I'm not going to admit how i stuffed up

[Guest]

OK. A question for those machinist type people or at least those that are familiar with inserting Helicoils (or in actual fact Recoil is the brand I am using).

A hypothetical question: If after drilling out the old thread (quite a deep hole), tapping the new thread for the new insert all the way to the bottom and inserting the new insert (6mm) too deep into the new threaded hole is it then possible to fit another insert above the one previously inserted.

In other words will the bolt screw into both the upper and lower inserts without binding in any way or is it going to be out of whack by a 1/4 or 1/2 a thread, etc.

Thoughts please. And remember this is a hypothetical situation as explained previously. Ummmmmm

[tkent02]

Hypothetically speaking, which bolt might we be speaking about?
I would think the two coils would bind up as the two nuts do when you are locking a bolt by double nutting, so if the deeper coil would be strong enough alone I would just use that.
If it's something like a cam cap bolt it might be hard to get an even torque with the other bolts...
Sounds like this is not a through hole?

Maybe you better wait for a machinist to chime in.

[old_chopper]

The threads of the two should line up fine. I'm not sure you need two inserts though. I would take the one out thats too deep and install another to the correct depth.

[kdo58]

i did it on a carb intake screw hole worked fine.

[hampshirehog]

You could get a longer helicoil and pull out the one that's fitted Don.

[Suzuki_Don]

Hypothetically it is a cam holder bolt and I am not familiar with the process of removing the stainless insert. My worry would be destroying the thread in the aluminium as I remove the stainless insert. And then this head is toast.

[Nessism]

Stacking two inserts is perfectly fine, as is digging out the first one (use a pick tool to carefully extract it).

[chef1366]

I've actually stacked helicoils on a cam cap.
That was a few heads ago but it held good.

[Suzuki_Don]

I've actually stacked helicoils on a cam cap.
That was a few heads ago but it held good.

Bill, were the helicoils in the cam cap bolt hole in the head.

[waterman]

It will be fine in the cam cap bolt hole. You should have 4 bolts holding it down, the other 3 are not stripped? I am pretty sure one of mine is partially stripped in my 650. You know that sinking feeling you get when tightening a bolt and it get almost tight and then keeps turning? Especially as you were just about done?

I found that the helicoils actually held better that the stock threads, on one head of mine I was stripping about every 3rd hole. If the tread didn't strip then the bolts snapped. I think the previous owner thought that more torque would fix the leaking valve gasket.

[Suzuki_Don]

It will be fine in the cam cap bolt hole. You should have 4 bolts holding it down, the other 3 are not stripped? I am pretty sure one of mine is partially stripped in my 650. You know that sinking feeling you get when tightening a bolt and it get almost tight and then keeps turning? Especially as you were just about done?

I found that the helicoils actually held better that the stock threads, on one head of mine I was stripping about every 3rd hole. If the tread didn't strip then the bolts snapped. I think the previous owner thought that more torque would fix the leaking valve gasket.

Ed I have actually replaced all (16) threads for the cam cap bolts in the 650 head while it is on the bench. The problem arose when I forgot to knock the tang off one of the thead inserts. So when I tightened the cam cap bolts the end of the bolt pushed against the tang before it eventually broke it off and this distorted the bottom part of the stainless recoil thread and chewed into the bolt as I threaded it into the hole. It then chewed the second bolt I put in as well.

I then ran a 6mm square tap down the hole to try and reclaim the bottom part of the thread and as I could not see what was actually happening as the tap went in the tap had caught the stainless thread and wound it to the bottom of the hole. Hence my current problem.

It's nothing that cannot be fixed. I could use a longer 6mm bolt, a 45mm instead of the standard 39mm bolt. I could try and pull the recoil out, but that would be difficult as it is about 6 threads below the surface of the head. I think I will just fit a short 6mm recoil on top of the other one that is already in there. I don't want to risk damaging this head after all the work that has gone into it.

[waterman]

It has been said confession is good for your soul.

As long as the bolt you screw in doesn't get caught on the remainder of the deeper insert, I don't see any problem of using the short threaded insert. When I had to reposition one of the helicoils, I used with a dental pick. I painstakingly unthreaded it from the hole. I am not sure this is possible if you have mangled it up in the bottom of the hole. Obviously don't want to do more damage.

Likewise, I would stick with stock length bolt, less likely to interfere with lower insert.

[Suzuki_Don]

Thanx Ed for your replies they have been helpful.

On another issue, you posted some time ago about a top end gasket set (OEM) for your 650 that you purchased on EBAY and you asked about 4 x metal crushable "O" ring shaped washers/rings. Did you ever find out what they were to be used for.

I have purchased the same and have these same parts in my set.

[chef1366]

Bill, were the helicoils in the cam cap bolt hole in the head.

Yes it was.
...................

[Suzuki_Don]

Yes it was.
...................

OK thanks.