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The Kneeslider

Doers Builders and Positive People

DIY V-Twins From Unexpected Places – the Home Made Junak 700

By Paul Crowe

Junak 700cc V-Twin from a 350 single cylinder engine
Junak 700cc V-Twin from a 350 single cylinder engine

Up until the moment I received an email from Kim Scholer, I had never heard of, or at least don’t remember ever hearing of, a motorcycle manufacturer by the name of Junak. According to wikipedia it’s a Polish marque, built from 1956 to 1965, though it seems there are some later versions, perhaps the company was bought and restarted? The old engine was a single cylinder 350.

It’s not a bad looking bike, but the reason I looked it up was because Kim sent me a link to a video of a Junak 700, a home made V-Twin and the engine sounds great. It starts on one kick, settles into a smooth idle and revs just fine when the owner spins it up a bit.

Original Junak 350 for comparison
Original Junak 350 for comparison
Photo found here

I have zero information on this V-Twin build, but if the Junak is no longer produced, there would seem to be little demand for any more of these V-Twin modifications, or a very limited demand at best. (Wording in the previous sentence was cleaned up after a comment below) It’s seems the builder produced this as a labor of love.

Very nice work and if anyone has more information on this build, send it in. I guess Royal Enfields aren’t the only bikes being twinned.

Video below:

Posted on November 19, 2012 Filed Under: Engines, Motorcycle Builders

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Comments

  1. Rafal says

    November 19, 2012 at 10:23 am

    Junak was manufactured in Poland in Szczecin at Szczecin Motorcycle Factory. Production of Junak, as other branches of industry in communist countries, was controlled by Soviet depended government. In short-cut: machine was great for it’s time and place of birth, yet the price was high. Due to multi site components manufacture reliability was at most average. Although costumers and the Junks’s developers wanted and worked on improvements production was cancelled by officials. Junak was exported abroad also to U.S.A. and Cuba. Till now the machine has cult status and great collectible value. Lucky whole technical documentation, and new engines prototypes has been saved. There is one driver starting on his own modified motorcycle in Czech Tourist Trophy.
    Rafal from Polnad (former 1964 Junak owner)

  2. MJ-Works says

    November 19, 2012 at 10:35 am

    A real motorcycle! It sounds very sweet indeed!

  3. Hawk says

    November 19, 2012 at 11:03 am

    The idle sound is very much like the Musket.

  4. Twisted Steve says

    November 19, 2012 at 11:13 am

    I’m a fan of that car alternator.

  5. meowy84 says

    November 19, 2012 at 11:20 am

    Like paul alluded to when he said he doesn’t remember hearing of Junak, the eastern bloc motorcycling products aren’t well known in the west (except perhaps the Russian Ural, East German MZ and Czech Jawa) but there were actually several makes of Polish motorcycles built behind the iron curtain such as SHL, WFM, etc. Most were rather pedestrian/utilitarian 2 strokes in the 125cc range. Since there was virtually no western imports at the time, the Junak was the only mass produced Polish 4 stroker in that time period and is sort of the Ducati or MV Agusta of Polish motorcycling (because of it’s original price and exclusivity compared to all the other Polish-produced bikes.) Not sure what Paul meant by “If it’s no longer produced, there would seem to be no market for any more of them, or a very limited market at best…” because the reality is quite the opposite. Since the fall of communism, the Junak has become the most coveted/collectible of Polish motorcycles.

    • Paul Crowe says

      November 19, 2012 at 11:43 am

      Not sure what Paul meant by “If it’s no longer produced, there would seem to be no market for any more of them, or a very limited market at best…”

      My wording there was a bit clumsy, but what I meant was, unlike Aniket’s Musket V-Twin for the Royal Enfield, an engine modification he can sell to a current and fairly substantial group of RE owners, the Junak V-Twin would seem to have a pretty limited market if selling them was ever a consideration. Especially if the Junak is collectible, how many owners would want to destroy the original engine with this, admittedly very nice, but non-original configuration.

      • meowy84 says

        November 19, 2012 at 12:31 pm

        Ah yes, that makes sense. I’m not sure on the production numbers but I doubt they were very high and yes since it’s not currently produced like the RE and because of it’s collector status in poland not many owners would likely do such a conversion now for originality’s sake like you mention.

  6. bicho says

    November 19, 2012 at 12:33 pm

    Very nice bike!Doesnt junak mean hero,or brave(man) in polish?

  7. Hooligan says

    November 19, 2012 at 1:09 pm

    If 40 years ago you said today we would be discussing obscure Polish motorcycle manufactures and the collectabilty of their bikes?. You would be removed and unpersoned.
    So Cuba got some? Hmmm wonder where they are they are now?.
    Probably running a irrigation pump in Santiago Province.

  8. Jiro says

    November 19, 2012 at 2:21 pm

    Nice work by the creator. I especially enjoy the rotation of the heads, one 90 degrees to the left and the other 90 degrees to the right. The central cam is cool, and I wonder if the exhaust became the intake and vice versa on one of the heads. I would love to see more on this bike. Any more back story on the bike?

  9. B50 Jim says

    November 19, 2012 at 2:38 pm

    Good work! I’m always impressed when someone decides to build a twin from two singles, then does it. The intake should work very well, and the exhaust reflects that of a Vincent. I like the idea of using a car alternator, and wonder why more manufacturers don’t do it? Sure, the exposed belt drive looks a bit cobby, but it’s highly practical and delivers plenty of amperage while being inexpensive and easy to replace, which no motorcycle alternator can say. All in all, this Junak looks just right.

  10. Scotduke says

    November 19, 2012 at 3:45 pm

    Great stuff – actually seen a couple of Junaks over the years and one was even on the road.

    I do like this home-brewed v-twin.

  11. Paulinator says

    November 19, 2012 at 9:33 pm

    Really interesting build. As mentioned by Jiro, it looks like the rear cylinder ports have been reassigned. The exhaust is now sucking and the intake is blowing. The builder has apparently taken quite a bit of fin off the front cylinder head around the ports…to balance cooling? I wonder if the valves were re-sized, as well. I love this stuff.

  12. mlewis says

    November 20, 2012 at 12:30 am

    I recall one of the then current cycle magazines running an article on the Junak. They were impressed with the bike but not with the performance compared to “modern” cycles, and said it was so solidly built about the only thing that would be hurt if it were pushed over a cliff would be the paint.

  13. joe says

    November 20, 2012 at 5:41 am

    An interesting bit of engineering and appears to work well.From one side,the original single looks a bit like a BSA of the sixties.A neat looking bike. I never liked those left sided kickstarts, always felt wrong and awkward compared to the righthand kickstarters on other brands.

  14. Racetrack Style says

    November 20, 2012 at 1:06 pm

    The original bike has a very good stance & the proportions look just right. e.g. The entire rear of the bike: seat, shock location & angle, and rear fender all gel

    The rounded fenders compliment the overall bike very well.

  15. Scotduke says

    November 21, 2012 at 4:18 am

    joe – left side kickstarts take getting used to and I certainly found the one on my Morini odd as it followed the two Triumphs and three Japanese bikes I’d had before – only one of which had an electric start although that wasn’t dependable and I usually ended up kicking it over anyway.

    After a while though I found the Morini’s left hand starter easier to use. The thing is, with a left side kickstart you can have the bike on its sidestand while you’re to the left holding the bars and throttle and kick it over with your right leg. This way to don’t have to straddle it and hold it up or balance the bike while you’re kicking over the motor, so you can actually put more force into it.

    Going back to a right hand kickstart was quite difficult and I really struggled when I was last riding bikes with right hand kickstarts, an early 60s Norton Dominator and a late 70s bevel drive Ducati (also with an undependable electric start).

    • todd says

      November 21, 2012 at 12:08 pm

      The worst are old BMWs. each awkward outward, left side kick spins the motor a 1/4 revolution.

      -todd

      • Scotduke says

        November 21, 2012 at 4:48 pm

        Some Guzzi V50s built for the Dutch Army have a really weird kickstart – never tried to use one and I’d rather stick to the electric start. The oddest I have tried is on a Fantic 250, two stroke trials bike. It’s on the right as I remember but the really peculiar thing is that the starter turns forwards towards the front wheel, rather than backwards towards the rear wheel. At least it was only a 250 so it didn’t take that much effort at least.

  16. Johnny says

    November 24, 2012 at 9:15 am

    This is the best Motorcycle site. Its a place for tinkerers, engineers and plain old curiosity. Well done!

  17. Wulkan says

    February 5, 2013 at 3:40 pm

    Hello

    I know something about this Junak V-2.
    This is a manual design, which dates back to the beginning of the 80’s twentieth century, however, by the defect of design, this engine over the years could not be used for normal driving. It was not until about 2 years ago, my friend’s effort, the engine has been redesigned and improved (as much as it was possible) to the present.
    Now the engine is running well.
    Here are links to other videos from this Junak V-2 (most of them are from the first before the optimal setting).

    http://www.youtube.com/watch?v=2AwY9XR0gaA
    http://www.youtube.com/watch?v=WhUieDWhROc
    http://www.youtube.com/watch?v=Qz45ox59Zk8

    PS: I know 3 Junak’s V-2 (in Poland) in use, all done by hand but differ in design, in particular the timing system. But according to my knowledge only the presented here is often used for rides.

  18. Stary says

    February 5, 2013 at 3:51 pm

    Hi,

    I know the owner of that 700ccm Junak. Any questions don’t hesitate to shout 😉

    Cheers

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