Head Stud Stripped - Post Rebuild

[Fingerscrossed]

Ok… I’ve worked through a lot of issues on this bike but finally got it running really well. I went on the first big ride since rebuilding the engine (refurbished crank, new pistons/rings, refurbished cylinders and head). I also did all custom wiring, blah blah blah. I went on a 200km ride, the bike didn’t miss a beat. I came back and changed the oil - looked good. There were some small flakes of metal in the oil pump filter, didn’t look too bad. Sump filter was completely clean. Oil maybe slightly shiny but not bad at all.

Went to torque the head studs - I previously torqued them to 30ftlbs. I got to no 8 in the diagram and it just span and span. I loosened it and the entire stud came out with the thread wrapped around the bottom… (I took the photo after removing it) I tried putting it back in but obviously it now won’t even tighten down enough to stop wobbling…

This post is part just venting - after so much work it’s frustrating to have to pull it all apart again, but also because I want to ask about the best way to re thread the hole. Anyone have any ideas or had this happen before? Did it just happen from being old or tightened too much previously? The other nuts tighten seem fine but I don’t want to fix this, put it back together and another one strip… could it have been the torque wrench was out of tune and I over torqued it? It didn’t feel too tight… I have torqued the head nuts about 3 times now post-rebuild using the same torque wrench and they’ve rotated less than half a turn each time, pretty much.

Also will I need new gaskets for doing the top end again? I used sealant on the head gasket so I assume so… the base gasket is the chemically treated one that expands. , help would be appreciated!

 

[GLJ]

I want to ask about the best way to re thread the hole.

I would use a heli-coil.

Also will I need new gaskets for doing the top end again?

I have removed the head/cylinder as a assembly. Make sure you only remove the stud nuts and the bolts for the cam cover. Leave the bolts under the spark plugs and the small bolt at the back of the engine in place. You can also leave the pistons in the cylinders. I would only reuse the base gasket if it looked perfect and then I'm not sure I would.

 

[bosco659]

Too bad this happened. Helicoil or Timesert will be needed. Not sure of the root cause - it may have been excessive torque at some point in its life. For me, I’d swap both gaskets do I wouldn’t have to do it all over again. For the other studs, I’d check for any sign of them coming loose and repair those if necessary. Nothing worse than having to go back and doing something over again if it’s apart already. Ask me how I know.

 

[Its been a long time]

Personally, I think I would be sorely tempted to helicoil all the larger studs. It's never going to be a problem ever again then. Given the work involved in doing just one, it kind of makes sense to do all of them. IMO.

 

[Fingerscrossed]

Ok thanks guys! Yeah I may as well order the gasket kit and replace both gaskets and the o-rings. I’ll check the rings have properly seated too.

Personally, I think I would be sorely tempted to helicoil all the larger studs. It's never going to be a problem ever again then. Given the work involved in doing just one, it kind of makes sense to do all of them. IMO.

I think I will do all of them - my only concern is more room for error on my part… I’ll take it slow, should be right!

The threads on the bottom of the stud look quite long, will a helicoil be long enough? I’ll look into it, I’ve used helicoils on the valve studs but I’ll do some reading as I haven’t used them all that much. I remember seeing a thread where someone helicoiled all threads in the engine

 

[Fingerscrossed]

Hi all, just an update - it was cheaper to get an old pair of cases and get them Vapor blasted so I just did that. Put it all together, went to put the clutch on and found a broken cush spring in the clutch hub

Anyway.. while I’m here, thought it’d ask - does this cam chain adjuster seem normal? It’s like if it’s not under spinning it loses a tiny bit of tension and pushes out (when it’s running it’s always spinning so I’m not too worried) it was doing this after I rebuilt the engine the first time and still doing it now. I put in a washer as there was no dampener washer on mine.

There is also a bit of wear on the pistons underneath the rings. Geoff from GeoffsXS in Sydney said it’s fine, and he knows his XS’s but I’m wondering if anyone knows what would have caused this after 200kms on a fresh crank, new pistons, rings and bore? There’s no depth to the mark, can’t get a fingernail on anything. Probably could make a new thread but I’m not so worried - but if anyone has anyone has an opinion I’ll hear it!!

 

[5twins]

I've revised my thinking on the head torque values, particularly those 8 big studs. I won't go over 30 pounds on them anymore. I had my head gasket start leaking and so I tried tightening those big studs to 35, but I could barely get them that tight, and I swear I felt the studs stretching, lol. And, it didn't cure the leak. I'm probably lucky I didn't have any pull out of the block like yours did. So, here's a "revised" drawing with the lower value. Get rid of that old one with the higher value, lol ......

No, your tensioner doesn't look "normal". The plunger isn't supposed to come out past the adjuster bolt like that. What year is the tensioner assembly? You may have some mis-matched parts from different tensioners, or maybe the damper washer you installed isn't thick enough.

 

[vr3506]

Ok… I’ve worked through a lot of issues on this bike but finally got it running really well. I went on the first big ride since rebuilding the engine (refurbished crank, new pistons/rings, refurbished cylinders and head). I also did all custom wiring, blah blah blah. I went on a 200km ride, the bike didn’t miss a beat. I came back and changed the oil - looked good. There were some small flakes of metal in the oil pump filter, didn’t look too bad. Sump filter was completely clean. Oil maybe slightly shiny but not bad at all.

Went to torque the head studs - I previously torqued them to 30ftlbs. I got to no 8 in the diagram and it just span and span. I loosened it and the entire stud came out with the thread wrapped around the bottom… (I took the photo after removing it) I tried putting it back in but obviously it now won’t even tighten down enough to stop wobbling…

This post is part just venting - after so much work it’s frustrating to have to pull it all apart again, but also because I want to ask about the best way to re thread the hole. Anyone have any ideas or had this happen before? Did it just happen from being old or tightened too much previously? The other nuts tighten seem fine but I don’t want to fix this, put it back together and another one strip… could it have been the torque wrench was out of tune and I over torqued it? It didn’t feel too tight… I have torqued the head nuts about 3 times now post-rebuild using the same torque wrench and they’ve rotated less than half a turn each time, pretty much.

Also will I need new gaskets for doing the top end again? I used sealant on the head gasket so I assume so… the base gasket is the chemically treated one that expands. , help would be appreciated!

Are your washers thick enough? When not, you don’t torque your cilinder/cilinderhead!! Also happens with some dome nuts in which the thread isn’t deep enough!

 

[Fingerscrossed]

Yeah, agree with the 30 ft-lbs!

No, your tensioner doesn't look "normal". The plunger isn't supposed to come out past the adjuster bolt like that. What year is the tensioner assembly? You may have some mis-matched parts from different tensioners, or maybe the damper washer you installed isn't thick enough.

Mines the Type C, 75 style with the thick copper washer, do you know the thickness? I don't think I can get the part here in Aus - I have a rubber washer from a newer style adjuster but it still too thin, I think.

It may be mismatched. It didn't have a washer on the adjuster when I took it apart and the wheels, carbs, engine and frame are all from different years...

 

[BowlingSS]

Hi all, just an update - it was cheaper to get an old pair of cases and get them Vapor blasted so I just did that. Put it all together, went to put the clutch on and found a broken cush spring in the clutch hub

Anyway.. while I’m here, thought it’d ask - does this cam chain adjuster seem normal? It’s like if it’s not under spinning it loses a tiny bit of tension and pushes out (when it’s running it’s always spinning so I’m not too worried) it was doing this after I rebuilt the engine the first time and still doing it now. I put in a washer as there was no dampener washer on mine.

There is also a bit of wear on the pistons underneath the rings. Geoff from GeoffsXS in Sydney said it’s fine, and he knows his XS’s but I’m wondering if anyone knows what would have caused this after 200kms on a fresh crank, new pistons, rings and bore? There’s no depth to the mark, can’t get a fingernail on anything. Probably could make a new thread but I’m not so worried - but if anyone has anyone has an opinion I’ll hear it!!

I would hone the cylinders.

 

[5twins]

The original copper washer was 2mm thick, the later rubber/metal one was 3mm thick .....

But if even the later thicker washer isn't thick enough to get the plunger flush with the end of the adjuster bolt, I'd say you have some mismatched parts. Either your plunger is too long or the adjuster bolt is too short. I'm afraid I don't have any specs on the '75 and older tensioners (bolt and plunger lengths) as all I've dealt with are the type D and E ones. Since your tensioner has the 6 bolt mount, you can swap a later one right on. I would watch eBay for a complete type E assembly. You don't want the type D because it has no lock nut.