Auto plug query

I am using two P-mags with auto plugs. I have a question about the plugs.

The tip where the lead clips on unscrews on an ordinary spark plug. I have never understood why. Is there a risk that the tip could unscrew with normal vibration, fall off taking the lead with it? I guess the answer is no, because it would happen with cars. Why not? Is anyone locktighting the tips on?

Thanks.

There are two types of NGK plugs...

...one with screw-on tips and one with permanently attached tips. I have the same set-up you describe in my -4. According to NGK, the permanent-tipped plugs are P/N BR8ES (stock # 3961). I haven't bought any yet, so I cannot confirm. Good luck.

My BR8ES

plugs don't have the screw on tips. I would not use locktite as it would likely insulate. Even it it did I would not worry. The clip inside the boot holds them, and the boot itself cannot rotate. Plus, you are checking your plugs relatively often.

Hans

same here

I have threaded on tips..Sometimes they are loose but never more than one turn..Boot never comes off.

Frank

Thanks everyone.

Mine are BR8ES (its written on them) as specified by E-mag, but the tops certainly can unscrew. I guess they make them two ways though I dont see how that is specified.

No one appears to have a problem so I guess I will relax.

The plug wire seems to hold the screw on cap fairly tight. I had the exhaust crack at the flange on #3. It cracked so much that it blew the boot off the plug. When I looked closer I noticed it held on to the cap and just yanked the threads out of it. 4 new plugs were purchased for a grand total of $7.74.

I run NGK BR9ES plugs on my dual P-Mag setup, I find lower CHT's with them. They have the threaded aluminum tips on them, but the BR8ES plugs I used to use also had threaded tips. Like Frank, I find them a little loose when I check them, but I don't think anything can get away...

I had BR8ES plugs on my snomobile (250cc rotax). I could get "solid cap" or "threaded cap" at the Ski-Doo dealership. I tried the threaded one only once but it was always unscrewing due to vibration (single cylinder). I sticked with the solid ones after that.

The Rotax part number was "897 055 NGK BR8ES". They came with a solid end and pre-gapped.

I learned to use solid cap NGKs by listening to the Quad City Challenger builders : their Rotax (447,503 or 582) is up side down on the plane.