I have been racing 2 strokes for nearly 20 years and have never had a seizure on a closed throttle running pre mix.
Apex Leisure in the UK specialise in NSR`s.
Take a look at the following link which shows some info on piston diagnosois and replating of cylinders.
http://www.apexleisure.co.uk/enginetuning.htm
You can E-mail Jo if want any technical info.
I know she visited Pukekohe race track last year on holiday in NZ.