| After much time and flow testing, we are
        happy to announce the release of our high performance cylinder head
        modification for late-model Sportster engines. The process of events that led to a
        significant increase in the flow characteristics throughout the entire
        range of valve lift is lengthy and tricky to say the least. Our flow bench techniques have enabled us
        to improve the low-lift flow of both the intake and exhaust ports,
        giving the engine a smoothly tuned effect, even with some of the more
        radical cams. The high-lift flow at .500 has been increased in the
        exhaust port by 28% and by 19%in the intake port, providing an exhaust
        to intake ratio of 84% at  500"
        lift, which is up from stock average of 78%. During the process, a large amount of
        metal is removed from the ports using our patented Tooled Finish, to
        give maximum atomization of the incoming fuel. The seat pockets are
        polished with a radius up to the valve seating area. The combustion
        chambers are matched to your bore size and polished to give the most
        effective flame travel. Dual spark plug conversion is the
        finishing touch to give your engine its full power potential and
        eliminate detonation. Our valves are handmade in-house from
        21-4N stainless steel with polished tuliped heads. The backside is
        machined with a . 750" radius to increase flow characteristics and
        nitrided along with the stem to minimize wear.  | The valve seating area measures
        .060"wide on the exhaust valves and .045"wide on the intake
        valves. The head diameter has been increased to 1.562"on the
        exhaust and 1.812"on the intake. This high-performance cylinder head
        modification package includes: • Matching and reshaping the intake
        manifold with our Tooled Finish to atomize the incoming fuel • Hand lapping the head gasket surface • Glass beading or painting • Testing valve springs • Assembly with our all Teflon valve
        stem seals to the specifications required by manufacturer of your
        particular cams Check out the flow chart accessible from
        this page, and you’ll see the dramatic improvement in breathing. These
        heads, like all FLO Headworks products, are guaranteed for one year on
        street driven motorcycles. Our work and products are guaranteed for
        one year. For an estimate on your particular application contact us
        directly by telephone at 805-481-6300. Or you can
        e-mail us.
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