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Thread: 5b not running right!!

  1. #1

    Default 5b not running right!!

    Have had the 5b 26cc for coming up to 2 years bought used and never had any issues with the engine, just the other day after being stored for 6 months or so I took it out and started it up it started fine bit high on idle so turned the screw slightly and let it get up to temp and gave it a good run on full throttle it was belting up and down and on low throttle with no hesitation, after 30 mins or so I could hear the engine hesitating on full throttle it was losing about 15-20% power then coming back every half a second or so. I checked the fuel tank and thought it was empty and was hoping it was that, after filing up I checked the primer bulb all full of fuel and it started up but after a couple of miutes it started doing the exact same thing so I turned it off thinking I might cause unnecessary damage to something else. Could it be something as stupid as the fuel cap has a blockage where the little hole is (I just remembered that from a youtube clip I watched when looking for tips when I first bought it) I hope its not a bloody engine fault, as I did not have any fuel mix ready for the first time I used my friends mix both mix at same ratio but Ive been using rock oil and he's using Castrol in a gold coloured bottle, I cant see that causing a problem but though I'd mention in case it could be..

    Last edited by chirri999; 25-05-2017 at 03:25.

  2. #2
    Baja-Forum Maniac llazaru's Avatar
    Join Date
    Apr 2012


    Could well be a blocked cap, also mixing different based oils together is a big no no so could be that too

  3. #3
    Baja-Forum Maniac spentallmymoneyagain's Avatar
    Join Date
    Sep 2014
    ''oop north lad''


    as above what laz said mate ,
    and also check that the fuel lines are not collapsed, split, and that the clunk is still on the line in the tank,
    also the bulb, check that when you pump the bulb that the fuel goes down the return line and doesn't come back towards the bulb when the bulbs released,

  4. #4
    Join Date
    Jan 2015
    Finland, Joensuu


    check carb diaphragm, usually when i have had some sort running issues i check that firs and 90% it has been faulty

  5. #5
    Baja-Forum Maniac coalminer's Avatar
    Join Date
    Jun 2011
    Mansfield ,Nottinghamshire


    Had a similar problem with my old original 26. Because it's a two bolt head , the bolts had come loose and blown the head gasket, it would run ok but once stopped it didn't want to go again. Check all studs and gaskets in the head, carb bolts and check carb insulator not broke/ loose.
    Check the coil hasn't come loose.
    As said above, not good to swap about with oils in the fuel.

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