Snapped studs on exhaust/cylinder head

[Hew]

Helicoils.

There are Helicoil kits for reclaiming threads in aluminium.
This requires the original damaged thread to be drilled out and then tapped a larger size. A spring steel insert is then screwed in which has the required thread sizes on the inside.
Most motorcycle repair shops should be able to do this with the head still on the bike.
The kits are readily available but the job should not be that expensive to have done, if you are not too sure.
This new thread should then be stronger than the original.

 

[littleredrooster]

Re: Helicoils.

There are Helicoil kits for reclaiming threads in aluminium.

Yeah, but, looking at the pics, it would appear that half the thread LENGTH has broken away; only three turns appear to be showing. I would not like to drill any deeper into the head to reclaim the length in case it breaks through into the exhaust port or cambox. Don't know how much metal is behind the thread, bet it's not very much!

 

[Big Lad]

After many phone calls and advice etc, I have decided to take both the heads off and take them to a professional to get the studs taken out, new threads put in with new studs and get the broken bit welded. Not the cheapest option for sure, but it's not worth me bodging it and having the same problem stuck in the middle of Europe when they snap again.
I could have had a used c/head put on, but my engine is a peach, so I didn't want to risk the chance of putting a duff head on. A new one was too expensive.
So, thanks again to everyone for their help. Hopefully by the end of next week it'll be sorted. Cheers

 

[Thomas]

After many phone calls and advice etc, I have decided to take both the heads off and take them to a professional to get the studs taken out, new threads put in with new studs and get the broken bit welded. Not the cheapest option for sure, but it's not worth me bodging it and having the same problem stuck in the middle of Europe when they snap again.
I could have had a used c/head put on, but my engine is a peach, so I didn't want to risk the chance of putting a duff head on. A new one was too expensive.
So, thanks again to everyone for their help. Hopefully by the end of next week it'll be sorted. Cheers

Have a nut welded on the end of the broken stud.

Just a simple touch of "pzzzt" and the nut is on.

Heat up the alu around the stud with a very small torch (solder torches do the job) and then tap the stud/nut on the head (not too hard ofcourse) to loosen it.

Turn it out.

Never ever use easyout or left taps.

 

[Big Lad]

And the result is ..................

A used cylinder head from Motorworks fitted and now everything is back to normal. That is cutting a very long story short.

Please check your studs now. Fit new ones if you can, before they snap. It is a NIGHTMARE sorting it out, If you are going to keep the bike for a while, I would change them asap as a preventative ( spelling ?? ) measure. Once again, thanks for all the help and advice.

 

[ferguscawley]

used cylinder head

Big Lad

Regarding the used head that you bought from motorworks - did it come with valves/springs & rocker arms already installed or did you have to transfer all your exisiting gubbins to the 'new' head ?

Ferg

 

[Vern]

OOOO, can I have the old head to play with pleeeeeeze, if it hasn,t gone to the big scrap yard in the sky

 

[brassmonkey001]

There are stud extractors available that work on studs that have some stud exposed ie not broken off flush.
They work on the principal of an eccentric cam type thingy so that as you try and undo the stud, the extractor grips it tighter. They are much better than using a pair of molegrips or two nuts, both of which methods tend to strip any remaining thread. These extractors don't require any thread, just a certain amount of exposed stud to get a grip on. They also work on left hand threads as well.

The secret to using easy outs is to use one thats almost the same diameter as the stud you are trying to get out. If you use one thats too small it WILL break off and will turn a pain in the arse into a major calamity. Its almost impossible to drill out a broken stud with a hand held drill without going off centre or drilling in at an angle. If you can, take the part off and get it set up on a pillar drill so you can drill exactly in the centre of the stud and at the correct angle. This way you can remove as much of the stud material as possible and then fetch the rest out with the easy out.

 

[Big Lad]

All the existing bits were transfered to the new head. I'll see if I can get the old head from the garage. Watch this space.