Home Forums 2-Cycle Racing Comer 80 Bogs out under load

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This topic contains 5 replies, has 3 voices, and was last updated by  Garth Bailey 4 years, 5 months ago.

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  • #34923

    Garth Bailey
    Participant

    Hello,

    My sons comer 80 was losing some of the top end speed so I decided to change the piston rings.  Now it will start and idle even hit the accelerator and flips up to high end sounding normal.  Pull the brake petal and give just a little or full throttle and it bogs down and dies.  If you release the brake quickly and feather the throttle sometimes you can stop it from stalling.  Can not get it onto the track it will not hold any load at all.  Same symptoms Hot or Cold

    Things I have done:

    Took head and cylinder off checked ring seat looked good

    Changed Heads

    Replaced all the seals top and bottom including o-ring, carb manifold gasket and carb gasket making sure pulse hole was open.

    Replaced Carb Manifold

    rebuilt carb

    moved carb to a running engine works perfect

    changed muffler (getting desperate at this point)

    A few questions after searching these boards

    1. Torque on Head I have found elsewhere where head torque is 80 inch pounds but I have seen on these forums 140 inch pounds?

    2.  The Head just to make 100% sure ( looking at the bottom does the narrow or wide side face the carb?

    3. Could it just be a bad set of rings?

    4. Could it be electrical?  From what I have experienced and  researched electrical on these comers is all or nothing.  If it is intermittent it would happen when hot.  Load on the engine is not going to change the behavior of the electrical right?  Noting that rpm does play a role when it dies only the load does thus leading me to believe it is compression related but what else could it be that I have not checked.  I am out of ideas!

     

    Thanks

    Garth

  • #34933

    Jim Campeau
    Participant

    Sounds like carb manifold gasket is in wrong way, check that the hole lines up with hole in manifold.

  • #34946

    Walt Gifford
    Participant

    Does it feel like it has compression when you crank it? Sometimes rings have burrs on the edges but, I’d suspect a fuel flow problem. Trace the pulse passage. Did you get the cylinder base gasket on right? Maybe a crank seal popped out, it happens. Do you hear a good base pop when you crank it with the spark plug out?

    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

  • #35114

    Garth Bailey
    Participant

    Gif,

    Checked all of the above all is correct.  I am wondering if maybe I got sold the wrong rings?  This is going to sound really dumb but I am out of ideas.  Every Comer 80 ring set I have seen new or used is bronze/brownish in color.  The rings I was sold and put in were silver in color?  Could the color difference be an indicator of the wrong rings?  I know it is a stretch.

     

    Thanks

    Garth

  • #35448

    Walt Gifford
    Participant

    The rings should go in without excessive filing for end gap of .012″. The side gap with the ring installed should be .001″ or less. Put an allen wrench in the starter nut and pull it through, it should fight you pretty good. If it pulls through kinda easy that might be it but, I suspect ignition.

    Did you try a new plug? You could pull the flywheel and check for a sheared key. Are the ground connections clean? Try a different coil.

    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

    • #36045

      Garth Bailey
      Participant

      Gif,

      you hit the nail on the head.  The base Gasket was wrong blocking the pulse into the block.   I went to my local Kart shop and asked for a base gasket for a comer 80 and put it in.  That blocks the pulse hole into the block.  Looked at the old one and the shape of the gasket is slightly Different allowing for the hole to be open.   In the future I guess I will just need to alter the gasket they sell me.

      Thanks for all your help!

      Garth

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