Converting a 250 to a 300

[pscook]

Originally Posted by Niall-griffiths

Does anyone know if a 05 300 cylinder will fit onto a 02? Also will the 250 cylinder head fit onto the 300 barrel or not ?as the mount on the 300 has broke

As above you need a 300 head to match the 300 cylinder. However, I have read that the newer 300's don't even have the lug, or at least aren't attached to the frame. It might be worthwhile to run without the lug bolted to the frame, supposed to reduce transmitted vibrations.

What condition is the 250 top end? Looking to sell it?

[Niall-griffiths]

The condition of the 250 head cylinder is very good, put a genuine piston kit in 20 hours ago also I might sell it but am unsure yet it really depends what I could fetch for it to make it worthwhile,

gasser let me know how u get on please mate !

[Niall-griffiths]

Could I get some options on getting the cylinder head and crancase ported do people think it will gain much in terms of power and smoother revving?

[pscook]

Originally Posted by Niall-griffiths

Could I get some options on getting the cylinder head and crancase ported do people think it will gain much in terms of power and smoother revving?

I believe the general consensus is to clean up the intake and transfer ports, then raise or lower the cylinder for exhaust port timing, and finally have the head cut for squish and compression. I don't remember reading any threads here about raising or lowering the port timing through port modification, it's typically raising or lowering the cylinder to expose or shroud the intake and/or exhaust port by adding or removing base gaskets (cheap and easy to undo).

I would be interested in hearing if someone widened the exhaust port, or moved the intake or transfer ports, or did any other porting and what gains (or losses) they experienced.

[Niall-griffiths]

Thanks for the reply, I have been told it would cost ?150 to port and polish my intake ,transfer and exhaust ports from a 2 stroke specialist who also makes his own performance pipes so I might send my cylinder to him and report back the results,I couldn't find any threads on anyone widening the ports either