250 to 300 cylinder swap (search for torque)
 

Has anyway swapped their 250 to a 300 with the cylinder head kit?
This is my first 250 2-stroke Iv always been a 4 stroke or 300xc KTM guy..
I really like my 2019 GG 250xc but it is in my opinion a zingy 250, like a yz 125.. (ok maybe not that zingy 😆) but you get the idea.
I like bottom end torque, I ride down low in the meat.
Iv looked at the 300cc cylinder head swaps on eBay.. just wonder if it will be worth the money? technically speaking it should be really? but I also have never rode a GG300 so are they tractor pull, grunt workers like the KTM 3honey?
Also, would swapping out the FMF fatty for a Gnarly make much of a difference? (Pre-cylinder swap that is) it would be nice to just swap out pipes in order to gain what I want but I just can see it making ?that big? of a difference alone.
And yes, most people will suggest ?do the gnarly pipe first and if it?s not enough so the cylinder swap??. Yes, thank you.. that?s great advice.
I?m wonder more if anyone has already experimented and could share their thoughts on rather the expensive cylinder swap is money well spent or is the slightly cheaper (not by much these days) gnarly pipe a good change to gain low end?

You can adjust the power valve for more low end power.
I have tried these pipes on my '18 250.
The Gnarly will give you more low to mid power.
The Fatty; more mid to top end power.
Pro Circuit. more mid to top end power and increased over rev.
Can't recommend the Pro Circuit. as the silencer inlet has to be expanded to slide onto the PC pipe.

Easy peezy
 

Turned 2 250s into 300s. If you like 300s the gasser will make you smile. If you like your bike to sing 250 if you want grunt 300. Gnarly pipe more torque and beefier build quality.
Good luck

Trying a decent needle first will change the power delivery

One more option is to convert your 250 into a 265 with a Big Bore kit. I built a 265 last summer and while it does not have the bottom end of a 300, it does make a nice increase over a 250 with better low end and mid-range power combined with the ability to scream up top.

who makes the 265 kit?

You need to send off your 250 cylinder and head. There are multiple previous posts about the big bore kits and who provides them.

I have heard that Tom Morgan does excellent work.

https://www.morganracingengines.com/tmrservices.html

The 265 big bore is awesome! I have built two but neither was a GG (Honda CR250 and a KX250) but have been considering it for my '11 GG EC250R. The 265 turned those MX bikes into great woods bikes with the additional low end they picked up yet they absolutely screamed when you opened them up. I used Millennium both times since they clean, port, squish, clearance, replate the cylinder, and reassemble the powervalves.

I have built 2 1 was stroked to a 265 and 1 was bored feel about the same going to stroke my 325 I think it will be a 340 will see