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50 cc problems

Discussion in 'Technical and Troubleshooting Torque' started by negatron, Nov 27, 2007.

  1. Hi all,

    I have a 04 Bolwell Tornado that's done only 1600 kms. I went for a evening ride just now and as usual the scoot started fine, and rode as normal.

    2 mins down the road travelling 60 km/h and at about 3/4 throttle, the engines just dies.

    I coast to a side street and try to get it started again using the electric start and it doesn't turn over.

    about 5 min later, i try the kick start and after about 6 or so tries the engine kicks over and suddenly the bike is riding like normal again and starts normally on the electric start too.

    Any ideas what the issue might be?
  2. I think that this can happen if the clutch overheats, by going uphill for too long, or starting uphill or using the engine to keep it still up hill, etc.. in all these, the engine could die and start again after it cools down. It pays if you had a good brake in period, not going 30-40 constantly, but riding to all the speeds, from low to high..

    If the engine reved up before it shut down, you need some oil!! You need to fill it up with oil about every 800k.. or fuel? As these machines can go on air, it is possible to run out of fuel and then restart the engine and have 10 k more to go with the fumes.

    In any way, give a call to the guy you bought it from..
  3. more details

    Hmm... not really an option as its a 2004 model that i picked up off a mate's mate.

    Oil was about half full at the time, and i had about at least 1/2 tank of fuel too.

    Not sure if it could be a heat problem as it was only 2 min after i started the journey.

    After the scoot started up again she ran fine. And i even took her up the foot of the hills for a bit of a mini cruise.

    And she's still working fine this morning.

    Just to be sure i'll go pick up some 2 stroke and fill it up later this week.
  4. Re: more details

    If you have half full oil, don't worry about it, it'll last for months!! Maybe some dirty fuel? Don't want to scare you, but 2 stroke engines can block/stop/piston stuck(don't know what's the correct expression) if they are overworked and after they cool down or you push start them, they are just fine/ I had that on an old vespa, full weight+ tent + bags etc on the highway riding full speed for 2 hours, 40c in the sun, the bike had it, engine block, back wheel stuck, played with the clutch and eventualy managed to make it start again, did the rest of the trip just fine, never came up again!!!

    Or it could be at its last, as a mate's mate mate, does not sound that good!!! Mind you, 2 strokes can last for ever!!

    come to think of it, did you warm it up before you left? if you went straight out, the cold engine was not ready for it, maybe that's why?
  5. ah ha!

    The warm up! perhaps the lack of of proper one was it. I normall let it idle for about 20 secs and then go.

    I guess it should be longer huh?

    how long should the warm up be?

    and do we just let it idle or should we give it a squirt of juice?
  6. Re: ah ha!

    different weather, different technic.. Let it by itself.. Mine, it sounds like an automatic choke, it revs it up and after a minute or so, it goes back to normal .. The trick is to turn on the engine first, then put on your jacket, gloves helmet etc so you spend that time doing something and not waiting.. Also, don't go straight to full speed or up hill, or if you have to, warm up your bike a bit more. 1-2 min for summer, 3-5 for winter..
  7. It does indeed sound as if it seized. The piston expands unevenly, catches on the walls of the cylinder and jams because the lubricant is even pushed out of the way.

    After it cools down a little the piston shrinks and can then proceed again. Unfortunately both the piston and cylinder are dameged through this, and should really be cleaned up. That's a workshop job, though.

    Best thing is to give it a good warmup before you give it heaps. Best way to warm it up: ride slowly as soon as you start it. Letting it idle with the choke on can fill its little crankcase with unburned fuel/oil mixture which then prevents it revving out properly.

    It's also possible, if fuel is really low, for the engine to run lean for a little while, which also causes it to overheat. You will usually notice this as a lack of power for some time before it eventually stops.

    All the best

    Trevor G