How hot?

Discussion in 'Motorized Bicycle General Discussion' started by Dougan, Jun 1, 2010.

  1. Dougan

    Dougan New Member

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    Just finished my first tank of gas and then some, so I feel like I'm pretty much done breaking in my bike.

    I'm a little worried about overheating the thing, though. After driving about half a mile at 20mph, I'll stop the bike. I can drip some water on the engine or exhaust and it boils off quite vigorously. Exactly how hot are these supposed to get before I get worried? Everything I know about 2 stroke motors comes from my experience w/ outboard motors, which run pretty cool, since they have an endless supply of water for cooling...
     
  2. Mac

    Mac New Member

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    I can just tell you how I do it, when It gets that hot, hopefully BEFORE it sizzles water off the head, I shut it down and let it cool for 10 min, normally, I only have to do this for maybe 2-3 tanks, depends on allot, just make sure you don't have any gasket leaks causing it to lean out. Good luck!

    Mac
     
  3. GearNut

    GearNut Active Member

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    Boiling water on the pipe is ok. Boiling water on the engine is not. It should evaporate in a hurry, but not pop and sizzle. What color is the spark plug?
     
  4. bairdco

    bairdco a guy who makes cool bikes

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    if it's running properly, heat really isn't an issue. i've burnt my leg on the head before (only after getting sideswiped by a car and having my leg forced onto it as i used her car for a berm,) and i was wearing shorts, and the exhaust will definitely get hot enough to melt your shoes or burn a hole in your pants (or, stop that nosy dog from pi ssing on it, after he touches his nose to it first:).)

    but i run my bike for hours non-stop at WOT in temps as hot as 100 degrees, and haven't had any problems so far.
     
  5. Dougan

    Dougan New Member

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    I will check the plug tonight but I am running it at 16:1 so not sure what to do if it is the plug.

    The exhaust seems to leak a little bit at the point where it connects to the engine. I only say that because there is a bit of oil spray. Would this cause it to overheat?

    I just drove it about 2 miles, at about 1/2 to 3/4 throttle the whole way, killed it, spit on it, and the head was easily hot enough to make it boil. So I'm convinced something's up.

    Does anybody else have any other input? It's a grubee skywhawk 66cc GT5. Slant head. Probably have put 1.5 tanks through it.
     
    #5 Dougan, Jun 1, 2010
    Last edited: Jun 1, 2010
  6. taddthewadd

    taddthewadd New Member

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    Back when I used to race 2 stroke rc cars we would put a drop of water on the head to see if it boiled or not. If it boiled we knew it was too hot and we would richen the mixture because it was too lean.
     
  7. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    16:1 will make for a lean fuel to air ratio...go to 24:1 or better yet 36:1. Check your plug, it should not be white or light grey.

    I have never spit on my engines though I have cussed at them on occasion...
     
  8. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    R/C cars run on alcohol, and should run much cooler than a gas engine....so that test is primitive at best.

    Just sayin'.
     
  9. stuartracing

    stuartracing New Member

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    It`s an AIR COOLED engine, so as long as you have air flow it should be ok as long as it`s not too lean....It`s when you are stopped is when the problems would start if anything....If I`m running mine and I feel it might be too hot I hit the kill button and pedal for a bit....
     
  10. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I have heard of them being idled for a looooong time without overheating.
     
  11. stuartracing

    stuartracing New Member

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    Ya me too.....No load...
     
  12. Cabinfever1977

    Cabinfever1977 New Member

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    These engines like running hot.
     
  13. Dougan

    Dougan New Member

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    I rode it home around 5, and pulled the plug around 8. It was brown/black crusted. I cleaned it off and it was silver underneath, but, the original color was very dark. I think if anything, my oil is too rich.

    Do you think I just need to give it time? I've run maybe a gallon through it. Hard to tell exactly because the tank slipped at one point and I spilled some (fixed the slipping problem).
     
  14. GearNut

    GearNut Active Member

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    Leave the mix as it is. Being heavy on the oil is causing the crust. The brown indicates a good air: fuel ratio. It sounds to me like your plug is perfect looking for an engine in the middle of breaking in.
     
  15. Cabinfever1977

    Cabinfever1977 New Member

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    If the engine stops and won't start back up right away,then its too hot.
     
  16. GearNut

    GearNut Active Member

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    Push the engine less hard and let is cool off more frequently. It will run cooler after the rings marry into the cylinder, after break in.
     
  17. Dougan

    Dougan New Member

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    From what I understand, after treating the first 20 miles as a very gentile, varied-speed breakin, and having a guaranteed 50 (probably more like 75-100) miles on the motor, the rings should be seated by now. Is this true?

    Given the miles I've put on it so far, and the fact that the "pinging" engine noises are completely gone, and the engine sounds like a very healthy engine when I rev it, I figure the "breakin" has to be pretty close to being done. I would love to believe that the only reason my engine is overheating is because it's not broken in fully yet, but, I'm a bit skeptical, since it's acting much more like I picture a broken in engine would.

    I do appreciate all of the feedback so far.
     
    #17 Dougan, Jun 2, 2010
    Last edited: Jun 2, 2010

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