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Hawk Motor ???

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    Hawk Motor ???

    Has anyone built a hawk motor with 2 front heads? I think I'd like one for the "modern Vincent" look.


    #2
    now i get this front/rear thing mixed up, but i BELIEVE that its the rear head that flows more on the exhaust then the front.. so the common conversion is a rear/rear head mod...

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      #3
      So, rear rear has been done successfully? Anybody got pics?

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        #4
        Awhile back Hord had one for sale.No real advantage,but if your just going for the look it's possible.You have to fab your own headers and collector.
        1\2 Liter Duc Eater

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          #5
          You guys do of course realize that whether you run F/R or R/R or F/F or even R/F you will never get the Vincent look you desire. The exhaust ports will always face forward and backward. Remember where the cam chain is? On the right side for the rear head and the left side of the front head so you need to turn the rear around and use it up front. Now the exhaust port is facing forward. Still.

          For the record the rear/rear headed superhawk idea was never proven. The rear head has slightly better exhaust flow but slightly poorer intake flow than the front head it replaces so it's a wash. You would be better off letting someone who has experience with Hawks (it would make JD happy to) build you a set a F/R heads and you'll be happy. Also you won't have to beg M4 to make you a special exhaust for your R/R abomination.

          Because of the R/R idea there a more front heads floating around than rears these days. If anyone needs one I have like 3 extra fronts.
          Faster than your mother... She's what the pros use.

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            #6
            Repeat information but years back I tested ported front vs. rear heads on the bench. Yes, the rear head flows quite a bit more... until you put exhaust pipes on the heads and test again. Then the flow levels right out. It's only natural, the rear has a built-in "diffuser" compared to the front. The rear still did flow a little more but it was something silly like 1 or 2 cfm. Couple that with the fact that either exhaust port will flow enough to support the craziest intake port, (ie, 70%+) and you have a myth... IMO. Somewhere somebody tested heads without exhaust pipes hooked up and we've been saddled with this whole rear/rear head thing ever since. Again, just my opinion and I've certainly been wrong before. But nobody has ever proven otherwise.
            J.D. Hord
            Keeper of Engine Nomenclature, 9th Order

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              #7
              I think that my race bike may be set up this way...? My front head exhaust exits to the left instead of the right. Would this mean that it has a rear/rear? My other Hawks all exit right off of the front head...
              Brandon


              88' (Gulf) Hawk GT
              and some non-Hawks...

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                #8
                Originally Posted by incogbdog
                I think that my race bike may be set up this way...? My front head exhaust exits to the left instead of the right. Would this mean that it has a rear/rear? My other Hawks all exit right off of the front head...
                no, the front exits to the left, and curves back around and under the bike.
                the rear exits to the right, and curves forward then under the bike.

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                  #9
                  Thanks for the info crash and Hord. I was daydreaming in the garage and realized there is no room for both pipes on the right side anyway. Boohoo.

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                    #10
                    If the front exhaust port itself points left, yes, you have a rear/rear setup. Not to be confused with which way the exhaust pipe points, because those vary.


                    Originally Posted by incogbdog
                    I think that my race bike may be set up this way...? My front head exhaust exits to the left instead of the right. Would this mean that it has a rear/rear? My other Hawks all exit right off of the front head...
                    J.D. Hord
                    Keeper of Engine Nomenclature, 9th Order

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                      #11
                      Originally Posted by Hordpower
                      If the front exhaust port itself points left, yes, you have a rear/rear setup. Not to be confused with which way the exhaust pipe points, because those vary.


                      Originally Posted by incogbdog
                      I think that my race bike may be set up this way...? My front head exhaust exits to the left instead of the right. Would this mean that it has a rear/rear? My other Hawks all exit right off of the front head...
                      In that case, it is a rear/rear... thanks Hord.
                      Brandon


                      88' (Gulf) Hawk GT
                      and some non-Hawks...

                      Comment

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