GAAAAAAAAH!!!!111; or, On Exhaust Studs

[xwhatsit]

So many swearwords running through my head...

I had a pair of salvaged Dunstall Decibel replicas on the bike, which were nice (deeper whir and engine seemed smoother) until I blew a hole in one header whilst sitting all day on the motorway system. That's all very well, I have two sets of stock silencers, so I put one set on today.

Cleaned everything in petrol, used new exhaust copper ring gaskets, then *NEEP NEEP* out strips one of the exhaust flange studs.

Still seems to have sealed up OK for the moment, but I know it won't last for long. I was sure it was the stud pulled out of the head at first (weakest aluminium head EVAR), but now I think it might just be the stud.

I have other (broken) cylinder heads, presumably with good studs. Is it possible to take out the existing one and swap it over? What if it's not the stud, but the cylinder head that's stripped? Helicoil time, or something else?

Cheers. I feckin' hate FASTENERS BOLTS THREADS GAAAAAAAAAAAAAAAAA *head asplode*

[What?]

Certainly possible to swap the studs over - you may need to give them a good soak with CRC for a day or two first if they don't come out easily.
But, if the head is damaged, it will need to be heli-coiled.

[Ixion]

You can certainly remove the stud from an old head for reuse (use double nuts to get it out) . When fitting it , especially if the head thread be weak,use some high temperature stud lock Loctite. Note this is not normal Loctite. It is specifically for studs, and specifically for high temp locations.

If the head thread be stripped , a couple of tricks to try to avoid a Helicoil are to try a longer stud. Often there will be good threads down deep, unstripped because the normal stud never reaches them. You can make a stud from a bolt by cutting the head off and cutting a thread on the 'blank' end. If there is no 'spare' thread in the head , you may be able to drill the hole deeper and tap it. Or, tap the head for a larger thread , and make a larger stud as above. (and drill out the hole in the exhaust flange)

[xwhatsit]

Thanks for the advice, guys! Did some Googling and it seems what I need to be worried about is getting the bastard out; they're heat-something-or-othered in and you need to `crack' the seal. Double nuts, I'm guessing you just stick two on and tighten them against each other, then try and undo it with a spanner on the innermost nut?

WD40, penetrating oil, I hear ATF is good for this as well?

Cheers very much. All my first mechanical experiences being with this 80s Honda, I have a loathing of anything to do with threads in aluminium. Gives me nightmares. O, for a cast-iron Brit...

On the side, the original silencers I'm using are... interesting. They're still sealing well, but the insides are rusted to bits, and as I used them today to get to and fro work they got louder and louder. The first time I fired it up there was rust and smoke and all kinds of shit coming out the end of the pipes. Has a fairly meaty thump, not unpleasant (if a little flat); you might call it natural debaffling :laugh:

[awayatc]

Double nuts, I'm guessing you just stick two on and tighten them against each other, then try and undo it with a spanner on the innermost nut?


That's indeed the way to do it...increase your leverage on spanner (with pipe or so)...or vice grips on the unthreaded bit has worked for me in the past..

If you go drilling as suggested make bloody sure you know how deep you can safely go,and tape your drillbit up accordingly...
Good luck

[terbang]

More than likely you have stripped the stud (best option really). If the thread in the head is stripped then your best option is a Helicoil. Warning, Warning, do not wring his neck..! In other words snapping off the stud flush with the head will be like having all your nighmares come true. And if this ever happens, then make sure the word 'Ezy out' never passes your lips (or enters your realm of thought). Penetrating oil, accuracy and patience are your friends here...