have a 2 stroke and would like to get a lil more speed

Discussion in 'Frame Mounted Engines' started by billy270, Jun 23, 2010.

  1. billy270

    billy270 Member

    i am building a 26 inch beach cruser.... what are the best ways of geting speed out of it i waigh about 200lbs i had 1 custom bike i done it was about 31 mph with out the baffel in the exaust all stock kit... i see some thing on the sprokets for the rear.... what would a 46 do over a 44 and how about a 50 over a 44 i am real new to this so be cool about it plz how about the carbs for the 80 cc any help is good
     

  2. beentryin

    beentryin Member

    smaller sprocket size means more speed bigger gives more power on lowend
     
  3. billy270

    billy270 Member

    so lets say i put a biger one on it would not go as fast..... and if i put a smaller it will go faster ...... so what if i was to put a biger sproket on the motor and a smaller in the rear prehaps revers with a 44 on the motor and a smaller on rear..... i need to be able to pick up speed fast and still have good enough power to haul my tool box ....
     
  4. beentryin

    beentryin Member

    if you go bigger in the front sprocket its like putting a smaller one on the back .so if you put bigger in front and smaller on back that'll be way to big of a jump for the power band of the motor.you will not have no lowend power for takeing off or hence getting you to top speed.or you can go with a shift kit to keep power up thru the gears
     
    Last edited: Jun 23, 2010
  5. billy270

    billy270 Member

    i dont know much about the shift kits i am reading a lil about them but my bike dont dave gears......
     
  6. Dobroknow

    Dobroknow New Member

    more speed...

    If you only have a one-speed cruiser , and a one-speed motor you don't have many options .
    i have worked on that combination for some time , just get a 36 tooth sprocket , and an expansion pipe if you have the $$$ .
    The shift kit is the only way to get low end take-off power AND high speed , 40 mph + . But you need to start with a multi-speed bike .
     
  7. billy270

    billy270 Member

    how much work u think it would be to start with a single speed and do u think the walmart schwinn is a good canidate for the shift kit
     
  8. NoelTheMole

    NoelTheMole New Member

    I'd actually like to know more about this aswell. I haven't built my bike yet, but I actually prefer 1-Speed Bikes. Does this severely limit my ability to go fast on the low and top end? Would an expansion pipe give me enough of a boost?

    I think my main concern is being able to take off fairly quickly as well as go up steep hills.
     
  9. AussieSteve

    AussieSteve Active Member

    Billy, first up, you really should have posted this in the 'Frame-Mounted Drive Trains' section, if it's a gearing problem, to get the most appropriate answers.

    It sounds like you're actually looking for more torque rather than speed, to carry weight.
    A speed increase, (gearing-wise), will decrease the bike's ability to pull a load.
    Some engine mods will be in order if you want both, with a single-speed bike.
    An expansion chamber will only give a decent power increase in one part of the rev range, the rpm that it's 'tuned' for. (Still worth fitting. I have one here that I'll fit soon when I get the time.)

    To get what you want, it's worth fitting gears and a shift kit. Best thing since sliced bread. I have one on my bike and would never go back to a single-speed.
    5mph in first, 50mph in 6th on a gradual downhill. Can climb anything.
    (There's some pics of the shift kit drive train in the album on my profile page.)
    How many other motor vehicles have only one gear? There's a reason for that.

    Billy, I meant to add this link. JPilot's Gear Ratio Calculator. It's a gear ratio calculator, (as the name suggests), that will calculate rpm for speed at a given gearing.
    Best way to get an accurate result is to sit on the bike with your weight evenly distributed and the valve stem at the bottom, then roll forward one turn, measure the distance covered, divide by pi, then enter that as the 'diameter' value.
    The primary gear is 20 teeth, the secondary is 82 teeth, countershaft is 10 teeth, then enter the rear sprocket size.
    Leave the other boxes as they are. (1:1)

    Let me know if I've forgotten anything.

    Noel, for your intended use, go with low gearing. ie. Large rear sprocket.
    (Low speed, higher torque.)
    That's the best for fast acceleration and hill-climbing.
     
    Last edited: Jun 28, 2010
  10. NoelTheMole

    NoelTheMole New Member

    Will I still be able to reach speeds up to 35mph? I just cant see myself spending $160+ on a shift kit when thats how much the engine kit costs.
     
  11. AussieSteve

    AussieSteve Active Member

    Needless to say, a shift kit will give you a higher top speed than with a single speed.

    You get what you pay for.
    If you want heaps better performance without spending any money.....?
     
  12. Stan4d

    Stan4d Banned

    Very good advise...I would add that using the search function, you might have found your answer. Or a thread that is already started on the subject. I have moved the thread to the appropriate fourm.
     
  13. NoelTheMole

    NoelTheMole New Member

    Well what is heaps better performance?

    Will the shift kit have me going an extra 10mph?

    Can I get nearly the same performance by installing a Racing Carburetor or new Exhaust?

    If I can get an extra 5mph with the Racing Carburetor at $50, that seems like a better value to me than 10mph with a Shift kit at $200
     
  14. jarz24

    jarz24 New Member

    gday guys,

    i have a 70cc star fire engine kit on a 26 inch bicycle. to my knowledge everthing is running great but i have a on board computer and it telling i only reaching up to 22 to 25 km's on full revs. i just can't seem to get anymore speed out of the bike.

    anyone got any ideas on would could stop it going faster?
     
  15. AussieSteve

    AussieSteve Active Member

    Noel, I meant all-round performance. Originally you said 'I think my main concern is being able to take off fairly quickly as well as go up steep hills.'

    That indicates that you want more torque rather than speed, hence my recommendation of a shift kit.

    Now you want more speed, so buy an expansion chamber and a smaller rear sprocket.
    That will make a bigger difference than a carb change. Many people have a lot of tuning problems with after-market carbs.

    Sure, the shift kit makes the bike faster, a good 10mph in my case on flat ground, but it has all the other benefits as gears. Your engine won't be constantly screaming as you ride down the road, the bike will be controllable at low speeds and it will pull up any hill if you set up the appropriate ratios.

    If you want more power only, the best increase for money is an expansion chamber.

    Have you searched and read the reviews on these products?
    I suggest that you do that.
     
  16. AussieSteve

    AussieSteve Active Member

    It's not really appropriate to hijack the thread with a separate problem.
    I suggest that you start a new thread in '2-Stroke Engines', outlining your problem.
    When you do, describe your plug colour as well. It will tell the story, more than likely.


    This bit doesn't make sense to me.
     
  17. Stan4d

    Stan4d Banned

    Steve's suggestion is second best....SEARCH, read and search and read some more. You did well by trying to post to a thread that seemed to be related and for that I give you kudos.
     
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