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Up Topic Open Technical Section / C1 Technical Chat / Confession of a bolt-mangler
- - By Clunkfish Date 17-05-2009 15:02
Whilst preparing to check the valves yesterday, I stupidly tried undoing one of the cylinder head cover bolts (the one right at the bottom, with the engine in situ) with a torx bit rather than an allen bit. This neatly turned the hexagonal recess in the head of the bolt into a circular one and now I can't get it out. Does anyone know of a good solution to this problem? :-(
Parent - By aware Date 17-05-2009 15:13
Parent - - By Gerona-bike Date 17-05-2009 17:21
We used to call them easy-out.  As long as you can drill a hole through the centre of the bolt you can insert the left hand thread grip of the easy-out and as it tightens up it will usually remove the screw thread.  Of course it is best not to drill right through if bolt end is open to an area in danger of contamination from debrise.  I presume the offender is counter-bored in and cannot be accessed by an external grip such as a mole.  We have welded a not through its centre hole onto broken thread or damaged cap and unscrewed with conventional spanner or socket on occassions but you need to know what you are doing.  If the issue is awkward to access then good luck and find patience because you will need it.
Parent - By Clunkfish Date 17-05-2009 19:32
Thank you for the advice, Grabit ordered via eBay (£13.28 incl postage) and I'll give it a go :-)
Parent - - By andogas Date 17-05-2009 21:54
Centre punch a hole on the top of the bolt and then tap round using a small hammer and a punch. This should do it - these bolt's shouldn't be very tight.

Alternately you can try banging in a larger allen or torx key - best to use just the bit or a socket as it will be difficult to tap in a key.

The other option is to make a cut accross the bolt head and use a flat blade screwdriver. All options will work with the top two most preferred.
Parent - - By bolt-on-billy Date 18-05-2009 07:00
I was going to suggest a flat hex bit ground to suit. the torx must have been too small as normally they are better if they are a tight fit. I often find I can salvage bolts with a torx.

those bolts are pretty crap really
Parent - - By Lawrie Date 18-05-2009 07:31
Easy-outs, (bolt extractors) are very good, but possibly not for these, because these bolts have a shallow recess, & can hit the bottom of the hole before it 'grips' the sides.

I have had 100% success by 'hammering-in' the next size up torx bit into the damaged hole, hold with pliers etc. & give it a good hard 'whack, so it will stay in by itself, then, place a ring spanner over the bit, push the end with your thumb whilst turning & it WILL undo!!
Parent - - By bolt-on-billy Date 18-05-2009 08:03
cant remember if mole grips will get in there.
Parent - - By Clunkfish Date 18-05-2009 10:18
Mole grips won't get in there as it sits in an indentation in the cover :-(

I did think about whacking the next size up torx in there but was worried about damaging the cylinder head - you reckon it would be OK Lawrie? Are we literally talking about hammering the torx bit in there...?
Parent - - By Lawrie Date 18-05-2009 12:46

>Are we literally talking about hammering the torx bit in there...?


Yes, don't worry, you wont damage the head, your biggest problem is access, 'cos me being me, I always used to drop the engine anyway, once its jacked up & made secure, you're looking at 30 mins or so to get it out, but I have the luxury of a bike lift-table & all the other stuff required.
Parent - - By Clunkfish Date 27-05-2009 22:30
I decided to try the Lawrie method first. Used the Bolt-on-Billy approach of jacking up the bike and letting the engine pivot so that the head is uppermost, then whacked a torx bit into the mangled bolt and hammered it in. I got a hex adaptor onto the torx bit, used a flexible shaft to a screwdriver to improve access and leverage, twisted like blue buggery and out it came :-)

Needless to say, the valves were fine so it was all a bit pointless but there you go. Replacement bolt fitted, everything back together and working nicely.

I've attached a picture of my latest exhibit for the black museum!

Thanks to all for advice, suggestions and encouragement :-)
Parent - By jp72 Date 28-05-2009 18:44
Amazing :)

Congratulation for sorting this out
Parent - - By Andrew Date 18-05-2009 10:27
It's all going to be much easier with the engine dropped down, or even removed completely. If you can organise it so that you can safely jack or lift the C1 about 2 feet and allow the engine to pivot down, after undoing the shock/springs and releasing a few cable clips, it will save you having to drain the coolant and undo all the connections for the engine out option.

I bought one of the Aldi or Lidl hoists for about £40 and mounted it on a beam in the garage. I put a strap through the C1 roof and just carefully lift. Undo the the rear suspension when the hoist has taken the strain, then the clips and just lift the bike up. The workshop manual tells you which clips to undo. The result is a surprisingly open area around the head which would help you to get a drill or grips in there.
Parent - By flange Date 18-05-2009 12:05
I remember servicing a Honda CB125 many years ago, I only had it a couple of days and broke the spark plug whilst trying to get it out. Had to drill the head and hexicoil a new thread in AKA off the road for a week! Now I change plugs with nice warm engines.

My point, your not alone, we have all mangled something somewhere, hope you get a workaround sorted soon.

S ;0)
Up Topic Open Technical Section / C1 Technical Chat / Confession of a bolt-mangler

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