Clutch lever out, engine has no compression, magneto won't spin.

Discussion in '2-Stroke Engines' started by kerryh, May 7, 2015.

  1. kerryh

    kerryh New Member

    gt5a has has been through two or three gallons of so far- so just barely past break in. Went to fire it up couple days ago by pedaling and popping the clutch instantly heard something of a metallic sound and then the bike just coasted. No resistance from compression whatsoever. Chain turns on small sprocket. No big deal. pulled the spark plug to look inside, the piston appears to be moving but it sure doesn't when plug in and pushing bike around. No sound of air or anything from around head gasket. What gets me is the magento doesn't spin though it looks like it want's to. I'm guessing something down in the lower crank case. Any one have any thoughts they can offer before I go in? I've never done a lower end opening before (not one that ran afterwards anyways). Know of any troublesome crap chinese parts that have a habit of breaking down in there? I am really worried that once apart I will not be able to get it back together and have it run again....
     

  2. dougsr.874

    dougsr.874 Active Member

    Sounds like the clutch is not tight enough...remove the right cover and turn the "flower nut" its called to the right...that will put more pressure on the clutch pads....also check the small drive gear on the end of crankshaft to make sure it's not broken or the key has sheared.
     
  3. kerryh

    kerryh New Member

    It's not the flower nut option. That was the first thing I checked. Besides the magneto would still be turning. When I removed the left side engince case cover the small beveled gear fell off into my hand, so I put it back in and tightened it. The drive system has contact up throught the tire and chain, continues thru to the clutch plat and large and samll beveled gears. It's gotta be something in the lower crankcase. Was hoping someone would read this and be like, "oh! that the damn xxx part that always breaks...."

    Whatever it is is not connecting the piston to to the small bevel. like a part has been sheared....

    thx anyway
     
  4. dougsr.874

    dougsr.874 Active Member

    Guess me or you have a difference of what is right & left...the small bevel gear in on the right side of the engine on the end of the crankshaft...if it fell of in your hands that should mean that the half-moon key is sheared under the bevel gear....
     
  5. crassius

    crassius Well-Known Member

    yep, or it just fell out when the gear came loose - look around bottom of case & on floor near where you opened cover
     
  6. kerryh

    kerryh New Member

    Ha ha, you are right doug. My bad. not the left but the right side of the engine.

    I'll look and see about the cresent but even so, the large and small bevel wheel are aligned and turn each other...shouldn't the piston move at that point?
     
  7. crassius

    crassius Well-Known Member

    only if that key is locking the small gear to the shaft
     
  8. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Look carefully, the bevel gear is only spinning on the shaft because
    the key is missing.
    Does the slot on the flat head bolt also turn?
    Do you hear the piston turning over?
     
  9. kerryh

    kerryh New Member

    that's really weird. I replied to this hours ago but I guess the post didn't stick. it read:

    Much oblige gentlemen. as soon as I saw the crescent I thought to myself you just asked the dumbest question ever. Alas, the key slipped right in.

    fixed, fired right up, GTG. Thx all.

    Moderator, you may close the thread please. Thx
     
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