Carby GT5 GEN 4 80cc: Rich or is this normal?

Discussion in '2-Stroke Engines' started by EnFlaMEd, May 12, 2009.

  1. EnFlaMEd

    EnFlaMEd Member

    Hey guys. Ive done about 90kms now on my engine running 16:1 ratio and I am wondering if the engine is running as it should. It seems to be progessively opening up but it does struggle up hills and will stall if held at WOT trying to go up a hill and also if held at WOT and then backed completely off. It seems to run from a choppy range with power to a smooth period with power and then into a choppy stage with no power that it sometimes struggles to recover from regardless of throttle input.
    The mixture screw is set at 4 1/2 turns as stated in the manual and the engine starts and idles well. Perhaps idles a little fast. The engine will not start if I try to use the choke. So I never touch it. (choke left down)
    One thing I have noticed which is why I am asking this is that the exhaust spits out a **** load of oily liquid. The pic below is after the engine has been run for about an hour. Is this amount of **** normal or am I just noticing it more because its basically dumping onto the cranks and frame?

    Cheers

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  2. pdxrhett

    pdxrhett Member

    Sounds like too much fuel is going into the motor - try messing with the mixture screw, maybe a 1/2 more turn might fix it
     
  3. Shadeslay

    Shadeslay Member

    That much oil would be normal for 16:1, the plug looks a little rich. Try going 7oz per gal, which should be fine for break in and may help with your performance issues. You can adjust your needle to a leaner mixture but that will do little for the spray running that rich. Something else you can do is add a copper street 45 or 90 onto the end of the pipe. To aim it down/away from the bike.

    Mixture screw? what carb are you using?
     
    Last edited: May 16, 2009
  4. danlandberg

    danlandberg Member

    If you are running a stock carb, there is no mixture screw. The screw on the stock carb is a slide adjustment. Try adjusting the needle, move the E clip up one grove away from the pointy end. This will allow more air to fuel mixture (lean it out). The slide and needle work together, so when you throttle up you will get more air to fuel.
     
  5. EnFlaMEd

    EnFlaMEd Member

    I am running the stock carb so yes it would be the idle screw I was trying to adjust the mixture with which I have since learned :p
    Thanks for the input guys, I will try adjusting the fuel mix and carb after I have run what is left in the tank through.
     
  6. Junster

    Junster Member

    Could you post a pic from the side of the bike and motor? One far enough away to show the whole motor? From the view showing the pedals the muffler seems very close to the bottom bracket. Making me think the motor is mounted leaning way forward. That could make the carb tilted far enough that the float isn't working very well. It may just be the muffler design.
     
  7. danlandberg

    danlandberg Member

    If your running a 2 stroke. You should have a slide type carb, but not always.(some 2 stroke carbs are butterfly style).If you have a side carb, Have you tried moving the E-clip a notch?
     
  8. danlandberg

    danlandberg Member

    At high altitude it is some times hard to get it just right for max HP out put! I have been thinking of an in-between type of adjustment.(With out drilling the main jet) Just have not had time to have my transportation to work down. I know the carb parts are small & a pain in the a** to work with, But try different needle settings! (If yours is a slide type carb)!!!! Give it a try,and see what happens.
     
  9. danlandberg

    danlandberg Member

    Where is the mixture screw on a stock 2 stroke? (48,66,"80"cc)
     
  10. danlandberg

    danlandberg Member

    Mixture screw??? Where??????????????????

    ?????
     
  11. EnFlaMEd

    EnFlaMEd Member

    I'll be trying to adjust the needle clip when I've run the tank of petrol I'm on now through as Ill also be changing oil mixture.

    Junster: Please check here http://www.motoredbikes.com/showthread.php?t=18076&page=4 for pics. The engine and carb are mounted on an angle that I'm not really happy with but I dont really know what I can do about it unfortunately.
     
  12. Shadeslay

    Shadeslay Member

    It does look like you are a bit limited in what you can do. I know with my jack shaft the engine didn't quite sit how I wanted, So I used a spacer on the bottom part of the back mount. In between the curved part touching the frame and the plate mounted to the motor. Which will help tilt the motor. If you have the flat part of the mount that comes with some of these kits "for the drilling the frame engine mount" that will work perfect, with some drilling.

    With that much of an angle it's doubtful it will correct it entirely, but it may help enough. And it shouldn't effect your clearance to the top tube by much. I'm not sure I would go more then a 1/4", but even an 1/8" should help.
     
    Last edited: May 20, 2009
  13. Junster

    Junster Member

    You are on a pretty good angle, it's enough that the float adjustment is going to be sensitive. I don't have a shift kit (whaaa) so I'm not sure if you can shorten the jackshaft to front sprocket chain with a half link and rock the back of the motor down a little or not. I guess if it gets alot worse going down hill and better running going up hill that would be a clue. You may just need to tinker with the float a little.
     
  14. EnFlaMEd

    EnFlaMEd Member

    Hmm thats actually a pretty good idea Shadeslay I might have a bit of a play with that. The motor actually stuggles going up hill and is good down hill but now that I think about it it does run smoother when going up a slight incline. I have an expansion chamber and boost bottle on order so once they arrive I might have a tinker with it all.
     
  15. EnFlaMEd

    EnFlaMEd Member

    Ok. I have followed Shadleslay's advice and spaced out the bottom mount which has made a slight improvement to the angle of the carb. As well as that I have now moved the needle clip up one notch, changed to premium fuel at a 25:1 ratio with synthetic oil, fitted a NGK BP6HS spark plug and fitted the SBP expansion chamber which came in the post :D
    The bike is definately running better now and accelarates alot harder and sounds great. However I havent really gained any top speed and the bike seems to have the same problems trying to rev as it did before. Im sure it has way more in it especially in top gear. If you open the taps it stops running smooth and sounds like its missing and gradually looses power. Its goes from a nice brrrrrrrrrrrrr to a bap bap bap bap if that makes sense and like before it struggles to recover unless you really back off the throttle. It really seems like it wants to go much harder but it just reaches this wall and dies in the arse. In someways it is a bit like a rev limiter on a car.

    ps: top speed is about 40-45kmh assuming I set my computer up right :)
     
    Last edited: May 22, 2009
  16. linnix13

    linnix13 Banned

    what i did was run my engine 14:1 for the first 500km(the manual said 16:1 for 500km) and then i leaned it out to 20:1 which i curently run 3000km later, i sugjest just sticking with the rich mixture until the break in is done,
     
  17. nadroj

    nadroj Member

    your carb is tilted too much and it is letting more fuel in
     
  18. danlandberg

    danlandberg Member

    I ran 7oz oil the first gallon, 6oz the 2nd gallon & now I'm 5oz per gallon (read that mixture in a thread) I don't have a speed-o that works right, so I don't know how many miles I am getting per gallon? How does your motor (engine) motors are electric. Run? Did you change the needle setting?
     
  19. linnix13

    linnix13 Banned

    when i ran it rich for the break in there was ALOT of visible smoke and oil caked the chasis, performance was poor and it wouldent idle. it stalled and fouled plugs. it slowely began to run better after the 150km mark, then i weened it to 15 or 16:1 and it kept getting better, i actualy probably went to 20"1 after around 300km and it kept geting better and better until 500km when it ran perfect, i have left the needle in the stock half way down position, trust me, the engines run like **** while they break in but it will get better, how many km do you have on it so far?
     
  20. danlandberg

    danlandberg Member

    I don't know how many miles I have on it yet (no speed-o) It runs really good now, on my 6th tank of fuel (about 3rd gallon). Can only guesstimate @ 100-150 a gallon maybe 300-450 miles, I'll say the lesser because of hills & wind conditions. I just received a slant head & gasket. Going to install this week end if I get the time, also have a speedometer on order. after every thing is installed, I"ll see how it goes!
     
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