career Pro Numbers for AMA Supercross and Motocross
* Career Numbers
** New Career Number for 2018

About the American Motorcyclist Association
Founded in 1924, the AMA is a not-for-profit member-based association whose mission is to promote the motorcycle lifestyle and protect the future of motorcycling. As the world’s largest motorcycling rights and event sanctioning organization, the AMA advocates for riders’ interests at all levels of government and sanctions thousands of competition and recreational events every year. The AMA also provides money-saving discounts on products and services for its members. Through the AMA Motorcycle Hall of Fame in Pickerington, Ohio, the AMA honors the heroes and heritage of motorcycling. For more information, visit
Not a member? Join the AMA today.
Source: American Motorcyclist Association