4 stroke engine stalling out

[double trouble]

another thought

I have worked on motors for 40 years. I was thinking that this was an electrical problem. I have had electric , magnetic and electronic coils that either worked fine when cold and acted up when warm or the reverse. Is your ignition coil remote like the 2 strokes are?
I have seen cracked coils on both cars and boats do this .
bad idle, stalling, poor running at speed, lack of speed.

 

[bideronit13]

Hey double trouble the first problem he found when the first stall happened was that it was overheated.
Motor oil keeps motors from overheating.
He also said that he'd get to the bike after a time of letting it sit then drive around his yard only one time and it cuts off.
I had a street bike one time that had a cracked cassing inside were you couldnt see it and it was an electric problem. It would even start until the casing was epoxied. If it was the coil it wouldnt run great for a lap then cut of and definetly the motor wouldnt over heat.
The only possable way the motor will over heat on an air cooled engine is bad oil, wrong oil, contaminated and so on and so on.

 

[double trouble]

in that case

I didn't realize it overheated. That is a sign of a cracked head or gasket , but he changed motors and same thing. I was trying to find something common to both motors. without being there , its tough to diagnose.

 

[bideronit13]

He only used the carb from the new motor to place on the old motor and not necasarily old because he only rode it four time when it stalled from the heat of the oil breaking down.
That could cause the head to crack, bearings to get ruined, warp the crank shaft.
But since it still fires up and runs fine before it again breaks down the oil that overheated and is bad it a good chance its going to be ok.

 

[Quenton Guenther]

Motor doesn't have a head gasket or removable head! The top end is one piece.

Can't be ignition issues as he had same problem with both motors.

It is most likely related to removing and installing the carburetor, as both motors had same problem.

Have fun,

 

[bideronit13]

When the oils really bad on something Im working on. What I do is drain as much of the sludge thats bogging the motor down. Put new oil run it for 5 minutes and drain it again. Then it should run fine.

 

[Mr Hydroseed]

New Update, got it running again.

Sorry for dragging this out so much, but I feel a solution is around the corner.
So I drained the gas again I used another new can and refilled with high octane and this time it ran like it did when I first had problems. Idles fine, power of idle from stop is good, could drive laps around my yard but when ever I back off the throttle and put it on again it stutters and stalls. After a few times of this I was able to feather the throttle enough to not stall but it would bog down for a few seconds then have power again. I haven't tried it but I bet if I just drove down the road for miles without backing off the throttle it would keep going just fine, but as soon as I need to slow down, corner or stop it would stall. I'm currently at an all stock setup except for the high flow K&N style filter. The mixture screw is at 2 turns i tried 1.75-2.5 Now isn't this suppose to tune the transition from low RPM into the main jet or is it an overall mixture setting for the entire power band? Thanks guys.

 

[Mr Hydroseed]

overheating???

I didn't realize there were replies when I posted the last update. I'm not sure were "overheated" came from? (Maybe when I said that on a long ride when the engine really warmed up to normal operating temps, the engine lacked power slightly as if i wasn't jetted rich enough. I'm pretty sure that I never indicated that it over heated, if i did, sorry.) Not to mention the fact that the 2nd motor never did anything more than a rough idle. I wasn't even able to ride it. I also filled it up with Mobil 1 full synthetic 10w-30. Its definitely not an oil issue. I used Seafoam in the fuel tank because I seem to always get water and plugged up carburetors on my lawnmowers and tractors. The gaskets on the carb connecting to the motor look brand new because they are. I did try spraying starter fluid all over the carb for increase in rpm, none.

 

[double trouble]

try a few things

1) if your ignition (cdi) is separate and using it for both motors, try a new one.
2) you carb might have a bad float or a bad needle/seat. something could be sticking in the carb when u try to accelerate.

Looking back , it sounds more like carb/gas problem.

 

[bideronit13]

I never had a carb fail in any way after only four rides.
What are you doing picking on this guy?