This bike is a bomb

Stolen bike is a science project with explosive potential.

“Jon” in Halifax NS posted an ad about his stolen Norco Bush Pilot commuter bike with a prototype engine that can “grenade violently” if it’s not fueled correctly. The engine was part of a project studying low emissions motors.

Explosive bike motor

The karmic blowback potential is marvelous, but it appears the bike’s owner really needs the engine back for his project.

Via this news story via Marcus in New Dehli.

6 Comments

  • September 27, 2011 - 11:32 am | Permalink

    Guess the New York press was right about the dangers posed by letting cyclists ride in bike lanes past foreign embassies. Especially now that we have access to grenade bike technology.

  • September 27, 2011 - 11:44 am | Permalink

    The juice box is a storage tank for fuel air mixture that’s drawn into the engine when the carburetor can’t keep up at WOT. I’m guessing the explosion would come from this box rather than the engine itself.

  • jdexter
    September 28, 2011 - 3:35 pm | Permalink

    Sort of Edwin – the motor is stroked/decked to run 17/1 compression. Above is a much older photo of a different engine on the mount. Here is a more recent shot of the engine:

    http://novascotia.kijiji.ca/c-buy-and-sell-bikes-No-questions-asked-250-reward-Norco-Bush-Pilot-Motorized-Bike-W0QQAdIdZ317194272

    I stuffed the case, ported and windowed the case and skirt to create a pressurized ‘strata-charge’ pulse back to juice box in-line on the manifold. So – the juice box is now operating a collector for the case charge.Was burning a little over 3/4 tablespoon of fuel per mile hauling about 260pds on 39CC’s (me + bike + slide rule)… BUT ..Requires that there is *no chance* of pre or post ignition or the entire charge cycle (case/box/head) can go off at once under pressure. Hence special mix, modified coil and regular port cleaning.I was thinking about an arrestor or a case/manifold blow off valve this winter, but it appears unlikely I’m going to get the chance now… damn-it ..

    Jon

  • September 28, 2011 - 3:48 pm | Permalink

    @Jon – The gear head engineering is all Greek to me, but let’s see, that 3/4 tbls per mile works out to something like 300 miles per gallon, right? or, for you Canadians, 130 km/litre.

  • September 28, 2011 - 4:31 pm | Permalink

    Simplified explanation (if I’m understanding this correctly):

    The stoichiometric ratio, which exactly matches the number of atoms needed for the reaction (CH chains in fuel + O = CO2 + H2O) for gasoline is just over 14:1 air/fuel. However, factors like fuel mixing, cooling the cylinder head, preventing nitrous oxide production (heat + oxygen + nitrogen = NOx) and the like mean most engines run at 12:1 or richer.

    (BTW, This is why you can’t have a “magic” carburetor: Even if you can run at the stoichiometric ratio you aren’t going to see a 100%+ improvement in gas mileage like some have claimed.)

    What Jon is trying to do is strata-injection: A rich fuel/air mixture gets the ignition started, and then the rest is handled with a lean fuel mixture. Honda’s old CVCC engine did this with two fuel/air mixes going into the cylinder via different valves, and direct injection systems do this with multiple gas pulses before ignition. Jon’s system divides up the mix outside the engine using the juicebox as one of the air/fuel mixtures. Add in the high compression ratio, and you have a very, very efficient and powerful (for its size) engine. On the other hand, you also have something that can be very finicky about operating conditions, especially detonation and, if the system isn’t flowing right, backfiring…into a metal can filled with an air/gas mixture optimized for combustion.

    This is a cool project, and I hope he gets his bike back.

  • jdexter
    September 29, 2011 - 7:04 am | Permalink

    Thx Edwin, you’ve got it and indeed, the system is finicky – and I’m using the juicebox well off it’s intended pressure rating (note the tie-down and the flash burn on the old plastic shroud).

    Closer to 80/90km to the litre CL .. The fuel formula doesn’t/can’t create as much power as straight gas and oil (I’d need to cast a custom head and really reinforce the case) , but overall provides improvement of about 20k to the litre. I was hoping for better – but that was the ‘prototype’ part.

    Also – given it is not a variable ignition, it is greatly impacted by weather conditions. Cooler provides better mileage – warmer, worse.

    I still remain amazed anyone would steal the silly thing – the bike was modified enough that it is not really ever going to be a bike again and the engine is pretty much un-saleable given it is a one off.

    Feeling pretty damned foolish to be frank – just never considered a situation where that engine would be under someone else’s butt.

    Appreciate your help getting the word out – at this point I’ll be glad if it doesn’t get sold to some kid who fires it up and gets the surprise of a lifetime.

    Thx – Jon

  • Leave a Reply