Need Helicoil Size For Spark Plug

Hey Gang - A helicoil put in by the previous owner of the bike popped out on my #4 spark plug hole tonight when I was putting in new plugs. I knew it was gradually sneaking it way out and tonight was the night it sprung free. The thread still looks in good shape so I only need to put in a new coil wire. I am going to put a little dab of red Loctite in the threads before I start to wind the coil into them.

What size should I be asking for when I hit the supplier tomorrow?

Cheers-Colin Firth-Ontario Canada

Just ask for a 14mm by 1.25(thread pitch) plug helicoil Colin.
That's the spark-plug size.

you are going to continue to see the coil back out from time to time, if you get the insert type from napa, it will be a better fix

Colin, I also suggest the NAPA insert... you can use some red Loctite and it will stay put. Problem with the NAPA plug inserts is that they only come in two lengths... too short and too long. (1/2" and 1" I think) so get the longer and cut to length which is about 3/4". I also think that if you have a helicoiled thread, the thread from a NAPA may not be the same... you can buy the tool to cut a new hole and see if there is enough material but I think I would just use a new helicoil and try some red loctite on the outside to hold it better.

Thanks gang - I'll pick up the new helicoil today and put a little dab of red Loctite on the outter part of the helicoil.

Cheers-Colin