KTM 640 LC4 Single Cylinder Track Bike Project
September 29th, 2008 at 8:17 am by Paul Crowe - "The Kneeslider"
When asked what they want in a motorcycle, some might say narrow, lightweight, great handling single cylinder with plenty of power. That was Kim Kronslev’s idea. He looked around, didn’t find what he wanted so he designed it and built one, based around the KTM 640 LC4. Although Kim began with the intention of making a road legal bike, his direction changed during the course of the project and what you see is a track only special.
There’s not yet much detail from Kim as far as specs go but he started by making CAD drawings of what he had in mind and finished with a track bike. It looks very minimal and super light.
Kim used the tried and true formula: idea + skill + work = real bike. Some really nice motorcycles get their start this way. Once you have something to work with, you can refine it until it’s exactly what you want. I like it.
Thanks for the tip, Bob!
More photos and link below:
Link: Kim Kronslev
Posted in Motorcycle Builders, Motorcycle Design
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24 Responses to “KTM 640 LC4 Single Cylinder Track Bike Project”
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September 29th, 2008 at 9:44 am
Fine work , I wonder if the choice to make it track only is because of licensing problems though.
September 29th, 2008 at 10:06 am
That is fine.
September 29th, 2008 at 12:18 pm
Nice. Looks like a similar concept to the 450moto.com bikes.
September 29th, 2008 at 12:38 pm
This thing has got some serious ground clearance
September 29th, 2008 at 1:34 pm
Nice bike, but curiosty kicks in, whats that cylinder sticking out the front of the sump? An oil filter?
September 29th, 2008 at 1:35 pm
I dont understand why the exhaust is 2 into 1 if its a single
September 29th, 2008 at 1:50 pm
Oil filter, yes.
2 into 1, split exhaust ports for the cylinder. Like an XR650.
September 29th, 2008 at 2:06 pm
I guess a good used MZ (MuZ as they were later known)is a little outdated. I can see why he’d start from scratch. Build it, build it, build it!!!
September 29th, 2008 at 4:32 pm
That looks nice, although in the riding photo it looks like it doesn’t need that much ground clearance, as far as the cornering is concerned. Maybe for weight transfer? I wonder if it’d be better closer to the ground. Still, very nice.
September 29th, 2008 at 6:19 pm
Now, that does look like fun!
Short wheel base/long swing arm…gotta flick like a switchblade!
September 29th, 2008 at 7:51 pm
stunning! There are rumours of an RC4 but Ive seen nothing confirmed (RC4 would be street legal). Guess this guy got sick of waiting. Great stuff!
September 29th, 2008 at 9:03 pm
Lowering the bike would probably complicate rear suspension config. if the desired wheelbase should remain as seen above. (it would require linkages)
September 29th, 2008 at 9:06 pm
…plus, he probably wanted the crank shaft and front sprocket centerline close to the axle centerline
September 29th, 2008 at 10:04 pm
Serious moto wood here. That’s really nice and looks pretty professional. Though I generally agree with this post’s equation, I think it’s more accurately summed up thusly:
idea + skill + work + *money* = real bike
September 30th, 2008 at 2:15 am
I’m a big fan of the single cylinder bikes. Huge kudos for making your very own.
September 30th, 2008 at 4:31 am
please, someone kill the trend of underseat exhausts, and high tail ends. this bike would look really cool with both a low reverse cone and a convential bum stop.
September 30th, 2008 at 4:34 am
sorry, that was ‘reverse cone megaphone’.
September 30th, 2008 at 6:02 am
Very well executed from model to real life, nice!
September 30th, 2008 at 9:11 am
Looks absolutely fantastic to me, if it had a numberplate and headlight it might even be a challenger for the title of “perfect bike”! I can understand that getting it registered is probably more legal hassle than it’s worth though, especially in Europe.
September 30th, 2008 at 1:55 pm
I wonder if he’s working on a full faring kit, although that may be one of the trickier parts to get visually right. I love what he’s got so far.
September 30th, 2008 at 3:27 pm
nice, I agree with zipidachimp. This is like my GB500 but with twice the power and much better suspension and brakes… which makes me also agree with B*A*M*F about the “money” thing.
-todd
September 30th, 2008 at 6:55 pm
Todd, you’re a lucky man to have GB500.
About 2 years ago I was constructing a budget to build my own bike for a cross country adventure. I started pricing pre-made components that I would buy (engine, lights, etc.), and then I started figuring up costs on likes like tubing, paint, and the like. Even using used parts whenever possible, I couldn’t make the numbers work well enough to have anything left for the trip.
I really admire anyone who goes ahead and builds a bike, because it’s never cheap. Even if the dollar amount was low, the hours involved were still huge.
October 1st, 2008 at 3:05 pm
Well…I think this needs a big thanks from the creator himself.
I’m really surprised to find my project here on Kneeslider, and I want to thank you all for the comments.
A few comments myself:
The ground clearance is a product of the rear swingarm geometry, as hoyt has figured out.
The missing license plate is purely because of mad legislation here in Denmark.
The original idea for the exhaust was below the engine, just like the new KTM Duke. This would have been nicer as zipidachimp points out, but it became too bulky if it was going to be effective (big volume), so functionality won over looks.
I am working on a small bikini fairing and a proper seat, but I can’t find anything suitable to modify, so I have to start from scratch, and this is quite tedious.
And money is a part of the equation. I could have had an exotic italian race bike for what this project cost, but that would not have been a third of the fun I have had now.
I’m not in favour of showing off, but I try to promote the idea of creating our own projects. It will never pay off money wise to do projects like this, but it’s really great fun and exiting. The downside is that it’s addictive, so I’m working on two new ideas for future projects.
Some basic data:
Weight: 130 kg including oil and water.
Power: 55 HP at the rear wheel
Wheelbase/Rake/Trail: 1350 mm/66 deg/87 mm
Tyres: 120/60-17 front and 150/60-17 rear
Brakes: PFM Race caliper and disc with custom hub
Front end: Ohlins FG845 fork with custom tripple clamps and custom caliper mount
Engine: Standard (now old) LC4 with Keihin FCR 41 carb and custom exhaust
Not as flickable as it can seem, but very neutral with no tendencies to any wallowing.
And above all: Great fun to build and to ride
October 9th, 2008 at 7:52 pm
Very nice bike, almost every manufacturer builds a great enduro bike. It makes me wonder why none of them are putting these great light and compact engines into a sport bike. Properly set up they would have a great handling fun bike with less of the top speed license losing potential.