28mph to 22mph? 80cc chinese

Discussion in '2-Stroke Engines' started by solitus3989, Aug 8, 2008.

  1. solitus3989

    solitus3989 Member

    my bike is either a gallant white horse or a donkey.

    according to my bike speedometer from fleet farm, my bike runs fine and goes 28mph (i don't crank it up that high for more than a few seconds, if i do at all) sometimes. most of the time, it is just stuck at this crappy 22mph, WOT.

    i think it is a problem with the killswitch... here is why.

    my dad and i put the engine on, and it ran like a top. in picture 1 down below, this is what it looked like about half an hour ago. when it could only go about 22mph. not sure what happened to cause the power loss.

    picture 2 is what it looks like now. i switched the black and red wires from the killswitch around. i don't think it makes a difference, but much to my surprise, i hopped on, and boom! 28mph! i hit the kill to make sure it works. it killed just fine. i started pedaling, dropped the clutch, and 22mph. now i can't get it to go anywhere again past 22mph.

    the speed dropped after i killed it once after switching the killswitch wires. coincidence? i don't know. the rest are pictures of the rest of the engine.

    in both pictures, my thumb and forefinger are grabbing the killswitch wire.

    the white wire is just taped off because that's the power from the engine, correct?

    idler chain may be issue? i think it's good and tight, but not too tight... i dunno. end rambling. maybe someone has had this issue before. it's only been a few weeks since installation...

    any help would be appreciated!

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  2. JemmaUK

    JemmaUK Guest

    It might be that the killswitch is still partially shorting the ignition - the stock ones are pretty much awful anyways - its worth replacing it.

    Unless you made any other changes to the engine its going to be an ignition problem. A suggestion would be to remove the killswitch and run the engine like that for a quick test. If you regain your 28mph top end then you know the killswitch is the problem.

    Check the plug for colour as well - you want a nice light tan, unless you are still in the running in period which may well mean a darker colour but I think its most likely something to do with the killswitch & ignition to be honest..

    good luck.

    Jemma xx
  3. solitus3989

    solitus3989 Member

    i unhooked the splice from the blue-blue connection, but left it grounded.

    it did not make a difference.

    i have a spare NGK-B6HS that i bought... brand new. hooked that up 3 minutes ago, along with a different spark plug wire i found in my garage. (my older bro's mazda won't be using THIS one!)

    still has 22mph max speed.
  4. pedalpower

    pedalpower Member

    looking at pictures I'm noticing that the master link clip is on backward (open end faces rear when on top/return) and the front motor mount doesn't seem to be a long term solution

    what size rear sprocket are you running? is the the motor run in? what mix are you using?

    I'm running 700c wheels and a 40 tooth and still on my first tank with a 20:1 and don't get anywhere near 28mph-no do I try. 22-24 is my average.

    and without the kill switch connected? you need a control in your testing.

    speed difference could be throttle related-I noticed the cable coming out of the carb doesn't look tight and straight up and down-I have a few threads showning on the barrel adjuster and a few at the throttle.

    Anyway, I'm not sure the kill switch is related to the reduced speed.

    how does it run? smooth, any hesitation?
  5. solitus3989

    solitus3989 Member

    hmmm the master link clip was never an issue before? because we had it on the other way, and it was binding inside the motor because it had that low of clearance at the angle it was going in on.

    i have 26" mountain bike tires, and a 44 tooth sprocket. at the moment im running 20:1, and it's my 3rd or 4th tank of gas.

    i think it runs just fine and dandy till it hits about 22mph... then it just feels like it lulls forward then i can feel it slowing down.

    ill try tightening the cable.
  6. solitus3989

    solitus3989 Member

    i tried tightening the cable. it was already fairly tight. up on top, ive been slowly tightening it as the cable stretches.

    riddle me this!

    used a voltage tester, and the killswitch will not complete a circuit. the killswitch is whack.
  7. stude13

    stude13 Active Member

    i think you need to remove a couple of links. there is a reason you were told your master is backwards, it is because the thing is backwards. dont let the head bolts get loose, throw away crown nuts. search carb tuning. mitch
  8. Skyliner70cc

    Skyliner70cc Active Member

    I see electrical connections that have exposed metal that may be touching the frame and shorting out. Possible for connectors to vibrate/resonate and not maintain good contact.
  9. JemmaUK

    JemmaUK Guest

    which would partially short the ignition and mean lost power? that might explain it
  10. pedalpower

    pedalpower Member

    another place to check is equal spacing between the spinning magnet and the coil (equal spacing=equal voltage?). maybe use manilla folder for spacer (that's what I put in the space to remove it). good luck.
  11. solitus3989

    solitus3989 Member

    ok. first things first. i need to get a new killswitch. this will probably also mean replacing that terrible brake that comes with the throttle.

    ill probably just hack both off, put my stock brake back on, and get a new switch...

    where you think. radio shack?
  12. solitus3989

    solitus3989 Member

    i tried taping off the blue/blue and the black/black connections... but that didn't make a bit of difference.
  13. dwsutton

    dwsutton Member

    Maybe it is the speedometer - mine is always off. Today it showed 64 mph - LOL

    Im going to an electronic speedo.

    My top speed WOT is 22 on flat terrain. At 28 mph are your teeth rattling ?
  14. Skyliner70cc

    Skyliner70cc Active Member

    Tape won't do it. I had wires pull out of those crappy crimped plugs. The wires should be soldered.

    Also, are you using stock plug? If so, replace it with a us or jap plug.
  15. solitus3989

    solitus3989 Member

    my speedometer isn't too far off. when it says 28mph, a friend riding next to me on a moped said 29 or something. so when im going 22, im probably only going 23 max.

    and it just feels like you are going really slow and on 25mph hour streets, i can't keep up with traffic anymore. :(
  16. relaxxx

    relaxxx Member

    Air filter is upside down. Probably due to lack of space but still not a good setup.
  17. solitus3989

    solitus3989 Member

    You are a genius on accident!

    i took off the air filter to see if i could spin it around somehow... or just to take a look at the situation.

    i noticed there was a strange goo on the outside of the air filter... (picture 1 and 2) it smelled like gas... i instantly knew something was wrong.

    i also noticed a groove (picture 3) on the air filter, where it sat on the frame... when the engine vibrates, it moves the air filter and vibrates it on the frame, making a groove.

    since there was gas on the outside, it was obvious. yup. just as i thought. (picture 4 and 5) rattled it against the frame and cracked my air filter.
    (in picture 5, i am applying pressure to widen the crack slightly for pictures sake)

    this would explain my recent power loss, correct? because it's basically a vacuum leak, now.

    so what do i do with this gaping hole? (picture 6)

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  18. solitus3989

    solitus3989 Member

    another update!

    i hop on my bike, expecting to get my power back... i thought it was the cracked air filter. much to my dissappointment, 20mph max again... disappointed, i close my fuel line while im still on the bike to drain the filter so i can take apart down below and try and figure out what my problem is...

    suddenly, i have power! i gleamed as my speedometer roared 23, 24, 25, 26 27mph! i let off for the approaching stop sign. i take a right, and open the filter again. 20mph. i close, it, and 27,28,29!

    i hear rattling...

    i quickly stop... and realize my killswitch is still broken and in need of replacing. i quickly hop off and disconnect the blue-blue connection and the engine sputters to a stop.

    lost a nut on the rear engine mount. still have one. i can match it at Ace Hardware. too bad metric is expensive...

    but now WHY am i FLYING with the fuel line CLOSED and CRAWLING with the fuel line OPEN!?

    im happy cuz i can duplicate the problem, now!

    (once again... 20:1 ratio, about my 5th tank of gas. im new at this... i know i should check the bolts more often.)
  19. Skyliner70cc

    Skyliner70cc Active Member

    a LEAKING airfilter is not a vacuum leak.
  20. relaxxx

    relaxxx Member

    My motor will rev like nuts if I forget to open the fuel line, on the last few drops of gas in the carb it will burn wide open. Even with no throttle. Something is not adjusted properly in your carb!