Just bought a MK2 CRM, when I picked it up the guy reckoned he didn,t trust the oil in frame premixer system and premixed at 40:1 in petrol tank.
Put one litre of 2 stroke in bike frame and filled up with petrol yesterday. Ran fine no smoke issues and ran fine over 50 miles.
Got home put bike in garage, looked tonight and there is a pool of 2 stroke oil under the left hand side of bike.

I realise I was duped by the bloke but where do I start in finding the problem?

All advice warmly welcomed.
Dave

Take the tank off and look at the oil sensor lighton the top of the frame. 10:1 that is where the oil is coming from.

Drain the oil a bit and remove the sensor. They can be made to fit tightly by roughening up the plastic a bit but depends on condition. Other ways are use some kind of sealant or get a new sensor (expensive & last resort). Or you can seal over the hole and get rid of the sensor completely but use the sight tube at the headstock and fill up the reservoir regularly.

Thanx for that KnackeredMK1 I will take the tank off tomorrow night and start from there.

Removed tank today, oil was pouring out of the sensor.
Removed sensor and caught remaing oil.
Used a pump out of a soap dispensor to remove most of remaining oil.
Cleaned everything up and put some rubber sleeving at the top of the plug above the actual sensor.
Used clear silicon when plug was nearly fully in and pushed fully home.
Siliconed all around plug and left alone for two hours.
refilled tank with 2 stroke, No leaks.
Thanx for the help