NGK spark plug question

[smvorndran]

I goofed the threads on my 85 YTM225 the other day. The stock plug is a NGK D7EA. The thread diameter is 12mm. Is there any reason why I couldn't drill it out and tap it for 14mm and use a B7ES plug, which is 14mm thread? I believe you can swap a D7EA or a D7ES, so why couldn't I just run a little bit bigger thread diameter. It's almost the perfect save. If that one gets goofed, then I'll need another head. By the way, there's room by the valves, so I shouldn't have to worry about the seats. Any thoughts? I can fixture it up on a knee mill to get it true & round, and power tap it straight thru. I love working at a machine shop.

smvorndran

[OldSchoolin86]

I goofed the threads on my 85 YTM225 the other day. The stock plug is a NGK D7EA. The thread diameter is 12mm. Is there any reason why I couldn't drill it out and tap it for 14mm and use a B7ES plug, which is 14mm thread? I believe you can swap a D7EA or a D7ES, so why couldn't I just run a little bit bigger thread diameter. It's almost the perfect save. If that one gets goofed, then I'll need another head. By the way, there's room by the valves, so I shouldn't have to worry about the seats. Any thoughts? I can fixture it up on a knee mill to get it true & round, and power tap it straight thru. I love working at a machine shop.

smvorndran
Why not just install an insert and get it back to stock?

[300rman]

yeah, if it gets boogered up again, any machine shop can fix it no problem.

[smvorndran]

My Honda dealer's going to throw a Helicoil in it for me tomorrow for $10. Problem solved! Thanks.

smvorndran