Top end planning.
 

So kind of new to this 2-stroke thing. Not worried about taking it apart, and back together.

My question is this: When I put the bike up for winter I am sending the head off to RB designs for the squish mod. Should I put a new pistion in it, or just rings, while I have it apart. Is this something that I just need to check the spec. What is the best brand. what is the drill here

What year model/more importantly how many hours on the current top end? Most here feel that 75-100hrs is a good time for new rings and while in there a new piston and little end bearing isn't a bad idea. Keeping all that in spec reduces wear on the cylinder as well. Others will tell you they have run theirs a lot longer (and I'm sure you can as all my top ends done around 85hrs have still been in spec).

If it was my bike I'd be giving it a full fresh top end in the off season to ensure a trouble free run next season. If you just want to get the head done, you really don't need to even bother pulling the cylinder. 2 fresh o-rings for the head and thats it.

I'm a fan of having multiple scoots. There is no off-season at my house.

The bike is a 09 gasgas 300ec, i will have to check the hr meter.

I have a second bike, which gets the winter riding, ktm 500xcw, winter is some of the best riding here in idaho's desert low-lands.

Any brand opinions on the parts?

I don't have a brand opinion but for best results (talk to Ron first for pointers) if you decide to use a new piston install your new piston (without rings) to measure your current squish as Ron will want that info when you send your head to him. New piston may differ from the old one. That way when you get the head back it matches the new piston.
I'm using Athena in mine and we put a Vertex in my kids. Budweiser vs Miller as far as I'm concerned.
Mine was an "A" cylinder and I put in a "B" piston when I did it per Jim Cook.
The kids was replated to "A" size by Millenium and that's also the piston we used for his.

The stock ones are S3 branded Vertex Pistons. I've had no issues with these. I have also used Wossner forged pistons with good results. Both are pretty similar price wise. Just take your pick cast/forged.

There should be very little difference in piston sizes regarding the squish setup. What may be a variable is if you decide to change the gasket stack to raise or drop the cylinder. Either way its probably not a bad idea to take a squish measurement after the fresh slug has been installed and then have the head cut to suit.

The local importer here said to match the cylinder with the piston, I am about to do my top end and I have a B cylinder (stamped on the inlet side) so ordered a B piston

I've always done the same thing matching an A with an A. The 'correct' way to do things is to have someone measure it all up to determine which size piston will be the best fit. The difference between sizes is a whopping 0.01mm.

Thank you, i had not thought of this. Great point.