Noob new gas kit built up... Starting?

Discussion in 'Motorized Bicycle General Discussion' started by Dirty Patches, Jan 28, 2017.

  1. Dirty Patches

    Dirty Patches New Member

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    I just finished building a 48cc gas bike kit on a old mountain bike. I can get it to start but if I give it gas or slow down it will die. Also just dies when I pull the clutch in as I'm slowing down.
    Got it to idle and somewhat take throttle barely once but not sure what it wants or how to get it there. Guessing its the fuel/ air adjustment but gets exhausting peddling this heavy thing to dump the clutch to try and start.
    Any tricks or tips to get these going and tuned for the first time?:-||
     
    #1 Dirty Patches, Jan 28, 2017
    Last edited: Jan 28, 2017
  2. TheNecromancer13

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    Try increasing the idle speed.
     
  3. Dirty Patches

    Dirty Patches New Member

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    So loosen or tighten the adjustment screw by the carb? Or is that another adjustment? Sorry very new to this.
     
  4. TheNecromancer13

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    Tighten the screw.
     
  5. Dirty Patches

    Dirty Patches New Member

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    Thanks buddy! Sorry for stupid questions, appreciate the help:)
     
  6. TheNecromancer13

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    No such thing as stupid questions. You're doing better than I did on my first build. I didn't even know what an idle speed is.
     
  7. Dirty Patches

    Dirty Patches New Member

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    So I messed with the Idle adjustment screw to no luck in any position, haven't yet done detailed fine tuning of it as its a real pain to pedal the heavy thing around to try and start. It almost responded to throttle while bombing a steep hill but didn't last long and got gas dripping out of the air cleaner pretty good....
    Any thoughts? Feel like a dumbass peddling this thing around haha.
     
  8. crassius

    crassius Well-Known Member

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    look up how to move the clip on the carb needle - you probably need it at the top or one off the top to allow the needle to hang deeper in the jet
     
  9. Dirty Patches

    Dirty Patches New Member

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    Turns out we can have a good laugh at my expense. The carb and all was mounted 90 degrees off... So turned it to the right position and got my first gas bike ride
     
  10. Dirty Patches

    Dirty Patches New Member

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    Any tips for engine break-in?
     
  11. Chaz

    Chaz Well-Known Member

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    There are differing opinions on breaking in. The main thing is not to overheat the engine. Also to have adequate lubrication, although this is usually not a problem as the carbs are pretty rich from the factory. You don't need to use the 16:1 ratio for the fuel/oil mix. Most experienced builders go with 32:1 from day one.

    Read lots and come to a conclusion that you feel comfortable with.
     
  12. Dirty Patches

    Dirty Patches New Member

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    Thanks for the tips! Seems you're right about the 32:1, I feel better running any 2 cycle rich instead of lean. I have thought about using "TRU fuel" 40:1 or 50:1 that they sell at most hardware stores. Would that be too rich? Would like to not be using ethanol (only gas where im at, even in the premium) and wouldn't mind seeing some smoke out the exhaust.
     
  13. quik225

    quik225 New Member

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    TRUFUEL is expensive, about $25/gal.
    In my area, finding ethanol free fuel is much easier than what it was 10 years ago. Used to be~ 5 vendors in a 25 mile radius, now there are 35-50.
    Here's a site where locations for real gas can be found.

    http://www.pure-gas.org/
     
  14. Dirty Patches

    Dirty Patches New Member

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    New motor would be worse but yea that is pretty pricey stuff! Getting the crazy mpg we get it wouldn't be so bad though. Been using ethanol treatment additive to get by for now.
    Yes sadly I had already tried that and a few other sites, even called every gas station within 10 miles:( I live in silver city NM right now, moved from Montana where non ethanol is everywhere. I think it's abundance is related to snow mobiles. The closest non ethanol gas is a 2 hour drive each way... Oh an my only vehicle is a motorhome so closer to 3 hours each way haha. So all that being said the cost will outweigh the alternative, just wondering if it will be ok for the motor at a 40 or 50:1 ratio. Wouldn't mind a little smoke, prefer to see a little.
     
  15. Agreen

    Agreen Member

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    90 degrees off!? That's awesome.

    I have to be honest, I don't use non-ethanol fuel in my bikes. I run them so much, it's never a problem.
     
  16. Potato_In_Exhaust

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    I don't think they matter for 2 stroke piston port motors....... whereas with 4 cycle it might effect the valves and valves seals more.
     
  17. Dirty Patches

    Dirty Patches New Member

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    Haha yea not my proudest moment, BUT to be fair I'm amazed that's all I messed up! The instructions are so bad as many have mentioned, gotta love youtube:)
    Well that makes me feel better about the ethanol, but not great. I worked at a hardware store that had a small engine shop/ Stihl dealer and about %75 of the repairs were from ethanol damage. Worn out seals and gaskets. Maybe these aren't as picky as a Stihl chainsaw or a Honda mower. It did a number on a 1985 Ford Ranger I had that had a carb engine. It would burn the fuel but ran like crap compared to when it had non ethanol gas and eventually ate away at seals leading to a cracked carb.
    Long story short I am uneasy about ethanol in 2cycle engines and carbs but the bike has been doing great:)
     
  18. Dirty Patches

    Dirty Patches New Member

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    Thanks for the input! Had it give me trouble with an old 2 cycle moped and old ford truck with a carb. It has been running great with premium gas and ethanol treatment, just wondered how everyone else gets by.
     
  19. Agreen

    Agreen Member

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    As long as it gets used, it's fine. It's when the stuff sits is when it starts to absorb water and corrode the internals of stuff.
     
  20. Dirty Patches

    Dirty Patches New Member

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    Now the new problem...
    My throttle is stuck at full so no throttle response and when I put in the clutch it just sits at high rev with little to no response with the idle adjustment.
    It happened after riding on a rocky beach and the whole handle twists back now.
    I took it apart and it doesn't have the little plastic nub that goes into the hole you drill into the handlebar so explains the twist but the handle is still pulling on the cable (appears to be anyway.
    Anyone ever dealt with this?? Hoping it is a cheap/ easy fix. Not sure if getting a replacement might be the best idea, if even possible.

    Decided to sell the bike and this of corse has to happen the next day. :-||
     

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