Don't know whether this makes a difference or not. When I was using cdi, I used both Rimfire & NGK plugs instead of the YS one with better results, on both 170 & 175. I converted both motor from regular to cdi myself with parts instead of getting factory issued cdi motors, & found the NGK/ Rimfire idles & transition better than the YS plugs. Also, using the tightening socket head screws on the connector terminal is a must.

Adrian