Gordon Jennings and crossflow two strokes

Discussion in 'Outboards' started by MikeLB, Mar 19, 2018.

  1. MikeLB
    Joined: Mar 2018
    Posts: 1
    Likes: 0, Points: 1
    Location: Vilas North Carolina

    MikeLB New Member

    Hi, Being formerly a motorcycle mechanic, and enjoying very much Gordon Jenning's Two Stroke Tuners Handbook, I cannot find a book or guidance about porting a cross-flow engine. Where can information, formulae, and/or a good discussion of same? T^hanks for your help and guidance. Mike
  2. boatbuilder41
    Joined: Feb 2013
    Posts: 160
    Likes: 4, Points: 18, Legacy Rep: 56
    Location: panama city florida

    boatbuilder41 Senior Member

    Whst particular cross flow are you porting???... Be careful about raising ports... Widen and square off is better than raising port height.... Increasing the height can build more horsepower but decrease the torgue .. The best performane gain possible from most outboards will come from the exhaust tuners... Look on a couple of boat racing sites .. Boat racing facts and hydroracer... Fast fred or tim kurtz will be your pros at this... I do believe fast fred may be a member on this site as well.. I dont know the guys .. But there isnt much of there material i havent read... Both .. My daughter and i built her boat .. We dont actually race it.. But we enjoy it very much.. Our top speed so far is 86.6 mph on gps with me.. And 89.1 mph with her ... She only weighs 90 lbs.. So it is much faster with her than me.. . its a big achievement from only 49.9 cubic inches.. It was based from a 60 hp johnson.. Porting helped us achirve these gains.. But our biggest gains would be our boat weight.. Its a v bottom 13ft 6 inch kennedy kraft.. Our boat weight is 206 lbs with a hydraulic jack plate .. Hot foot... Control box.. And steering all on board... .. Tim and fast fred has reached well over 100 mph with these same based 3 cylinder engines... ... The record i believe is 114 mph for this class... So these guys would be the masters of 2 stroke porting for sure....
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