The problems continue, but it's running

[Kickstart70]

I've got my Grubee Starfire 48cc running, but I'm hoping for some input on the remaining problems...

1. Tiny bubbling and smoke at head bottom when hot - I've tightened the head bolts when hot but it continues
2. Set needle at highest setting (leanest setting) but it's still running revved way to high
3. Throttle cable has about 1cm slack, even with adjustments all the way out...how can this be best adjusted?

Side note: I've gone to a #41 roller chain....AWESOME. It made it so much simpler having that extra width.

 

[Greg58]

It sounds like you have a leaking head gasket, that may be causing the engine to idle high. Most kits come with a spare head gasket, very simple to install. The trick is making sure the head is not warped, a trick I learned on this forum is sand paper taped to a flat piece of glass. then hold the head flat on the sand paper and use a rotating motion to smooth the head, use fine sand paper.

 

[GearNut]

Also, a lean burn is a HOT burn. It can do serious damage to the engine quickly, and cause an engine to idle/run faster than normal.
A leaking head gasket can cause this issue as previously mentioned, as well as lowering the slide needle down as far as it can go.
You stated that you set the needle at it's highest setting.
Highest clip setting? (lowering the needle = lean)
Highest needle setting? (raising the needle = rich)
Which one?


There is an idle speed screw on the side of the carburetor, in the center of the bore where the slide fits down into. If you remove the slide and look down into the bore you can see where the screw pokes through.
Also, it is possible to install the slide backwards and doing so will not allow the slide to go down all the way.
There is a groove on one side of the slide that aligns with a guide pin inside the bore.
There is a small ramp on the bottom of the other side of the slide that aligns with the idle speed screw.
These must match up correctly.

 

[Al.Fisherman]

As to the head leak...Remove the head and mill it. Most come from the factory that are not flat..some worse then others.

 

[wheelbender6]

Before removing the head, you may want to try a name brand spark plug if you haven't already. The spark plug that came with my motor kit didn't seal well.

 

[wan37]

I had the same problem.Gearnut is right before messing with the head check the throttle barrel thats goes in the carb its not seating on the idle screw right .The barrel has a idle grove in it...any other ?'s just ask theres alot of people in here that help.