2002 Derbi GP1 50 Project

Discussion in 'Battle Scooters' started by woodsrider-boyd, Jun 6, 2014.

  1. woodsrider-boyd

    woodsrider-boyd Wow, these guys are fast

    Joined:
    Apr 19, 2005
    Oddometer:
    513
    Location:
    WA
    Hey folks,

    I thought I would start a thread about my new project, a 2002 Derbi GP1 50, since there is hardly any info out there on these Spanish beauties. Just picked it up and I'm chomping at the bit to get into it. Non-runner with a reported coolant leak from the water pump. Was running fine otherwise according to the PO. We will see.

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    I have a garage full of bike and car projects lined up, but this one may have to jump to the top of the list. Here it is settled in next to a friends Honda 70 that I am giving a spring freshen up to.

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    Question: can anyone recommend another good scooter forum or two where I can learn about the Derbi and it's Piaggio engine?

    I found a few part suppliers and have both a soft copy and hard copy of the service manual so I'm good to go that way.

    Been wanting a scooter forever, so hopefully this will work out, can't wait to see.

    Ed
    #1
  2. Dan V.

    Dan V. Been here awhile

    Joined:
    Aug 8, 2013
    Oddometer:
    205
    Location:
    Pothole City, West Michigan
    Looks like a nice one! Luckily you have the Piaggio engine in it, otherwise you might have been fooked. I have a Derbi Atlantis - basically the same engine - and it is one fast and fun scoot. I have a DR70cc cyl installed with a mild pipe and it rocks. The Piaggio engine is the same as in many models of Vespa and Piaggio scoots, so finding info on the engine is no problem, as well as obtaining engine parts. I have a Haynes manual for Piaggio, so that is a must have if you are getting into scoots.

    Bad news is - it is a Derbi. Derbi parts are unobtainum here in the US. Was a time when parts were available out of Florida, but Ozzie sold all his stock. You may have to haunt Ebay, or try overseas for Derbi parts.

    Good Luck with your project. The GP1 was a top end scoot in it's day - and still very desirable.
    #2
  3. villageidiot

    villageidiot Long timer

    Joined:
    Apr 29, 2010
    Oddometer:
    2,328
    Location:
    Orange County, CA
    For most any engine related stuff, try 50cc.nl

    They're a mega 2 stroke small bore supersite. I've had good(great) experiences with them. Used to get pallet loads a month delivered.
    #3
  4. woodsrider-boyd

    woodsrider-boyd Wow, these guys are fast

    Joined:
    Apr 19, 2005
    Oddometer:
    513
    Location:
    WA
    Thanks!

    I was able to do just a bit of research before I bought it, and I did note that its quite the little performer and that it had the fairly common Piaggio engine. If it had not I would not have even considered it.

    And if I find the top end is toast I am considering going with a 70 cc kit, might as well.

    Fortunately I didn't pay much for it, and the guy selling it is a scooter guy, seemed like an honest guy, so I'm pretty sure I'm getting what he described.

    Again, we will see. Worse comes to worse I decide its not worth fixing up and sell it as is for what I paid for it, or I part it out and recoup my meager investment.

    But I have a history of resurrecting otherwise dead bikes, so I'm hoping for the best with this one.

    Let the games begin!
    #4
  5. Chillis

    Chillis Land Barge Pilot

    Joined:
    Aug 25, 2005
    Oddometer:
    4,200
    Location:
    Spring Mountain Range
    You can make that bike fly! I would get on racing planet USA website and get a shopping list going.

    Easy 70mph bike can be made of it.

    You could also do a skelley or however they spell it. Strip the bodywork and have a tube framed bike.
    #5
  6. woodsrider-boyd

    woodsrider-boyd Wow, these guys are fast

    Joined:
    Apr 19, 2005
    Oddometer:
    513
    Location:
    WA
    Thanks for the links guys. Right now the plan is to get it running reliably and safely, probably keep it stock. Maybe put a 70 cc kit on it if the top end is toast.

    It will be shared with between myself and my two teenage daughters so I don't want to let them loose on a crazy fast scooter right off the bat, especially since this thing is reportedly pretty fast right from the factory.

    If they end up not riding for whatever reason, then yes, perhaps some performance mods if I end up loving it and becoming a super scooter nerd (I could easily see that happening).
    #6
  7. rspratley

    rspratley Adventurer

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    Portugal
    #7
  8. woodsrider-boyd

    woodsrider-boyd Wow, these guys are fast

    Joined:
    Apr 19, 2005
    Oddometer:
    513
    Location:
    WA
    Excelente, muito obrigado!
    #8
  9. scubabiker

    scubabiker Been here awhile

    Joined:
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    Location:
    Norway in a nutshell, AKA stord island
    im a member of a website called scootershack.co.uk very good webiste, is yours the version with the stupid chain drive? the engine is the samme as a gilera runner sp50, aprilia sr50 a piaggio nrg 50 and many others, lots of good tuning parts available from places like adrenalin pedstop, pmtuning and a few more.
    #9
  10. scubabiker

    scubabiker Been here awhile

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    May 13, 2014
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    Location:
    Norway in a nutshell, AKA stord island
    #10
  11. woodsrider-boyd

    woodsrider-boyd Wow, these guys are fast

    Joined:
    Apr 19, 2005
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    513
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    More good links, thanks!

    And no final drive chain, its belt driven.
    #11
  12. woodsrider-boyd

    woodsrider-boyd Wow, these guys are fast

    Joined:
    Apr 19, 2005
    Oddometer:
    513
    Location:
    WA
    Finally got some time to work on the Derbi. I was hoping to get the water pump and shaft pulled and replaced without having to split the cases, but the water pump impeller is stripped off its mounting nut, so I have to split the cases to replace the impeller.

    At this point I think I'm just going to replace the crankshaft bearings and seals and put in a new piston, rings, and small end bearings plus gaskets, seals, etc. Keep it stock on the piston size, no big bores at the moment.

    Will call Racing Planet in the next day or two and see if they can help me get the right parts ordered up.

    The waterpump and its seized up shaft are behind the oil pump on the shaft on the lower left.

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    The waterpump, shaft and bearings were frozen in the cases bad. Did days of soaking with penetrant, heat, cold, couldn't get it to budge. Finally got a threaded rod welded to the end of the shaft, then rigged a brace and wrenched the water pump out. Watched a youtube video with narration in a language I did not understand to get that tip. Been watching a lot of Piaggio engine rebuild videos in languages that I do not understand. Lots of narration and explaining that I am not getting. :dunno

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    Backing the waterpump out.

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    #12
  13. woodsrider-boyd

    woodsrider-boyd Wow, these guys are fast

    Joined:
    Apr 19, 2005
    Oddometer:
    513
    Location:
    WA
    Finally freeing it up.

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    And its out. What a mess.

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    Pulled the seal in there, will clean it all up when I split the cases.

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    Gave the bike a thorough washing before I got into it.

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    Next up is ordering up some parts and removing the motor, then splitting the cases.

    Only problem is that my Lectron carb just showed up for my Husky 125 so I may get diverted for a bit while I install and fiddle with that and of course get out on some test rides. :evil
    #13