speed and low end questions and problems

Discussion in 'General Questions' started by noble b, May 21, 2012.

  1. noble b

    noble b Member

    so i just put a new 36t sprocket on my new bike to get a little more speed and it seems that its only going as fast as the stock 44t that came with the kit. im only hitting 24 25 tops when the wind is not in my face. also sense i changed it the low end is bogging down when i first start it kind of like when you switch gears to fast in a manual car is the best way i can explain it. on the speed is that normal? and what can i do about the low end? if any one can help i would greatly appreciate it.

  2. The_Aleman

    The_Aleman Active Member

    Sounds like your engine isn't tuned very well. I ran a 34T for several years and had no problems hitting 40 if I wanted to.
    Your setup is single-speed, it's not gonna have a lot of power at low rpm. But it should pick up pretty well at 15+. 24, 25 w/36T should be firmly in the torque band.
    These engines aint created equal, some are slow, some are fast, some vibe a lot and some don't. First place I would look at is your carburetor tho.
    Sounds like you're lean. Keep in mind: these aint motorcycles. They have limited power and capability. Don't expect too much out of em.
  3. motorpsycho

    motorpsycho Active Member

    ummm, any time you go to a smaller rear sprocket, you will lose low end torque and take off power.
    Look at a 10 speed bike, assume that you're peddling it....1st gear is a big sprocket on the hub...VERY easy to pedal from a stop, lots of low end torque, you won't get much speed because it's so easy to pedal, you will get up to the top speed quickly. it takes very little energy to get the bike moving, and it takes a lot of energy to keep the bike going at a decent speed.
    5th gear is a tiny sprocket on the hub, hard to pedal from a stop, no low end torque, but once you get it going, the peddling is easeir and your speed is pretty fast. it takes more energy to get the bike moving, but once it's moving it takes very little energy to keep it going at a decent speed.

    you will ALWAYS make a trade off when you swap rear sprockets. bigger than 44 tooth will give you more low end torque, less top end speed. smaller than 44 tooth will give you less low end torque, more top speed...you can't have both unless you go with a shift kit.

    what size wheels and tires are on your bike? taller wheels and tires will giove you more speed, shorter wheels & tires will give you more low end torque.
    the wheel and tire size also limits the top speed / low end torque.
    how much do you weigh?
    rider weight can also limit top speed and low end torque. if the bike has to pull 150 pounds from a dead stop, it will get up to speed faster than if it has to pull 220 pounds from a dead stop. but, weight shouldn't have much to do with the top speed because as we all know, heavier objects can move faster than lighter ojects once they're moving. (compair a car to a freight train.) a car and a train can both go 100 mph, but the train has a lot more weight behind it...more inertia, which takes A LOT longer to get it stopped. the car can hit 100 mph quicker than the train because it has less weight to pull.

    but if you are not getting any more speed out of it with the smaller rear sprocket, it is possible that your carb is not tuned right, to allow the engine to rev like it should.
    if it is too lean, the engine will bog at w.o.t. and the speed will be limited by that.

    as the aleman said, no 2 engines are alike....there are screamers and there are lemons.
  4. noble b

    noble b Member

    psycho im about 165 my wheels are 26" and as far as i know its not bogging out when i hit top speed also what is w.o.t. and yall have any suggestions on how to tune the carb.
  5. motorpsycho

    motorpsycho Active Member

    w.o.t means wide open throttle.
    tuning a carb is done by trial and error, because no 2 engines will run the same with the same jetting . if you do a search here, I'm sure you'll find a sticky thread all about jetting. and tuning . Al fisherman has some of the best tuning tips on here. I could explain it all to you, but it would take forever typing it out on my phone.
  6. noble b

    noble b Member

    I understand thank you ill check out al