Thread: Johnson "70mod"

  1. #81
    Team Member skeg's Avatar
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    Quote Originally Posted by hupiveneilija View Post
    Ill do that, thanks!
    Have to find studs & nuts somewhere.

    BTW Good Morning!
    If you find someone that make heads studs please post it

  2. #82
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by hupiveneilija View Post
    I have original mainjet now, dont remember what it is in those carbs. Made 1 WOT and shutdown, plugs look ok. Pulled head off last night, pistons seems like ok to me.
    Have to do those reliefholes with J-B and assemble the head back, then can go out and drive more so that i can see how pistons look by the transferports.

    Must get tachmeter wich shows to 8000.

    Ouh yes, I replaced those reedbodies, wich Ive stuffed all around, with stock ones. It felt like fighting against itself in high rpms. Better now but weakened lower end, have to find that sweet middle.
    And stock tuner in Place, still revs like hell with 18in prop.
    There is some tuning to make.

    Btw is it any good to use coppergasket spray with headgasket?
    I would fatten your main jet if you have raised your ports and bumped the compression, as soon as you load that motor with the bigger pitch prop she is gonna melt the exhaust side out. Main jetting for sst60 spec motors is generally 72 and 73 your probably like a 65. You want to go fat and work your way down not a lot of clean wash on those pistons it does show some but that could be lower rpm wash.

    Fuel is power if you haven't increased your jetting to flow more fuel your either gonna burn it up or you haven't really made any increases in noticeable power (ie. factory jetting is usually a little fat)

  3. #83
    Team Member hupiveneilija's Avatar
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    Quote Originally Posted by LittleCharger View Post
    I would fatten your main jet if you have raised your ports and bumped the compression, as soon as you load that motor with the bigger pitch prop she is gonna melt the exhaust side out. Main jetting for sst60 spec motors is generally 72 and 73 your probably like a 65. You want to go fat and work your way down not a lot of clean wash on those pistons it does show some but that could be lower rpm wash.

    Fuel is power if you haven't increased your jetting to flow more fuel your either gonna burn it up or you haven't really made any increases in noticeable power (ie. factory jetting is usually a little fat)
    In my carbs, wich are from 1992model as my engine, they are 50. There are so many variations of these carbs and every single one have different jetting.
    How much You think I go first up from stock? If I go 60 its 20% more. Too much?

  4. #84
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by hupiveneilija View Post
    In my carbs, wich are from 1992model as my engine, they are 50. There are so many variations of these carbs and every single one have different jetting.
    How much You think I go first up from stock? If I go 60 its 20% more. Too much?
    60 will most likely be too much as that's more like a 37% increase in area, but I would rather go more then needed and start making some jetting passes and work your way down. I prefer reading piston wash over plugs, if you are going to read plugs you need to make sure you are looking at the base of the plug for reading, using one method to confirm the other is the best

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    Team Member hupiveneilija's Avatar
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    Ok. If I have something like 55 I go with that or make one for those I got. If you think 60 is too much. I have plenty of carbs in a box! Also have three carbs from 2cyl, they are bigger than 70 ones. Maybe try one day.
    Actually I have tried those before with old boat, it felt kind of a stronger for take off but made bowls empty after 3500rpm. I think that pump doesnt made enough then.

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    It's funny how in 1989 they had two sets of carbs, the early sets had 65s and the later ones had 52s in them and in the early 90s they went to 50s. I just learnt something. I wonder if you would benefit from a set of older carbs.

  7. #87
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by hupiveneilija View Post
    Ok. If I have something like 55 I go with that or make one for those I got. If you think 60 is too much. I have plenty of carbs in a box! Also have three carbs from 2cyl, they are bigger than 70 ones. Maybe try one day.
    Actually I have tried those before with old boat, it felt kind of a stronger for take off but made bowls empty after 3500rpm. I think that pump doesnt made enough then.
    the Bridgeport 70hp 56er carb has the same venturi size as the two cylinder. Are your carbs form the 56er 60hp motor?

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    No they arent, from 1992 70hp. I think biggest 3cyl carb. I have three sets of 60hp carbs, way smaller. Those three even bigger than 70 I think they are from 2cyl 60hp.
    Ive got all 3 model of 70 plus later blacktops.

  9. #89
    Team Member hupiveneilija's Avatar
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    Quote Originally Posted by sharpeye Mike View Post
    It's funny how in 1989 they had two sets of carbs, the early sets had 65s and the later ones had 52s in them and in the early 90s they went to 50s. I just learnt something. I wonder if you would benefit from a set of older carbs.
    Yes and thoseearly 65 dont have idle jet at all, dont have even hole for that. 52s have idle jet, or viceversa dont remember wich way😂. Then there is middle jet, some have for fuel, some for air. Fuel version have screw front of it. And this new version with idle screw. And ovalport blacktops with idle screw and 2 jets.

    Tube from bowl to venturi different in all carbs.

    Older with chokeflaps. Somewhere like -83 and on primerchoke.
    Very confusing.

  10. #90
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by hupiveneilija View Post
    No they arent, from 1992 70hp. I think biggest 3cyl carb. I have three sets of 60hp carbs, way smaller. Those three even bigger than 70 I think they are from 2cyl 60hp.
    Ive got all 3 model of 70 plus later blacktops.
    2 cylinder 60hp carbs are same venturi as the 1992 70hp

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