300/250 top end swap.

[mclark302]

Seen an add where a guy was selling his 250sx top end beccause he installed a 300 top end on the bike. Is that possible? I need a 250 cylinder but have a complete 300 top end.

[tkjracing]

hi this swap will work but your bike needs to be 06 or newer they have the same 72mm stroke as the 300 the 300 top end can be older just bolt it on rejet your carb and have fun i have done this no my 07 250 sx love it

[compmoto]

I have available(as of last week) a top end from '95 model 300, that I would like to install on a '92 model 250 engine. Does anyone know if these parts are compatible ?I may not be able to get the pieces now, as the guy had other interested parties. Busy bee !





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[tkjracing]

hi sorry but you can olny swap heads on 06 and newer 250 and 300 they have the same stroke of 72mm your 92 250 69.5mm stroke the 95 300 73mm hope this helps

[gary jp4]

Originally Posted by tkjracing

hi this swap will work but your bike needs to be 06 or newer they have the same 72mm stroke as the 300 the 300 top end can be older just bolt it on rejet your carb and have fun i have done this no my 07 250 sx love it

I think this is the other way around. Anyway, he wasn't talking about the head it was the whole top end. Seems to be a lot of mis or missing info on this. Must not have been done much.

My 2003 250 SX has a 72.0mm stroke like the newer 300's. Isn't it the older 300's which have a different stroke. Actually, all the 250's and 300's I could find even back into the 90's all have a 72.0mm stroke. What's up about 2006.

Sounds like fun. Anybody have any more info on this swap. How is top end of an 300 EXC compared to a a 250 SX?

Gary

[N*E*R*D*]

Finish This... I Am Interested In This Modification.

[compmoto]

the rod stroke says it all... I also have found a '90 model 250 partsbike, that also needs a top end. What's the EZ way to tell if the parts are compatible? My local KTM dealer has fell victim to the economy, and obamanomics ... do I go with online parts fische, and part numbers which are same ? thnx
Who makes/sells plastics for older model KTMs ?