porting differences

Hi all

Does anyone know what porting differences where between the years of 2004 to 2009 oe even 2011. I have a 2009 and the engine is quite snappy. I also have a RM250 with an engine of a 2007 but the cylinder is 2004. It has now a fatty pipe and the silencer is the PC304. It is quite nice but still not so snappy as the 2009.

Could it be the porting or can it be done over the jetting and timing?



what pipes are you running?

On the YZ250 2009 all stock but it has a vortex ignition to replace the OEM one. On the RM250 with the YZ250 engine year 2007 a fatty with a PC 304 silencer and Vforce 3 reeds with cage.

Generally since 03 the cylinders have been the same.

I take it your jetting is very similar on both bikes and the squish is similar.

If so try swapping pipe and reeds to see if it makes any difference.

09 and 04 are original porting I presume.

Thanks, good to know. Tomorrow I have a look at the timing and change the setting too.



Your vortex will also give it more snap

Yeah a little I think but before when I had the OEM CDI it still was better then the RM.

I'll try a new coil as I had to use the Suzuki coil and I can not ride the bike at 100% after about 80% the engine has less power.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now