Lower gearing options

Discussion in 'Motorized Bicycle General Discussion' started by FlyingHorse87, Jun 30, 2010.

  1. FlyingHorse87

    FlyingHorse87 New Member

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    I started breaking in my first build yesterday and it's become apparent that a bigger rear sprocket is needed. I know the engine will have a little more power when broken in, but I weigh 250 and theres a lot of hills were I live. I found a 60 tooth sprocket from BGF and seen that King's make sprockets up to 80 tooth. Are there any other options? I thought about buying an off the shelf sprocket for #41 chain and drilling mounting holes in it, has anyone tried this?
     
  2. corgi1

    corgi1 New Member

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    Where did you find off shelf sprokets that big? And drilling is possible as long as it is really centered
     
  3. mapbike

    mapbike Active Member

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    Several places online that sell parts for goKarts have 48T, 60T & 72T sprockets for the #41 chain.
     
  4. mapbike

    mapbike Active Member

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    I have a 36T on a bike right now that I paid $8 for and then drilled it myself it works great..!

    I would not go with a 60T, if it were me I would go with a 48 - 50T, BGF sells the 50T on Ebay, a 60T will leave you with a very low top speed like maybe 15-17MPH or so, you would have plenty of power but no speed at all, I am 200lb's and I really like the 41T I also live were there are hills but it will pull me up a pretty good one and still run 20-25MPH when I get to the top of most of them, and about 15-18 on a couple of pretty long ones.
     
  5. Goat Herder

    Goat Herder Gutter Rider

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    At 6 foot tall 250 pounds I haul all manner of grocery's etc. A 40 tooth was my all time favorite. How is that motor breathing they are very finicky about restrictive air filters.
     
  6. BarelyAWake

    BarelyAWake New Member

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    Hmm...

    Usually ppl find that after break in they're engine runs a lot better and the stock 44t geared a lil low if anything, I'd recommend holding off playing with the gearing for a lil while till that's sorted - once the motor is fully broken in and you've the fuel/air mix adjusted - reevaluate *shrug*

    You may indeed find you still want to regear, but until the engine is dialed in fully you may under/overestimate the amount and need to do it again... just a thought - I find changing/mounting the kit sprocket tedious at best lol ;)
     
  7. FlyingHorse87

    FlyingHorse87 New Member

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    Thanks for all the ideas. I ordered the 60T from BGF last night, that should give me plenty more torque. I'm not too worried about to speed, just using it as basic transportation around town and camp.
     
  8. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    I concur with Barely, Your engine will get more power the more it breaks in!
     
  9. CoastalCruiser

    CoastalCruiser New Member

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    Isn't there a smaller pinion gear available somewhere? That'd lower the ratio.
     
  10. ferball

    ferball New Member

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    I weigh in a 320-325. I run the stock 44t sprocket, I have a few hills, and I do need to pedal assist on one but honestly I was very surprised that at how little I do end up pedaling consider all the hills in my area. The only reason I have contemplated the larger rear sprocket was for taking my bike off road. I still might switch it because I find that the only time I ever run full throttle is when I go up hill, on level ground 1/2 to 3/4 throttle is more than fast enough on my deathtrap MB.
     
  11. FlyingHorse87

    FlyingHorse87 New Member

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    I agree about almost going too fast with a 44T sprocket, my bike can barely stop from top speed. Maybe the coaster brake just needs adjusted? What brand and size engine are you running?
     
    #11 FlyingHorse87, Jul 1, 2010
    Last edited: Jul 1, 2010
  12. ferball

    ferball New Member

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    Not sure of the brand, i think it was PX-80 or something like that, it is slant head everything stock, except the spark plug which I upgraded this morning which seems to smooth out the ride when I at WOT. Way more fun than a grown man should have.
     
  13. Tad Bit Tipsy

    Tad Bit Tipsy New Member

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    I would keep my money in the pocket until you have broken the engine in, then make a decision on wether to go up or down on tooth count. Yea I've seen some people with up to 72 and 80T on a sprocket and they run ok, but your 2-stroke is going to be pushing hard to go over 20 to 25. If that's ok then go for it, but I would baby step my way up. Switch out to a 48T, then go into the 50's or 60's, but jumping straight to something way up there could be a disappointment.
     
  14. taddthewadd

    taddthewadd New Member

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    I have a stinger 66cc with a SBP expansion chamber. I have a 38T and a 56T. For me the 38T was too fast and ran really crapy at low speeds. Then I put the 56T wanting to go off-road. What a world of difference. At all speeds the engine sings along beautifully. It almost takes off from a standstill without feathering the clutch and accelerates to top speed almost instantaneously. It runs great off-road and on-road. To me it is the perfect balance for both. I would estimate it runs around 15-18 mph at a comfortable rpm (not vibrating real bad, about 2/3 to 3/4 throttle) which is about as fast as I could go without the engine so brakes still are very efective.

    When I was 20 years old I would have tried to make this bike go 50 mph and probably end up in the hospital but now I am 29, married, and have an 18 month old son. So now safety is more important and the bike is more reliable and safer at 15-18 mph with the 54T. It is also very good at climbing very steep dirt paths in the mountains (my bike is a mountain bike).

    Hope this helps.
     
  15. FlyingHorse87

    FlyingHorse87 New Member

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    Thanks tadd! Even though it's still breaking in the 44T just isn't cutting it for me, all there is are big steep hills in my area. People actually come to ride up my street training to race up a local mountain!
     
  16. taddthewadd

    taddthewadd New Member

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    Hopefully you like that 60T. If not you can always change it.
     
  17. taddthewadd

    taddthewadd New Member

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    For me I wouldn't want to go any bigger than 56 (I weigh about 165 #'s), but it sounds like your hills are pretty steep so the 60 might be perfect for you.
     

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