Because you have a side exhaust engine the oriëntation of the transfer channels could be a bit off. But yes it is possible that it is only at the main transfer port but with the better engines not usual.

http://www.novarossi.it/2012/images/...ande/08723.jpg

On this picture you will see the under edge of the piston is for a part shortened. It has 2 functions:
1) not to touch the crankshaft at the lowest position
2) to open a gap at the intake ports when it is at the highest position.
The long side on the piston is to keep the exhaust closed at the highest position.

But no, it has nothing to do with the running temperature. Thes small simple engines just run on a higher temperature. To give an example, I had a Kyosho .15 engine running at 170 degrees celcius, that hot the blue head colored purple. But hey, the engine did run fine.