Two stroke advice needed please

Aidan1150 said:

I found that the two cables which operate the power valve were broken, so I got some new ones and fitted them.

Does anyone know how to set the power valve? I'm reluctant to start the bike and do harm until I know that the PV is correct.

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i think you may find that the power valve has seized, and that's why the cables are broken. might be worth a check?

As long as the PV hasn't broken up inside you'll do no harm by running it with the cables attached or not.
As cookie say's, check the PV rotates freely before you go any further.
If it is there is nothing to stop you pegging it open and going for a blat to see if that cures the top-end issue.
Somewhere there will be information on the rev range at which the PV should open.
Looking at that set-up I would imagine that if you replace the cables and adjust up the free play, the servo should open the PV at roughly the right point in the rev range. Just try it and see how it goes.
In basic terms, the sooner it opens, the quicker it'll take off (at the expense of bottom end) and vice versa.
I used a digital tacho connected to the coil to set up the PV on my KTM.
If you go down that route you might find you need to half the value you get on the tacho to allow for it being a 2stroke.

The powervalve on the dt125 should be set so when the engine is idling.. its closed with just a smidgen on free play on the cables.

Then rev it up to check its opening freely.

Its better to have it working or itll feel cack.