[jonnyuk]

Hi,

another question from me. i have noticed the threads in the spark plug holes aren't great some will have to be repaired. could someone tell me the spark plug thread size.

cheers...

 

[longdistancerider]

12mm x 1.25 pitch
https://www.ngk.com/product.aspx?zpid=9696
I'd suggest using and actual insert rather than a helicoil since these are threads that are regularly used. Helicoils are ok for rarely used threads, one time assembly stuff

 

[jonnyuk]

Thank you very much. I take your point about the insert, will look at the time serts