Engine Trouble 66cc 2-stroke engine bogging? help me!

[pineiroadrian]

ok guys im having an issue with my moped. its got a 66cc 2-stroke engine. right now its using 25/1 fuel ration i believe. the fuel in the tank has been sitting there for a while. i started the bike and let it warm up. then when its all nice and warn, the bike idles perfectly, i rev the engine slowly and its all good untill it get to high rpm. and if i punch the throttle it just boggs??
i got on it and rode around, it was fine at low speeds, but when i give it throttle it seems like it looses power and just boggs. my carb has no lsn or hsn adjustments. could it be that the fuel filter is dirty, or that the gas ha been sitting for too long?

thanks in advace for the help

 

[NBP MotorSports]

Check this post, I just finished reading it, you might find it helpful.
http://www.motoredbikes.com/showthread.php?t=11986

Phil_McCracken Phil_McCracken is offline
MBc Member
	  	
I sortta thought this has been done before, anyway I'll add a couple of things.

1. The clutch operating arm, out of the box it is at the wrong angle for smooth and light operation, it tends to "pull" the inner cable.
Ive added a couple of pics, its on splines, if you moved it towards the carby a couple of splines you get a straighter run for the inner cable and makes for 2 finger opperation and longer cable life.

2. Ok the magneto, has been said you should seal the grommet for the wires and the cover to stop water entering, while the cover is off have a close look at the magneto winding and check for any stray strands of wire.
I was chasing a misfire and one night i was running it out the back and noticed a spark jump from the crank case to the frame.
I took off the wiring, coil and mag and found this almost invisible tiny strand hanging out of the winding, Ive added a pic with an arrow, is hard to see.
Misfire gone and for sure it would have eventually caused magneto failure.

 

[motorpsycho]

did it always run this way or is this a recent problem? what is the weather like where you live? if it's really cold out, the cold air will make an engine run leaner than it would when it's warm outside.
normally a bog at 3/4 to wide open throttle is because the air-fuel ratio is too lean.

 

[Pablo]

It could be old fuel as well.

What does your plug look like?

 

[pineiroadrian]

did it always run this way or is this a recent problem? what is the weather like where you live? if it's really cold out, the cold air will make an engine run leaner than it would when it's warm outside.
normally a bog at 3/4 to wide open throttle is because the air-fuel ratio is too lean.

recent problem. makes sense cause its the first time i started it since it got cold. im in FL but its in the 30-50F range. .
im gonna drain all the old fuel anyways. clean the carb, and put fresh fuel in there. what ratio should i use now?

 

[pineiroadrian]

It could be old fuel as well.

What does your plug look like?

the fuel has been sitting.
ill take the plug out and snap a pic.

 

[pineiroadrian]

pictures of my engine to help you help me

guys i really need some help my bike starts and rides at low speeds perfectly, but when i get up to speed or give it more than half throttle it just bogs, the rpms seem to go down and it has like no power. its not my carb because, i completely tore it down and cleaned it today, the jet is clear. and i cleaned both valves aswell, checked my magneto and put a new fuel filter/ tubing. took my head off and this is what i saw. (in the pics).
i think im too lean, i dont really remember what the mixture im using is but its like 25:1. should i go leaner like 40:1? and i moved the clip on the slide needle to the top (leaner). should i put in a new plug and put in 40:1 or what would you recomend? the weather here is like 60-70. please i need your help, theres a buy coming on sunday to buy the bike and if its not running properly he wont buy it thanks in advance.
-Adrian

 

[i_Bones_i]

That plug is drenched. Did you flood it out trying to start it right before you took it apart? How many oz. of oil are you adding to a gallon? That plug looks to me like it has ALOT of unburned oil on it. You're using 2-stroke oil right?? Things being wet make the carbon deposits look even darker in color. How many hours are on this engine? We run oily premix compared to your average 2 stroke because our direct drive bikes run extended periods of high RPM, so extra carbon build-up is bound to happen in this type of situation. But if we didn't run oily mixes our bikes would be likely to overheat on long hauls. It's hard to say what's really wrong from looking' at a few pic's of your piston and plug, wish I could hear it run. I'm no mechanic so everything I just said might be equal to I am only applying my own common sense. GL fellow mb'r and I hope u get the problem solved.

 

[pineiroadrian]

Thanks bones
And your wish will come true, I took a
Video of it right before taking it apart. Here's the URL http://www.youtube.com/watch?v=ZqpORCDq3DU
I think I'm using 18:1? Or around there. I think I'm too rich, because I'm still fueling from the big batch of gas I mixed when I was breaking it
In. That fuel has been sitting for many months too. So I cleaned the piston, cleaned the plug, emptied out my fuel tank. Gonna go get fresh gas tomorrow and use 40:1? That's why I'm debating my bike has
80 miles on it give or take a couple.

 

[i_Bones_i]

Well, she runs smooth on idle and seems fairly responsive. It could be old fuel I suppose. Something else to check though, you said it loses power on top end, perhaps the baffle in the muffler is getting clogged with gunk? With only 80 miles on it, its unlikley but it would explin both power loss on top end and extra carbon buildup in the cylinder. If it cant get rid of exhaust fast enough at high rpm it would restrict it's power and also it would leave exhaust in the cylinder and create a dirty burn.