New to the group

[FtKnoxJim]

Just got by bike and the 66cc kit, put it all together last week, got running ok.

Noticed exhaust was full of oily black stuff so I placed carb pin from 2 slot to 1 slot. reduced the fowling but caused the bike to run too lean and I blew a hole through the top of the cylindar about the size of the quarter...

Lesson learned...DO NOT LEAN THE FUEL TOO MUCH!

Any one else learn from the school of hard knocks?

 

[xseler]

Howdy & welcome!

The 16:1 break-in oil recommendation is too much oil in the fuel. A better alternative is a 24:1 or a 32:1 mix. Does just fine without all the issues.

Good luck on get'n your machine up and running again!

 

[maniac57]

Moving the needle should not cause a failure like that, no matter how far you move it.I'm guessing something else caused it to break.
I run 40:1 and don't have much gunk build-up in the exhaust.

 

[Huffydavidson]

welcome to the forum ,that's a shame I know the feeling my first kit blew up too.yeah all train your feelings should not cause catastrophic failure like that .hopefully you got a warranty send it back

 

[2door]

Not quite sure what you mean by "blew a hole through the top of the cylinder".

Do you mean the piston? A hole in the cylinder could be a manufacturing flaw like a poor casting.
If the piston burned through that would be the result of a massive air leak or running the engine too long at WOT with no exhaust pipe/muffler. Carburetor clip position would not give you a lean condition sever enough to damage anything.

Oil content or fuel to oil ratio is important. As was stated, the kit recommended 16:1 is too much oil. The odd fact is that the more oil you use in the mix the leaner the fuel to air ratio becomes. Less oil alows more fuel so a 24 or 32:1 ratio actually enrichens the fuel to air mix.

Tom

 

[chainmaker]

Welcome to the forum Jim. I'm betting the failure had more to do with the motor being one of the ones that were doomed right out of the box....it happens. Post a pic if it's the head you can most likely get a nice machined replacement that won't fail. I spent some time in your neck of the woods in the 80s at Ft. Knox besides the mud and clay it is beautiful.