noob to the motorized bicycle scene

Discussion in 'Motorized Bicycle General Discussion' started by dumpstercrusher, May 20, 2013.

  1. dumpstercrusher

    dumpstercrusher New Member

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    sup guys, im new to the motorized bicycle scene so Im trying to learn as much as I can because this is just too much fun! so glad i pulled the trigger into buying me a kit and a bike. Anyways, i bought my 80cc kit off ebay and just have some questions regarding if this is normal or not. (Honestly i wish i went with a reputable engine kit than ebay but this will have to do till this motor explodes or dies). I mixed the right oil to gas ratio for the breaking it in portion but bad at keeping speeds since ive already tried maxing it out lol (almost ran thru a gallon) and ive been having oil leakage down my exhaust and some carbon build up on the top of my cyclinder head next to the spark plug and was wondering if this is all normal? I have to put a paper towel under the exhaust when i put the bike in the basement because of the leaking issue. Also after running it 15 mins or so the motor gets extremely hot to the point where when u try to adjust the idling screw it does nothing as opposed to when you start the bike up cold and the kill switch obviously stops working so i have to either pull the choke up or twist the fuel cut off to stop it. Im thinking about switchin out the crappy head for a new bigger head to help with heat and also add some more power. Yesterday i also changed the throttle little clip to adjust from lean to rich (have 5 slots and put the clip into the second to first) and it ran pretty good yesterday and i didnt seem to have that problem wit the kill switch not working. well i tried to take the bike out today and it wouldnt fire up so i took out the spark plug and the end was black and moist and i read thats not where u want it cuz its running too rich so i put the clip back to the middle and it seemed to fire up better this time. Just want some insight from experienced guys
     
  2. dumpstercrusher

    dumpstercrusher New Member

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    My goal is also to get this thing up to 50mph or close to it but still able to cruise with no problem
     
  3. BigBlue

    BigBlue New Member

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    Unless you build a race engine, it will eventually destroy your engine to run it at top speed, especially trying to race downhill, full throttle. Expect to spend big bucks for a race engine. Arrow has a race engine for $900 and a street racer for $500. http://www.arrowmotorizedcycles.com/motorized-bicycle-engines.html

    Good Luck,

    Chris
    AKA: BigBlue
     
  4. dumpstercrusher

    dumpstercrusher New Member

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    Think those engines would last if im crusing and when i need it i do full throttle? curious. Lot of money for just a 2 stroke engine lol but no where near compared to a built motor for a car.
     
  5. 2door

    2door Moderator
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    50 mph is an unreasonable expectation. It isn't impossible but improbable to expect that kind of speed from a basically stock engine. 35 to 40 is about tops unless you want to spend some serious money and possibly compromise the engine's life.

    These are motor assisted bicycles, not motorcycles.

    As for your other problems, adjusting idle speed when hot, it sounds like you might have an air (vacuum) leak. Check your carburetor to intake manifold connection and the intake manifold gasket to cylinder. Once adjusted you shouldn't have to readjust the idle speed if everything else is good.

    What fuel/oil ratio are you running? The clip position on the needle only effects fuel flow up to about 3/4 throttle. Anything above that, flow is controlled by main jet orifice size. The needle is raised out of the jet after 3/4 throttle. If your plug is black and oily I feel your oil ratio is probably too high. You shouldn't be higher than 24:1. If you are following the instructions that came with your engine and running 16:1, that's most of your problem.

    Don't expect the engine to perform to its maximum potential until you have 2 to 300 miles on it. These engines are slow to break in and need some time to seat the rings and gain max compression.

    Tom
     
  6. maniac57

    maniac57 Old, Fat, and still faster than you

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    If you follow the kit instructions and use 16:1, it will continue to be a pig. Change to a ratio of 32:1 for break in. 16:1 is simply too much oil for the engine to ever run right.
    I have used 40:1 for many many years even during break-in and have never had any problems.
    Just use a good quality two-stroke oil. (NOT MARINE)
     
  7. dumpstercrusher

    dumpstercrusher New Member

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    thanks for the responses! i will def check the carburator to intake manifold for any leaks. ill retighten everything and test it out again tomorrow if the weather is good. I dont remember ratio but i just followed the directions thats on th back of th bottle. 8ozs of two stroke oil to 1 gallon of gasoline which im using 87. Since this is my last tank i will change up the ratio and hoping that will def fix my problem. Just too much oil spuing out the exhaust and one of the bolts to the crankcase o_O Do you also agree that i bought a crappy ebay motor kit for $140 compared to other name brands that are much more? I really want to change out the cylinder head to reduce heat and possibly increase low end performance. These little engines are too much fun! lol so little money compared to my car lol
     
  8. dumpstercrusher

    dumpstercrusher New Member

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    Also will advance auto parts have a better two stroke engine oil compared to walmart? i forgot the brand but it feels to low quality to me
     
  9. maniac57

    maniac57 Old, Fat, and still faster than you

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    I use ebay kits myself and all the china two strokes are basically the same, no matter the claims of certain sellers. The only people I know of actually upgrading the china kits are arrow and dax, and the prices of both reflect it.
    If you continue to overheat, CR machine and Arrow make a heads and several members have been using puch moped heads with good results. Search puch head for more info.
     
  10. dumpstercrusher

    dumpstercrusher New Member

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    now u make me feel better lol ill def look into that. what about the "FredHead" from thejakebike.com or the high performance head from pistonbikes.com. They look the same except the performance head from motovelo.us. Do you know if they are direct bolt on without modifications?
     
  11. maniac57

    maniac57 Old, Fat, and still faster than you

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    No idea as I have not used the heads mentioned.
    Try the high performance forum for more on high comp heads and what is needed to use one. I've heard several people had to drill the holes bigger for the puch heads, but thats about all the info I have.
    Sorry.
    You should really wait until the engine is broken in and tuned correctly to start buying hot rod parts...just my opinion.
     
  12. dumpstercrusher

    dumpstercrusher New Member

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    i would wait but since im coming from the world of hookin up my car with performance parts, suspension and others, it gets very addicting to not be one of the normal people running factory motors lol but hopefully once i change the oil to gas ratio in my next tank it will be broken in to go on longer cruises during nice weather.
     

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