02' DT125R losing power at top end

[Blaze.Vile]

When my DT get's into 5th and 6th it starts to lose power and struggles to pick up revs, does anyone have any ideas why?

[Calum]

Is the bike modified?

[Blaze.Vile]

@Calum it has a giannelli down pipe and dep sport end can

[Calum]

@Blaze-Vile and the jetting is standard

[Blaze.Vile]

I believe so, what size jet would i need ?

[Calum]

@Blaze-Vile 210 Stock main jet.

To be fair, I would have to refer to the manual to know.

Is the bike still restricted? The 2001-04 models were the worst for restrictions.

Reed Valve, CDI, Exhaust.

[Blaze.Vile]

The bike is no longer restricted

[Blaze.Vile]

@Calum 

This is all the manual says about jets and reed valves

[Calum]

@Blaze-Vile Sounds like it could be an electrical fault.
Check CDI, Coil, Spark Plug, HT Lead etc.

Air box isn't restricted. Air filter clean from debris etc?