295cc Big Bore


Send us your existing top end and we will modify it to be 295cc.

This setup offers better performance and reliability than any other 295cc big bore setup on the market… we know this because we carefully tested the others before designing our own! All our big bore setups are dyno tested and our porting and combustion chambers are computer designed using professional software.


Send us your complete existing top end and we will do the following:

– Bore, port and replate your cylinder. Often significant welding is required prior to boring to strengthen the cylinder… this is included. Porting is computer designed and the replating is done in Australia by Electrosil.

– Design and machine a custom combustion chamber profile. This is one of the key benefits of our 295 setup compared to the others… we offer a much better combustion chamber profile, designed to resist detonation and make jetting easy, while giving broad smooth power. All heads are designed to run on 91-98 octane fuels.

– Modify the powervalve to suit the new bore size and porting.

– Supply new top end parts including piston kit, top end gaskets and a little end bearing.


In short you will receive your top end back ready to install with all the parts needed to get it up and running ASAP.

Turn around time is usually 3-4 weeks due to the complex work involved.

Unless you ask for something different we will setup your 295cc top end to produce a broad range of power… it will make around 55rwhp with loads more than a stock 250 everywhere from idle up to peak.


If you decide to go ahead with a big bore setup you MUST send us an accurate squish clearance measurement taken with the top end you intend to modify. When sending the parts please send us the base gasket, complete cylinder including powervalve, head, head gasket if applicable, and of course the squish clearance measurement.


The standard price for this setup is $1550, however this can vary by up to $100 depending on the individual parts we receive.

Please DO NOT pay for this 295cc kit online. If you want to go ahead please call us and book your job in then we will take payment when its completed.



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