Engine Trouble 66cc/80cc Stock engine will not idle

[sh4d0wm4n42]

Ok lemme try to break this down into simplistic terms where even an idiot can understand. When trying to start the engine, I first lift the choke lever up all the way. I then start pedalling to get forward momentum. I then release the clutch. Once the engine turns over I lower the choke all the way. I then continue to pedal. I then hit the throttle slightly and hear the engine start to bog down. What I mean by "kick into gear" it's exactly what it says... Kicking into gear is where I no longer have to pedal and the throttle maintains the speed... However, that takes a great deal of effort. It's the same thing on a stick shift car where it kicks into gear when doing a push start.

As for messing with the idle screw while trying to hold the throttle, it's doable, however I'm still having to pedal and that's taking the majority of my focus while keeping balance and managing the throttle. I've tried messing with the screw, but nothing happens. I'm not sure how simple that may be to understand, but I have tried, to no avail... As for the possibility of debris being in the crank case or fuel pooling up, it's possible... The only time I've had the header off was when I had to replace the head gasket within the first month of riding. And pulling the clutch while being on the bike moving forwards does kill the engine... So yes, something is wrong, but that's why I'm here posting and asking for help because I'm at a complete loss as you what's wrong.

The problem I'm having is, in trying to start the engine I need to be able to warm the engine up in order for it to actually run, but I can't get idle to work... Bearing in mind this is my first build, treat me like I'm a complete idiot that has no clue what he's doing if you must... But I'm not a complete idiot... I understand the basics of engine mechanics. I just don't understand why nothing I do is making this work. And I will say that video posted of trying to start the engine in the morning, it's too dark now to get good video.

 

[FurryOnTheInside]

Ok lemme try to break this down into simplistic terms where even an idiot can understand. When trying to start the engine, I first lift the choke lever up all the way. I then start pedalling to get forward momentum. I then release the clutch. Once the engine turns over I lower the choke all the way. I then continue to pedal. I then hit the throttle slightly and hear the engine start to bog down. What I mean by "kick into gear" it's exactly what it says... Kicking into gear is where I no longer have to pedal and the throttle maintains the speed... However, that takes a great deal of effort. It's the same thing on a stick shift car where it kicks into gear when doing a push start.

As for messing with the idle screw while trying to hold the throttle, it's doable, however I'm still having to pedal and that's taking the majority of my focus while keeping balance and managing the throttle. I've tried messing with the screw, but nothing happens. I'm not sure how simple that may be to understand, but I have tried, to no avail... As for the possibility of debris being in the crank case or fuel pooling up, it's possible... The only time I've had the header off was when I had to replace the head gasket within the first month of riding. And pulling the clutch while being on the bike moving forwards does kill the engine... So yes, something is wrong, but that's why I'm here posting and asking for help because I'm at a complete loss as you what's wrong.

The problem I'm having is, in trying to start the engine I need to be able to warm the engine up in order for it to actually run, but I can't get idle to work... Bearing in mind this is my first build, treat me like I'm a complete idiot that has no clue what he's doing if you must... But I'm not a complete idiot... I understand the basics of engine mechanics. I just don't understand why nothing I do is making this work. And I will say that video posted of trying to start the engine in the morning, it's too dark now to get good video.

I thought you have the stock jet with the C clip on the middle notch of the needle, and you were going to try the next notch up when you get a chance?
This is the most common carb setting that ended up working for the break-in stage of stock engines that is mentioned in relevant threads on the forum, IIRC.
(I never even tried it on the middle notch because of this).

This could well be a combination of problems; but if you start with the very likely too rich condition that will help with the general engine performance not just the idle, and then the cause of the difficult starts might be easier to spot.


Just to see if I'm on the right track..
I have never used the choke to start my engine as it's already set rich (I actually like the choke to kill the engine), so I'll ask..
What happens if you try to start your engine without using any choke?

 

[Street Ryderz]

Ok so firstly when you set the choke leave it choked until the engine is running and able to pull some then reach down and open it,And since it's getting colder you may have to leave it choked for a bit until it (engine) warms up.Next setting the Idle is done while you're OFF the bike with the clutch disengaged,Riding it with the engine loaded will be a false setting because as soon as you pull the clutch lever in (clutch disengaged) The idle will be high if set that way and this is where the issue is in that once the engine is running and the clutch disengaged it should keep running, It may not idle down real low but with some throttle input it should be running and if it stops aburptly as soon as the clutch is pulled that leads me to think that the engine is still seeing load and that load is internal.

 

[FurryOnTheInside]

I'm also wondering what the more experienced members would say about a weak magnet?

OP hasn't confirmed strong spark seen outside the engine while cranking it over manually.

 

[sh4d0wm4n42]

When I first got the engine installed I never messed with the choke... But even then it kept getting harder and harder to start. At first I barely had to move more than 100 yards if even that far and it'd start up and I could use the throttle almost instantly... But after about 2 months it continually took longer and longer. But I also had more hills at the time so a downhill ride made it much easier to start. Now I live in an area with mostly flat terrain, and it's gotten so hard to start. I can get the engine to slightly run, but as soon as I touch the throttle, the rpms drop fast and it gets harder to pedal.

I've got the c ring raised up one notch, but it seems to have made no difference... And I'm so confused that I'm considering the possibility of debris in the cylinder. Going to remove the crank case in the morning and check for debris inside. Just gotta go pick up my tools from a friend that I loaned them to earlier this evening.

 

[Street Ryderz]

I thought you have the stock jet with the C clip on the middle notch of the needle, and you were going to try the next notch up when you get a chance?
This is the most common carb setting that ended up working for the break-in stage of stock engines that is mentioned in relevant threads on the forum, IIRC.
(I never even tried it on the middle notch because of this).

This could well be a combination of problems; but if you start with the very likely too rich condition that will help with the general engine performance not just the idle, and then the cause of the difficult starts might be easier to spot.


Just to see if I'm on the right track..
I have never used the choke to start my engine as it's already set rich (I actually like the choke to kill the engine), so I'll ask..
What happens if you try to start your engine without using any choke?

He is basicly trying to start it with no choke currently.Cold engines even rich don't like to burn larger A/F charges but still run fine at part throttle until some heat starts to build.

 

[sh4d0wm4n42]

Spark isn't what I would consider strong though... But it will spark slightly while holding it to the outside of the engine... So possibly bad cdi then?

 

[sh4d0wm4n42]

And correct street. I've tried finding a way to not cold start but that's why I'm trying to understand why it won't idle when I initially start it up and then come to a stop. When I stop, regardless of whether or not I hit the clutch, the motor kills off.

 

[FurryOnTheInside]

Spark isn't what I would consider strong though... But it will spark slightly while holding it to the outside of the engine... So possibly bad cdi then?

IMO instead if a CDI, try a new plug wire and NGK boot and plug. That should cost about the same, but it's more things tried, and they are all upgrades anyway so it doesn't matter if those weren't the cause, it's a win/win.
I believe it's supposed to be a resistor boot for a non resistor plug, non resistor boot for a resistor plug such as the iridium plugs (which is what I'm using myself).
Check soldered connections on mag wires.
Check the mag has good metal to metal contact to the case.

 

[Street Ryderz]

I'm also wondering what the more experienced members would say about a weak magnet?

OP hasn't confirmed strong spark seen outside the engine while cranking it over manually.

The spark must be ok if once it's running it can burn under higher load and cylinder pressures at what ever rpm he rides it at.Pulling the plug and seeing if it rotates freely at the bottom of the stroke would tell alot.