Cross threaded plug

Scratcher09

Scratcher09

Been Around the Block
I'm embarrassed to even post this, but I started to cross thread the #2 spark plug on my GS1100. I went a couple turns before figuring it out. Now I can not get it to thread properly. Is there any other way to fix this without removing the head? I know I can run a tap from the inside out if I remove the head, but I'm trying to avoid removing the head.
 
Helicoil insert would work. But I would recommend a time sert kit. Can all be done without removing the head. Kits aren't cheap but they have great reviews. Google them or if all fails your machine shop can install it for you.
 
Call you local snap on or Mac tools guy, the thread chaser is 20-25 bucks and will fix that right up. if its really bad resort to what Drey6 said!
 
A standard tap will do fine, if it's only the first few threads. Grease the living hell out of the tap before you start cutting to catch those nasty little aluminum chips. We do this on aluminum heads quite a bit at the dealership when people decide to do their own tune up and over torque their plugs and blow one out of the head. Of course we're also cutting the threads out and inserting a heli-coil but the idea is the same. Just make sure your tap is going in straight and you're hooking into the old damaged threads. Last thing you want to do is to start cutting new threads.

A thread chaser will work too as someone suggested if you can get it to thread. Once again though, grease the hell out of it.
 
I would think you would never get a tap to chase the threads properly from the top side, without ruining the remainder of the threads, that tool you posted is the way to go for sure.
Either that or you could fashion a thread file by grinding up a spark plug to scape the top 2 damaged threads but using the remainder of the threads as a guide.
It's a cost/ time calculation.
 
mg42gunner said:
A standard tap will do fine, if it's only the first few threads. Grease the living hell out of the tap before you start cutting to catch those nasty little aluminum chips. We do this on aluminum heads quite a bit at the dealership when people decide to do their own tune up and over torque their plugs and blow one out of the head. Of course we're also cutting the threads out and inserting a heli-coil but the idea is the same. Just make sure your tap is going in straight and you're hooking into the old damaged threads. Last thing you want to do is to start cutting new threads.

A thread chaser will work too as someone suggested if you can get it to thread. Once again though, grease the hell out of it.
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no on the standard tap this is coming from expert experience
a standard tap is tricky in this situation 50 50 chance at baest it will take skill and a lot of luck
that back thread deal is wazoo get that sumbitch and git r done !!
 
That thing is cool.
My only question is going in blind what's to stop you from expanding it in the wrong place and just royally fucking your threads? I guess it would have a natural tendency to fall into the threads, but still seems like it could go wrong if you arent careful.
 
SONIC. said:
That thing is cool.
My only question is going in blind what's to stop you from expanding it in the wrong place and just royally fucking your threads? I guess it would have a natural tendency to fall into the threads, but still seems like it could go wrong if you arent careful.
Click to expand...
thats when reading the instructions comes into play
 
Instructions and directions are for bitches :D

(Jen, as the only female on here I apologize for the vulgar use of "bitches" meaning females" hahahah)
 
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On the subject of helicoils, watch out for a wrong drill size called out on 10mmX1.25. it calls for a 31/64 which is for a 12mmX1.5 instead. It should be a Y drill!
 

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If you have the room a drill bushing, can help you guide the drill, giving you a surface to reference from, using the flange against the head surface.
Then use can use a home made tap guide, yours will have to be round. I just counter bored a block for the thread cutting teeth, with the stem having a guide bore. A thread insert, like in the head repair thread, is a very good repair if you have the room. If not, you will to use a thread insert of a helicoil type. The insert shown in the head repair thread,
had a locking ring that was pressed in place. Factory threads sometimes use roll form taps that will allow a no go gauge to fail the thread. Also factory threads can be inferior to the bolt specs.
 

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The back tap came in today and it took about twenty minutes. Done! It worked perfectly. I coated it my tool with grease and put it in the hole (yes, I did just say that). Then I expanded it almost all the way. Pulled up till I felt it engage the threads. Twisted it out. Removed all the grease and put new grease and did it again, this time expanding it 100%. The grease that had gathered around the outside of the hole had a tiny bit of shavings in it. I used q-tips (some bent at various angles) to clean any grease in the hole. The grease I pulled out with q-tips had no shavings at all. Spark plug went smoothly with only my fingers. I am impressed with this tool and would recomend it to anyone with this problem. It does have to have good threads to start off on, so if your threads are mangled all the way through to the chamber then this would not be an option.
 
Scratcher09 said:
The back tap came in today and it took about twenty minutes. Done! It worked perfectly. I coated it my tool with grease and put it in the hole (yes, I did just say that). Then I expanded it almost all the way. Pulled up till I felt it engage the threads. Twisted it out. Removed all the grease and put new grease and did it again, this time expanding it 100%. The grease that had gathered around the outside of the hole had a tiny bit of shavings in it. I used q-tips (some bent at various angles) to clean any grease in the hole. The grease I pulled out with q-tips had no shavings at all. Spark plug went smoothly with only my fingers. I am impressed with this tool and would recomend it to anyone with this problem. It does have to have good threads to start off on, so if your threads are mangled all the way through to the chamber then this would not be an option.
Click to expand...
I have used that tool on at least a dozen occasions....it has worked mint in every case.
 
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