Also start with the easiest problem first pull the carb give it a good cleaning check air filter fuel filter fuel lines sparkplug all of the easy stuff the timing is pretty easy I tried to read and comprehend the timing but you tubed it and found it was easy I hope you find the issue

 

Well finally got around and got 10mm fitting for my tester and compression check on the 70cc.

The best I could get out of it is 62 PSI.

Would this make sense why I can seem to keep this this running?

 

 

Thanks for all you advice.
I ended up taking the motor apart and found out that I had a piston with worn down rings.
I bought a new cylinder and piston and rings.
I checked the valves and they are tight with alot of carbon build up on them. I poured some alcohol in the combustion chamber to see if they leaked.
After getting it all back together I still have a bog.
With the float set at 10 degrees above with the carb upside down.
The needle clip in the middle and the air screw turned out 3/4 turn.
It won't even start with the air screw turned out 1 1/2 times.
The plug is BLACK. It is a stock carb (PZ19)
My head is spinning.
Thanks
Jay

 

Hi Jay,

Sorry to dig up an old thread but I need to know if he solved this. I have the same issue. Identical symptoms on my sons 110cc quad. I have tried a new carb, CDI, Coil, and spark plug. Idles fine, no power, sputters out.

Were you ever able to solve this? Very frustrated, if I can't figure it out soon, I will have to scrap it...

Thanks in advance for the reply.

 

I figured it out! I'm a fool!

Really what happened, is I cleaned the air filter and oiled it, just like I have done on every bike I have ever owned. I guess that the air filter oil is too thick. No oil is required on these cheap air filters.

Took the filter off, and it ran like a champ. The filter is now going to be washed and put back on without the oil. I will probably go buy a real foam filter soon.