Help troubleshooting hot stall issue

Discussion in 'Board Trackers and Vintage Motorized Bicycles' started by wret, Jun 27, 2017.

  1. wret

    wret Member

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    A couple of weeks ago a made a 30 mile trip to work. At about 20 miles, while coasting to a stop light, it stalled and did not easily start. I put on the choke and a lot of throttle and got it started again, although pretty rough. I tried to keep the revs up to prevent another stall but at another light a couple miles later it quit again and would not fire choke or no choke. I fretted and let it cool a few minutes and tried it again and it fired right up.

    Last night after an easy ride of only a few minutes downtown, again while coasting to a light, it quit. Again with choke a got it to fire but couldn't keep it running. It died and wouldn't restart. I walked a mile home, hooked up the trailer and went to pick it up. Got entertained by a passerby who gawked, drooled, asked a lot of questions, and guessed that it was a 1916 :)

    Back home I kicked over and it fired immediately. I pulled the plug and the color looked great but I will pick up some spares on tonight.

    Any clues what my be causing these hot stalls? I'll be riding in a parade next week and need to make sure its reliable. It would be embarrassing to have to push it past 30,000 people.
     
  2. indian22

    indian22 Well-Known Member

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    Sorry Wret that I don't have a definitive answer, but I'll offer a few observations about my two CG 125 engines. First I'm totally impressed with the motor/trans, but the CDI is not very robust and though I've not experienced any CDI related problems with my two engines some of the karting guys have. This may have something to do with the use they are put to in extremes of weather.

    Some CG xxx clone engines are are shipped as short blocks. I added Mikuni carbs to both of mine, later to discover they were knock offs though marked Mikuni. I experienced erratic starting and running problems problems with one and ordered a true Mikuni, problem solved. The problems you described were similar to those I experienced with the clone carb. I spent a lot of time working on the offending carb, cleaned, replaced jets, adjusted, tested etc. to no avail. New carb has run great as shipped from the factory right out of the box.

    All this said I ascribe to the old maxim "most carb problems are electrical in nature" before replacing or even working on the carb I replaced all the electrical components, one at a time & checked for good ground and wiring connections (including both soldered and plug units. Start with replacing the plug.

    Like I said no answers just a few suggestions that don't nearly exhaust the many issues that could be causing engine problems. Best of luck & hope you have it sorted before the parade.

    Rick C.
     
  3. wret

    wret Member

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    Thanks Rick. It occured to me that the rather recent relocation of the coil to the proper magneto position (under the exhaust pipe), may be a contributing factor. I think I've got a spare and will see if I can add some heat shielding. I'm also going to check/clean the carb and petcock screen but in my case it runs if I can keep the revs up so it doesn't seem fuel starved.

    Next time I take it out I'll bring the ratchet, not just the spark plug socket so I can acctually check for spark while it's still hot. Doh!
     
    #3 wret, Jun 27, 2017
    Last edited: Jun 28, 2017

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