Wood Eagle

[Wood Eagle]

Stihl MS 362. The thread which receives the spark plug has loosen so that the spark cannot be tightened and therefore shakes loose. Has anyne tried a method other than a rebore to solve this?

[Stubby]

43 minutes ago, Wood Eagle said:

Stihl MS 362. The thread which receives the spark plug has loosen so that the spark cannot be tightened and therefore shakes loose. Has anyne tried a method other than a rebore to solve this?

Helicoil .

[pleasant]

A heliciol kit is your answer if you want to keep it original, but unless you already have a kit, or know someone that has it would be just as cheap to stick a decent pattern pot and piston on it...or original if you're feeling flush.

[spudulike]

Not sure what the "rebore" means but you typically start with trying a helicoil. This is best done with a lead in tap but make sure you start the tap off well as you want the receiving thread to be cut dead square with the surround of the plug hole. BTW - use a decent quality tap, the really cheap ones are...well....cheap and the resulting thread form will NOT be cheerful. V Coil do some decent kits and good quality.

 

If this method fails then you can use a reamer to open the hole up, a tap to retap the hole and then an insert that can be put in with Loctite. Personally speaking and having used both methods, a helicoil provides a strong and relatively simple repair. 

I usually stuff the cylinder with paper cloth (still fitted to the machine), form a cavity just under the plug hole and grease the tap liberally when using it. If you put the bar in a vice and get the plug hole as horizontal as you can, it helps.

[Wood Eagle]

Thanks for the advice guys. Much appreciated. I’ll give the helicoil a go.

[adw]

You need to to get the tap completely plumb to the cylinder, a quick tip if you have one, is to put the tap into the chuck of a pillar drill, clamp, or hold the cylinder, bring the drill down and turn the chuck by hand to start it off, this will keep t perfectly plumb to the cylinder. Try to get a quality heli coil kit, Armstrong make good kits.