The Kneeslider

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Kawasaki KR-1S with Suzuki SV650 Power

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Kawasaki KR-1S with Suzuki SV650 power by Jan Merckx
Kawasaki KR-1S with Suzuki SV650 power by Jan Merckx

The KR-1S before surgery
The KR-1S before surgery
Jan Merckx had a little Kawasaki KR-1S 250 two stroke, nice bike, does everything right, but he really needed something with a bit more grunt, problem was, he liked the little bike, buying something big and heavy just didn't seem right. Sounds like time for an engine swap, and after considering his options, he settled on the Suzuki SV650, a four stroke V-Twin, narrow enough to squeeze in between the rails, but of course, there's a little matter of that rear cylinder. Not to worry, Jan's a persistent fellow, and frames can be modified, so the project began.

Kawasaki KR-1S with Suzuki SV650 power by Jan Merckx
Kawasaki KR-1S with Suzuki SV650 power by Jan Merckx

Jan began fitting the engine with the aid of an old broken frame he had on hand, it fit, sure enough, but that rear cylinder meant the rear suspension was going to have to be completely redesigned, something to do with basic physics and objects trying to occupy the same space at the same time.

After all of the usual cutting, welding, milling and miscellaneous metal bending operations you would expect in a project like this, plus seven years of effort and a whole lot of dedication, Jan had his bike. There's a build thread on the KR-1S forum over in the UK and well worth a look. I won't even try to pick and choose among the build photos to show you in progress shots, there's a lot of them, so head over and see for yourself.

These projects are always great to see, a bike, an idea and a whole lot of persistence bring about something you can't buy anywhere and Jan can be justifiably proud of his work. Nice job!

Link: Kr-1S forum

The SV650 V-Twin almost looks like it belongs there
The SV650 V-Twin almost looks like it belongs there

Posted on Filed Under: Motorcycle Builders

Comments

  1. Awesome build, but I have to wonder I’d find a three-inch reduction in wheelbase (over a stock SV650) really worth all that work.

  2. I don’t know if this guy has more ingenuity or tenacity, but he definitely has both … amazing.

  3. Hm, it still got the same amount of power (just at 1500 RPM lower), I wonder if it weighs less than a stock SV?

    What worries me is that he removed the (apparently useless) frame reinforcement right behind the headstock. Didn’t he have another frame with a busted-off headstock? This one might fail sooner – then again, maybe this modification will allow the frame to flex over a greater area than just between the headstock and the brace.

    If it was me, I would have installed a new set of rings in the Kawasaki and put a larger counter shaft sprocket on it for touring.

    -todd

  5. Hi all,

    tnx for the comments, and tnx to Paul for showing it.

    some remarks :
    * I still have the 2-stroke KR-1S ! I love it to death and it’s all the bike I want for having fun on my own. But it’s not the bike one needs when someone is on the pillion seat and you have to try to keep up with bigger faster more modern bikes.
    * @ Todd : I don’t care how much it weighs or compares to a stock SV. I just wanted a KR1 with enough grunt for easy riding with my misses at the back. For a blast on my own I’ll take the 2-stroker every day. I have some more KR1’s on my attic and am also building a KR-1S with a KX500 engine for trackdays 🙂
    * about the removed reinforcement behind the headstock : it was my opinion that the front cylinder has taken over that job where it is bolted to the frame, and the space was much needed. the bike has already done about 5.000km and I thoroughly checked the frame before sending it to the painters.

    • Oh good. I didn’t catch the part where the cylinder head attaches!

      My question about the power was that if it made any difference. Sure, you have the same amount of power as the original motor but at a lower rpm so you will need to raise the gearing to get the same road speeds. Raising the gearing will slow the acceleration. How is there an improvement? Is it that you didn’t like using higher RPM all the time or do the KR motors wear out from sustained speeds for some reason? Thanks.

      -todd

      • there is absolutly nothing wrong with the power of a KR1-S, nothing ! I love it . I’m 45 years old and have had lot’s of bikes, up to 135BHP, but since buying my first KR for racing purposes (17-18 yeasr ago), I totaly fell in love with it and still do. it’s all the bike I need to have fun on the roads and allthough it’s only 65BHP, it’s plenty to have great fun at still reasonable speeds. This litle gem gives back way more than any modern sportsbike can offre (at the same speeds).
        if it’s just us (me and the misses at the back), it still is ok-ish, but when having a (kind of faster) ride out with others , you do have to make the engine and gearbox work very hard, up to a point where it’s no longer fun/comfy and it more becomes like “racing with somebody on the pilion seat”.
        I do not only love the KR’s 2-stroke engine, I also love the fact that it’s a small leightweight bike and the way it handles. That’s why I wanted/needed another extra bike : basicly the same one , as fast, but whith much more grunt.
        So that’s where the “improvement” lies if you want to call it that way. but I don’t see it that way. Basicly I now have 2 similar roadbikes and each has it’s own purpose : the stroker for having fun on my own, the “diesel” for having fun when the misses comes along. an example : people often ask me why I putted those very heavy Z1000 exhausts on it, and if it wouldn’t have been better to put on some leightweight aftermarket ones. well, obviously I find them very beautiful, but also as the bike is built for duo-riding, weight is not important 😉

  6. Good to see this kind of work, very inspirational. Ive got an RD 400 engine in the shed that I,m thinking of stuffing into a restored Aermacchi/Harley SX 250 with a weak engine that I dont ride much. I looks like it may just fit with a bit of tweaking.

  7. Hmm. I suppose it’s more about torque than horsepower, yes? Since I’ve never even seen. KR-1 in person, I’d never approve of this kind of conversion, but I am working on a Hyosung GT250R/DR400 hybrid myself, so I understand the allure.
    I don’t like the helmet fairing. But it’s your bike, dude.

    • Well, I kinda agree not to break up older/rarer bikes and use the parts to make specials, but as I have more frames than entire engines, and the same goes or the entire world (on fora, frames are offered for free but thrown away as nobody goes to collect them and postage often is way to costly to have them send to me), and don’t see this one as blasfemy.

    • sure. during daytime I ride with it closed. at night, I have to open it.
      funny thing is that when the bike is parked somewhere, people are interested to find out where the lamps are/what’s behind the visor, and gently try to open it, but don’t dare cause it needs a little more than gently to open. so they try to look inside from behind, from the bottom, … 🙂

  9. Are those first-gen Z1000 “pickle fork” mufflers?

    (Also, props to Paul for posting 5 consecutive non-trike articles…I didn’t think you had it in you ; ) )

  11. Nice bike! But that helmet/headlight cover creeps me out for some reason. Can’t put my finger on it.