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Thread: New four stroke twin

  1. #1
    Diamond geezer 500 Club
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    New four stroke twin

    http://www.flydiver.com/HTML/JCV-360Specs.htm

    Spotted a new Verner engine on their website; liquid cooled flat twin, very light indeed; perfect for SSDR trikes as air cooled is patchy for reliability.

    Is this what the HKS should have been?

    Kev

    Attached files brochurejcv-360.pdf (124.9 KB)

  2. #2

    New four stroke twin

    Seriously high RPM... only 180cc... Love to hear that going, would bring a new sound to microlighting reminicent of what the Honda RVF brought to bikes...

  3. #3
    Diamond geezer 500 Club
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    New four stroke twin

    Hello Brian

    If you do the math its 175cc in each cylinder, or near enough 350 cc; that's 62mm bore x 58mm stroke each pot.

    That's about 100bhp per litre, pretty conservative in the motorcycle stakes. (My bike's the soft tune version at 675cc and 100bhp, the sports is 120bhp or 178bhp/litre)

    Looks to me like they've done the same trick as the old aircooled unit; used off the shelf parts bolted onto a custom cast or CNC crankcase and crank, this time liquid cooled to get the horsepower per cc up.

    This looks like two 175cc commuter bike unit barrels and heads, each producing max 17.5bhp with 14.5bhp continuous.

    Again equivalent to a commuter bike in fast cruise, and a softer state of tune than a 125 learner legal bike.

    That engine would shave ten or twelve kilos off the average weight of a 447 on a Chaser, and put it straight inside the SSDR weight and wing loading limits, yet keep the pod and so on.

    If it's real, it's big news.

    Kev

    PS they mailed back to say

    Price e4,480

    Exhaust e250

    35bhp @7,500 rpm (max 5 mins)

    Max continuous 29bhp @6,400 rpm

    Engine Dry wt 26.7kg

    Exhaust 1.58kg

    Water Cooler wt 0.75 kg

  4. #4

    New four stroke twin

    Hello kev

    Ahhhhhhhh...

    Forget to switch the brain on some days...

    I have recently been looking at the engine on the Verner site and only done half the maths... it's a twin of course and now the 360 name makes sense! As a previous owner of a verner engined x'air and contrary to popular sentiment, I am a bit of a fan of the simple engineering philosophy they employ, their customer support is good also.

    We just need a dealer in this country to stock a couple now, maybe I could persuade a loan of one to bolt on my SSDR Trya, I'd happily give it a go.

    Cheers

    Brian

  5. #5
    Diamond geezer 500 Club
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    New four stroke twin

    If they are right about the weight, a standard permit single seater Trya was around 126 kilos; target weight for SSDR was 110 kilos as the wing was 11 square metres

    Using that engine saves around 13 kilos over the 447, plus the iron engine mount was 'orribly heavy; three kilos should be pretty simple to shave off with plastic wheels, and maybe alloy instead of steel wing hang bracket cheek plates. I'd also bin the strut suspension and go for Chaser style bracing wires.

    That would be a nice little machine with a big fuel tank and luggage space too. Quite the SsdR tourer we've been looking for.

    Who's first for the plunge? I didn't know the backup was so good.

    Cheers

    Kev

    PS it would be wise to bargain out of them the origin of the motorbike parts though, so that spares can be had if the Czech company disappears...

    Brian Fallows wrote:
    Hello kev

    Ahhhhhhhh...

    Forget to switch the brain on some days...

    I have recently been looking at the engine on the Verner site and only done half the maths... it's a twin of course and now the 360 name makes sense! As a previous owner of a verner engined x'air and contrary to popular sentiment, I am a bit of a fan of the simple engineering philosophy they employ, their customer support is good also.

    We just need a dealer in this country to stock a couple now, maybe I could persuade a loan of one to bolt on my SSDR Trya, I'd happily give it a go.

    Cheers

    Brian

  6. #6
    not real name 500 Club
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    New four stroke twin

    I still don't like the price tag - since the 447 is much less than half that. Does anyone know of any good (small) epicyclic gearboxes so that a decent motorbike single can be clagged to it.

  7. #7

    New four stroke twin

    Bill for that sort of power would a belt drive not be a lighter cheaper option?
    When you say a 447 is less than half the price is that a complete engine, box, carbs and everything or just a bare motor?
    Also would not a lot of the savings not be eaten up by having to remove the original gearbox and sort out new crank cases?
    I think that the days of really cheap engines are over. Even if the base engine is cheap by the time you've mucked about making it suitable for aircraft and given the very small customer base the unit cost is going to be quite high.

    I hate these engine threads I always come over as really negative. I'm not, honest, but I just don't see cheap power being an option these days.

    I'd love to reengine my S5 but the MZ201 is about 3.5K, the rotary thing is around 5K and solo is around 3.5K It just doesn't make sense on an aircraft with a value of 2.5K.

  8. #8

    New four stroke twin

    Belts have a huge advantage (especially V-belts), because they absorb the torsional vibration between prop (=flywheel) and engine (crankshaft accelerates/decelerates between power strokes). The Rotax boxes just about crack the problem with their dog clutch and cush drive, but there have been many casualties on the way. Witness the Hewland two-stroke gearbox in the ARV Super 2. It kept breaking - and Hewland's speciality was racing car gearboxes!

    We used to get considerable wear on the teeth of the alloy toothed belt pulleys due to abrasive runway dust. That's why I prefer V-belts to toothed - plus they're more elastic - despite extra weight and slightly lower efficiency.

    Dave

  9. #9
    Diamond geezer 500 Club
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    New four stroke twin

    Hello Dave, I'd appreciate your input.

    Jezza Harris was insistent that toothed high capacity belt was the way to go, but I'd got personal experience with the virtues of Polyvee in industrial applications, and they are certainly the thing they choose to use in car accessory dirves for long life where timing isn't a particular issue.

    Even Paul Robshaw's earlier German Vee twin had Polyvee for the drive off the vee twin.

    However toothed slender belts such as these

    http://www.chris-knight-mcs.co.uk/ac...nversions.html

    seem to work well too.

    I reckon the belt is a better drive if well designed than a gearbox; it only looks old-fashioned.

    Kev

  10. #10
    not real name 500 Club
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    New four stroke twin

    If Jezza says it's all right, that's good enough for me. Damn, it is a pity he does not join in any more - a very valuable member he was.

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