Introducing the BTR KTM Flat Track Attack
“How about that one?” I asked, as Jens Krüper and I walked around NCCR AB’s picturesque property. “The KTM?” he responds. We both stopped to look. We were hunting for the right bike to rebuild and resoul. The bike in question was a 1988 KTM LC4 600 Enduro. The bike's engine was the first in a long lasting legacy of powerful, torquey liquid cooled four stroke “singles”. The first generation LC4 (Liquid cooled 4 stroke) engines were developed after KTM saw the writing on the wall for their powerful 2 stroke offerings. With environmental restrictions closing in, KTM was the first to switch to racing the 4 strokes in 1987. The powerful platform immediately dominated racing events wherever it was entered and convinced other companies to develop their own big four stroke single cylinder engines. Thirty one years later, the venerable KTM LC4 we were staring upon rested against a boat behind stacks of tires. Her bright blue seat was tattered. The gleaming white plastic fairings were tarnished by years of long days in the sun in the summer and snow and rain in the winter. NCCR is located in the heart of the Hälsingland of Sweden where the sun can never go down or never come up. Harsh winters had left the once proud race champion rusted and dull.
NCCR AB which will be covered in an upcoming feature is a fantastic motorcycle shop with a primary focus of Buell, EBR, and V-twin performance motorcycles. For the last few decades, they have brought innovative and creative products to the market. In addition to a stellar parts catalogue, NCCR builds one-off custom machines and develops bleeding edge concepts that advance motorcycle science into the future.
Before the bike sat for ten years in the sun, mud, and snow, she was reworked into a supermotard machine with slick smaller tires and some electronic add ons. The first generation of KTMs were special because they had a unique color scheme. At this time, KTM had yet to find its distinctive orange and black paint style so the 600 LC4 came with white fairings, a blue engine and a red frame. The bikes were rather decked out. This particular LC4 had Brembo brakes and Brembo master cylinders. The long traveling suspension was provided from a company called White Power, which KTM would eventually own in 1995. White Power had been making race proven equipment since 1977 with many championships won with its equipment across all fields of motorcycle racing.
The KTM deserved to be run through the Hälsingland once again.
Having moved the tires and manhandled the bike into the open grass, the years of damage became even more apparent. Rain and snow had done a real number and we knew we would need to completely break down and restore or replace a significant portion of the bike. Undaunted, I began to strip the bike to get a better taste for the work reward ratio. The first sign of trouble came when the screws holding the tail fender on crumbled into dirty muck when we tried to remove them. At least the scarred fairings came off easily.
Once the fairings, gas tank, and seat were removed, we stepped back to evaluate the platform’s potential. The rare blue engine was an immediate eye catcher that we would keep original and as a center point of the custom build. The blue had to translate into the rest of the future paint work. The other immediate eye catcher was how unique the bike looked when stripped down to the frame. Without the tall seat and vertical-ish translucent plastic gas tank the flat topped visual of a dirt bike was completely gone. The long travel forks and upswept subframe had what could only be described as a wonky chopper aesthetic. We immediately began to formulate a design image. The rear subframe had to be angled downward so the rear lined up parallel to the ground and that a proper classic metal gas tank would have to be manipulated to fit the wide triangle frame. The initial drawing leaned to a flat track racer without the flat track V-Twin.
Back to it, we broke the chain and found a match to replace it with. Jens provided us with a D.I.D. 520 X-ring he had used back in the day on one of their acclaimed race bikes. Still as shiny as the day they originally mounted it, the chain would continue its full speed life on the KTM. When we attempted to remove the rear wheel to verify the structural integrity of the very rusted wheel tensioners, the first roadblock reared its head. The rear axle was rusted tight into the swing arm. To address the issue, we sprayed copious amounts of WD-40 in every crevice and hammered both sides of the assembly with a plastic hammer while working on other aspects of the build. After a few hours of intermittent hammering and excessive WD-40 boarding, the axle was finally free. To keep the problem from rearing its head again, we soaked every nut and bolt as well as the axle in a cocktail of brake cleaner and even more WD-40 then sanded them down with a rough grit paper followed by a more gentle finishing sandpaper.
Between abuse sessions, we found that the German made Bing 54 carburetor and the KTM/ Brembo brake systems were more clogged up with rust and residue than the arteries of a McDonalds bathroom regular. These too were dealt swift justice in the form of breakdown, brake cleaner, and sand down.
The problems didn’t end there, unfortunately. The venerable KTM 600 from this period is kickstart only. No E-starter. To fire up, the rider kicks down on the kick pedal and rotates a magneto that is also used for ignition timing. Frustratingly, the cover of the Swedish made magneto housing was missing a see-through screw-on window used to assist in gauging the location of the magnet to adjust timing. As a result, what would have been a well insulated critical part was left open to the weather. The magnetic points were coated in rust and the housing was a dustbowl. These two received the torture sessions of WD-40, brake cleaner, and an electric sander this time for extra oomf. Once reassembled the quality of spark dramatically improved. Initially, we only saw a weak spark from the wire without a plug. Once the plug was put in, no spark could travel. After the magneto spa day, the spark was bright, strong, healthy, and blue. I know because I felt it a few times by mistake
In the last two weeks and roughly 20 man hours, we have made fantastic progress while working amongst other projects. We have verified spark, compression, and correct timing. We are probably going to replace the Bing carburetor out of distrust, but other than the severe corrosion within it, the bike as a whole has only been hurt skin deep. On the bodywork side, in the last two weeks we have selected and modified an old BSA metal tank to be used on the KTM. While the original tank was wrapped low around the bike and angled back and down, the new BSA tank sits parallel to the floor and provides a larger fuel capacity even after cutting into it.
In the following week, we will finish the tank’s metal work and prep for painting. We will also begin the mock up of the custom, classic car inspired, rear tail section. Our design inspiration comes from the large circular rear tail lights of the 1963 Ford Galaxie. We hope to have a sleek, well lit rear with the sturdiness to handle off road abuse. We will also finish refurbishing the four piston Brembo brakes and relocate the water pump to a less visible location. We look forward to updating you.
Blacktop Ranger Advice:
When restoring a vehicle, take nothing for granted. Murphy’s law is king. If it can get rusted, damaged, or repaired incorrectly in the past; assume it has been.
With kickstart 4-strokes, ignition timing and spark strength are critical; Do whatever it takes to ensure you have the strongest spark possible. Test it first, so you don’t have to pay the price later.
Metal is resilient, just because a part is incredibly rusty, doesn’t mean it cannot be saved! Restoration requires patience and manual labor. The majority of our man hours so far have been spent sanding, spraying, and hitting to break free and clean parts. In the end, 90% of them have functioned perfectly after treatment.
