Thread: Johnson "70mod"

  1. #251
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by hupiveneilija View Post
    Drilled. Top is 32, fuel jet.

    Anyone else, is 25:1 too much oil?
    We run 25:1 in our two and three cylinder motors.

  2. #252
    Team Member hupiveneilija's Avatar
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    👍. Got temp up to 45*c by stiffening the spring. Must limit flow more.

  3. #253
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    realy need to know the head temp itself, water temp dont equate to what everyone else using as their guide to outboard engine temp.

    I think you already have the flow right, your low water pick up will not be making the flow much greater than the normal inlets, the actual pump is
    still doing the pressure to the powerhead. you might get extra 2 or 3 psi but thats about it. not worth talking about.
    you still get loads of water dumped out the adaptor and over the exhaust tuner, you have not restricted any of that flow have you ?
    and when idling stationary it is not different at all to normal pick ups for gathering water to the pump.

  4. #254
    Team Member hupiveneilija's Avatar
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    Long drive behind, everything worked fine! Engine in one piece and running😂😂.
    Got temp to 60*c on wot, pressure like little over 3bar and lower speeds thermostat limits it ~85*>90*c as its supposed to.
    Went over 7000rpm almost all 75nm. Must have been around 6nm near finish on wot 7400rpm. Not a single hickup. Knock knock!
    Havent look for pistons yet how the flushmarks are.

    Think its time to put blue block together too see what tuner cutting really did. And then try again those 1.5in carbs with bigger jets to see if they make any difference.
    Have to get somewhere 1 used 0.030 piston to make that first block usable. Really want to know how it work.

    Got plugs out, pistons have quite thick carbon layer in the middle and flowmark on the side is as wide as mans forefinger. I think it run real rich now.

    Picture of plugs. Those were almost new before this, thick oily carbon layer like pistons.
    Pistons from up:3,2&1
    Attached Images Attached Images     

  5. #255
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    your temp reading is not the reading it should be, you need to know cylinder head temp not water temp.
    if cylinder head went to 90c you would have a very poorly engine .. plus the overheat alarm will go off at 80 deg c.

    you need to put the sensor on the outside of the cylinder head. Not in water gallery.
    Also thermostat is not working correctly as it should be fully open at 143 degf= 61.6deg c.....


    spark plugs look very strange for a fully synthetic 2 stroke oil mix, they look like running on 4 stroke oil, it is not burning good if running high rpm .
    what exactly is the oil you are using ? what brand etc.


    Here is my plugs when running for 2 hours at idle only (1,000 rpm) cylinder head temp 62c fuel ratio to oil 40 to 1 , mercury premium 2 stroke and 5 month old stale petrol 91 octane.
    Attached Images Attached Images   

  6. #256
    Team Member hupiveneilija's Avatar
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    Little update. 7800rpm.
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  7. #257
    Team Member Roflhat's Avatar
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    That's fast now!

  8. #258
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    Quote Originally Posted by hupiveneilija View Post
    Little update. 7800rpm.

    Any thoughts of getting a Nitro foot? Probably worth 3 to 4 knots but you will have to look for another prop.

  9. #259
    Team Member Hevi Kevi's Avatar
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    Quote Originally Posted by hupiveneilija View Post
    Little update. 7800rpm.
    big case and no pad, you're flying! Nice job.
    Critchfield 15" 56ci OMC
    RapidCraft Cyclone 15" 56ci OMC

    Thanks hupiveneilija thanked for this post

  10. #260
    Team Member hupiveneilija's Avatar
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    Quote Originally Posted by sharpeye Mike View Post
    Any thoughts of getting a Nitro foot? Probably worth 3 to 4 knots but you will have to look for another prop.
    I think i stay with big case, stronger and parts are easy to find. Can use bigger prop for rough conditions though hard to find proper one. And it got wide usable speed range with 1 or 2 in boat, so i think its very good compromise now.

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