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Thread: GK 4 stroke snowmobile engine, no gearbox

  1. #1
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    GK 4 stroke snowmobile engine, no gearbox

    Kev and Denis were discussing this on FB a couple of days ago,, and already it's lost in the disorganisation.

    Looks like a 650 cc einge with about 58 bhp.

    http://www.gk-engine.com/engine/6500...le-engine.html

    600cc-2-stroke-2-cylinder-motorcycle-engine56498928109.jpg

    800cc too:

    http://www.gk-engine.com/engine/800c...e-atv-utv.html

    800cc-v-twin-cylinders-snowmotorcycle-atv-utv03380398941.jpg

    Net weights include CVT and gearbox which could both be binned.

  2. #2
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    Thanks Steve

    https://wholesaler.alibaba.com/produ...280231805.html

    Ace Aviation sent over a picture of a Can Am Quad's Rotax V-Twin, as I'd designed them a simple reduction drive unit for the Briggs and Kohler etc., John wanted to discuss how to adapt his product to suit it. Water-cooling and fuel injection with four valve heads and wet sump made it attractive too, the power outputs ranged from 48 to 89 hp and no internal work at all to buy tuning parts for.

    His customer didn't realise that Ace Aviation don't mess with engines, only making redrives and trike/wing combos with ready made two strokes, so pulled the enquiry thinking John would steal his ideas.

    The big news I'd spotted immediately was that as Quad transmission is often auto via a variable belt drive, there was none of the usual grief converting a motorcycle motor, or hacking the integrated suspension off a scooter unit. A nice flat crankcase side and a part parallel output shaft means adding a redrive plate was easy, just unbolt the case, trace the bolt pattern and mount the plate using longer bolts and stand off spacers, or an alloy ring mimicking the outer profile.

    The Chinese unit in the link looks like a copy of the Rotax 800cc, and claims 56 hp, sitting nicely between a 503 or 582. With transmission it is only $2045 plus shipping, so may be even less if ordered as engine only.

    You'd need a wiring diagram from the engine makers to power the EFI, plus a suitable regulator for charging, and maybe a spare casing gasket to allow it to be unbolted to sort out the hole pattern but this looks a bargain compared to getting the same go out of an industrial engine?

    I'm quite excited about the potential; That Quad engine is going to be built to run around in mud and forests, on farms or thrashed on roads, there is only external work to do hooking up fuel and electrics, the makers will produce their own settings manual for service. Reckon the most attention will be finding a way to mount it strongly on a trike frame

    The key point was finding a ready-made four stroke of the right weight and power, that also doesn’t happen to be lumbered with a motorcycle gearbox to get rid of, and isn’t fitted with a massive heavy flywheel to suit a piece of agricultural machinery. It is designed for a pretty similar range of power output and as aircraft owners will fuss over it and change oil regularly, should run forever.

    I wish that thing had been around when messing around with the Briggs, the cost of the engine whole with fuel injection is less than the cost of the tuning parts I had to buy…

    link I sent you was for $2008 and that was complete with variable auto belt drive and a 4wd gearbox. Engine on its own should be a lot less.
    Chinese V-Twin makes 56 hp, enough to fly a two seater, you would need 20 grooves in my reduction drive pulley, so a 72 mm wide belt. Rest of the parts are many enough for that job.

    Cheers

    Kev
    G-KEVA
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    650 is 41 KG without the CVT judging by the rest of the range. Two slim exhausts and a redrive together with a radiator probably 48KG. Looks like a very good alternative to a 503, albeit a bit tall but what a motor. Worth the back of an envelope to work out if it will go in a MiniMax!

  4. #4
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    Engine Pricing Structure small.jpg650 is 41 KG without the CVT judging by the rest of the range. Two slim exhausts and a redrive together with a radiator probably 48KG. Looks like a very good alternative to a 503, albeit a bit tall but what a motor. Worth the back of an envelope to work out if it will go in a MiniMax![/QUOTE]

    One I was looking at is 46 kilos but kidding my self not to add radiator and coolant, anyone hazard a guess?

    Spec on the Quad motor

    Engine:

    1.Model name: KB2V91MW
    2.Engine type: 4 stroke, 8 valve, EFI, 2V cylinder,Gas Engine

    3.Displacement: 799ml
    4.Bore×stroke: 91×61.5mm
    5.Compression ratio: 10.3:1
    6.Ignition: IDI (Inductive Discharge Ignition)

    7.Fuel supply type: EFI

    8.Cooling system: Liquid-cooled
    9.Starting system: Electric
    10.Max torque and rotate speed: 70N.m@5000r/min
    11.Rated power and rotate speed: 42kw@6500r/min

    42 KWatts is 56 horses but GK quote more, perhaps transmission losses; good swap for a 503 or accept a loss and replace a 582, around half the fuel burn so gross weight for a journey is similar.

    Here's the prices for the engine, that is actually lower priced than the Briggs 23hp industrial engine before tuning and flywheel lightening! To this I'll have to fund carriage ($500 to the USA) and VAT probably
    Attached Images Attached Images
    Last edited by Kevin Armstrong; 30th November 2017 at 20:04. Reason: added spreadsheet picture
    G-KEVA
    BMAA 5696

    "If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: it's all balls."

    R.J. Mitchell :- Designer of the Supermarine Spitfire

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    The only difficulty is that the engine is 23 inches tall but It really needs to be put in a MiniMax. I could see it burning around six litres an hour at a decent cruise and sounding just fabulous. I think I shall have to mock up a max firewall and start saving up my pennies. If it will fit, it would make the perfect powerplant.
    Carriage to UK may be less than US. Does it rotate clockwise, looking at the PTO? Suppose I could set it low down... (goes off to fetch slide rule...)

  6. #6
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    Quote Originally Posted by tomshep View Post
    650 is 41 KG without the CVT judging by the rest of the range. Two slim exhausts and a redrive together with a radiator probably 48KG. Looks like a very good alternative to a 503, albeit a bit tall but what a motor.
    It would be nice to think that some effort might be made to replace 503/462 units for which spares can no longer be had.

    It might be interesting for the Tech Office + volunteers to look at an orphaned microlight with 503/462 and see what could be done to mod to accept this engine instead, to extend the life beyond the point where the engine spares are no longer be had.

  7. #7
    Quote Originally Posted by tomshep View Post
    The only difficulty is that the engine is 23 inches tall but It really needs to be put in a MiniMax. I could see it burning around six litres an hour at a decent cruise and sounding just fabulous. I think I shall have to mock up a max firewall and start saving up my pennies. If it will fit, it would make the perfect powerplant.
    Carriage to UK may be less than US. Does it rotate clockwise, looking at the PTO? Suppose I could set it low down... (goes off to fetch slide rule...)
    Redrive would put the prop shaft higher up so height may not be such an issue ??

  8. #8
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    DSC_0136.jpgDSC_0135 (002).jpgDSC_0123 (002).jpgUpdate:-

    After removing the gearbox and belt drive, had a lucky discovery, apparently they must have an eye on the general industrial market as it would be a superb fire pump or similar application where high power and low weight is required. A full SAE bolt pattern undrilled was cast into the cover, so an Ace reduction drive bolts straight on after tapping out the cast holes. Helicoils were added to allow more torque on the bolts, but decided to add in more beef on the redrive and propeller mounting. This took the form of simple plates bolted to the upper cylinders into yet more spare threaded holes, as the intention is to make it really easy to convert for micro use.

    After playing with lots of bolts and spacers a direct thrust line (or pull line if in a tractor rig) was established so the prop pushes through spacers to a tubular link to the trike pylon/seat back area.

    Off the shelf rubber mountings, actually engine anti vibration mounts were fixed, one on back of trike, one on engine with tube between to take thrust without hopefully transmitting vibrations.

    where the gearbox bolted on is a strong point so sketched up a simple mount using the rubbers retrieved from the gearbox mounting, the two aren't opposite each other so used 3"x2"x1/4" alloy angles in 6082(T6) running across; the angle is made in imperial sizes for some weird reason, although my drawings are all metric.

    Left to do:-

    Got the adapters to create exhaust stubs, as this is fuel injection need to create pipes at least 700-800mm long to allow fitting the oxygen sensors far enough from the exhaust port to give decent longevity, at least 300mm, also need at least 500mm after the sensor to prevent air getting back up and messing up the sensing.

    Wiring is something I loathe but luckily the harness provided has each special plug to each socket on the engine parts, so you just plug it all together, if the plug matches it is correct, luckily noticed on the pdf diagram they sent that No One Cylinder injector feed wire, coil supply and oxygen sensor are all tape marked, sure enough each feed had a yellow marker.

    Reckon for Microlight use the option for the carburated engine would suit a wider audience, as then its just mount, exhaust and radiator to sort. Certainly vastly less piping than a 912 for instance, probably comparable to sorting a 582
    G-KEVA
    BMAA 5696

    "If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: it's all balls."

    R.J. Mitchell :- Designer of the Supermarine Spitfire

  9. #9
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    Great stuff! I favour fuel injection as you will not have icing difficulties and the fuelling will be unaffected by attitude. Looks like a lovely engine.

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