KTM 300XC-W TPI 2-STROKE: FULL TEST

Congratulations, America. We finally got the KTM 300XC-W TPI this year. It’s been in Europe of over a year, while we got only a limited run of the 250 version. We’ve been hearing about Jonny Walker calling the 300 a cheater bike. Cody Webb has won or chewed at the gold for almost a year on one, and in the extreme enduro arena, every top KTM (and Husky) racer chooses to run the fuel-injected 300XC-W TPI.

Slim ergonomics, a 2.4-gallon tank, a nice side stand that tucks up and a tidy plastic skid plate mate to ODI grips (nice!), Neken bars, good hand shields and a side-access air filter.
Slim ergonomics, a 2.4-gallon tank, a nice side stand that tucks up and a tidy plastic skid plate mate to ODI grips (nice!), Neken bars, good hand shields and a side-access air filter.

BEHIND THE SCENES
Although this fuel-injected machine runs cleaner than any carbureted machine, it is not approved as an EPA-legal machine. It was developed to meet the strict Euro 4 standards. This closed-course machine uses the same 72mm by 72mm stroke and bore as last year’s carbureted machine. The power valve is actuated by exhaust gases that force it open as they increase in velocity and push harder against the flap or valve. The goal is to provide the machine with usable power that expands as the engine revs. The cylinder features two lateral domes that hold the fuel injectors and supply fuel to the rear transfer ports. The downstream injection provides proper atomization of the fuel with the upstreaming air. This is where the bike is cleaner, as there is less unburnt fuel, more effective combustion and fewer emissions.

The ergos, brakes, clutch ease, starting and smooth performance all make the 300XC-W TPI an off-roader’s dream machine.
The ergos, brakes, clutch ease, starting and smooth performance all make the 300XC-W TPI an off-roader’s dream machine.

The 300’s engine management system (EMS) has a control unit that you’ll find under the saddle. This unit ascertains the ignition timing and the amount of fuel injected, which is based on air intake, throttle position and the engine’s fluid temperature. In layman’s terms, there’s no more jetting required to deal with altitude and temperature changes. Like last year’s TPI engine, it’s fit with a 39mm Dellorto throttle body with the airflow regulated by a butterfly that is operated by a normal throttle. A throttle position sensor provides airflow data to the control unit, while a bypass screw allows you to adjust the idle speed. There is a cold start, which opens a bypass supplying more air. Remember, this is an oil-injected machine (no premix), and this means that the crankcase receives zero lubrication. With oil injection, there’s an oil tank (the filler is directly behind the steering head), and oil is supplied from the oil pump and mixes with incoming air to lubricate crankshaft bearings and the cylinder/piston. The oil-injection system is said to reduce up to half of the smoke from the exhaust system over carbureted models and has a capacity of 0.7 liters, enough for five to six refills of fuel.

The oil-injection filler sits in between the gas cap and the triple clamps. It holds .7 liters (23 ounces) of oil, which is good for five to six tanks of petrol. KTM’s triple clamps are super adjustable for riders who prefer different bar positions.
The oil-injection filler sits in between the gas cap and the triple clamps. It holds .7 liters (23 ounces) of oil, which is good for five to six tanks of petrol. KTM’s triple clamps are super adjustable for riders who prefer different bar positions.

With the chassis, there are few changes from last year. KTM’s XC-W line comes fit with the WP Xplor fork and shock, whereas the XC versions come with the AER air fork, and their rear end runs through a linkage system. The Xplor fork uses springs in both legs, features separate damping functions for each leg (compression: left, rebound: right) and adjustments are found on top, where access and clicks can be altered with a flick of the dial. There are 30 clicks on each damping circuit. This year’s fork has been fit with new valving that wards off the excess dive of last year’s fork and has better resistance to bottoming via the sealed hydro-stop feature.

The PDS rear shock comes with a progressively wound spring, and the linkless system is highly touted by riders who opt for technical terrain over higher-speed racing. The plastic preload adjuster is a returning sore point. KTM kept the kickstarter on the 300, though we have never used it.
The PDS rear shock comes with a progressively wound spring, and the linkless system is highly touted by riders who opt for technical terrain over higher-speed racing. The plastic preload adjuster is a returning sore point. KTM kept the kickstarter on the 300, though we have never used it.

The WP PDS shock mounts directly to the swingarm—again, no linkage. Damping is handled via a dual-piston design that targets a progressive arc to damping curve. A progressively wound shock spring aids in the gradual rise in damping feel and action. There are several advantages to the link-less PDS system. Ease of maintenance (including removal) and ground clearance in ugly terrain are at the top of the list. The chromoly steel frame is a KTM tradition and offers proper stiffness and good feel (through energy absorption factors). The frame is super light and uses an aluminum subframe fit with a side-access air filter. The saddle is firm and thin, offering good mobility, and the 2.4-gallon fuel tank retains good lines for rider movement. It carries an integrated fuel pump and a fuel-level sensor that lets you know when things start getting close to the panic level. The wheels are fit with CNC-machined hubs and black D.I.D Dirt Star rims. Tires are Dunlop. AT81s are mounted up both fore and aft. Brembo brakes and Wave rotors handle the stopping duties.

On long sustained climbs we got the 300 to boil over. We’re going to install a fan. Both suspension ends are plush, the fork is too divey and riders over 175 pounds will need stiffer springs.
On long sustained climbs we got the 300 to boil over. We’re going to install a fan. Both suspension ends are plush, the fork is too divey and riders over 175 pounds will need stiffer springs.

THE ACID TEST
The 300XC-W, equipped with enduro lighting, a nice little odometer and a skid plate (a tidy plastic unit), weighs 229 pounds without fuel. That’s about 5 pounds more than last year’s XC-W carbureted model. Starting via the button is instantaneous, and we never had to fiddle with the cold-start button. It feels fairly thin. The ergos are good, and the saddle-height-to-peg relationship is good for an average-sized human. Our over-6-foot crowd felt cramped and moved the handlebar mounts to the forward position to give them a bit more room. The ones with cranky knees screamed for a taller saddle.

Right out of the hole, the bike is silky, quick and immediate. There is almost no vibration, and this fact alone makes it feel fast. The clutch pull is nice and smooth, and the engagement allows for good modulation when the terrain gets tricky. It’s crisp, feeling like a spot-on jetted machine, and the transition from roll-on into the mid meat of the powerband is linear yet wonderfully potent. If anything, it feels maybe a skosh lean here, but as you transition into the upper pull, it yanks long and hard. Again, the lack of vibration is huge here! Without belaboring the point, it’s clean. Pulling smartly, it craves short shifting and lugs down, making really nice traction in ugly zones where grip is limited. Stalling was never an issue, and the nastier terrain showcased the strong bottom-to-mid power, which is the heart and soul of the bike.
We also did some major-league hill-climbing, and here the bike showed a strong blend of power with enough on top to keep the wheel spinning on sand climbs. It also revealed that the middle goes lean when you drop off the powerband and are forced to clutch it and fight to get the rear wheel to hook up. It’s not a detonation feel, more like a tinny lean spot that you would normally ride around. But, every once in a while, it sits on the only chair left in the theatre. We’re working on a fix here with a programmable ECU, but that won’t happen until next month. We had no drama with shifting. It’s smooth, and the six-speed gearbox has very usable first through fourth gears. Fifth gets taller and sixth is an overdrive. Matted in sixth and you’re haulin’ boots! We stuck with the stock gearing, which is 13/50 and very rarely used first. Second and third are great trail cogs, and with hill-climbing, it depended on the lead-in to the mountain.

UPS — Clean and free-feeling power • No glitches in power flow • Six-speed gearbox is spaced wonderfully • Virtually no vibration

In the handling department, the 300XC-W TPI is focused yet soft. For the causal trail rider, the suspension is plush. It loves rocks, roots and trail junk, sending little back to the pilot. Faster conditions demonstrate that the Xplor fork is better on the big hits, but it dives and wallows far too much for an aggressive rider. It’s sprung for a 170–180-pounder. Larger riders and high-end aggro youngsters will have to go stiffer. Big guys will need springs front and rear. But, be that as it may, the suspension is balanced and does many things well. We ended up going four to five clicks stiffer on the fork compression, added a quarter-turn to the shock’s high-speed compression circuit and ran the rear sag at around 105mm. There has been a glug of chatter about the pluses and minuses of the PDS rear end. Pundits who push linkage say that the PDS rides too high, won’t squat in successive hits and makes for a springy/floaty ride. On the other side are the off-road aficionados who praise the PDS’ ability to handle rocky terrain far better than any linkage bike. If you look closely at what the high-end KTM racers use, it really depends on the conditions. Cody Webb runs PDS on his EnduroCross machine and his extreme enduro 300. Taylor Robert runs PDS on his two-stroke and linkage on his desert machines. Jonny Walker uses PDS technology on all of his extreme racing machines.

In our off-road world where our riding zones range from hard and rocky to loose and sandy, the tires play a huge role. In the loose high desert, the Dunlop AT 81 is not ideal. The front wanders and pushes no matter the input. We switched to a Dunlop MX3 up front, and it was wonderful. In the harder-packed, cobby test area, the front AT 81 does a decent job of maintaining front traction. Out back, the AT 81 works nicely in roots, rocks and hardpack. In the loose stuff, it’s average at best.

Here’s the quick and dirty on other facets of the 300’s character:
Brakes: Super strong mated to good feel. Love the adjustability at the lever.
Footpeg: Nice and wide. Good grip. They’re actually 6mm taller on the XC-W compared to the MX machines.
Bars/grips: The ODI grips are excellent. No problems with the Neken bar or the bend. The testers liked it. Again, KTM has good adjustability at the handlebar perches with stock and forward positions, so you can dial in the ergos.
Pipe/muffler: The silencer is long, the note quiet and the mounting sleeve is quite cool. We’d like to see a spark arrestor. The expansion chamber is plated and must do a good job with the power, as it’s quite adept. Still, it hangs in harm’s way, and ours has several good-sized dents in it from trail abuse.

The starting system is superb. KTM has this dialed in via the lithium-ion battery and a tidy starter motor.
Make sure that you use the proper oil in the injection system. It must say two-stroke injector oil or two-stroke oil and injector-friendly. We used Motorex two-stroke oil, which is compatible with oil injection.
We are not huge fans of the stock rims. We put several good-sized dings in the back rim early on.
Fuel mileage on the TPI is better than the carb machine. We’re getting about 52–58 miles out of a tank, running in the high desert. With the 2.4-gallon tank, we’d start getting nervous at 40 miles.
We only got the 300 to steam hard on one horrendously long hill. Still, we’d like to see a radiator fan on it.

HERE, THERE AND EVERYWHERE
There is no doubt that if you’re a two-stroke devotee and off-road is your forte, then the KTM 300XC-W TPI is driving the bus to enlightenment. Is it perfect? No. In some applications, the suspension shines, but, overall, we need less wallow and dive and more precision. This doesn’t mean that we want it stiff, just stiff enough to stay up in the stroke and still retain the plushness that a versatile off-roader demands. Power-wise, we’re impressed. It’s strong down low, pulls incredibly clean and yanks on top with a lusty roar. But, it has a small chink in the armor in the midrange where it feels lean. Next month we’ll be testing some ECU mods and will pass this information on, but overall this machine sparkles. It’s light. It handles. It makes brutally effective power, and it’s fun. It gets a big wow.

SIX MONTHS LATER

Living with the KTM 300XC-W TPI machine is no great burden. This machine satisfies the off-roader’s needs like Aspartame fuels a Diet Coke fanatic. Incredible bottom-to-mid power is highlighted by a vibration-free response, allowing even the pedestrian pilot to conquer trail obstacles while feeling like Jonny Walker. It’s clean. It has a button. The power is seamless, and it craves ugly stuff. Over the last four months we have ridden this machine at least twice a week and have learned volumes about maintenance, upkeep, minor flaws and how to charge the machine with more vigor.
We have been working with Jeff from Slavens Racing to find some additional meat for the powerband and to learn basic tips for living with a fuel-injected, oil-injected and highly evolved machine. Jeff’s history goes way back. First, he’s a huge off-road riding advocate from Colorado, and second, he loves two-strokes. He built Rodney Smith’s race engines for years, was a suspension specialist and runs his company with a straightforward plan—make the bikes better, test the products that work, and give riders this information so they can get the right goods and learn how to do it themselves.

There’s a chunk of mods that we have been using for months—Kreft suspension, Enduro Engineering guards, the Get ECU, Trail Tech’s radiator fan and TM Designworks’ guide—and still love them. We have been testing several FMF pipe/muffler combos, added a Scotts damper, SXS handguards, Moose Racing wheels, EBC brakes, and Emig ODI grips.
There’s a chunk of mods that we have been using for months—Kreft suspension, Enduro Engineering guards, the Get ECU, Trail Tech’s radiator fan and TM Designworks’ guide—and still love them. We have been testing several FMF pipe/muffler combos, added a Scotts damper, SXS handguards, Moose Racing wheels, EBC brakes, and Emig ODI grips.


     So, what we have come up with is a project where we deal with some of the weak points. We have made suspension updates, ECU mods, ergonomic changes, added performance bolt-ons and then dealt with maintenance on the injected machine. Slaven Racing graced us with its pre-ride checks, what to keep an eye on and performance mods they have tested and endorsed.

THE FIRST STAGE
Several months ago we dove into the biggest dilemma we faced, getting the soft suspension to work for a larger or more aggressive rider. In stock trim, there is no doubt that it’s plush. In fact, we have four friends who have bought the 300 TPI machine and really have no issues with the suspension. They like how it reacts and absorbs the rocks, roots, ruts and detritus that come with tight enduro riding. But, most of them weigh under 175 pounds and are so enamored with the sweet, smooth power they bounce right over the suspension drawbacks. The bottom line is that plush and soft suspension is far better than stiff and harsh damping for the off-roader.
     We had Kreft Suspension re-work our dampers, and nearly four months later we’re still overjoyed with the modifications. The Xplor fork required some dramatic changes to the compression paths and spring rates to get it to stay up in the stroke yet retain a strong ‘plush’ factor. Out back, they went stiffer on the spring rate, stuck with a progressive coil and re-valved it to track, and respond to a larger variety of off-road inputs. For our 200-plus-pound rider, it wasn’t even close. Back to back with stock, the Kreft machine is just as cushy but can handle speed hits, whoops and G-outs with an appetite that the stock fork lacks.

In the garage with parts floating everywhere.
In the garage with parts floating everywhere.

We strongly sanction E-Line’s carbon fiber pipe guard, which still protects the vulnerable stock chamber. TM Designs’ chainguide has been hacked on and abused, still with no drama to the drive chain, and Bulletproof’s guide strengthener keeps the chainguide from bending and derailing the chain in a direct hit. Enduro Engineering’s rear disc guard has been attacked and has survived trail hammering, and its front aluminum lower fork-leg guards have been abused yet are still strong.

Out back Moose Racing wheels, Sunstar sprocket and chain, TM Designworks guide and Bulletproof’s guide strengthener.
Out back Moose Racing wheels, Sunstar sprocket and chain, TM Designworks guide and Bulletproof’s guide strengthener.

STAGE TWO
Our focus with Stage 2 would be power—not really the amount of usable thrust, but addressing the leanness when loaded hard and revving it under duress. In trail conditions, short-shifting is key, and the engine offers superb, tractor-like response. No drama. Hill-climbing with the throttle slammed in second or third gear for long periods showcases that the ECU comes mapped lean. It’s very similar to a carbureted machine jetted too lean. It lacks meat and won’t pull with authority. Because this is a closed-course machine, switching out the ECU with an aftermarket unit is totally legal.
     Slavens Racing is a big Get ECU supporter. In Jeff’s words, “The stock maps are too rich at very low rpm, and that causes them to load up upon initial startup. The overly rich condition makes the power delivery soft down low then above too lean, which gives tinny, weak power that pulls in to a decent top end. The Get ECU (with custom Slavens maps) corrects the rich and lean issues and creates a much stronger and more linear power from bottom to top.”

Using up every millimeter of Kreft’s modded dampers.
Using up every millimeter of Kreft’s modded dampers.

Our first mod was installing the stock Get ECU with its two maps. One was for straight power. Map two was with traction control. Installation was simple (though the instructions were weak); we routed the map switch and then set the ECU in its compartment above the airbox. We felt a strong improvement in roll-on but an equally impressive boost in the midrange. It was meatier, resulting in more usable power. We liked it, but at $984, it was a mod for a Beverly Hills dentist. Slavens remapped it with his numbers. Jeff customized a setting that took away some of the rich initial feel and then richened up the mid and top settings. His map two was a dumbed-down traction-control setting for slippery, rocky, ugly conditions. Big difference here! Stronger roll-on, a nice strong mid portion, and a robust rev-it-out mode made the machine come alive. The machine gets additional torque and a power gain throughout—all making the machine easier to ride.
     Jeff is also a big believer in adding compression, calling it the cheapest way to add low-end grunt. The Slavens Mule component head kit is manufactured by S3 for Slavens and uses compression ratios to maximize performance for low and high elevations. The kit consists of the head shell and two inserts—a Low-Elevation Mule insert for riding at 0 to 6000 feet of elevation and a Mountain Mule insert for high elevation (6,000-12,000 feet). Its forged aluminum offers increased coolant capacity and does not require race gas. We went with the hi-compression insert for our elevation, and you must have the GET ECU with the Slavens maps, since it’s too lean stock and you’ll run the risk of cooking your motor. The result? Wow! The machine got considerably stronger. It is a touch snappier but a total tractor in low- and mid-power riding zones. Ultimately, the S3 Mule hi-compression head and the GET ECU were like an IV of steroids. They made it stronger everywhere but just as rideable. Of note, the kit does not come with new O-rings but is very easy to install.

We ran the MotoZ Arena Hybrid both fore and aft. They both have flexible knobs and love nasty terrain. They are DOT legal!
We ran the MotoZ Arena Hybrid both fore and aft. They both have flexible knobs and love nasty
terrain. They are DOT legal!

While we protected our stock expansion chamber with an E-Line Carbon fiber guard, the stock KTM, which is excellent power-wise, is easily crushed or dented severely. They’re consumable, so unfortunately you’re going to have to have a replacement system. FMF Racing builds its Gnarly pipe out of thicker material and is designed to enhance the bottom power. We’ve been beating up the Gnarly system for a month. It may have a few whacks, but it does hold up incredibly well. It moved the power around and when mated to an FMF Power Core II muffler (designed for the TPI machines) a fairly strong hit in the mid-range replaced the linear band of power. Stronger more aggro riders liked it, the trail riders like it smoother.

The FMF PowerCore muffler is for closed course only and gives the bike a harder hit. Good for some riders and terrain, but for snotty and tough trails, it’s too much.
The FMF PowerCore muffler is for closed course only and gives the bike a harder hit. Good for some riders and terrain, but for snotty and tough trails, it’s too much.

THIS AND THAT
Wheels: The stock rims are lightweight but prone to easy damage. Take care during break-in to keep the spokes taut. We wanted an additional set of wheels and went with Moose Racing’s Wheel Kits. You must assemble them, but they’re priced separately, with the rim at ($119.95), MXI hub ($185.95-219.95), spoke kit ($43.95) and spoke nipples ($35.95), which look great and hold up nicely. We added EBC’s larger front rotor kit and its rear disc and carbon pads. The larger rotor enhances the stopping power. We’ve gone through the stock chain and sprockets (both of which were durable) and replaced them with Sunstar sprockets with the EXCR1 O-ring chain. We have used Sunstar kits in the past and like the rear sprocket’s durability and the chain’s strength and lack of stretching over time. Quality stuff.

With the stock ECU, a blue pipe means it’s running lean.
With the stock ECU, a blue pipe means it’s running lean.

Tires: We have tested a glug of rubber. For our neck of the woods, good marks go to the Golden Tyre Fatty front and the 323 rear, Metzeler’s MC360 Mid, Shinko’s Cheater and the MotoZ Hybrid. We’ve been sticking with the MotoZs mainly because they make great traction and hold up as well as any rubber we have tested. Inside them, we’re big on Mousses now (hate flats) and have been running the new soft Nitro-Mousse foam inserts. They give better feel for tight off-road (feels like less air pressure). We don’t leave home without them.

Stock, the KTM 300XC-W TPI is smooth. With the Slavens Get ECU and head, it is that but much stronger. It’s still controllable and tractable for all terrain. Once we piped it with an FMF pipe, the machine got some hit, which made our higher-end riders smile.
Stock, the KTM 300XC-W TPI is smooth. With the Slavens Get ECU and head, it is that but much stronger. It’s still controllable and tractable for all terrain. Once we piped it with an FMF pipe, the machine got some hit, which made our higher-end riders smile.

Cockpit: We’re still running the stock bars, but they’re attached to PHDS handlebar clamps. These babies are excellent and take some of the jolt out of the trail. Grip wise, the new ODI Emig bolt-ons are right at the top of the list. We love the additional padding on the top of the grip! We have one of our editors who needs a tall saddle and is using a tall MX Control Tech seat with excellent results. It has ribbed channels where your legs pinch the saddle, and it helps keep you in the right stance in rough terrain. We have tested a Seat Concepts kit, which is cushier and offers good feel and fanny traction. Honestly, the stock seat cover and foam are hard and slippery. The IMS Core pegs are incredibly beefy, and they offer a lower version, which our tall guys prefer.

The dongle is used heavily with the Get ECU, allowing you to reset many facets of the adjustable
The dongle is used with the Get ECU.

Handling: We added a Scotts Performance steering damper after we rode Dicks Racing’s modded bike a few months ago. The damper lets you run the fork softer and takes out the willies when things start getting fast and rough. The adjustability is superb. The ability to stay on the straight and narrow when the horse starts to shake its head is much appreciated.

Funnelweb’s filter has a greater surface area than stock and works well.
Funnelweb’s filter has a greater surface area than stock and works well.

AND SO…
Frankly, we love the KTM 300XC-W TPI stock. The suspension mods were a big improvement. The Slavens Get ECU was a huge improvement. The S3 Mule head and FMF exhaust combo is stellar. Add in our well-tested product mods, and life with the 300 is bright. Here’s a big thanks to everyone who played a role in our “Living with the KTM 300XC-W TPI”!

 

INTERNET CHITCHAT, COMMON QUESTIONS AND KNOWN ISSUES
      By Jeff Slavens

Seizures: The most common seizure is a “cold seizure,” which is caused by riding too hard before the engine is up to its normal operating range of 175 to 185 degrees Fahrenheit. Cold-seizure definition: when the piston heats up/swells faster than the cylinder and the piston-to-cylinder clearance is lost.
Oil-pump failures: There is a lot of talk about the pump not providing enough oil or completely failing. This is a non-issue because I have not seen any failures, and the pump rate is more than adequate. It’s made by Mikuni, and they have been making quality pumps for many years.
Cracked fuel filters: The 2018 250 and 300 TPI models had quite a few cracked or poorly sealed fuel-tank filters. They leaked at the seam where they were glued together. The result was a loss in fuel pressure (should be 50 psi) that made them start hard and have lean/weak power. The problem is easily diagnosed with a fuel-pressure gauge or by looking in the fuel tank. If the filter is leaking, there will be air bubbles in the fuel and sometimes they spray fuel horizontally across the inside of the tank.
Is the oil pump activated by the ECU? Yes, the ECU controls the oil pump.
Is the oil pump adjustable? With the stock ECU, the pump rate is fixed. With a GET ECU, it is adjustable with the software, not the phone app.
Does the oil pump have the same pump rate for all rpm? No, it varies according to rpm—about 150:1 at idle and around 30:1 at high rpm.
Is the TPS adjustable? It is not manually adjustable or electronically adjustable with the stock ECU. With a GET ECU it can be set with the kill button and the wake-up dongle and can also be adjusted with the software.
How to prime the oil pump and why? If you remove the throttle body to install reeds or to perform other maintenance, you must remove the oil line from the throttle body. This often creates an air bubble in the line, and the bubble needs to be removed via the priming procedure. Hold the throttle wide open (may require an assistant). Plug in the wake-up dongle. Wait at least 5 seconds, then release the throttle. If there was air in the line, you will hear the pump clicking. Wait for it to stop clicking and unplug the dongle.
Does the fuel injection adjust for elevation? Yes. The fuel-injection system is called an open-loop system. That type of system does not have a Lambda sensor (like street bikes and autos) that adjusts the air/fuel ratio as you go up or down in elevation; however, it does have an ambient pressure sensor that signals the ECU to make minor program adjustments as you go up and down in elevation. This does not work as well as the Lambda, but it does help.
What does the stock Six Days map switch do? The handlebar-mounted map switch on 6 Days and Husqvarna TE models changes the ignition timing curve from the standard mode to a more mellow, dumbed-down mode for slick conditions.
What does the cold-start knob do? When the engine is cold, the FI sensors report that information to the ECU and it richens the fueling. KTM claims that you should pull the cold-start knob (which adds air) to compensate for the additional fuel. My experience is that pulling the knob makes it start harder.
Should I add a little pre-mix oil to the gas? No. Fuel is injected into the transfer ports (TPI = transfer port injection), and the fuel transfers to the top of the piston and the combustion chamber. The additional oil would never reach the piston skirts or the bearings. There have been people who have clogged the fuel filters when they run premix.
Two overheating issues: The TPI models tend to run a little hot because of the lean stock fueling map. If you own one and have some miles on it, look at the head pipe portion of the pipe. It’s likely purple or blue from extremely hot exhaust gas temps. This overheating scenario doesn’t cause the engine to boil over the coolant, but it can cause premature engine wear and poor performance.
     The second overheating scenario is caused from lack of airflow. When climbing gnarly hills in first and second gear or picking your way through a tight, rocky ravine, there just isn’t enough air flowing through the radiators to cool the engine. The only cure is a fan kit. I set my Trail Tech unit to engage at 188 degrees.

CRAZY SERVICE INTERVALS (FROM THE OWNER’S MANUAL):
The Slavens S3 head has changeable domes for additional compression.
The Slavens S3 head has changeable domes for additional compression.

1. Change the oil pump at 80 hours. Only clean oil goes through the pump, so it should easily last 200 hours.

2. Change the piston and rings at 10 hours. Unless
your name is factory KTM rider Taylor Roberts, this is laughable.

3. Change the piston and rings at 40 hours. For normal riding, 100–125 hours makes more sense.

4. Change connecting rod and all engine bearings at 40 hours. Actually, 350–400 hours is usually when this is required.

5. Change in-tank fuel filter at 40 hours. It’s a big filter and should easily go 80+ hours—unless you get a bad tank of fuel with water.

Jeff Slavens listens to Tom Webb’s report following a mapping change to the Get ECU.
Jeff Slavens listens to Tom Webb’s report following a mapping change to the Get ECU.
WEBSITES

www.fmfracing.com

www.mooseracing.com

www.slavensracing.com

www.getdata.it

www.enduroeng.com

http://pacificpowersports.com/products/motoz-tires/

http://nitromousse.com/www.trailtech.net

https://www.decalmx.com/

https://odigrips.com/

https://www.scottsonline.com/

www.tmdesignworks.com

www.bulletproofdesigns.com

www.funnelweb-filter.com 

 

 

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