Engine starts fine and then Bogs down?

Discussion in 'General Questions' started by StrontiumEthics, Aug 14, 2010.

  1. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    On one of my engines I have a problem that is driving me crazy. The engine bogs down and does not reach its highest RPMs. After a long trip around town it started to act funny last week. Here are the 2 possibilities that came to mind.
    Electrical system, and fuel system. I started off by opening the carb and looking inside to see what was going on. I thought maybe the float might be to high so I slightly bent the wishbone arm downward. Then I started her back up It started off fine but after about 25 secs of riding engine began to bog down. Then I changed the carb and the same thing happened. THen I tested the coil with a multimeter and it read 358 ohms. I switched the spark plugs. But something that I found particularly interesting is that the spark plugs were really rich when I removed them, and the needle is at its highest notch. Even more strange was that this never happened before and I rode my bike ALOT. Right now i am bout to go test the CDI, and take a look at the sparkplug again. If there are any suggestions please feel free to assist! Thank you.

  2. GearNut

    GearNut Active Member

    Have you recently changed your oil to gas ratio to a higher one? That would make the air:fuel ratio richer. (IE 20:1 changed to 32:1)
    A dirty air cleaner will too, but I figure that you all ready would have thought of that yourself, same with a loose and falling choke.
    A partially plugged up muffler can do it as well.
  3. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    Wow Gearnut! Its like your a magician. I actually did change from 20:1 to 32:1 cleaned my air filter and adjusted the choke. But I did this before the problem happened. Today after making some time I managed to find out the problem. The problem was indeed electrical related. I believe that the CDI went bad somehow because when I changed it, and the muffler, the bike ran just the way she should. All the time I was doing test rides fuel actually dripped out the muffler. It had to be either the fuel was to much for the engine or the engine wasn't burning it. If I changed the carb the it must be that the engine wasn't burning it! Thank you for the help. = ) What are some problems that you have had with these little gremlins before?
  4. motorpsycho

    motorpsycho Active Member

    actually i have read several times that the gas-oil ratio does not affect the air-fuel ratio...they are 2 separate things.
    if your gas-oil ratio has too much oil in it, it will make it harder for the spark plug to burn the mixture and the plug will become oil fouled resulting in a bog.
    this is what i read, not 100% sure if it's true or not.
  5. GearNut

    GearNut Active Member

    More oil mixed in the fuel raises the specific gravity of the fuel and also thickens it.

    Given the same orifice, or jet size, fuel mixed at 32:1 will flow more through it than fuel mixed at 20:1.