For all those Derbi owners who have had cut-out issues.

[tommysmithfromleeds]

I don’t know how many users on here are Derbi owners, I know only of Alexlebrit and myself. However, after searching for solutions to the above problem I have found many others out there who suffer from cut-out issues. This fix is for the Derbi Cross City, Terra and Mulhacen.

The issue is this; you insert the key into the ignition switch, turn the tank selector to ‘ON’, start the engine and ride off only to come to a stuttering halt after a while. When you switch the tank selector to ‘RESERVE’ the problem goes away. Some have said it is the fuel filter, others the petrol cap (lack of holes creating a vacuum). These suggestions are wrong; the culprit is a piece of plastic pipe. Allow me to explain.



Above is a picture of the tank selector valve that has been deconstructed. The turning knob has been removed and the fuel filter has been unscrewed. Usually, the fuel filter (black) will sit over the plastic pipe (green) and screw into the valve (silver).

When the tank selector is set to ‘MAIN’, fuel travels through the green pipe to the carburettor. The green pipe is there to ensure the engine cuts out when the main tank is getting low (towards 1.5litres) so you then switch to the reserve. The issue is that the plastic pipe is too long, and is jamming into the top of the fuel filter, thus preventing fuel from getting to the carburettor.

Solution, trim the pipe down by 15mm. By doing this you still have a safety net as these Derbi models do not have fuel amount gauges, so you still maintain a reserve tank. But your allowing fuel to get into the green pipe and thus into the carburettor.

Pleas note: you do not have to deconstruct the valve body to fix this problem, simply remove the tank selector from the bike, unscrew the filter and trim the pipe. When you remove the selector:

1- Place a big pile of sand under the engine (to soak up and spills)
2- Disconnect the pipe at the bottom first (simple spring clip, removed with pliers)
3- Drain the petrol using the selector (make sure the bike is perpendicular with the ground so all the petrol comes out)
4- Remove the selector from the petrol tank pipe (simply unscrew the jubilee clip and pull it out by the nozzle with pliers)

I hope this post helps those who are afflicted by this problem, if you require any more advice let me know as I have a few more pics, but there a bit blurry. DISCLAIMER: This is a rough guide only, not a ‘how to’. If you are unsure what to do go see a mechanic. If you destroy your bike or set yourself on fire it ain’t my fault.

[Alexlebrit]

Oddly, I have had the occasional cut out with my bike, but it doesn't have a reserve tap like you say.

I wonder if its still got the tube though.

[tommysmithfromleeds]

Quite possible, I would imagine that Derbi (Piaggio) would use stock parts for the entire 2008 - onwards range. Looking at the scematics on the AJ Sutton website, there does appear to be a similar fuel filter.

DERBI Terra 125 ADVENTURE E3 FUEL TANK. Genuine/Orginal/OEM Derbi Spares, Derbi Parts, Service Items and Derbi Accessories.