How To Repair Snowblower Spark Plug Thread

Jun 28, 2022 at 4:40pm ET

Dearest RideApart,

I was recently performing some maintenance on my bike when, due to some inattention, I cantankerous-threaded one of the spark plugs. I was told that the right fashion to fix this is to remove the head and run a tap through the hole or I could utilise a Helicoil. 1 sounds expensive and the other sounds similar a pain. Is there a cheaper, easier, more DIY-friendly solution? Some tool I can use at domicile without removing the head to fix this problem, or am I totally screwed?

- Sergey

Hey at that place, Sergey!

Ugh, what a nightmare. Cross-threading a spark plug has always been 1 of my top-three bicycle maintenance nightmares, right up there with dropping a wheel off a lift and ever having to do whatsoever kind of work on a commencement-generation Golden Wing. Whoever told you that the best and correct manner to fix a cross-threaded spark plug hole is to remove the head and run a tap or thread chaser through it was correct. Whoever suggested that Helicoils were a pain wasalso right. There is, nevertheless, a cheaper and easier alternative to pulling the head. It'southward called a dorsum tap and information technology works wonders.

Y voila, the respond to your prayers. Probably.

Run across, recently I cross-threaded a spark plug—the kickoff fourth dimension in 20 years of riding and wrenching—on my CB450K4. I was both mortified and heartbroken. Mortified considering I damn well know meliorate and heartbroken considering I've already put and then many hours into the old Honda and it runs like a champ, so the thought of having to pull the engine (which you need to practise to go the head off) simply sickened me. And so, afterwards sitting on a stool and staring at the cycle for a while, I took to the Cyberspace to meet if there was a manner I could fix this without ten more than hours of work. The Net coughed up the back tap.

A back tap is a hollow length of steel with a rod running through it. 1 finish is threaded and can expand thanks to a retractable/extendable plunger. The other terminate has a knurled aligning knob. Back taps come in numerous sizes from a bunch of different companies (I bought a 14mm Powerbuilt version off Amazon for around $xl bucks) both online andIRL,equally the youths say.

To apply information technology, y'all simply button the plunger out to make the threaded stop as minor as possible, grease it upwardly really well, and insert the threaded finish into the hole (after y'all make sure your piston is at the lesser of its travel, of class). Then, you turn the knob to retract the plunger which spreads the threaded cease out. Retract the plunger until the tapjust fits and is in the thread correctly. Then slowly and carefully, with a wrench or ratchet, back the tap out of the hole. Once it's out you lot clean the tap off actually well, re-lube it, and echo the process with the plunger retracted a little further. You do this until the plunger is fully retracted into the tool and the threads are at their maximum spread. If you're careful, and lucky, your threads will be fixed and make clean in no time.

The back tap's biggest advantage over, say, a traditional thread attorney is that every bit you lot back it out of the hole y'all drag all those tiny bits of metal out with the grease. This sure beats threading a chaserinto the hole and praying that the shavings stick to the tool instead of falling into the cylinder. I did perhaps 6 passes with my back tap until the whole was cleaned up and I could thread a new spark plug in by hand. Not besides shabby.

At present, I do accept a couple caveats. My threads were more often than not intact and the damage only extended about a third of the way down the threads. If yours are super chewed up, fully stripped out, or otherwise heavily damaged, a back tap may not be the right solution to your problem. In that instance, you may have to pull the head and have the pigsty tapped by a professional. Also, if you don't know what you're doing y'all can impairment your threads even further with a back tap. If you're confident in your wrenching skills, grab one and have at information technology. If yous're not that confident, become a mechanically-inclined friend or hire a pro to do it for yous.