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Tomos 4hp air cooled.........Help please! MK2

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  • Tomos 4hp air cooled.........Help please! MK2


    Thanks Riptorn, i got your message despite the original thready being closed, nt sure why it was closed???
    Anyway i fitted a new plug NGKB6HS and it was running ok (i have since been recommended to use a B8HS and i have this on order as original Tomos plug was Bosna F80 so in the same heat range as NGK B8HS)
    I had engine running well in the tank as before but now suddenly i had issues where i could not start it at all. After some checking and double checking i found it was my "adaptor" to allow my Tomos 6mm fuel coupling to fit the new fuel hose that is 8mm, long story short i bodged it and this caused a fuel stoppage :-)
    I now have a proper 8mm-6mm hose joiner on order with the plug as well as having the Tomos fuel coupling on a 6mm piece of fuel line that will be properly joined to the 8mm line from the external tank.
    Hope to test again next weekend with freshly mixed fuel, will report back.

    Best regards


  • #2
    Re: Tomos 4hp air cooled.........Help please! MK2

    I closed your original thread, Kevin. It was old and was hijacked. I missed your post from yesterday. Sorry for the inconvenience.


    • #3
      Re: Tomos 4hp air cooled.........Help please! MK2

      Hey Kevin, My Tomos is up at the cottage, but I am pretty sure it has a Champion plug in it. Did you check the lower unit for water? Mine leaks pretty bad. How about the ID plate on the bottom?
      Be careful with the throttle, petty flimsy. Don't over crank it.


      • #4
        Re: Tomos 4hp air cooled.........Help please! MK2

        Hi Riptorn

        My motor has the plate missing. the lower unit screws are in their real tight and i could not get them out last time i tried. I would like to replace the lower unit oil as i have no idea how old it is. I am hopefull that once i have my new correct heat range spark plug and hose reducer there should be no reason why it should stall. Since buying this motor i have replaced the fraying throttle cable, replaced the carb float that did not float (also have spare carb now), replaced the spark plug, made good the spark plug cap connection to HT wire, cleaned out card and needle valve and seat, replaced the external fuel tanks fuel line/priming bulb. I will need to replace the pull start cord later this season as there is some slight fraying evident. If all goes well she will serve me for some time to come. I like her as she is lght and simple but i would like more power/speed to push my 2.7m airdeck dinghy.
        I will re-test this weekend and post the results here (testing in water filled wheelie bin)
        Best regards



        • #5
          Re: Tomos 4hp air cooled.........Help please! MK2

          Hi Kevin
          I am surprise you can get parts for the old Tomos. As soon as I get up to the cottage i will take a picture of the plate and send to you. I think it came from Yugoslavia or some place around their. Very rare motor. Not too many around.
          Lower unit, Spray with WD40 or sewing machine oil or what have you and let sit for night with the screws heads facing up. Use a heavy duty screw driver and crank with pair of vise grips on the screw driver. Make sure the screw driver fits tight. Push down hard when cranking so it does not slip (both ways to crack). Must be dry if it's that hard to unscrew. I wouldn't run it till you change the gear oil.
          thanks rtorn


          • #6
            Re: Tomos 4hp air cooled.........Help please! MK2


            latest situation with the new NGK B8HS spark plug and new fuel lines is that she runs longer with no signs of stalling but after an hour or two in the test tank i give a throttle blip and response is lagging a bit. so i adjust the air fuel mix to get a better response but as i stopped the engine to adjust to the rough position in the maintennce manual she was hard to restart as she was hot under the cowl. I let her cool for around 15 mins and after a few spluttery attempts she fired into life as normal and i adjusted the air fuel to give a good throttle response. It appears to my thinking that she is getting too hot under the cowl as heat built up pretty quick once engine was stopped. anyone else had this with this motor?

            Any ideas without drilling more air holes in the cowl?




            • #7
              Re: Tomos 4hp air cooled.........Help please! MK2

              It may be different in a cool water with a breeze. I don't think those motors were made for full out for that length of time. Might want to leave the cowl off when full out.
              Or try a cooler plug. Are you using regular unleaded?
              Your original post http://forums.iboats.com/showthread.php?t=489142


              • #8
                Re: Tomos 4hp air cooled.........Help please! MK2

                Hi Riptorn

                When i test the motor i have it running in a water filler wheelie bin and it is running mainly on idle, i give it some throttle blips from time to time. I hope to get out on the river this weekend so i will try running it with the cowl off to see if that improves things. will report back once done:-)

                Best regards