Do you mean part number 17 on the picture and im pretty sure that's the crankcase breather.

yeah, they're road legal and Restricted but theres also a 200cc version. Pretty much Suzuki's competitor for the DT i think, doesn't seem like it sold too well though.

You also could have got one of these around that time.

They're fairly uncommon as well, have one in my garage in pretty poor condition.

This is exactly what mine did and it turned out to be the CDI but on the wires that recieved voltage it was a really low amount for less than a second to make it twitch, I was lucky and found one for £25 on ebay, you can also try searching for CDI from the Derbi GPR125 2T as im pretty sure its the same.

There's one in France for slightly cheaper than you have found.

http://www.ebay.co.uk/itm/DERBI-125-GPR-RACING-BOITIER-ALLUMAGE-CDI-2004-2008-/172221604252?hash=item281935219c:g:SmMAAOSwagdXSKlk

Got the nut off now, used
@MIGHTYMAN 's advice and put the engine back in the frame. Thanks guys

I've had another look and still cant find one, but from looking in the haynes wiring diagrams there is no fuse on the DTRE and X models?

where is the fuse located? I looked around the battery but couldn't find it.

My bike was idling while putting my gear on then just cut out, all lights on the clocks went out too. Used the kick start and it started again but the lights flicker as if its only running off the generator? I checked the battery with a multi-meter and it is still charged but the voltage doesn't increase when the bike is held at high revs.

Do you mean part number 17 on the picture and im pretty sure that's the crankcase breather.

This is exactly what mine did and it turned out to be the CDI but on the wires that recieved voltage it was a really low amount for less than a second to make it twitch, I was lucky and found one for £25 on ebay, you can also try searching for CDI from the Derbi GPR125 2T as im pretty sure its the same.

There's one in France for slightly cheaper than you have found.

http://www.ebay.co.uk/itm/DERBI-125-GPR-RACING-BOITIER-ALLUMAGE-CDI-2004-2008-/172221604252?hash=item281935219c:g:SmMAAOSwagdXSKlk

I think @aidan1996 has a speedo.
http://dt125r.co.uk/topic/337/dtr-dtx-parts

yeah, they're road legal and Restricted but theres also a 200cc version. Pretty much Suzuki's competitor for the DT i think, doesn't seem like it sold too well though.

You also could have got one of these around that time.

They're fairly uncommon as well, have one in my garage in pretty poor condition.

I had my cylinder rebored and put the power valve back in but it looks like it sticks out further than the cylinder wall and could be hit by the piston. Whats the best way to reduce the size of the valve ?

Got the nut off now, used
@MIGHTYMAN 's advice and put the engine back in the frame. Thanks guys