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This is all the parts necessary to build a 400ex or xr400 to a 440cc. Includes choice of Namura (12.5 to 1) or (11 to 1) compression piston kit(piston,rings, pin and clips) Namura Big Bore sleeve and cometic big bore top-end gasket set(head and base gasket and o-rings for 89mm kit). This is a drop on kit(no engine case modifications are necessary) We charge $125.00 for the machine work to re-sleeve your cylinder. We press out the old sleeve,bead blast the cylinder, bore the cyinder to accept the oversize sleeve, counterbore the cylinder for the flange on the top of the sleeve, re-surface the top deck of the cylinder so the sleeve is even with the top of the cylinder,then bore and hone to the finish size. If you send us your cylinder to do the machine work we will pay the return shipping on your cylinder.


400ex head work and porting.

Option 1. Bead blast head, Multi-angle valve job, re-place valve seals and tru gasket surface $150

Option 2. Bead blast head, re-place valve seals and tru gasket surface. Multi-angle valve job. Port and polish head-->Intake ports are smoothed and casting flaws removed, glass beaded finish to prevent fuel/air separation, combustion chamber polished, exhaust ports enlarged and polished and new valve seals installed. Total $550.00

Option 3. Bead blast head, re-place valve seals and tru gasket surface. 4 new Black Diamond 1 mm oversize valves. Multi-angle valve job. Port and polish head-->Intake ports are smoothed and casting flaws removed, glass beaded finish to prevent fuel/air separation, combustion chamber polished, exhaust ports enlarged and polished and new valve seals installed. $650.00

Free return shipping