DERBI GPR50 PLEASE HELP!

Zippyreid · L Plate Warrior Joined: 13 Jan 2013 Karma :

hello i bought a derbi gpr50 in november, its a 01 plate and i put a derestricted cdi into it and its spead doubled getting speeds off 105kph! Very Happy

and all was good until a few days later it kept braking down, its battery was low on power so i charged it up and it made no difference. one minute it will be fine the next it will have no power (engine still runs, but its not pulling) we checked to see if it was maybe over heating but you can hold the engine block so i dont think it would be that, another thing we might have thought was that it maybe needed a service? but not sure if needing a service would cause that.

any help would be great thanks just so i have a rough idea what is wrong Smile

mentalboy · World Chat Champion Joined: 05 May 2012 Karma :

Did you do any preparation for making your ped go faster besides putting in a CDI?
Sounds to me like you've buggered something!
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Make mine a Corona.

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

A derestricted GPR50 will only just about see 50mph.

You will need to change the exhaust, sprockets and the CDI for the 50 to be derestricted properly. Thumbs Up

mentalboy · World Chat Champion Joined: 05 May 2012 Karma :

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

GPR50 is a geared 50 "super sports"

Zippyreid · L Plate Warrior Joined: 13 Jan 2013 Karma :

no i did no other prep as i didnt think a derestricted cdi would improve the speed i thought the exhaust was what limited it, but it has a full arrow exhaust system which either came standard or previous owner fitted.

i was thinking about swapping back to previous CDI to see if it was maybe the CDI?

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

If it starts and runs, the CDI would be working.

Compression test the engine.

Zippyreid · L Plate Warrior Joined: 13 Jan 2013 Karma :

how would i go about doing that? sorry im new to all this

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

mentalboy · World Chat Champion Joined: 05 May 2012 Karma :

Mex1co · L Plate Warrior Joined: 01 Feb 2013 Karma :

Hi im the op's dad this thing has been a learning experience for me thats for sure just a quick question if anyone can answer for me if he was to run it with pre mix fuel would you remove the oil pump or just empty the tank.
Thanks in advance.

Mex

P.addy · Red Rocket Joined: 14 Feb 2008 Karma :

Mex1co · L Plate Warrior Joined: 01 Feb 2013 Karma :

Cool thanks.

Nope. · World Chat Champion Joined: 17 Feb 2011 Karma :

Leave the 2t pump alone. You really want it working, if you remove it you have to increase the jet sizes to compensate for the oil in the fuel.

With regards to the acceleration problem, I would swap the CDI back and check the connections. I had a similar sounding problem with my GP1 and it turned out to be that one of the connectors on the CDI had worked loose. With the connection not working it was effectively hitting the limiter at just above idle speed.

I presume that since you've changed the exhaust you've up-jetted?
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Former: Derbi GP1 50, Sachs XTC 125, Suzuki GSXR 400 GK73A, Kawasaki ZX7R, Suzuki DR250, Yamaha RD350
Current: 2011 Yamaha XT660Z Ténéré, 2003 Yamaha YZR-R1 5PW (In Build), 2009 Kawasaki ZZR1400