S3 Race 250 Port Matched Cylinder and Head

[Jakobi]

Hi Everyone,

As I've been saying in a few different threads on here I have decided to change my 2010 EC300R to a 250 to see which I prefer.

I ordered the parts through Mark at GoFasters who provided great customer support. He answered all my questions and had everything in the mail and headed towards Australia in no time. All up it was great value with the Cylinder, Piston, Rings and clips coming in at $625usd, and the S3 head with 3 inserts being another $210usd. Quite cheap for what you get.

The workman ship on the parts is stellar and levels above the stock cylinder. I will post pictures of my 300 jug when it comes off to show a comparison regarding the casting of the stock cylinder and the hand port matched work of the S3.

I am interested to see how the base gasket stack will go to get the port timing correct, where the squish band ends up after this, and what the trapped volume and compression ratio are using the black insert (high high comp). With my 300 and its S3 I found the CR came up higher than I would like, while still having the squish band bigger than ideal by around 0.5mm. If this is the case I will ship the 250 head off with the 300 and have them both machined to correct the squish and CR. The plan will be to machine the insert to required specs and then lap the base of the head to match the inserts new reduced height.

I'll also be cleaning up the ports on the 300 while its off the bike which may get a thread of its own.

See pics below.