2011 convert EC250 to a 300?

[redrider]

Anyone convert a 250 to a 300? Seems like it would be easy. Any thoughts?

I have a 250 and a 300. The 250 is my backup bike and it's ready for a top end rebuild. Was wondering if anyone has done the conversion.

[Jakobi]

Originally Posted by redrider

Anyone convert a 250 to a 300? Seems like it would be easy. Any thoughts?

I have a 250 and a 300. The 250 is my backup bike and it's ready for a top end rebuild. Was wondering if anyone has done the conversion.

Its easy as pie. Bolt a 300 cylinder and head on it. Fit appropriate piston. Done! The powervalve is the same and will fit right from the 250 jug into the 300, as will the exhuast spigot. Same base gaskets for both models. The inner o-ring on the 300 head is bigger.

I am about to do the opposite. Turn my 300 into a 250.

[LukeDuke25]

You might as well get it ported for optimal power while you are in there!

[Jakobi]

Why would you want to go and ruin Gas Gas' beautiful engine characteristics by smashing into the ports?

I'm not saying you couldn't turn it into a fire breathing dragon. Its well do-able, but generally not why people buy GG in the first place. If you want port work done make sure you have someone you trust do it.

However, while you do the top end it is a perfect time to match the ports a bit better if they are out, and to clean up any rough casting internally (stay away from the nikasil). I'd also highly recommend setting the port timing using the base gasket stacks so that the piston is level with the bottom of the exhaust port at bdc, and then measuring your squish on reassembly of the head and getting that modded from there. Some came with mega clearance - almost twice that of ideal. This will gather you some good performance gains, better economy, and also retain the engine characteristics we all love.