Fuel mixture advice?

[BostonGeorge]

Currently have a vekta 5 with a Zenoah G34 ported motor. Right now I'm running 28:1 Fuel mixture, I drove it this weekend and within five minutes the plug blew. plug looked pretty dark when I took it out, I wondering if I should be running a richer fuel mixture LIKE 25:1 or maybe the truck is too rich recently just finished breaking in ? any advice ?

 

[WoodiE]

@BostonGeorge what spark plug are you running? I typically run 30:1 ratio in my engines.

 

[BostonGeorge]

@BostonGeorge what spark plug are you running? I typically run 30:1 ratio in my engines.

NGK CMR7h