My 2002 Derbi GP1 Scooter Project

[Tyler VR]

I've been on a couple test runs and it seems to run okay, but it needs some re-jetting. I'm using the k&n style air filter that came on it but it bogs at WOT, plug looks like its running lean but gets up to around 45mph. I tried to put the modded stock airbox on and now it runs too rich and only gets to 40mph.

I figured out my keihin oko main jets will work on this dellorto carb, it had a 95 and I went up to 105. Switched to a uni filter and now I'm getting up to 50mph, might even try a bigger main jet. I still need to work on getting the idle a little higher, the idle screw is turned all the way in and turning it has no effect. Changing the needle clip position hasn't helped either, looks like it's running rich at idle so I need to order a smaller idle/pilot jet.

I've been learning as I go with this dellorto carb but this scale helped me get a better handle on it.

[ped]

Hi Tyler. you can pickup jets at your local dealer. I do

[Tyler VR]

Hi Tyler. you can pickup jets at your local dealer. I do

Good to know, but I all ready ordered some from treatland.

[Tyler VR]

Got it together, rides pretty good.

DSC07002 by Tyler V, on Flickr
DSC07005 by Tyler V, on Flickr

[ped]

What a nice scooter.
Italians make nice designs.

[Tyler VR]

What a nice scooter.
Italians make nice designs.

Thanks, The styling is what attracted me to this scooter, they have pretty good performance too. It rides nice but I'm still getting used to the quick take offs from a stop, maybe not the best scooter for stop and go traffic. The drive face has been de-restricted and has 5.5 gram rollers, clutch looks stock but I don't know for sure.

[Meatball]

Seems as if theres a few aftermarket go-fast goodies available for this. I stumbled across on a few sites. Let us know what you like (and dont like) about these compared to Honda's offerings. I can tell the braking is improved over our good ol' USA standard drums. What else?

[Tyler VR]

Seems as if theres a few aftermarket go-fast goodies available for this. I stumbled across on a few sites. Let us know what you like (and dont like) about these compared to Honda's offerings. I can tell the braking is improved over our good ol' USA standard drums. What else?

Yeah the amount of aftermarket performance parts for these piaggio engines is crazy, I just wish I was rich enough to afford them. I think there's 4 name brands that make BBK's, different stages of performance within those brands.

You're right about the braking, this is my first scooter with disc brakes and they're awesome. I guess most of my scooter experience has come from 50cc Honda scooters from the 1980's so it's hard to compare to this 2002. The size of the scooter is a lot bigger than the older Hondas, sits higher/wider and is also about 200lbs with a steel tube frame, not like a honda stamped out frame. Derbi was made for performance and Honda was made for economy, it's a whole different world.

If I ever win the lottery I'll build up a piaggio engine like this:
https://www.youtube.com/watch?v=uP2dpyHbhCI

[Tyler VR]

Well the ebay kit popped a head gasket, just under 100 miles. I was heading to work when it overheated, it was running when I turned it off but wouldn't restart. When loading it up in a truck I saw coolant dripping from the exhaust pipe.

I all ready pulled the head off, the head gasket o ring just doesn't fit in the groove good enough. I could probably get it running again if I get the correct thickness o ring to fit in the groove. But my plan is just to buy a malossi 70cc top end kit.

[Tyler VR]

Got the malossi top end kit, its a lot higher quality than the ebay kit.

DSC07023 by Tyler V, on Flickr

[Meatball]

When you said you had bought an Ebay kit, I was like...

Good call on the Malossi...

[Tyler VR]

When you said you had bought an Ebay kit, I was like...

Good call on the Malossi...

The ebay kit seemed good up until it popped the head gasket, it came down to the head gasket o-ring the kit came with didn't match the o-ring groove on the head. A replacement gasket kit I ordered came with a o-ring with was a thinner thickness, that probably what should have come with the ebay kit.

The ebay bbk was $110, plus a connecting rod bearing I bought $12, plus a water outlet pipe I needed$15.
The malossi bbk was $178 and it came with everything plus carbon reeds.

The new malossi top end has been installed and I can tell it has better performance over the ebay kit. I'm still working on jetting but have made it passed 55mph with a new malossi drive belt , runs really good.

[Tyler VR]

The GP1
IMG_0106 by Tyler V, on Flickr
IMG_9652 by Tyler V, on Flickr

[Meatball]

[Chadzilla1]

Do you still have the GP1? I just bought one for 250. But it’s not running. The carb is dellorto 17.5 is that stock carb ?? Also there there are two ports I don’t know what they are for on the carb. I know the oil, main fuel, and vacuum Ports. But the other two what do they connect to? My carb was missing the fuel lines and oil line so don’t know. If you still own please need pics

Thanks
Chad