Changing to a 4 stroke

Discussion in '4-Stroke Engines' started by Tyler6357, Mar 11, 2012.

  1. Tyler6357

    Tyler6357 Member

    I think my 2 stroke engine is dead. I'm thinking of replacing it with a 4 stroke engine I'm thinking of getting a center mount 4 stroke and sticking with my current chain direct drive but I have some questions.

    (1) Can I use most of the same parts I have from my 2 stroke kit? Can I just buy a new 4 stroke engine or do I need to get a new kit too?

    (2) Are the 4 stroke engines much heavier than the 2 stroke ones? Can you still peddle with the engine off if you have to without having a heart attack?

    (3) Can I expect an increase in speed and power if I get the 4 stroke?

    (4) Will my bottle boost upgrade work the same with the 4 stroke?

    (5) I was thinking of getting one like this maybe.-----> http://www.bicycle-engines.com/49cc-powered-stroke-engine-shaft-p-157.html
    I will be using it on pretty steep hills in my area. What engines do you recommend?

    (6) Anything else I should consider before getting a 4 stroke?


    Here is a pic of my bike!!
     

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  2. #1. No, the motor mounts will be different. The final drive chain and rear sprocket can remain. I expect you will need to buy a speed reduction gear box, chain reducer, or belt driven reducer. It might be possible to find a 4 stroke engine your present reduction set up would fit, but I wouldn't bet on it.
    #2. Just a little heavier. Not enough to make much difference when pedaling.
    #3. Not a big difference, depending on the engine. A 4 stroke of the same displacement might have a bit less high RPM power, but have a bit more low RPM torque.
    #4. No.
    #5. The gear ratio will have a great deal more to do with your bike's ability to climb steep hills than the engine choice.
    #6. Have you considered a quality Japanese 2 stroke, like a Mitsubishi, or Tanaka? They will give as good or better performance and are much longer lived and more reliable than any Chinese built engine, 2 or 4 stroke. I know the Tanakas and I think the Mitsu are CARB and EPA approved, so will be readily available in CA. The Japanese Honda and Subaru-Robin 4 strokes are also better, but are wider. Width of a 4 stroke is the problem when mounting them in the frame, rather than on a rack above the front or rear wheels. You will need a wider set of pedal cranks to clear a wider engine. Using the direct drive and clutch system you are using now, instead of the centrifugal clutch and recoil starter most 4 strokes and the Tanaka/Mitsu use, will allow you to narrow a 4 stroke quite a bit, but the engine will still be wider than what you have now. Finding a manual clutch to fit, or modifying a new 4 stroke orTanaka/Mitsu to use your clutch might be difficult. I prefer a recoil starter and centrifugal clutch, but that's just me.
    If I was thinking of doing this and had to have an in-frame mounted engine, I would consider purchasing a new EZ 4 stroke kit and scrapping what you've got now, in spite of it being a Chinese made 4 stroke. Look over EZs kit and see what you think. My first choice would be a Golden Eagle or Staton-Inc drive kit with a Subaru-Robin or a Tanaka on a rear rack type set-up.
     
    Last edited: Mar 11, 2012
  3. Tyler6357

    Tyler6357 Member

    Thanks for posting! To be honest, I haven't really considered anything yet. I was just thinking of upgrading to a 4 stroke engine and wondering how reasonable it is for me to do so. Thank you for answering my questions. I will check out those Japanese 2 strokes. If I can get a decent 2 stroke that will last and is 66cc's then I am happy to stick with the 2 strokes. I was kinda assuming the 4 strokes are better, more powerful and more durable too but maybe I was wrong about that. This is my first MB and I'm still kinda new to this hobby but I sure do love to ride it. I will check out those EZs too. Also, I might be able to fix my current 2 stroke engine.
     
  4. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Check out Affordable Go Karts in Santa Barbara.
    They make some very nice 4 strokes and they are an EZ Motorbike dealer too.

    Affordable Go Karts also races the fastest motorized bike at the SoCal Motor
    Bicycle races.
     
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