Bad Helicoil/stripped tappet cover

[Tecrekka]

I just about had my bike straight. After a week of sorting carb issues in preparation for a 1700 mile trip, she's been crippled by the simplest of things, stripped tappet studs (doing valve adjustment). I've never had to deal with anything like this and I'm not sure how to proceed. If anyone has suggestions I would really like to hear them! Thanks in advance!

 

[Liftedzuki]

Just pull the stud out with vice grip and replace?

 

[Tecrekka]

Well, the problem is two instances here. One is just the stud that has stripped off at the end, which would be the easier of the two to replace but I don't want to make it worse. If It is just pulled out then there is noting left for a stock stud to adhere to properly. The other must have been damaged before and therefore required the use of a helicoil. I haven't found information on whether or not there needs to be a larger helicoil to replace one that has been damaged or how exactly that works. I don't want this to end up being a much more major repair that it already is?

 

[Liftedzuki]

Worst is just have someone tig it and re drill and tap

 

[Paulrxs650]

I had exactly the same problem last year. I did a temporary fix with JB Weld, which held oil tight all season. Back end of last year I had the idea to fix it "properly"

So:

1. Drill the offending hole to 10 mm or larger to suit your needs and run a tap down into it
2. Take some 10 mm round bar (or larger as above) and cut of about 50 mm
3. Take a die and cut a thread down it
4. Drill a holedown the length of the bar in preperation to take the thread of replacement stud - simpler if you have a lathe but can be done carefuly in a drill press or by hand
5. Tap the hole with the relevent tap
6. cut to your desired length
7. Screw into the enlarged hole in your head
8. File to flush finish
9. Dab of loctite and install new stud
10. Ta Da!

 

[weekendrider]

Like Paul I've used jb weld successfully for this repair. But I think the success depends on how striped the hole is. You need at least a little interference/contact to make sure you end up straight.

Couple of questions. Picture #1 shows the threads on the stud on the nut side are stripped. When you removed it from the head did the threads from the head strip?

Using a helicoil or other thread replacement you oversize to tap threads for OD of the helicoil.
The helicoil ID will be the original size.
A bushing with threads on inside and out.

 

[Halloweenie]

I usually try to steer people away from helicoils, in favor of either Acme threaded inserts or Keenserts. They are simple to install and do not rip out easily as helicoils do. You just drill the hole to the OD of the insert, tap it, insert the Acme or Keensert, and tap in the locking pins. They provide an excellent solid base with which to work with a good ID thread.

 

[Tecrekka]

I had exactly the same problem last year. I did a temporary fix with JB Weld, which held oil tight all season. Back end of last year I had the idea to fix it "properly"

So:

1. Drill the offending hole to 10 mm or larger to suit your needs and run a tap down into it
2. Take some 10 mm round bar (or larger as above) and cut of about 50 mm
3. Take a die and cut a thread down it
4. Drill a holedown the length of the bar in preperation to take the thread of replacement stud - simpler if you have a lathe but can be done carefuly in a drill press or by hand
5. Tap the hole with the relevent tap
6. cut to your desired length
7. Screw into the enlarged hole in your head
8. File to flush finish
9. Dab of loctite and install new stud
10. Ta Da!

Awesome! I will try the JB for now, I think there may be enough on there to get a good bite. So if I get this correct, basically I will be making a threaded sleeve to go in the enlarged hole where the stud formerly resided? Is there any issue with not getting this absolutely square? I was worried some serious machining would have to be done to get it perfect.

Like Paul I've used jb weld successfully for this repair. But I think the success depends on how striped the hole is. You need at least a little interference/contact to make sure you end up straight.

Couple of questions. Picture #1 shows the threads on the stud on the nut side are stripped. When you removed it from the head did the threads from the head strip?

Using a helicoil or other thread replacement you oversize to tap threads for OD of the helicoil.
The helicoil ID will be the original size.
A bushing with threads on inside and out.

Sorry I should have been more clear with that photo. The stripped threads on the nut side is the opposite tappet cover on the right intake. It looks from the parts descriptions that this is just a double threaded stud? I wanted to make sure before I just started twisting on it with vise grips, potentially making a minor problem worse

I usually try to steer people away from helicoils, in favor of either Acme threaded inserts or Keenserts. They are simple to install and do not rip out easily as helicoils do. You just drill the hole to the OD of the insert, tap it, insert the Acme or Keensert, and tap in the locking pins. They provide an excellent solid base with which to work with a good ID thread.

Sounds promising, I'll definitely look into that.

Thanks very much for everyone's input, hopefully someday I will be able to reciprocate.

 

[Paulrxs650]

Hi, yeah basically a threaded sleeve or a simple heli coil in effect! The squarer and true the better, however in this application you do have some tolerance

 

[Tecrekka]

I think I may try and go with the Keenserts if I can find them at the local bolt and screw place tomorrow. As much as I really like the idea of fabricating the part myself, I'm somewhat limited as to my tooling selection at the moment. Considering it's pretty off-the-shelf, the Keenserts look very appealing.
I'm finding some mixed data on the stud size. Boats.net calls for 90116-06017-00 BOLT,STUD (8mm x M1.25x30mm) for the three hold cover and MikesXS shows a 5V4-11101-00-00 (Boats # for the whole cylinder head assy) 6mm. x M1.0 x 30mm stud. I'm pretty sure it's the 8mm but wondered if any of you knew off hand?

 

[Halloweenie]

I didn't know before, but Keenserts also come in stud form, too.

http://alcoafastener.thomasnet.com/category/general-purpose

 

[trance]

I had this exact same problem w/my bike. Previous owner had stripped one out, and put a larger stud in. Of course, it came right out too. I just drilled and tapped and installed a helicoil. Not familiar with Keenserts or Acme but if they are better, use them.

Mine was a 6mm x 1 stud. You can buy new studs from mikesxs.

 

[Tecrekka]

So the 6mm x M1.0 is the right stud, and this is what I found at ACE. The depth of the hole on the head side is about 10.5mm. I suppose I'll cut off some of the new stud and hit it with a die to clean up the threads on the end. I'm kind of talking out loud here but I would like you guys input as to the slight difference in the length of the end of the two studs. I would imagine, that is long as I don't over tighten a stud it should be fine. By the way this is the stud with the stripped end and not the one that's going to require some type of insert. I'm going to try to source some keenserts for the other tomorrow. Thanks again everyone for contributing!

 

[Tecrekka]

Thanks Trance, I was typing my post as yours was posted. The helicoil would certainly work and I'll use it if I can't get the Keensert. After researching them a bit, and if I were more impulsive person, I would replace everyone aluminum contact on my bike with the Keensert!

 

[Halloweenie]

After researching them a bit, and if I were more impulsive person, I would replace everyone aluminum contact on my bike with the Keensert!

That's how I felt when my machining professor taught me to use them. I felt dumb for using helicoils in the past.

 

[ReycleBill]

I'm not familiar with the Acme but you can't go wrong with Keenserts. I used helicoils for 30 plus years but I'll never use them again.

 

[weekendrider]

On the length. Unless your swap to open nuts you are working with 2 closed end holes.
When both bottom out something is going to give. And if they bottom out before the cap is tight you have a leak.

 

[XSLeo]

Looking at those studs the new one should be shortened on both ends. Center the unthreaded part of the new with the unthreaded part of the old and you will see just how much needs to come off both ends.
Leo

 

[Tecrekka]

I'm not familiar with the Acme but you can't go wrong with Keenserts. I used helicoils for 30 plus years but I'll never use them again.

Certainly seems the way to go, I am trying to source them locally today.

On the length. Unless your swap to open nuts you are working with 2 closed end holes.
When both bottom out something is going to give. And if they bottom out before the cap is tight you have a leak.

I see. I would guess the point of the capped nuts would be to avoid over tightening, but then I'm sure one. can still spin the stud when it's in.

Looking at those studs the new one should be shortened on both ends. Center the unthreaded part of the new with the unthreaded part of the old and you will see just how much needs to come off both ends.
Leo

Looking back I see that I did align then to mismatched sides. I'll take some off of both sides to get it as close as possible to the original.

Thanks guys.

 

[Tecrekka]

Damnit damnit damnit damnit!