Exhaust stud holes stripped on 250n

pepperami · Super Spammer Joined: 17 Jan 2010 Karma :

I`m starting on the exhaust of my Superdream 250n ready for it`s new(er) exhaust coming soon.
So after a soaking of Plus-gas for the last couple of days, I finally got some movement from the studs.
After much gentle/slow/steady easing, all four studs are out
However every silver cloud has a dark lining.
On inspection of the studs, it is clear they have never ever been out of the engine and were very corroded.
Also two of them were stripped!

So my question is : what is the remedy?
Is there a next size up I can put in after I have cut a new thread?
Will I need to get the holes Heli-coiled.
Is there enough meat for me to drill a bit deeper and put in some longer studs of the same diamiter.

Your advice is much needed
Many thanks oh mighty BCF
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Serendipity · World Chat Champion Joined: 07 Jun 2006 Karma :

I'd vote helicoil.

It worked for me on both RXS100: https://www.bikechatforums.com/viewtopic.php?t=149709

...and CBR600.

Cheers.
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2016 CBF1000F - Commuter heaven | 1994 CBR600FR - Awaiting defibrillation

Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

Have you tried running the correct tap dowm the stripped holes. sometimes there is enough metal to form a new thread. If you have a lathe you could make up new studs with a larger diam thread on the one end and drill and tap out the head otherwise it is a thread insert like Helicoil (which I hate) and in either case use plenty of copper grease
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stonesie · World Chat Champion Joined: 04 Jul 2010 Karma :

Time sert is much better than helecoil but to buy a DIY kit is expensive, a local engineering shop might do them.

https://www.ebay.co.uk/sch/i.html?_trksid=p5197.m570.l1313&_nkw=time+sert+kit&_sacat=0&_from=R40

pepperami · Super Spammer Joined: 17 Jan 2010 Karma :

Thank you chaps.

Those inserts look interesting?

There might not be enough metal there to cut another thread/repair the thread for the standard bolts/studs.
The standard studs are 6 by 1.0 .
I have a 7 by 1.0 tap, so I am thinking about cutting a new thread and using the next size up bolt.

I seek your thoughts oh mighty BCF, any potential problems doing that?

I can always revert to Heli-coils ?
____________________
I am the sum total of my own existence, what went before makes me who I am now!