1996 KTM Duke 620 Third Edition #443

The First Production Super Motard

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This bike began its life collecting dust and slowly rotting at Dick Allen's Honda / Yamaha in Newhall California (then JMG Motorsports, now Santa Clarita Motorsports). It sat beside its numerical sibling until March of 2000. At that point my friend Forrest and his brother happened upon the pair. Not really needing the bikes, they made a stupid low-ball offer on both bikes figuring it would never be accepted. It was. And so my friend and his brother were the proud owners of a matched pair of book-end Dukes.

Shortly thereafter, Forrest (AKA: Frosty) went on a group ride with a bunch of us from work. Up to that point, I had only seen the Duke II models which I really liked. I just assumed Frosty's would look the same. Oh how wrong I was. It's a shame that KTM doesn't make more effort in showing up at the big motorcycle shows with their new models. For a guy like me with 7 or 8 major magazine subscriptions to not even know of this bike for more than 5 years is just criminal. Frosty had spent a bunch of time detailing the bike including polishing out the bare aluminum Akront rims. It was a gorgeous sunny day when I first laid eyes upon her. She glimmered in the sun. The yellow paint isn't solid, nor is the black. Both are a subtle metallic finish that sparkles under sunlight. It was spotless, it had those W I D E aluminum rims laced up with stainless spokes and shod with low profile, sticky radial tires. It was little more than a dirt bike with huge sticky tires--a go-cart with two wheels. This is not a bike about touring comfort, all out speed or profiling. It's about the celebration of sudden, sometimes violent directional changes--pulling G's for the sake of pulling G's. From that day forward, we had an agreement that while I didn't need another motorcycle, I got first shot at her when he decided to sell.

What The Heck IS a Duke?

I guess you have to start with what a Duke is NOT. It's not a dirt bike. The Duke has wide 17 inch rims front and rear, setup for sport radial tires. The Duke is painted, not just molded plastic. It has street instruments. It has a helmet lock. I guess if you had to compare it to anything that already existed I would have to say that it's a flat track / TT bike built for the street. In the past few years, the European phenomenon of Supermotard or Super Moto has started to catch on here in the United States. Supermotard was born out of a nearly forgotten ABC series done in the late 70s called SuperBikers where motocross bikes were fitted with dirt track tires and wheels and raced on a combination of pavement and dirt. The series was kind of a flop here but the Europeans took to it where it has been growing ever since. The Duke isn't exactly that kind of bike but it's pretty close--in street trim.

They were produced in limited numbers and each was serialized on the top of the triple clamp. These are the world-wide production numbers I've seen listed elsewhere on the Internet:

Total: 2500 Dukes worldwide

Some think the cluster goes too far for the bike's mission: a small speedo and a few idiot lights is all it should need. I disagree. It's complete without being overkill. It's got a resettable odometer and a tachometer that appropriately is graduated in "beats per minute". The tach needle bounces frenetically, adding to the bike's hyperactive feel. The biggest annoyance is the oil pressure idiot light. It's calibrated a wee-bit too high. It falsely reports a "low oil pressure" condition under 2000 RPM. I've since found out that this was a common and known problem. The solution? Replace the switch. I guess KTM quietly replaced the switches in the pipeline and the new ones are calibrated to a lower pressure. Frosty chose to ignore it. I've done the same to this point, though currently, a replacement is in the mail.

The LC4 Gets its Button Pushed

Powering the Duke is KTM's LC4 engine (Liquid Cooled, 4 valve) in 609cc trim. No, you didn't read that wrong. While the bike is a "620", the engine displaces 609cc. Confusingly, the later "640" KTM engines, displace an actual 625cc. Don't worry about why except that KTM wanted to differentiate them from one another. This is basically the evolution of the engine KTM introduced in the late 1980s when they began building their own 4 stroke (as opposed to the Rotax powered KTM thumpers built in the early 80s). Originally a less than reliable engine and not the easiest starter, KTM continued to refine it over the years. As of 2004, this engine is still in production. The First and Second Edition Dukes lacked electric starting. Not a problem for young guys with long inseams and good knees. Having a number of old injuries and a 31 inch inseam means I'm not going to have a lot of success kickstarting a big thumper with a left side lever. The good news is that beginning with the 1996 model, the street-bound LC4 models got electric starting. Sadly, the battery looks like a bit of an afterthought on this model. It was less-than-seamlessly integrated as evidenced by the huge bump under the right side plastic sidecover. Yup, they bolted a big battery tray to the outside of the frame and buried it under that lump on the cover. The good news is that it matches the weight and bump created on the other side by the muffler. You'll also notice the black "Electric Starter" decal on the same sidecover, proudly proclaiming that this is a thumper that even us tired, old guys can own.

Braking is by Brembo. White Power suspension keeps those huge tires in contact with the road. Yeah...I almost forgot...it's "WP" suspension here in America. Unfortunately "white power" means something entirely different here than in Europe. In the United States it's WP Suspension (now owned by KTM). In Europe it's a company started by a guy named White. Eccentric chain adjusters with dished-out cams, replace the normal slotted adjusters. The travel is shorter than on the off road bikes: 5.5 inches up front and 6.7 Rear. It's enough to soak up terrain you're likely to find in the street without so much that the bike pogo's or pitches going into corners. Based on the specs, you might expect the bike to be skittish or jumpy. Quite the contrary. The bike simply becomes an extension of you. The road feels 150% wider and mid-corner line adjustments aren't just possible but downright routine. Riding on mountainous roads, you never know what you'll find around the next corner. Avoiding a mid-corner rock or pine-cone is no sweat on the Duke. While the Duke performs very well at lower altitudes, climbing big grades above 6000 feet, the big single starts starving for oxygen. At that altitude she only pulls up to about 80 MPH. After that, acceleration...umm...gets sluggish. The good part is that most of my local roads are ridden at much lower speeds (read: much tighter). In that environment the Duke takes over. Nothing like chasing a guy on a big liter-bike into a section of road and chomping on his heels for ten miles.

Is there a Downside?

The biggest downfall of this bike (in my opinion) is the fuel capacity. While 3 gallons might be adequate for motocross or short distance off road use, it's simply not enough for road use. While the bike can manage 50 MPG, mid 40s is more realistic when being ridden hard. Leaving yourself 0.5 gallon for reserve, that's only 110-120 miles before needing gas. That's a lunch ride for me and I'd rather not have to stop for one gallon of gas in the middle of it.

From the factory, the US Spec KTMs in the mid to late 90s came with Edelbrock QuickSilver carburetors. I guess they were chosen for their performance at wide open throttle and their ability to be tuned to meed US emission requirements. The rest of the planet got the normal Dellorto 40mm that came on all of the off road KTM's here in the US. The Quicksilver seems to really have poor low end fuel control (based on what I've read and heard from others). They don't seem to start well, hot or cold and also surge at light throttle settings. Ironically, the off-road, quad people seem to love them. On Ebay, you can find them listed under KTM with no bids but under TRX 400, they'll be bid into the hundreds of dollars! My 1997 KTM Adventure 620 also had a Quicksilver that the previous owner unceremoniously pitched in favor of the Dellorto. For those interested in doing this swap, you have to look no further than the KTM Duke parts manual. It seems that the listed throttle and choke cables are for the Dellorto and the carb itself is available as an assembly (on the carburetor page). Ironically, the Quicksilver is 'the exception' and is listed on a 'US Parts Only' page in the back. Despite arguments to the contrary on the Yahoo KTM discussion group, I feel the Dellorto is the easiest solution to the carburetion problem on this bike. Other solutions will run into problems with proper cables and getting air boot plumbing to fit. You might squeeze an extra few peak horsepower out of a flat-slide Mikuni or Keihin but I doubt it is worth all the trouble. I rarely ride my bike at peak RPM with a wide open throttle and I have few complaints about the 40mm Dellorto, now on three of my motorcycles.

So Why Did the First Owner Sell it if it's Such a Good Bike?

Well it seems Frosty is a man of many hobbies. He had three motorcycles in the garage and a half finished kit aircraft. Now he IS a motivated guy so his kit isn't going to go unfinished. Wisely, he recognizes that you must "strike while the iron is hot" so when the need to purchase his last 'assembly kit' came up, he looked to the only source of instant cash he had: two of his three motorcycles. His XR400 was already gone when he sent me this email:
Greg: Help find a home for the DUKE!
I have a SPECIAL PRICE for you today as the airplane kit fund is broke (ouch)!!!
Special veterans day sale!!!!
Give me a Call
I've omitted the price but suffice it to say that it was a give-away, put up or shut up deal. It was well under low blue book. He didn't want to deal with low ball offers and guys who call but never show up. He knew it was going to a good home and the sale would be painless. Obviously I took it. Bike number eight in the garage. Life is good!

What am I going to change? I removed the passenger foot rests (and lovingly packed them in a box). I ordered the factory luggage rack to replace the twin grab rails. While not as pretty as the minimalist rails, I have a really nice KTM tail-pack for my Adventure that is too convenient to leave at home. Because of its rare nature, I'm going to leave the bike pretty much stock and enjoy it. I'd rather ride than tinker.

External Link

Tom's scans of the original Cycle World Road Test

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