by Aussiecrf230 » Sun Jul 19, 2020 3:34 pm
Hi barfy and welcome to the site.
Something you will have to check is how bigger bore you can get before you can no longer use the standard head gasket and have to start using expensive specialty gaskets.
Looking at the parts list the barrel and base gasket are same part numbers for a 2006, 2007 and 2017.
I think you can get to 250cc before you run into trouble from what I have read.
I think a better bang for buck would be install a better camshaft that can still be used with standard valve springs and rejet. Check that it doesn't kill the low speed tractability just for top end power.
A good cam for a 230 will improve torque across the rpm as they are a short duration cam to start with. Always use new rockers with a new cam no mater what. Keep the old ones labelled with what lobe.
That assumes the bottom end is still OK. They do last if oil is changed.
A fresh slightly higher compression piston and rings might help freshen it up too, and the cam manufacturer would be able to suggest what compression to use.
Don't go too high on the compression, 10:1 would allow standard fuel with a bit of a cam and shouldn't cause detonation. There are higher compression pistons around but would need to be used with bigger cams, ported heads etc.
The thing is any engine is a sum of good parts that work together.
This engine can be made to be fast, it is just the cost easily gets crazy.
Then you need suspension to keep up with the power.
If your son wants to go faster at some point it needs to be considered to upgrading to either a 250 or 450.
Ray
Australia
CRF230F 2004
C30F Power Up needle
Mains 132
Idle 45
2 turns out
Baffle out, Screens In
It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas