Spark Plug Thread Repair Kit Suggestions?

[Rivets]

Sgkent, how do you repair a stripped spark plug hole on a 2-cycle engine? Buy a short block? I’ve saved a lot of engines by installing a helicoil with no disassembly. To keep chips outside the cylinder I coat my tap with tons of grease and slowly run the tap into the hole. Don’t go too far in before backing out the tap, cleaning it, regreasing, and repeat. It may take a half dozen passes, but I don’t remember a time, but cheaper than a tear down. I always inform the customer of the odds of possible failure before attempting, but almost everyone is willing to take the chance. Only once I can remember where I failed.

 

[StarTech]

Ever heard of grease? It catches nearly all of the shavings and in the case of aluminum rubbing alcohol. Now also on two cycles you just keep the piston above the intake port and use hi pressure air to blow out the shavings thru the exhaust port. What few left are discharged as you cycle the engine with the muffler still removed. Actually if you inject air while drilling to create a back pressure can help too. Now this would require a block plate with an air injection port. Beside on four cycle small engines you could simply remove the cylinder head; unless, got a cylinder jug like Honda. Then you just treat it as a two cycle jug.

Basically there is more than one way to do things.

Matter of fact tapping aluminum is a lot easier with the alcohol then with cutting oil like Tap Magic. As usual you tap a few threads, back out, clean the tap or drill bit. Reapply the lube and repeat as often as needed.

As Rivets said 99% of the time you are successful. That one 1% is a small risk to take besides the other option would be replace the head or cylinder jug otherwise. At least you tried.

 

[Tiger Small Engine]

Huh? I was machinist in a well known high end racing and fleet machine shop once. I can't imagine any reputable mechanic letting drill and tap filings fall down into the cylinder to get caught in the cylinder and whiz around, or wedge the valves open a bit. THAT sounds like something from the third world or Bob's DIY Old Oak Tree Garage. I am out of this forum if that is the preferred method of repair. Frankly, I'd just get a good used head off Ebay from a seller with a 100% rating and 5,000 items, check it for warp and replace the head. Most heads are fairly easy to remove because small engines usually say in the manual to decarbonize them every so often.

How many people actually remove a cylinder head every once in a while to decarbonize it? Way less that even remove the engine shroud to check for dirt, debris on cooling fines and top off engine.

How expensive do you think it would be to buy a used cylinder head off of EBay, remove the one on engine, then install the used one? Might as well adjust the valves while you are at it and lap them.

Read the other posts on handling the metal shavings. Happy Thanksgiving .

 

[StarTech]

I thought that what decarbonizing fluid is for. On Stihl 4-mix brush cutters the carbon actually can seize the piston. The fluid cleans the cylinder, valves, rings, and the piston.

 

[Hammermechanicman]

Interesting thread (pun intended) on spark plug holes.