grubee or regular motor

Discussion in 'General Questions' started by battery, Apr 30, 2015.

  1. battery

    battery Member

    I need to buy a new 80 motor for my bike. I was wondering if there is any difference in performance/longevity between the grubee long crank shaft or regular short crank shaft motors.

  2. Purple Haze

    Purple Haze Active Member

    Theoretically, a longer crank improves low-end torque at the expense of top-end rpm. In reality, these engines don't do well at high rpm anyway due to vibration.
  3. crassius

    crassius Well-Known Member

    just don't get a pre-2012 motor with unbalanced crank
  4. battery

    battery Member

    I did notice I was getting much higher rpm with the short crank motor. It also ran a little smoother. But it was also running leaner on the same carb. My ling crank did last me much longer. About 500 hard miles with the jack shaft kit getting me up to 50mph. What I like about the regular short crank motors is the head has more fins for cooling.
  5. butre

    butre Well-Known Member

    "half breed" engines are the best balanced of the common 66cc types, but need an extra base gasket or two and the top of the cylinder decked by quite a bit to make any real power. PK80 motors make the most power from the factory, but often need considerable crank balancing. GT5 motors fit somewhere in between. any other designation like "flying horse" or similar are just brand names and typically don't mean anything. anything branded by grubee, dax, screaming roo, arrow, jake, or other "boutique" brands are the fastest and most reliable, but they all come with a price tag that's at least double what an eBay engine costs, which is already double what they go for from the factory.

    the best reasonably priced engine now that rose is selling mostly lemons are the half breed motors from pistonbikes. if you want a real performer for under $300 without doing any really hard work get a half breed bottom from pistonbikes for $100 and a cr machine stage 1 top end kit for $180. then pick up one of mzmiami's snake pipe copies for $55 and you'll really be screaming
    Last edited: Apr 30, 2015
  6. battery

    battery Member

    So I should not buy the ebay motor that says rose 3236a in the picture? I was about to as it has the fastest shipping
  7. battery

    battery Member

    Well bought the rose motor. I believe it will be short crank.
  8. butre

    butre Well-Known Member

    a lot of rose motors are fine but the ones I've been getting have been pretty out of balance lately. not bad enough that you'll be stuck doing 15 mph but they'll definitely do some vibrating.