Scooter
Community

Need help, scooter jusr stops

Last post 06-06-2013 12:25 AM by INMA. 12 replies.
Page 1 of 1 (13 items)
Sort Posts: Previous Next
  • 05-31-2013 01:44 PM

    Need help, scooter jusr stops

    Hi people, just fitted a 70cc kit to my sons Benelli x49, when riding the bike goes ok, running on standard carb,air filter and exhaust, bike goes along at around 70kph then just dies, when stopped you can start the bike straight away and will go along again at same speed and then do the same thing.Also not sure if related but since the rebuild when I turn off the bike with the key it keeps running having to use the kill switch and then I need to able some throttle to stall the bike.

    Got me confused,any help or suggestions would be appreciated.

  • 05-31-2013 03:56 PM In reply to

    • Greg
    • Top 200 Contributor
    • Joined on 06-08-2008
    • Tuart Hill, Perth, W.A.
    • Posts 133

    Re: Need help, scooter jusr stops

    Try taking the fuel cap off next time see if there is a vacuum when released (vapour lock) if so you need a breather vent for the fuel tank (odd it didn't do this before), running on is either ignition timing and or to much compression

    Larger bore in the same cylinder head space = more compression

    Greg

     

    Yamaha Tmax 500, 2010 Black ... Sold her for ...
    Suzuki V-Strom 650 2012

    Perth W.A.
  • 05-31-2013 05:25 PM In reply to

    Re: Need help, scooter jusr stops

    Thanks checked fuel cap, no vacumn when released, but worth a try

  • 05-31-2013 05:38 PM In reply to

    Re: Need help, scooter jusr stops

    sounds electrical, go back through your wiring perhaps?

    Slow Down & Enjoy The Ride
    2012 Kawasaki W800
    Go the Retro
    Looking for another BeeWee :)
  • 06-02-2013 01:14 PM In reply to

    • INMA
    • Top 50 Contributor
    • Joined on 03-19-2009
    • Posts 837

    Re: Need help, scooter jusr stops

    Sounds like soft siezing due to running lean and not enough lubricant.

    The piston overheats because it needs the fuel in the air to cool it, then under high loads it slowly grabs the bore causing the engine to stop.  Each time it stops it does more damage to the piston and bore until the rings will jam and it won't start due to lack of compression. 

    On an alloy piston with cast iron bore and good lubricant, an engine can survive a few soft siezes and be useable.  If you did not increase the lubricant and run the cylinder in for 500km, then you may have damaged the piston and bore.

    When you change a piston and cylinder on a two stroke, it is essential to retune the carby to cope with the extra air being sucked into the bigger cylinder.  Two strokes run great running lean but the heat buildup and other stuff will cause the engine to fail.

    There is a good chance you have already damaged the piston and bore beyond salvage.  When I upsized my engine, I bought 3 pistons and bores in-case I had issues. I did not have problems at the start but after many thousands of kilometers, a crack in the aircleaner caused a soft sieze and I needed to replace the piston and bore.

    Welcome to the world of hotting up two strokes.

    2001 Yamaha Zuma, DR Evo 68 cylinder, Leo Vince TT derestricted, Delorto 17.5 (#98 jet), standard aircleaner, RMS fan, Race CDI, Standard oiler and premix @ 75:1 Shell SX2, Doppler SR3 variator, RMS clutch, RMS R rear shock absorber and Pirelli SL26 tyres.
  • 06-02-2013 01:17 PM In reply to

    • INMA
    • Top 50 Contributor
    • Joined on 03-19-2009
    • Posts 837

    Re: Need help, scooter jusr stops

    I just read the bit about not being able to shut it down.  That sounds like its dieselling at idle which is caused by extreme heat in the cylinder and probably a damaged spark plug.

    The compression ratio could be too high for the fuel you are using.  If its makes rattling sounds you need higher octane fuel.  Many engine mods from overseas are set up for 98 octane fuel.

    2001 Yamaha Zuma, DR Evo 68 cylinder, Leo Vince TT derestricted, Delorto 17.5 (#98 jet), standard aircleaner, RMS fan, Race CDI, Standard oiler and premix @ 75:1 Shell SX2, Doppler SR3 variator, RMS clutch, RMS R rear shock absorber and Pirelli SL26 tyres.
  • 06-02-2013 01:51 PM In reply to

    Re: Need help, scooter jusr stops

    jakeollie:

    Hi people, just fitted a 70cc kit to my sons Benelli x49, when riding the bike goes ok, running on standard carb,air filter and exhaust, bike goes along at around 70kph then just dies, when stopped you can start the bike straight away and will go along again at same speed and then do the same thing.Also not sure if related but since the rebuild when I turn off the bike with the key it keeps running having to use the kill switch and then I need to able some throttle to stall the bike.

    Got me confused,any help or suggestions would be appreciated.

     

     It could also be a kink in the fuel line and running out of fuel,and running on could be ideling to fast. good luck.

    Why is it since i've had this bike nobody cuts me off ??.
  • 06-02-2013 01:56 PM In reply to

    • Blam
    • Top 75 Contributor
    • Joined on 08-25-2008
    • Nowhere near you, thank God.
    • Posts 437

    Re: Need help, scooter jusr stops

    Yep, I agree with INMA. It sounds like you haven't upjetted the carby. It's running so lean it's seizing and when it isn't seizing it is so hot in the cylinder the fuel is igniting without the need for a spark.If you have upjetted - there is an airleak somewhere.

     

     

  • 06-03-2013 09:06 AM In reply to

    • Paul
    • Top 50 Contributor
    • Joined on 05-16-2008
    • Brisbane
    • Posts 652

    Re: Need help, scooter jusr stops

    defo fuel realated for the first step in diagnosing, kinked line or running too close to the engine maybe causing it to evaporate prior to delivery

    Cheers,
    Paul

    Now Scarabeo 300 June 11 with Arrow pipe..oh yea!
    previously Scarabeo 200 (with gpr pipe) Oct 09 - June 11 (18,450km)
    previously Vmoto Monaco Apr 09 -Oct 09

    *lusting after a GTS, but a few good models for 2013*

  • 06-03-2013 09:53 AM In reply to

    • INMA
    • Top 50 Contributor
    • Joined on 03-19-2009
    • Posts 837

    Re: Need help, scooter jusr stops

    Forget the advice regarding fuel lines etc.  Your symptoms are very clear and point to a cylinder upgrade that has gone wrong.

    I suggest buying a standard cylinder, head and piston and putting it back to standard.  The current cylinder, piston and head is probably damaged and will not last much longer.  You will need to replace it before you can get the scooter to run reliably.

    Scooter forums are full of people without the knowledge buying cheap parts for a 50cc 2 stroke then abandoning the scooter when it dies.  Put it back to standard or do the upgrade properly.  There is no future running the engine as is and its not likely to last long due to the existing damage.

    2001 Yamaha Zuma, DR Evo 68 cylinder, Leo Vince TT derestricted, Delorto 17.5 (#98 jet), standard aircleaner, RMS fan, Race CDI, Standard oiler and premix @ 75:1 Shell SX2, Doppler SR3 variator, RMS clutch, RMS R rear shock absorber and Pirelli SL26 tyres.
  • 06-04-2013 11:22 AM In reply to

    • Greg
    • Top 200 Contributor
    • Joined on 06-08-2008
    • Tuart Hill, Perth, W.A.
    • Posts 133

    Re: Need help, scooter jusr stops

    What exactly did you get in the kit ?

    Greg

    Yamaha Tmax 500, 2010 Black ... Sold her for ...
    Suzuki V-Strom 650 2012

    Perth W.A.
  • 06-04-2013 05:16 PM In reply to

    Re: Need help, scooter jusr stops

     thanks for the advice, increased the main jet size and scooter no longer stops, had a70 installed so upgraded it to a 80..thanks again

  • 06-06-2013 12:25 AM In reply to

    • INMA
    • Top 50 Contributor
    • Joined on 03-19-2009
    • Posts 837

    Re: Need help, scooter jusr stops

     

    If you have not increased the oil going into the engine you will still have trouble.

    If you put oil in the petrol at 100:1 mix plus the oil injection, that is a good guess since you don't have fuel consumptions.

    You may still need to tune the carby with other jets depending on the color of the spark plug.  Better to be a bit rich than lean.

    Run in should be over 500 km.

    2001 Yamaha Zuma, DR Evo 68 cylinder, Leo Vince TT derestricted, Delorto 17.5 (#98 jet), standard aircleaner, RMS fan, Race CDI, Standard oiler and premix @ 75:1 Shell SX2, Doppler SR3 variator, RMS clutch, RMS R rear shock absorber and Pirelli SL26 tyres.
Page 1 of 1 (13 items)

 

ADVERTISEMENT

©2007 ScooterSales.com.au