2010 cylinder
 

Looking for 300 head and cylinder to buy.

The s3 kit is a pretty good deal. If you can't find one used.

where are you finding the 3s kit?

Quick google

http://rypusa.com/s3-gg-300-ported-cylinder/

Has anyone used one of these cylinders? I'd be curious to know how it compares to stock.

Research carefully and ask before you buy, pictured cylinder is for trials and RYP is a trials specialist. I believe he is also the S3 importer so he should be able to get a cylinder. These cylinders were very popular 5-6 years ago and highly regarded for the most part if I remember correctly.

Eric

I have a 250cc one on my old donk. Had the ports etc measured up and compared against 10 model. All the info is in the thread. Finish is good, no complaints. They have raised the exh port a bit chasing more top end power, but nothing that can't be fixed by running a slightly thinner base gasket stack.

I purchased mine through gofasters back when they were the go to for gas gas.

S3 head
 

Motocross center has s3 heads just got a 250 and 300 3 months ago

there are several of them on Ebay both new and used.