what motor do i have

Discussion in '2-Stroke Engines' started by alpha, Jun 3, 2012.

  1. alpha

    alpha Member

    this is my motor what one is it. i cant tell. i think its a 50cc.

    i know i dont have pics of it with my new engine but im using a thumb throttle

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    its the same one just dont have a pic of it on my bike
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  2. Greg58

    Greg58 Member

    The only way to find out is to measure the bore. The piston is 40mm on a 48cc and 47mm on a 66cc, if you don't want to pull the head you can remove the exhaust, lower the piston and use a wood dowel or screw driver to slide in the cyld till it touches the back side of the cyld. Then mark the dowel at the flange then subtract the distance from the flange to the piston. The remaining would be close.
     
  3. alpha

    alpha Member

    ok will do that, but still whats ok to put on this motor, some parts im afraid to buy and put on there cause most parts are cheaper feeling than the parts on this motor, i like the slant head but i wanna buy one that looks just as sturdy
     
  4. Al.Fisherman

    Al.Fisherman Active Member

    Truthfully, the cylinder, piston, and rings are not interchangeable from 49cc to 66 cc. Not really sure about the crankshaft and rod as some same cc pistons are different, everything else that I know of is interchangeable. I have never seen a 66cc with 6mm cylinder studs, all I have seen is 8mm studs, which doesn't mean they didn't make them.

    These pistons come off the same size cc engine. Note placement of wrist pin holes.
    [​IMG]
     
  5. alpha

    alpha Member

    i understand that, i know the crankcases are not compatible. i found a video on youtube that shows all the differences in the 49-66. im preaty sure i have a 49cc but my other 49cc have the 8mm studs, while this one has the 6mm


    so what do i do about the air filter, what should i use due to the fact of stock one not fitting. is it ok to run without
     
    Last edited: Jun 4, 2012
  6. Greg58

    Greg58 Member

  7. Al.Fisherman

    Al.Fisherman Active Member

    It appears that you have a NT speed carburetor, a filter for any NT should work.
     
  8. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    It is a 66 cc made by Nantong Jai Li.
    The cylinder head has the small fin on the edge too.

    Grubee Starfires look like this and have 6 mm head studs.
    They were my favorite motor but have not been imported
    for a while.
    I think this motor is still imported as an unbranded kit.

    You don't have to take anything apart to size a motor.
    The space between the 4 head studs is the way to tell.

    Lay a head gasket over the 4 studs, bingo!
    the 50 cc head gaskets are a bit smaller than a 66 cc.
     
  9. alpha

    alpha Member

    all of my motors must be 66cc engines then just by chance. anyways, with the filter do i have to have one or do i really need one or can i run without one for a bit?

    but ill look again ill look at a head gasket
     
  10. Greg58

    Greg58 Member

    The one I posted above from sbp should fit in the space you have. The problem with running without a filter is dirt and dust can and will damage the engine if you run it very long. Measure the head stud spacing, on my 48cc bikes they are roughly 1 5/8 inches apart.
     
  11. alpha

    alpha Member

    i took the head gasket from my other engines and its the same spacing as all of my other ones stud wise. and i also have taken the head off the bike compared piston diam, and they are the same, but the head looks different compared to any of the other china motors i have or seen, is this better quality? looks and stout, and quality of build so far have got me loving this motor. this is the first one i have really had no problems with. other than tuning so now its down to my lack of tuning a 2 stroke.

    so i ran it to work and back maybe a 1/2mile to and from. the motor is waking up and 4 strokes here and there rarely.

    the odd thing witch weirded me out was it was about 50*f out today and on my way back from work is when it was this cold, the warmer and warmer my bike got, the less and less throttle it wanted but kept at full speed, if i went to far it would bog out. i would coast for a min let it idle out then get back into it and it would go full out, then thin out a bit. but it never died, and when i got home i let it idle to make sure it was good on oil, im prob running 20:1 right now due to it being new

    how many tanks should i go through before i go to 35:1
     
  12. Greg58

    Greg58 Member

    Two full tanks of breakin fuel is what I run then maybe 32/1.
     
  13. alpha

    alpha Member

    thank you
     
  14. alpha

    alpha Member

    well today i wrecked the bike on gravel in front of my house, well that loosened up all my mounts some how.

    anyways i got to work and my mounts started getting really loose, so before i got off work my brother came over to put it back together. and he didnt tighten all the bolts well it striped one of the front mount bolts so i dont know what to do now ****
     
  15. Greg58

    Greg58 Member

    Did the threads on the bolt or in the case strip? If its the stud it will screw out, if you are using a bolt remove it to see how many threads are left in the case. If the threads go deeper you can use a longer bolt or better a piece of all thread with loctite on it. Take two nuts jam them together to remove or install studs, good luck. Greg
     
  16. alpha

    alpha Member

    its in the case. i have the sick bike parts motor mount cause of how large my frame is. so i dont have studs just small allen grade 8 bolts
     
  17. Greg58

    Greg58 Member

    If no threads are left you can try a thread insert, you drill and tap the hole bigger then screw the insert in covered in loctite then let it dry.
     
  18. alpha

    alpha Member

    a helicoil?
     
  19. Greg58

    Greg58 Member

    Yes, the only problem may be the soft alloy of the case. Go very slow turning the tap in and out to clean the threads only going about 1/8 to 1/4 of a turn deeper each time using plenty of oil to cool and lubricates the threads.
     
  20. haytom

    haytom New Member

    it should be on the engine, on the manufacturing plate
     
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