Why the 500?

The KTM 500 EXC seems to me like the perfect bike for ultra light adventure enduro expeditions. After over 40.000 km on the KTM 690 Enduro R, I realized that the limits of what I could do on that bike had been reached. To be perfectly honest, I actually had been toying with the idea of a different type of bike since Eastern Dirt 14, where we’d been through some pretty rough terrain on our 690’s. There were four issues that I felt were definite advantages of the KTM 500 EXC.

Weight

The energy a rider spends on a difficult trail is directly proportional to the weight of the bike. The weight of the bike similarly affects the probability of spills and the energy spent on recovering from them and continuing the journey. Picking up bikes is energy consuming. Even with the 690, there were two or three instances, when I couldn’t pick up the bike by myself after a spill. All cases involved the bike being on a muddy trail. I was tired and could find no purchase for my MX boots on the slippery surface. I felt utterly helpless and embarrassed having to be helped with my “light bike”. The stock 500 EXC weighs around 112 kg without fuel, which is around 27 kg less than the 690.

Suspension

The 500 EXC has great suspension already in stock form. It needs very little modification to work well in adventure enduro. The PDS design is very simple and has a minimal amount of bearings down low in harms way. The bikes with linkage suspension have many more bearings prone to dirt and water, which results in more maintenance and more spare parts to carry.

Engine

The 500 EXC has a good engine, producing enough power for adventure enduro. It has plenty of bottom end grunt for cruising and explosive power higher up for when you need it for obstacles and whatever. What’s best is that the engine doesn’t seem to be prone to stalling even with lower revs.

Gearbox

The 500 has an enduro gearbox, so the first gear is nice and short. It makes life a lot easier with tricky starts on steep technical terrain. The sixth gear is tall enough to keep a nice marching pace on transits, even with an enduro final drive gearing.

Design fundamentals

The two main fundaments for the design of the build are intertwined. One affects the other and vice versa. The final build is a delicate balance of terror between the two.

Go light

The obvious and easy goal was to keep the bike as light as possible. This fundament of course also spilled over to equipment and gear selection. It’s been an interesting journey of rethinking and tweaking everything over and over again. I always fancied myself as going light on the 690, and compared to many it was true. However, looking back now reveals a completely different reality.

Keep rolling

The bike should be able to survive up to 20.000 km rides, and not just one. This is the interesting challenge, as there is very little real world data about this. I’m hoping that with the correct build and maintenance schedule it can be done. Time will tell.

The Build

Handlebars

I prefer to use aluminium rail hand guards, instead of the OEM ones that are mounted from a single point. It’s not only for hand protection, but the rail also does a great job of protecting the handlebar, levers and throttle tube from damage in falls. The handlebar vibrates a lot, so instead of using the supplied sheet metal screws, I prefer to drill the mounting rail and bolt the deflector right through.

Even then I use Nyloc nuts or thread locker to make sure they don’t roll open in the vibration. I just cut the original closed grips to fit the rails, but a better option is to get a pair of dual compound open grips from KTM. I always use grip donuts, to avoid blisters on the outside of the thumb joints.

Levers

I went with Midwest Mountain Engineering’s  Clever Levers to ease the strain of clutch pull on the finger joints on long expeditions.

Pedals

I have a pretty narrow skid plate, which doesn’t offer much protection to the pedals. To give them a better chance of surviving small tumbles, I went with Hammerhead Designs, which seem very sturdy pedals. The shifter is mounted on the engine with a single bolt, so it’s a good idea to make sure it doesn’t loosen and rotate off. Hammerhead produces a handy lock wire bolt for the shifter pedal which works like a charm. The brake pedal has the tendency to scoop trail debris between itself and the clutch cover. At worst, the jammed debris could break off the pedal. A security wire from the pedal to the frame will significantly reduce the risk of that happening.

CLUTCH

Apparently the brake lever tip teeth have a tendency of puncturing the clutch cover in falls. The P3 carbon clutch cover protector will prevent this from happening and also protects the cover from boots scratching it. Further back, the clutch slave cylinder guard should keep the clutch in working order after a snapped chain whiplashes though the front sprocket.

THROTTLE CABLES

The throttle cables are somewhat exposed on the top of the handlebar, and the KTM metal protector will give them a better chance of surviving a beating. To make sure the cables stay where they’re supposed to while fitting the tank, a set of bungees will do the trick. I run a strip of inner tube on both sides of the frame, from the tank’s top mount to its side supports.

SKID PLATE

I originally decided to go the same route as I did with the 690; to carry engine oil in the skid plate for impromptu oil changes. The tank plate and oil added 6 kg to the bike, so it clashed heavily with one of the main design principles. Ergo the P3 Carbon skid plate. Not only is it light and strong, but it has to be the most beautiful skid plate I’ve ever seen.

EXHAUST

The factory slip on silencer worked fine, but I decided to go with the FMF Competition silencer. It’s a little lighter, which will make a difference as it sits high on the bike. It also adds a little torque and power throughout the entire rev range. To be honest, I somewhat regret not spending the extra coin on an Akrapovic, as their build quality is superior to the FMF.
To keep my riding pants from melting, I fitted an SXS carbon exhaust guard. It was pretty small, so I upgraded to a P3 Carbon pipe guard, which is much longer and also protects the header section in addition to the pants. In the other end of the pipe I have a Giant Loop Hot Springs heat shieldto keep my luggage from melting on the silencer.

RADIATOR

The 2016 KTM 500 EXC had a radiator fan already fitted from stock. If it hadn’t, I would definitely have installed one. I run a Trailtech engine temperature gauge on the radiator with the EZ-Install fin sensor, and the reduction in temperature is dramatic when the fan kicks in.

It’s a good idea to lock wire the radiator protector shrouds or they might fall off in the heat of things. With the 19 litre tank there’s no need for rigid radiator protectors, but the tank actually needs protection from the radiator tabs. Bolting some tank rubber bungs on the tabs will do.

FUEL

The bike has a single 19 litre KTM Powerparts fuel tank. It’s large enough for most of the time, but for sections where fuel is scarce, I’ll carry a collapsible bladder for the extra fuel. Having a single tank has its risks though, and destroying it somewhere far off would potentially have catastrophic consequences. So I’d prefer the fuel load spread into at least two tanks, but have yet to find a system that is solid in terms of design and within my budget. So I suppose I will work on some way of protecting the most damage prone sections of the tank instead for now.

I didn’t bother with putting an extra fuel filter or replacing the standard micro filter with a Golan or equivalent. Instead, I’ll keep an eye on the in-tank filter and do frequent changes of the micro filter. Every time the quick release is opened, the O-ring should be lubed with silicone grease before closing. If it gets too dry, the female connector will potentially catch on the O-ring an tear it, resulting in a fuel leak. I protected the the fuel tank quick release with a section of MTB inner tube. It’s tied in at the bottom, to prevent crud flying up into it. I left a small hole for draining water though.

AIR FILTER

The air filter cover comes fitted with quick release pins. It’s handy for quick maintenance but also carries the risk of the cover coming accidentally dislodged by a boot or something else that catches on it. So I prefer it screwed on instead. I’ve also upgraded the standard air filter bracket stud to the factory version to avoid any malfunctions on the trail.
I use the standard TwinAir pre-oiled air filters. They can be washed out with normal dish washing liquid and then re-oiled. However, I prefer to carry several filters instead of washing and oiling one or two on the trail. This is because the weight of the liquids alone will be more than three filters. The preoiled filters are light and can easily be carried compressed into small ziplock bags.

The airbox and intake sit very low on the bike, which will be a problem in deep water crossings. The airbox actually has a drain hole in the bottom, which will let water enter through it freely. I have yet to solve this puzzle, but I suppose the answer will be somewhere between waterproofing the airbox and building a temporary snorkel for the intake.

FINAL DRIVE

I prefer to run the standard enduro 13:50 gearing with SuperSprox Stealth sprockets. I also experimented with 14:50, and while it tops out at 150 km/h fully open, I found the first gear too tall for technical stuff. The 13:50 is fantastic on first gear technical ground and will still roll nicely at highway speeds up to 110 km/h. I suppose for rides with long sections of tarmac, carrying a 13T and 14T front sprockets might seem appealing, but I find it a little counter-productive.

I’d rather not carry the extra weight for weeks if I only need it for one or two days. Also, with the standard chain, the 14:50 gearing will bring some rear tyres too close to the swing arm and start wearing out the mud flap. I run the chain with a quick link, and a TMD chain guide with replaceable bottom slide. I lube the chain with an OSCO chain oiler, and use whatever oil I have a t hand; mostly engine oil.

SUSPENSION

The stock suspension is really nice, and all I needed was a stiffer 80 N/mm spring in the shock to compensate for the luggage. Once the static and riding sags were set, the suspension seemed to work very well with a bit of trail tweaking.

I will most likely add a preload adjuster collar on the shock, as the OEM plastic adjuster rings will probably get eventually damaged if used frequently, which is the case with loaded/unloaded riding. The forks are still completely stock, but I added a set of fork bleeders.

WHEELS

In stock form, the 500 has the rear sprocket bolted directly onto the hub. It’s fine in dirt, but on tarmac it may have serious consequences due to the lack of natural damping. The front sprocket may start to wear out the countershaft, causing it to eventually fail. A damped rear hub will counter this problem and also ease out the impact throughout transmission in general. I originally had a KTM damped rear wheel, which works fine. However, I splurged on a set of Haan Wheels hubs with a damped rear and Excel 18/21 A60 rims. They should be stronger and lighter than the originals.
I still mostly run Mitas C-02 rears, and have been really happy with the Maxxis OEM front tyre. Both seem to last forever under the 500. I still use standard tubes that can be patched up, and aluminium valve caps with integrated valve core tools.

BRAKES

I love a clean office and modified the front brake to run rally style between the headlight mask and front fender. It does not interfere with navigation equipment and thus far has never caught on anything on the trail. The modification can be done with the OEM brake hose, and needs nothing more than patience and a few zip ties.

The rear brake is fitted with a cylinder extender. It should cool down the brake fluid and extend its life, but the jury’s still out on that one. Another modification to the rear brake is fitting a thicker closed brake disk, to reduce wear on the rear brake pads. With the standard open brake disks, I’ve gone through brake pads in a single day of riding in wet and sandy conditions.

ENGINE OIL

I replaced the standard oil plug with the factory version, for extra durability and a smaller chance of the plug loosening and falling out. Theoretically the factory oil pump cover cools the oil a little, but it’s in fact there because it looks cool. Guilty as charged.
The oil volume of the 500EXC has been debated until exhaustion, with different volume expansion methods from high volume clutch covers to external oil coolers. In fact I have a Twin Air oil cooler sitting in my garage, and despite the fact that it will add oil volume and reduce temperature, I never got around to fitting it.

The reason I left it out is that it adds weight and four wet connections i.e. fail points. It requires special oil filters that are hard to find even in Europe. Additionally, it adds complexity to the oil change procedure and requires verification of oil flow, which seems close to impossible to do with the 19 litre tank on. So in my view that’s a lot of extra hassle and risks for a little bit more of oil. I’d rather just do oil changes more frequently.

IGNITION MAP SWITCH

The ignition map switch is there to facilitate the change between standard and soft ignition maps. Most of the time I run on standard, but the soft map may be useful in technical terrain and if fuel quality is dubious or low octane.

Steering damper

I’d never used a steering damper before now, and running with the Öhlins/Scott was quite a revelation. It does make the bike track really nicely on soft or rocky terrain.

ENGINE TEMPERATURE

I fitted a Trailtech temperature gauge with the EZ-Install fin sensor. It’s really handy for keeping an eye on how the engine is doing in steep, technical and slow terrain. It continuously shows the current engine temperature and regularly flashes the highest reached temperature from the last few minutes.

WIRING AND COMPONENTS

While the bike is new and clean for the last time, it’s a good idea to add little extra protection to the wiring. Dirt combined with vibration will quickly start eating away any two surfaces that move across each other. Especially so with the insulation of electrical wires, which in turn creates shorts which may turn out to be plentiful and hard to find. So it’s a good idea to make sure as little dirt as possible reaches the wires and that they remain immobile. Copious use of electrical tape and zip ties will work fine with a section of mountain bike inner tube for extra protection in high abrasion areas.

All wire housings are cut a little before the connectors to ensure efficient water drainage. I usually tape over the housings and connectors if they are mostly dry. If there is a risk of the connectors being submerged, I leave them open to avoid trapping water in the housing, which will eventually slowly seep to the connectors and corrode them. I spray all connectors with contact cleaner regularly to avoid any problems. The starter and fuel pump relays in the back of the bike should be secured to their sockets with zip ties as they can fall out when the going gets rough.

AUXILIARY WIRING HARNESS

KTM manufactures a handy auxiliary wiring harness, which I use for all extra instruments and power supplies. It’s wired directly to the battery and has a 7.5A fuse. I use it to power my navigators, LED high beam and 12V accessory power supply. I’ve added a main switch for it to kill power to the navigators and accessories when necessary. I used to connect all the accessories with connectors, but they’re bulky and prone to failure in the tight space of the headlight mask. So now I solder everything instead and the rats nest is gone. Instead the cables now tuck in nicely.

ACCESSORY POWER SUPPLY

I currently use a dual supply unit with a 12V cigarette lighter socket and USB socket. It’s mounted on the navigation clamps. I will most likely change it to a single USB as I have no need for the cigarette lighter socket any more.

INDICATORS

The stock bike came without indicators installed. It was an easy plug and play job essentially, but after already the first ride, half of the the exhaust side indicator was gone. So I went with some tiny LED indicators and a soldered LED indicator relay for the correct timing of the blink. I’ve extended the cable on the turn signal warning light to have it nice and high on the instrument panel. Otherwise I’d just ride along all day with the indicator blinking.

IGNITION SWITCH

The 500 only has a steering lock, but no ignition switch. It seemed rather risky, so I fitted a general ignition switch with closing loops in both key positions. When the key is on the on position, the switch closes the ignition loop and the bike starts and runs. In the off position, the switch closes the kill switch loop and bike stops and will not run. The ignition switch is mounted on my ghetto instrument panel.

HEADLIGHT

The Baja Designs SII LED spot is a beast for its size and weight. It’s also very reliable and packs enough power for my use. I will wire an extra switching relay into one of the accessory switches on the instrument panel to have control over whether to use the OEM head light or the Baja Designs SII LED spot from the original handlebar headlight switch.

MIRRORS

The 500 came with two static mirrors. I prefer a clean cockpit when riding offroad, so I replaced the mirrors with a single Acerbic left hand side folding mirror. It’s mostly tucked away behind the hand guard.

SIDE STAND

The stock side stand is configured to pop up automatically when the weight of the bike is off it. I found it to be rather risky and luckily there was a replacement bolt in the bike’s accessory kit that sorted it out. I also tried the KTM big side stand foot, but found it impossible to fit onto the side stand. It’s just as well, though as it’s not really necessary.

NAVIGATION

The bike has two Garmin Montana 600 navigators. There’s two because I ride solo a lot and like to have a backup in case something goes wrong. I lock the top navigator in portrait and have it tracking up with a static track on the map. The bottom navigator is locked in landscape and tracks north with a topographic overview of the area.

Both navigators are locked into powered Garmin cradles, which are held on the RMS Universal Navigation Clamps with RAM mounts. I keep the RAM mount of the top navigator loose enough to be easily swung back and forth between seated and attack positions without needing to adjust the tension bolt.

INSTRUMENT PANEL

The handlebar was starting to look like a Christmas tree, so I devised a ghetto instrument panel from 4 mm aluminium sheet. The mounting surface is roughly 120 x 50 mm and has holes for mounting the ignition switch, two waterproof accessory switches, the turn signal warning light and the engine temperature gauge. It’s all very Mad Max in it’s functional design, but cleaner, as my buddy Rafal noted.

LUGGAGE

I currently run with 2 x 15 litre XCountry Hobo version panniers and a 3.4 litre XCountry Hobo version mask bag. So a total volume of 33.4 litres for luggage. I used to also run a Giant Loop Fandango tank bag, but found it too disruptive for body position and also to interfere with the venting of the fuel tank. So I ditched it and couldn’t be happier with the current setup.
The XCountry panniers mount on the bike without a rack, but need a tail mount point. I bolted some D-rings right on the tail fender with large washers, and so far they’ve been holding nicely. In the front the panniers are strapped right onto the frame. Even with the front and back connection points they still seemed to swing too much to my liking, so I fitted an extra D-ring on the side panels and run a strap from there to the top of the subframe. They’re now stable enough.
After looking into several different pannier setups, I must say that the XCountry panniers tick all the essential boxes for me. They’re light, waterproof, quick to open and close and sturdy. They are also easily expandable with the handy zigzag bungees on the outside. I regularly carry two 1.5 litre water bottles in the back at the end of the day before hitting camp.

BOLTS

Many of the aftermarket stuff such as skid plates have different bolt head and types than the rest of the bike. I usually replace all after market bolts with high quality stainless steel hardware. I make sure the head is a Torx key size that I need to carry in my toolkit anyway.

HAUL LOOPS

The tail can be easily moved around from the luggage straps or just by grabbing the tail, so I only fit a haul loop in the front. It’s another ghetto edition, made from 25 mm webbing and some hardware. It does what it’s supposed to and tucks away nicely behind the headlight mask

Full service history

Check spoke tension
Check rim lock tension
Check valve nuts
Check coolant
Check steering limiters
Stabilize and protect wiring
Grease axles
Grease steering stem bearings
Adjust handlebar position
Anti seize brake pad pins front
Anti seize in triple clamp bolts
Align forks
Rear sprocket 50-T
Weigh bike

Anti seize chain adjuster bolts
Anti seize brake pad pins rear
Grease kickstand bolts and spacers
Grease countershaft
Front sprocket 13-T
Stabilize throttle cables to frame by seat bungs
Change oil and filter 1
Change oil and filter 2
Check valve clearances
Check valve shim sizes
Check radiator hose clamps
Secure starter relay with ziptie
Secure fuel pump relay with ziptie

Check radiator fan
Replace fuel prefilter
Adjust idle speed
Loctite kickstarter bolt
Loctite sprocket bolt
Loctite shock bottom bolt
Loctite chain guide bolts
Grease PDS hem joint (outside only)
Grease swing arm bearing
Mitas C-02 rear tyre
Headlight alignment
Electrical spray on all connectors
Full bolt check
Protect frame abrasion areas & recheck wiring stability
Check fairing screws
Tank protector rollers to radiator shroud tabs
MTB inner tube over fuel line quick release
Rear shock spring 80N/MM
Align forks
Tune suspension

Oil and filter change
Air filter change
Replace Hammerhead brake pedal tip bolts

Change oil and filter
Check valve clearances
Replace valve shim EX RIGHT
Check valve clearance EX RIGHT
Replace fuel prefilter
Replace air filter

Secure tank breather hose
Adjust idle
Front sprocket 13-T
Lock wire shifter pedal bolt
Loctite luggage strap bolts
Loctite panel bolts

Replace oil and filter
Metzeler Unicross tyres

Replace oil and filter
Replace air filter
Replace fuel micro filter
Check valves
Replace rocker arms

Rear shock service and preload adjuster
Fork service
Maxxis tyres
Replace rear brake disc
Replace coolant
Replace clutch fluid
Replace front brake fluid
Replace rear brake fluid
Grease rear wheel bearings
Grease sprocket carrier bearings
Rear tyre mud flap
Check the front brake linings
Check the rear brake linings
Check the free travel of the foot brake lever
Check the radiator fan

Adjust clutch and brake levers
Adjust throttle position sensor
Balance Haan wheels
Check the steering head bearing play and grease
Check and grease the swingarm bearing
Check shock bottom heim joint
Replace shock bottom heim joint
Replace rear sprocket 50T
Replace front tube
Replace rear tube
Check the spoke tension
Change spark plug
Replace chain
Check valves
Check clutch steel discs
Check clutch friction discs
Protect subframe abrasion
Check clutch pressure plate
Grease all moving parts
Check all hoses
Check cables for damage and protect routing
Full bolt check

Check suspension settings
Replace fuel filter
Replace air filter
Replace oil and filter
Replace power relay
Replace front sprocket 13T
Tune suspensions
Check electric problem 12 V USB outlet

Replace oil and filter
Replace air filter
Replace fuel filter in tank
Check valves
Check timing chain: excellent condition
Replace front brake disk
Check steering head bearing
Check clutch

Replace oil and filter
Replace air filter
Replace fuel microfilter
Install DIY kill switch
Replace front sprocket 13T
Wash air prefilter
Mitas C-02 rear tyre

Replace oil and filter
Replace air filter
Replace fuel microfilter
Wash air prefilter

Replace oil and filter
Replace air filter
Replace fuel microfilter
Wash air prefilter
Check and adjust valves
Replace rear brake pads
Replace front brake fluid
Replace grips
Replace foot peg cotter pins
Front sprocket 14t
Replace clutch master cylinder membrane
Full bolt check
Replace spark plug
Dunlop D606 tyres

Replace oil and filter
Replace oil sieves and caps
Replace air filter

Shock service
Replace fork seals
Clean forks
Replace fork oil
Fork Service
Replace spark plug
Replace spark plug connector
Replace rear shock bottom bearing
replace timing chain
Ignition cover gasket
Oil and filter
Replace brake fluid
Replace clutch fluid
Valve clearance check and adjustment
Remove navigation clamps
Short arm for Garmin cradle
Remove lower Garmin cradle
Remove Baja LED
Remove 12V outlet
Remove relay and reconnect headlight
Medium fuel tank
Replace in tank fuel filter
Fix sidestand
OEM plastic kit
Replace rear indicators

Replace tyres, Michelin AC10
Clean fork seals
Lube fork dust covers
Reattach valve case breather hose
Relocate temperature gauge
Navigator to handlebar
Oil and filter
Remove navigation panel
Remove navigation clamps
Clutch lever, orange
Brake lever, orange
Factory oil filter cover
Install mousses
Stickers on rim holes
Replace air filter
Lithium Ion Battery
Hammerhead brake pedal
Hammerhead shifter pedal
Hammerhead titanium pegs
Hammerhead side stand
Full titanium Akrapovic system
Install horn
Check headlight alignment
Check brake fluid levels
Check clutch fluid level

Install EnduroTech light mask
Replace front wheel bearings
Replace rear wheel bearings
Replace sprocket carrier bearings
RAM mount for fat bar
Replace swing arm bearings
Replace swing arm chain slide orange
Replace chain slide
Replace chain
Replace 13T front sprocket
Replace air filter
Replace air filter dust cover
Replace fuel micro filter
Replace footpeg pins
Replace fork oil
Replace white hand guards
Replace side stand bolt and other parts
Rewire navigator
Protect clutch hose
Tighten LED bolts
Secure LED ballast
Install rear indicators
Secure rear indicator wires
White tail section
Orange frame protectors
Seal steering lock from water to steering head bearings
White side sections