Derbi Senda 50 full derestriction

Discussion in 'General Scooter Discussion' started by Karmafield, Feb 21, 2019.

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  1. Karmafield

    Karmafield New Member

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    Hello,

    so I recently bought a Derbi Senda DRD Racing 50 SM 2009, and it seems to be fully stock. It goes around 47km/h.
    I am completely new to all of this, so I'm sorry if I'm getting something wrong.

    My friend has a 2005 Senda Limited edition, with a Ducati unrestricted CDI and 21mm carburetor (originally ~13mm), and goes around 80km/h.

    As I understand, my bike's CDI is restricted? And it should get changed to an unrestricted one.
    We're both thinking about derestricting our exhausts, but when derestricting exhaust, what's all of the re-jetting thing about?
    I have a 17.5mm stock Dellorto carb, so what main jet should I put in?
    Can't I just adjust the carburetor with the airflow/fuel screws?

    Would this be a full Derbi Senda 50 derestrict?
    Would appreciate if someone explained. Thanks [​IMG].
     
  2. Sam phantom

    Sam phantom Active Member

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    702
    So I have a very similar bike to yours 2005 (very similar engine if not the same) to derestrict. there’s one in the exhaust at the manifold end and possibly in the rear muffler, will need a dremmel to remove it but tbh it’s much better to just get a sport pipe there cheap enough then check the mouth of the carb for a gold plate they don’t always have this one

    Iv not touched my cdi and it tops a good 55mph

    Don’t touch the carb settings you just want to upjet 10%

    Mine had a 60 now has a 66 runs great spark plug perfect
     
    Last edited: Feb 21, 2019
  3. Sam phantom

    Sam phantom Active Member

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    702
  4. Sam phantom

    Sam phantom Active Member

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    I forgot to mention also that these bikes are governed quite heavily by the number of teeth on the sprockets for top end or bottom end depending on what your after
     
  5. Karmafield

    Karmafield New Member

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    Thank you!
    Appreciate the reply!
    Ok, I'll get to my bike soon and will check the carb and exhaust you mentioned. :)
    I am actually relieved, cause I tought I'd need to order a new CDI, cause the Euro 4 engine
    had a restricted CDI.

    Also a small question. You mentioned not to touch the carb, just up the jet by 10%. It doesn't run lean on too rich? I am really curious cause saw some a lot of engines failing like that on youtube.
    Cheers. :)
     
  6. Sam phantom

    Sam phantom Active Member

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    Well there’s a question lol it depends on so many factors tbh if you want it 100% then it’ll need to be roller banked

    But the rule of thumb is upjet 10% with a sport pipe derestricted

    No other mods
     
  7. Sam phantom

    Sam phantom Active Member

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    702
    I don’t know about the cdi tbh mine is not limited
     
  8. Sam phantom

    Sam phantom Active Member

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    702
  9. Karmafield

    Karmafield New Member

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    Oh, I guess that should do it. Thanks!
    Well I guess mine shouldn't be too. It seems only from Euro4 they start to get restricted. I just couldn't find any information so I made this thread to ask people who also might face the same problem. Tbh I don't know why my friend's bike has a Ducati CDI. Maybe the previous owner who put it up, thought the original was restricted, cause he was in the same situation like me.
    Read the page. Seems I get the idea, but I guess I'll just have to go to my friends dad sometime to make for sure. He's really experienced with all of this.

    P.s Love your bike :)
     
  10. Sam phantom

    Sam phantom Active Member

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    702
    Use good two stroke oil and don’t keep the throttle pinned back for long periods of time at max speed and you’ll be fine

    9 times out of 10 these bikes are just thrashed so hard that’s why you see them all messed up on YouTube.. a little bit of mechanical sympathy gos a long way with these bikes
     
    Last edited: Feb 21, 2019
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  11. scubabiker

    scubabiker NITROJUNKIE

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    I've got some good knowledge on these bikes.
    Where abouts are you?
    Different countries have slightly different restrictors im led to believe. Also different years are restricted and geared different.
    Stock exhaust and cylinder is 7hp without the restrictor
     
  12. Karmafield

    Karmafield New Member

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    Ahh, basically extremists or newbies, like in my case. Guess I'll have to seem some people here in my country to teach me a bit.
     
  13. Karmafield

    Karmafield New Member

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    Well, in fact, I am from Latvia. The bike was originally in Finland, just got brought here.
    Is the 10% upjet when derestricting true?
     
  14. scubabiker

    scubabiker NITROJUNKIE

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    Yeah Finland has the same rules as here in Norway.
    You will need to upjet if you are derestricting it.
    I would check the wheel bearings and oil pump cable. Totally a common problem on those.
    If you have any questions just ask ive rebuilt and fixed hundreds of these.
     
  15. Karmafield

    Karmafield New Member

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    Hmm okay, thanks! Will take a look. But about the jetting: Is there a perfect recipe or should I do like Sam mentioned, 10% up after derestriction? Any tips?
     
  16. scubabiker

    scubabiker NITROJUNKIE

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    There is no perfect method or magic number, its all trial and error.
     
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  17. Karmafield

    Karmafield New Member

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    Huge thanks! :)
     
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  18. scubabiker

    scubabiker NITROJUNKIE

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    I've spent 2 days jetting a yamaha in the past, sometimes its a LONG process
     
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  19. Karmafield

    Karmafield New Member

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    Holy.... I thought it takes +- 2 hours. But how do you know when it's jetted correctly? You just KNOW or give throttle, see how the engine reacts? Check the radiator heat? What's the science?
     
  20. scubabiker

    scubabiker NITROJUNKIE

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    How the engine reacts. The last 1/8th of throttle. After it feels right you double check by checking colour of the spark plug.
     

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