Engine still VERY slow and boggy after new carb and plug

Discussion in '2-Stroke Engines' started by mastafoo, Sep 25, 2009.

  1. mastafoo

    mastafoo New Member

    Ever since I finished my bike I was amazed at how much power it had, I never took it to full throttle because it would probably break something. Now, the amount of power it has is ridiculously low. It very slowly accelerates to 10-15mph with the throttle wide open, and makes a strange boggy sound when I go full throttle. Before this problem, I could just slightly twist the throttle to achieve this speed. Fuel also comes out of the air intake, I can see the back of my bike is wet after rides. No oil is leaking, however. I installed a new carburetor, and the engine showed no changes in performance. I installed a new spark plug, and again it behaves exactly the same. I observed that before I had this issue, the gases coming out of the exhaust had more of a "punch", like little explosions even when idling. Now they are very weak. I flushed the exhaust with gasoline to clean out as much sludge as I could, but there is no improvement in performance. I remember leaving the petcock open a few times for a number of days and when I got back there was oil dripping out. I would start the bike and it would smoke but then get better and return to normal. My fuel is 32:1 and is relatively fresh. Anyone have any ideas on what is causing this?
     

  2. Flapdoodle

    Flapdoodle Member

    My first thought is a float problem. What color is the plug?
     
  3. If changing carby didn't help sounds like something going on around intake manni maybe. Have you checked to be sure it is unobstructed, tight to cylinder? Fuel mixture coming out air-intake sounds like backpressure.

    Scotty
     
  4. Also, maybe try taking muffler off and running for just a quick test unless you have a spare(good) one laying around. Sorry for the double post but I just thought about a process of elimination.
     
  5. sphynx.0029

    sphynx.0029 Member

    i recently had this issue and i found that if you move the needle in the carby it will yield results. take the top off the carb, remove the cable from the sleeve then remove the needle (don't lose the "c" washer ya need that. then there is a black clip on the needle, towards the short end is less fuel and towards the long end is more fuel. mind the carbon buildup on the piston head tho.
     
  6. GearNut

    GearNut Active Member

    When the engine in my Hawthorne had fuel dripping out of the exhaust, I had to adjust the float level in the carburetor to a lower setting. It was too high and would not turn off the gas flow like it should. This condition caused fuel to pour out of the needle jet inside the carburetor throat, and into the engine, and out of the air cleaner. There is no way the carburetor can properly meter the fuel when the float level is too high.
    The fuel eventually filled up the flywheel cavity inside the crankcase. The flywheels were "drowning" in fuel.
    I had to blow out the fuel inside the crankcase with compressed air. It took about 2 minutes to get it all out.
     
  7. mastafoo

    mastafoo New Member

    Yeah well I checked the plug and it's black and oily. I don't unscrew it when the engine is hot but wait a few hours. Anyways, I'll try to figure out how to adjust the needle and see if that works, maybe the new carb is messed up as well. As for carbon on the piston/inside the combustion chamber its been only 200 miles, and If I do take off the head to clean carbon out will that ruin any seals or do damamge? Also, I'm trying to take apart my exhaust but the series of discs inside it won't come out. There could be blockage causing the backpressure, so I'll have to somehow pull it all apart.
    I don't have any spare exhaust pipes and I think running the motor without one might not be a good idea. Gotta love these happy time clunkers...
     
  8. GearNut

    GearNut Active Member

    Removing the cylinder head will require a new head gasket in order to guarantee proper sealing. In a pinch, you can anneal the old one with a propane torch or electric stove to soften and re-use it. Rub bar soap on it and get a good layer evenly on it. Heat the gasket untill the soap turns black, then remove it from the heat source and let it air cool. Being carefull to not bend the gasket, lay the gasket on a hard, flat surface and wipe the bar soap residue off as well as you can and your are done.
    This in no way guarantees that it will re seal, but it will give you the best chance possible.

    Excessive exhaust back pressure will cause poor operation for sure. Unfortunately I have not disassembled your style of muffler, so I am not of any help there.

    The descriptions you have given towards gas residue on the rear of the bike, and excessive fuel dripping out of the muffler are classic symptoms of a float set too high.
    Gently bend the float lever arms down, away from the carburetor body just a little bit at a time, perhaps 1/16 of an inch. It is better to sneak up to the proper setting by adjusting it a few times rather that bend it too much the first time and cause a lean condition in the carburetor. A lean condition can easily cause severe damage rather quickly.
    Good luck, and have patience. I have a feeling you will need it!
     
  9. mastafoo

    mastafoo New Member

    Good news, I removed the muffler to rule out the backpressure theory and it turns out the bike performs like a beast without it. By that I mean better than it has ever before. Of course it is very loud and I've read that it is not good for the bike to run without one. So I guess the only thing I need to do do now is somehow dismantle and clean my pipe. That's much easier said than done. I've tried flushing it with gas twice, and a good deal of black sludge came out. The bike still performs the same, however, so there may be some solid carbon deposits that aren't dissolved by the gas and must be manually removed.
    I also bent my float lever slightly before removing the exhaust, which didn't have any noticeable effect. Still, I would like to know how to distinguish between a lean and a rich condition to prevent any damage.
    - nick
     
  10. GearNut

    GearNut Active Member

    A rich condition will blacken the sparkplug with a wet, oily residue, and make the engine run sluggish at high engine speed. It will usually start easily without the choke engaged.
    A lean condition will have the sparkplug color white, possibly silvery white.
    Silvery white is very bad at the silver is actually aluminum deposited from the piston top. The engine will run very well at lower speeds, but surge at high speeds. Also you will notice that the engine runs very hot.
    A tan colored sparkplug is desired, tan to light brown.
     
  11. tacoshell4

    tacoshell4 Member

    the cat is prob jammed up
     
  12. Toysaresuss

    Toysaresuss New Member

    Best way to fix it is put the old stuff back on. :)
     
  13. mastafoo

    mastafoo New Member

    I've tried using a pressure washer, dish detergent, and even flushed it with gasoline many times and cannot get the clog out. I remember when it was new I could blow into it easily, now it is very difficult. I hit it with a wrench and threw it on the ground to loosen the carbon and that only partially worked, I saw chunks of it come out. It's still the same, though...Any tips on how to clean a pipe or get the guts/discs out?

    I'm considering getting a new pipe for $35 if I cannot clean this one out in the next week...
     
  14. GearNut

    GearNut Active Member

    If you really do not care about the outside finish, and do not mind painting it with Hi temp exhaust header paint when done, then you could try to do what I used to do to my 2-stroke dirt bike exhaust.
    Build a nice fire for the evening. After you get a good bed of coals going (5 or 6 logs) throw the pipe into the center of the coals. Let it roast for a while.
    It will stink and smoke. I recommend avoiding the smoke. After an hour or so remove it from the fire with a piece of long stiff wire or metal tubing. Let it cool down.
    Fish a good length of discarded bicycle chain inside it (wire the chain so you will not loose it completely inside the pipe! you may never get it out!) and use the chain to knock loose all the krispy krud you can out of the inside.
    If your pipe is a catalyst type, I do not know if any of this will help. It is the best method I know of though for 2-stroke exhaust.
     
  15. tacoshell4

    tacoshell4 Member

    nice dude!
     
  16. crackers

    crackers Member

    Gear Nut my engine was flooding and I had to adjust the float to get it to stop but it was doing this for awhile. Can you explane how to go about blowing out the crank case. I have a compressor but don't want to damanage anything. Your's is the first post I've read about blowing out the crank case. Makes since through and that raw fuel can't be good for the bearings. Thank's Crackers
     
  17. GearNut

    GearNut Active Member

    Actually the excess fuel will not hurt the bottom end components, it just will not let the engine intake/ tranfer cycles function properly. Kinda like breathing through your nose with sinuses full of snot.
    1. Remove exhaust pipe.
    2. Remove sparkplug.
    3. Look down sparkplug hole and slowly turn engine over untill the piston is all the way down at the bottom of it's stroke.
    4. Use an air nozzle with a long skinny tip and carefully guide it down into one of the transfer ports in the cylinder. http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=42424
    A thin rubber hose attached to the nozzle will work too (aquarium air hose). Be very carefull to not scratch anything inside there!
    5. Obviously be carefull of the fuel spray that will be blown out of the engine.
    Blow out the engine for about 2 minuits.
    6. Reassemble everything.
     
  18. crackers

    crackers Member

    Thanks GearNut, I think I better go with the gun and the hose, sounds like it woud be safer for me. I should notice a performance increase if its not breathing, its running a lot better just not being flooded all the time. Haven't really ran it any length of time just started it and it sounded 100% better. Thanks again
     
    Last edited: Oct 8, 2009
  19. crackers

    crackers Member

    I bought the Harbor Freight gun yesterday and blew it out today, I used a full length of shrink tube on the end of the gun, fit great. Nothing but air came out so everything below must be ok. I just needed the peace of mind knowing my crank case wasn't half full of gas. Years ago I had a 390 Ford engine that had a leaky diaphragm in the manual fuel pump and it was leaking gas into the crankcase. I found this out after the explosion, there was a backfire at the carb. and then a loud boom, blew the hood open to the safty latch, blew the valve covers off (the valve cover bolts were still bolted into the heads it just ripped them off, blew the dipstick up and droped the pan. So I'm a little gun shy of fuel in a crankcase. This probably couldn't happen in one of our little engine's but I needed the peace of mind. Thank's again
     
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