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Stripped spark plug?


brewcrew

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Can the threads for a spark plug be repaired on an old Honda atv? Guy claims that’s most of what is wrong with it but I haven’t looked at it myself. How much would it cost to helicoil or similar? I’d hate to try fixing it just to have it blow right out due to compression.

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I don't know but I wouldn't trust a helicoil,guy I put one in his Ford pu,lasted a day or 2.I have had  Ford V10 done several times with inserts by a garage and no issues with it.I really would think you could do something similar. If the price is right what about just getting another head.

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Can’t put a nut on from behind?😂

 

the inserts for the purpose work pretty well, I know of several fords that have spit plugs that are now running around with those in them. 
use copper never seize when installing the new plugs in them. 

https://www.napaonline.com/en/p/SER2125?cid=paidsearch_shopping_dcoe_google_monthly-special_202309&campaign=GSC-Promos&campaign_id=6478906937&adgroup_id=78844950918&adtype=pla&gclid=CjwKCAjwvrOpBhBdEiwAR58-3PDxr5q2zfLmQoeYet66nPWhJT8NIbW0oTLdJHHDQgyq0Ydf-dYbsBoCOyQQAvD_BwE&gclsrc=aw.ds&

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Yes!  it can be repaired . 
 

But ! I don’t believe anything he would tell me. I would investigate everything. All those pieces of aluminum from cross thread ing went down in the cylinder .  that needs has to be bore scoped for grooves  in the cylinder wall.
 

 

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It’s a Honda though. Piston  would probably eat those little shavings right up, spit them out the exhaust and still run another 20 years.

I got a threadsert spark plug repair kit from Napa probably 15 years ago (it was cheap) and put it into a Kohler motor. Right on the machine. Stuck a shop back over the hole to try to get some of the filings out. Motor is still running today.

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1 hour ago, TractormanMike.mb said:

Aluminum head so welding won't work. What model atv, engine size?

I’d bet against you on that one.  Welding  aluminum isn’t that tough.  Way easier to do than cast iron.  Cross threaded the oil drain plug in a vertical crank Briggs many years ago.  Cracked the pan so it leaked like a sieve.  Gouged out the crack, welded it up, retapped the plug hole and the engine runs to this day.

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I do not remember much about the kit that I got from Napa other than it was easy, and it was cheap, and it worked 100%. I’m sure that my store still sells the same kit or some modern version of it and it looks like it would be able to do on that ATV rather easily.
Gas tanks sits pretty high above those, I think you have plenty room to sneak it right in there.  Cheap and easy enough that perhaps the seller would let you install it before you even bought it, if you wanted to negotiate a strange deal like that.

 

 

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Yes I agree on welding, had my machinist year ago weld up a plug hole on a Johnson Seahorse.  Machinist claimed the threads are stronger then the original cast threads.

But in this case I would attempt to do a threaded insert.

Scott

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Easy repair with an insert. Kit comes with the tap and a few inserts. Local parts store or Amazon. I've done a couple and it was quick and easy. Be careful starting the tap straight in. It's not worth the time and effort to weld; inserts work and stay in. I have helicoiled one but the inserts with a positive stop are easier. Aircraft cylinder heads are factory helicoil for strength but they're a special type that positively locks in. Replacing one requires special tooling.

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Someone should be able to Heli-Coil that for less than $50 if you don't have the kit.

All shops have them. Talk with your automotive machine shop in the area.

Heli-Coil is a stronger thread than the original aluminum.

One can grease the drill bit and tap and catch 90% of the chips.

When done, turn it over with the starter with no spark plug and blow out the remaining chips.

Put a new plug in it and drive it.

There are other kits also, like Timesert, that do as good a job.

Depends on what your machinist likes and uses

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Even if a few chips make it into the combustion chamber they're soft aluminum and will get blown out the exhaust causing no harm. It's an easy fix in situ. I've done it twice on small engines with stripped aluminum heads. Get the kit, follow the instructions, and carry on.

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