chinesse 80cc ht power problem

Discussion in '2-Stroke Engines' started by 66fury, May 10, 2009.

  1. 66fury

    66fury New Member

    i have built two motor bikes with no issues at all.my last build(80cc ht) however starts fine and revs up fine,but has no power at all once you engage the clutch.barely has enough power to propel its self. i am using the same gas mixture as in the other motorbikes(wich run fine) already tried swapping sparkplugs with one that runs fine,nothing seams to help.any ideas? possible carb gasket issue? i did notice one of the head bolts were lose and torqued it down,could one bolt being loose have blown the head gasket? any ideas or help would be apriciated.thank you.:icon_cry:
     

  2. bluegoatwoods

    bluegoatwoods Well-Known Member

    Hmmmm...... when I was reading your post the notion that maybe it's running lean came to mind. Very lean, it sounds like. So you might want to check that intake.

    Though your head gasket could well be leaking, I wouldn't have expected that to make such an obvious difference in performance. I would think that you'd be able to see the burnt and unburnt fuel leaking out if it were that bad.

    But on the other hand, I haven't even taken one of these engines apart. Yet. So I'm hardly an authority.

    Someone will come along with better suggestions than I can give. Good luck.
     
  3. Pablo

    Pablo Motored Bikes Sponsor

    Well after running it hot and hard, what does the plug look like?

    I mean without narrowing it down - problem could be the carb, spark, lack of compression or plugged exhaust..etc...

    Did it run better after retorquing all the head nuts?
     
  4. 66fury

    66fury New Member

    reply from 66fury

    never been able to run it long and hard as it has lacked the power from day one.it idles fine and revs fine until its under even the slightest load then it just bogs and has little power not enough to ride it.retorquing the head bolts did nothng at all for it.
     
  5. Pablo

    Pablo Motored Bikes Sponsor

    So the exhaust is not plugged in the least?

    It also sounds like an air leak as long as there is good fuel flow.
     
    Last edited: May 12, 2009
  6. Skyliner70cc

    Skyliner70cc Active Member

    Things to rule out (repair, replace)

    Carb airleak. Hope you didn't use stock gasket.
    Partially clogged carb jet.
    Partially clogged inline fuel filter. I never use the screen filter that is housed in the fuel valve assembly. they clog easily from the rust in the tank.
    Stock spark plug. Its junk, replace it.
    Some newer engines have a very restrictive exhaust. I had same issue on an engine and i replaced the muffler with an older style one and power came back.
    Cylinder head base gasket often is cut too large at factory and partially blocks engine transfer ports. This is a fairly common problems.

    Other potential issues: I've had two engines so far (not recently) that were missing one of the piston rings. Hole in engine block (1 engine to date), etc...etc..
     
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