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Post by chrisbws on Jul 19, 2019 4:26:43 GMT -5
so I've just changed the carb on my 98 mbk booster rocket to a dellorto 12 phbn, I adjusted the idle screw and air by myself and starts first time in morning by kick starting, the electric start button has a bogging sound to it(carb has manual choke cable).Now after the scooter starts it will boggle down when not reving the engine, it will run fine when accelerating but in the first hour or so of running the engine dies at traffic light stop and will start again no problem,so is the idle too low? I've seen that the valve adjustment could be too but I have no ideea where they are on my scooter. here is a pic of my sparkplug after 20 km of riding is it good or indicate bad mixture? (sry for bad eng)  |
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Post by pinkscoot on Jul 19, 2019 7:20:25 GMT -5
Welcome, your plug looks good so thats not your problem. Your scoot is a 2 stroke so you have reed valves. Though they can be adjusted its not a normal maintenance item to adjust. What RPM is your scooter idling at? How many turns do you have on the A/F screw? What notch is your needle set too? Is your battery in good shape? Are you using the stock air box? Any or all of these things could be your issue.
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Post by ThaiGyro on Jul 19, 2019 10:17:46 GMT -5
I have a few questions. Yes the plug looks OK...but just, ok. Are you running an injection pump (factory) or mixing your own fuel? Air box? Pod filters?
Secondly, have you cleaned and freshened up the carb? Float level is right? Float valve is fresh? (They would tend to leak at idle. Even a tiny bit would cause a problem) For the record...I do not idle my 2T's.
Especially with oil injection...causes that black goo over time. Partially burnt oil deposits. They cling to scratches in the liner, or ring grooves or anything that is "cooling", and then hug each other. (They grow) I suspect that is what you see at the edge of the plug in your picture. That oil collection is from low rpm/idle.
Third...no ignition issues? Timing is perfect? Coil output at idle is good? (Try turning off the headlamp at idle...or unplug it wile running). Could be your alternator is simply old. My '84 Honda would not idle well with perfect AF ratio tuning, when I still had half wave alternator. The reason I switched to full wave was that simple test. Too much headlamp draw at idle. (and high humidity)
Lastly...I will say this over and over and over...please do yourself a favor. Try to fix one thing at a time! Really! Two strokes and 4T high performance engines are simple. However, you MUST know what the real issue is. Fuel? Air? Ignition? Tune one thing...run it. Record your settings/results. Try another...Record your settings/results.
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Post by ThaiGyro on Jul 20, 2019 3:59:57 GMT -5
Hey chrisbws...your English looks good to me. If you need a response in another language...let us know. Many people here from countries outside the US of A. I am American, but live in Thailand. Spanish is real good, or French, or Thai, or Japenese...but pictures always work! So does laughing and crying! Universal!!
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Post by chrisbws on Jul 21, 2019 12:44:49 GMT -5
Welcome, your plug looks good so thats not your problem. Your scoot is a 2 stroke so you have reed valves. Though they can be adjusted its not a normal maintenance item to adjust. What RPM is your scooter idling at? How many turns do you have on the A/F screw? What notch is your needle set too? Is your battery in good shape? Are you using the stock air box? Any or all of these things could be your issue. hi i dont know the rpm, i dont have revometer, i also dont know how many turns on the af screw but it sits slightly outwards 1 or 2 turns from the middle,needle is in the middle of 6 notches,new battery,stock airbox and new filter |
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Post by chrisbws on Jul 21, 2019 12:50:45 GMT -5
I have a few questions. Yes the plug looks OK...but just, ok. Are you running an injection pump (factory) or mixing your own fuel? Air box? Pod filters? Secondly, have you cleaned and freshened up the carb? Float level is right? Float valve is fresh? (They would tend to leak at idle. Even a tiny bit would cause a problem) For the record...I do not idle my 2T's. Especially with oil injection...causes that black goo over time. Partially burnt oil deposits. They cling to scratches in the liner, or ring grooves or anything that is "cooling", and then hug each other. (They grow) I suspect that is what you see at the edge of the plug in your picture. That oil collection is from low rpm/idle. Third...no ignition issues? Timing is perfect? Coil output at idle is good? (Try turning off the headlamp at idle...or unplug it wile running). Could be your alternator is simply old. My '84 Honda would not idle well with perfect AF ratio tuning, when I still had half wave alternator. The reason I switched to full wave was that simple test. Too much headlamp draw at idle. (and high humidity) Lastly...I will say this over and over and over...please do yourself a favor. Try to fix one thing at a time! Really! Two strokes and 4T high performance engines are simple. However, you MUST know what the real issue is. Fuel? Air? Ignition? Tune one thing...run it. Record your settings/results. Try another...Record your settings/results. i dont understand the first question about the oil mix but my scooter has 2 separate intakes for oil and fuel ,air box? what is that?pod filter also?. carb cleaned few days ago, float level sits just under the line where the carb and float bowl meets so i need to raise it slightly higher but idk how,float valve? idk what that is. the oil deposits are harmful for my sparkplug or carb? not sure exactly what you meant. (timing is perfect? Coil output at idle is good?) care to explain in more detail please, alternator idk where it even sits...is that around the flywheel? |
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Post by ThaiGyro on Jul 22, 2019 8:06:51 GMT -5
Not an uncommon issue chrisbws. You already have a great start. You asked smart questions. For you...so much to learn. I trust that you have time and patience. There is too much to tell and so much to learn. Maybe a few things at a time?
Your carburetor needs to be clean and have no air leaks. Try to get it into that state. The air-box is connected to the carburetor. Some people remove the box and install a "pod" filter with no box. While you can make this work, it is harder to get right and often requires more fuel flow. Many opinions with this. Your air-box is the plastic that usually contains the filter in the middle. Many ppl get rid of these as if they are "restrictive". They are designed to be "efficient". Keep it!
Pre-mixing is the only fuel & 2 stroke oil option that we have...as a replacement for the factory oil pump arrangement. On older scooters, the original pumps can become less reliable. None are the same, really. At idle can pump too much oil or not enough. Many are not consistent delivery through the rpm range. Pre-mixing eliminates the pump requirement by either remove it or blocking it. You then mix fuel and oil in a container and put it in your fuel tank. Simple and reliable. You mix at the factory recommended ratio. Somewhere around 40 to 1. Forty parts fuel to one part oil.
Let us start there! Tell us what you have related to the carb and air-box. Take photo!
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