more top end speed after run in

Discussion in 'Motorized Bicycle General Discussion' started by 4wdingman, Dec 24, 2008.

  1. 4wdingman

    4wdingman New Member

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    will my 70cc happytime motor gain more top speed after run in cauce i have done 50km and it can only get up to about 40km?? Could it could be cauce i am not getting enough air into the carby?
    Thanks
     
  2. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I have had kits that ranged from 25 mph (40 kph) to over 35 mph (60 kph).

    A lot depends on the engine, which intake it has, how well the ports are matched, what type of muffler, ect.

    Most all of them can be made to run 50-60 kph with a little work.

    Break-in does help, but I think a lot of it is due to "tweaking the engine and components" during the break-in period.
     
  3. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    How is your mixture? What color is the plug?...that's where I'd start.
     
  4. 4wdingman

    4wdingman New Member

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    well i am running 20 to 1 and the plug is a nice brown colour!!
     
  5. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    You'll get a little more power and maybe speed if you go to 24 to 1, or even 30-32 to 1 synthetic oil.

    How's the break-in going? Has it picked up any speed yet?
     
  6. Spunout

    Spunout MB Builder Extraordinaire

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    i noticed a big difference in out-of-the-box power, between bushing and bearing motors.

    bushing motors were quick from the start, but bearing motors dont achieve total power until you're into the third tank.

    its a new motor. everything's tight, and the rings havent seated yet.
     
  7. 4wdingman

    4wdingman New Member

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    well when i first got it, it had a bit of power but no top speed so i drilled some holes in the carby filter cover and that made a bit of a different to the top speed but it seems to be not getting enough air.
    Like when i ride i can put it full and it will get up too a speed and then the exhaust will make a vibration noise and it just wont go no more.

    Thanks
     
  8. Dave31

    Dave31 Moderator
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    Have you checked your motor mounts? It is possible the fuel is foaming in the carb due to lose mounts or excess vibration.

    :-||
     
  9. 4wdingman

    4wdingman New Member

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    well I have rubber between the frame and the mounts,and it is a smooth to ride.

    Thanks
     
  10. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Sound like it is going into a four cycle when it "gets there". Try a leaner carb setting. (one notch up on the needle.)
     
  11. old motorbike

    old motorbike New Member

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    So far, new (16:1) it reached 28 mph with 44 tooth. After a few hundred miles, 24:1 with a shift kit it has gone 36 mph with a tail wind.lworider1
     
  12. 4wdingman

    4wdingman New Member

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    how do you make a leaner carb setting?? What needle?

    Thanks
     
  13. 4wdingman

    4wdingman New Member

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    thanks all I put the needle up one spot and she run's great it will top out at 40km and i am still running it in just a questiom. how much oil should i use, i am using 25-1 and blowing the smallest bit of smoke but the motor get real hot do you think i should go to 20-1??


    Thanks
    .wee.
     
  14. slipdrive44

    slipdrive44 New Member

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    Spooky Tooth recommends 20 to 1 with synthetic oil for the life of the engine. do this and she should last a decade.
     
  15. 4wdingman

    4wdingman New Member

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    thanks i will do
     
  16. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Yes, if you use synthetic, you can use that much oil.....not really needed though and make sure you are not running lean due to the high oil content.
     
  17. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I will bet a dollar that if it's hot, and you go to 20:1 it will get hotter and make a carbon-y mess.

    The reason is simple. More oil=less gas in the fuel to air ratio. Going from 24:1 to 20:1 will make the engine run leaner, and if it's already running hot, it WILL run hotter.
     
  18. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Going to 20:1 will make MORE smoke as well.
     
  19. slipdrive44

    slipdrive44 New Member

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    More oil should not necessarily make the engine run hotter. Alot of the heat comes from friction.
    Also the actual extra amount of oil from 24-1 to 20-1 should not have a noticeable effect on leaning out the engine especially if it is high quality two stroke oil designed to mix cleanly with gasoline.

    Some oil when mixed will make the gasoline murky, but I use Bel-Ray Si-7 synthetic racing oil and the gas turns to look like blue Gatorade, very clear and light.

    Personal Experience: Using a high quality synthetic oil will reduce smoke output to near zero.

    I run 20 to 1 in my 80cc with Bel-Ray Si-7 and you cannot even see the exhaust. even not moving holding WOT
    Furthermore I have tuned the engine to hit 40mph, my speedo top speed tells me 42.1 peak, this seems like a result of reduced friction and it does not get very hot.
     
    #19 slipdrive44, Dec 31, 2008
    Last edited: Dec 31, 2008
  20. Dave31

    Dave31 Moderator
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    I love the Bell Ray...I recently switched to Lucas semi-synthetic because its cheaper. So far I am liking it for the price.
     

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