Purchase Options
PO-4VLV-VJ $695.00 4-Stroke Head Port and Valve Seat Machining (4-Valve)

PO-2VLV-VJ $495.00 4-Stroke Head Port and Valve Seat Machining (2-Valve)

PO-5VLV-VJ $795.00 4-Stroke Head Port and Valve Seat Machining (5-Valve)

*Customer must send in their cylinder head to DRI to have porting/machining done. New heads are also available.

All porting prices are plus any parts required. Valves, Guide Seals, Guides, HD Valve Springs etc.

For additional information see 4-stroke Head Builds see - HP4 Valve Train Kits

DRI offers the highest quality ATV 4-Stroke porting on the market today.

All port designs have been tested and designed on DRI�s in house Super Flow bench.

DRI head porting and valve seat modifications are designed to give maximum horsepower, torque and reliability.

All DRI 4-Stroke Head porting includes valve seat machining (SERDI).

Guides are removed for head porting (most models)

Guides are modified or replaced with upgraded design (most models).

All 4-stoke parts and valve seat work is done in-house by master technicians.

DRI master technicians, Danny and Loren, have over 50 years combined experience with ATV engines.

DRI uses their own in-house SERDI valve seat cutting machine. This is the same machine (smaller version) as Ferrari uses for their F1 engines. This machine is also used by engine builders in NASCAR, IRL and CART. This SERDI machine allows users to cut valves seats to near perfection.

DRI is believed to be the only ATV High Performance engine builder in the world to regularly use a SERDI to cut its 4 stroke valve seats.