QuestionI went to strip down the carb and instantly seen that the fuel inlet port was partialy choked. I removed the plate which holds the throttle & choke onto the carb and the air/fuel mixture and idle screws and blew out all the ports with compressed air. I could see that the fuel being blown out was dirty. I repleced the screws and plate and tried to start the bike again but couldnt even get it to start now. I then removed the carb dismantled, cleaned it and rebuilt it and tried again, but still could not get it to start. I have been adjusting the air mixture settings and idle screw but dont realy have a clue where to start from. I am deffinately geeting fuel to the cylinder and the plug is sparking. I dont know where to go from here. I have also noticed that there seems to be some oil being blown out the exhaust when im kicking it over. Please help.
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Followup To
Question -
my sons yamaha pw50 packed in about a year ago. when i bought it it had been rebored and fitted with an over size piston. on stripping the engine down i noticed that the cylinder head had been fitted upside down. the cylinder was badly scored as a result of carbon build up at the exhaust port. the bike had also been rebuilt without an element in the air fliter. I have cleaned up the cylinder with delapena gear and rebuilt the engine with new piston rings (clearance = 0.55mm) and gaskets. The engine started within 4/5 kicks but stopped shortly after. I have been tinkering with the carb settings and can get the bike to start from time to time but it still cuts out after a few seconds. can you offer any advice.
Answer -
This can be so many things.. start with fuel: Is the bike getting fuel? Try pouring a little in the cylinder with the plug out and trying it.. if it starts it's not getting fuel. Do a complete fuel path cleaning/inspection... from gas tank to cylinder intake, complete carb disassemble and cleaning.. Include the oil tank as well, check settings and ensure it is feeding correct amount of oil.
AnswerAssuming the spark plug isn't fouled, try tightening the air screw all the way until it seats, then go 2 1/2 turns out. Screw the idles screw all the way in until it seats and turn that about 4 turns out.
Now, make sure the oil pump setting is correct - you need a special tool, called a dial indicator for this - it should be approx .02". If you don't have that tool, lets assume it's correct - just make sure it is using fresh oil
Did you try pouring a little in the cylinder with a fresh plug? did it start?
the oil coming out sounds is prob normal, as these little bikes always do that, but it could also be a sign that it's getting too much oil.
I'm also assuming the cylinder problem you had is not causing this.
So based on these assumptions - try what i've said above and lets go from there.
