motor spits

Discussion in '2-Stroke Engines' started by bikeman6969, Jun 29, 2008.

  1. bikeman6969

    bikeman6969 Member

    my bike starts right up and goes good untill i get to 20mph then it starts to sputter it does not die but it does not go any faster either it is a brand new kit is it to lean? please help

  2. BSA

    BSA Guest

    Try partially using the choke. If you get better performance with the choke in partway your definitely too lean. Does the rpm's of the motor go up when you put the clutch in? If you've done a good few miles pull the spark plug and see what colour it is. Google reading spark plugs, it should be a nice toasty brown colour. Good luck.

  3. bikeman6969

    bikeman6969 Member

    Thank you bsa i will give it a shot
  4. badmoon

    badmoon Member

    i have the same trouble when i reach some speed in flat road i heard that sound change and the speed cant grow up and when i hit something the speed turn on to normal and return in 10 sec to the weird mod ;s i dont know what to do i read that can be the airfilter or the sparkplug not sure really ?

    we have to do a video of that problem that seem to appear of all of us .
    Last edited by a moderator: Jul 3, 2008
  5. miczer01

    miczer01 New Member

    I have the same problem when it reaches about 30 kmph
  6. BSA

    BSA Guest

    Check if your running too lean or if you have an airleak. Start and warm up the engine and then hit the choke fully, it should kill the engine straight away.

  7. badmoon

    badmoon Member

    i have tried the airfilter and doesnt really help . i will try too change the needle clip to other place.
  8. miczer01

    miczer01 New Member

    In one of the articles I read that I need to change the chinese plug to ngk b6hs and this is something which I have to do tomorrow but i also have a problem that due to lack of space I had to use a short plug can anyone tell me another plug model?(in case that the ngk b6hs is long)
  9. BoltsMissing

    BoltsMissing Active Member

    Was going to say the same, it now seems a standard procedure to do away with the kit's plug, lead and plug cap.

    From own expirience so far,
    1st cab off the rank to sort out in these kits:
    NGK B6HS, NGK Right Angle Cap and
    quality copper lead, (more copper stands)

    must be all 3 to remove all doubt and one of ther simplest to do.
    There are other plug types but I ain't tried any yet.
  10. Clotho

    Clotho Member

    I am experiencing a similar problem. My kit is new as well. I have replaced the plug,lead and boot. I have checked for air leaks. I have tried 2 different carbs. (See my post 'Upgraded Carb') I have adjusted the needle from lean to rich and back again. I tried a larger size jet in the standard carb. This just caused the motor to not rev past about 3k.

    This isn't my first Happy time build but I haven't seen this problem before. It feels like a fuel problem but nothing seems to correct it.
  11. 5-7HEAVEN

    5-7HEAVEN Guest

    Mine's sputter too.

    I had no problems with my 1.6 hp Robin, but my new Mitsubishi 2.2hp engine sputtered and fell flat on its face at the top end ...ALL the time. I tried the engine with friction drive and gear chain drive, with same results. The spark plug looked okay, but I replaced it anyway, with no results.

    Just for kicks, I removed the ADA-1 goped pipe from my pocket bike engine and bolted it onto my Mits engine in one hour. I expected the engine to become much louder, but it's actually a little quieter, and with less engine vibration at idle. It has that "tinny" sound of old V8 headers at idle.

    The low-end might've suffered a bit, the midrange power gained a little...and the top end is simply AWESOME. If allowed to, the Mits engine will now rev past its redline, so I have to be careful. There is absolutely no sputtering or falling flat on its face anymore.

    Originally, I had thought maybe that this engine had a governor. I now believe my problems were caused by excess exhaust backpressure from the stock muffler.

    I did have to saw off the pipe's mounting bracket to get it to fit. Everything else fell into place, after replacing the long exhaust studs and trimming the plastic exhaust cover.

    I'm super happy with the ADA-1 goped pipe.

  12. miczer01

    miczer01 New Member

    I have a little leacage from the
    exaust would it make any difference in high speeds?
  13. JohnnyLoves

    JohnnyLoves Member

    Did all of you start having this problem after the exhaust mod? I know I did, and after reading the other thread it became aparrent I was having the exact opposite problem as everyone else....It seemed everyone was becoming too lean after the mod, but I was majorily rich! I've been working on it and so far drilling the main jet smaller has taken care of my sputtering at WOT. However, with the main jet smaller I've had to increase my needle setting to compensate for the smaller volume of fuel...the engine runs better, spark plug is cleaner and it now pulls its own up hills. not quite finished yet however because it still sputters a bit at WOT which means my need to make the jet even smaller.
  14. QuadManiac

    QuadManiac Member

    How do you drill the main jet smaller? Do you fill it with something (solder for instance) and then drill a new, smaller hole? Else, I can only see how drilling will make the jet's passage larger and therefore run richer.
  15. Ghost0

    Ghost0 Guest

    Yes soldering the hole shut and redrilling works very well, I do it to all my engines. I find that after you rid yourself of the air leaks and especially with a tuned pipe the stock jetting is way too big. Stock on the happy time is a .70mm and I am down to a .60mm
    Here is where you can get the drill bits.
    I ordered the 25pc Carburetor Drill Set #R25WS74-50
  16. jamesburr36

    jamesburr36 Member

    Sounds to me like the needle's clip is assembled above the silver C-washer instead of between the C-washer and the barrel. There is another thread that describes how the manufacturer's instructions and associated pictures are incorrectly assembled.