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2010 CB600F plug issues [message #298956] Sun, 04 February 2018 22:06 Go to next message
anardon is currently offline  anardon   United Kingdom
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(1) Club Racer
Hi all, I need to helicoil one of the plug holes in my head as its completely stripped.

Can this be done without removing engine and head?

Any recommendations for an engineer in Surrey that can do it?

Thanks, Bob

[Updated on: Sun, 04 February 2018 22:12]

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Re: 2010 CB600F plug issues [message #298958 is a reply to message #298956] Sun, 04 February 2018 22:46 Go to previous messageGo to next message
Kermit is currently offline  Kermit   United Kingdom
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(22) Giacomo Agostini
Hi (again) & welcome Thumbs Up

I only have limited knowledge of helicoils having bought a few M5/M6 DIY kits to successfully helicoil your more standard stripped threads but based on that limited knowledge, I wouldn't have thought so due to the process which (at least with DIY kits) is:

a) Drill out the existing holes thread to approx normal size + 1/2mm or so (using specific sized drill bit matched to the kit)
b) Tap the hole with oversized tap matched to outer thread size of the helicoil
c) Wind in the helicoil till its home then iirc it snaps off

Sounds easy enough and it is fairly straight forward on none internal parts but the problem comes with a) & b) resulting in lots of metal chaff coming up (good) and some dropping down (bad) into the space below. Magnets on a long pointy stick thing won't be any good to fish that stuff out as the head will be alloy and while I guess some clever mechanics may have developed some sort of dentist style suction tool and be able to inspect for anything remaining, it'd not take much in the way of specs of metal filings to damage the bore even though I guess there's a good chance the first firing up may well expel most of it.

The other possible problem if the above can be resolved, it there room on a CBR6 above the cylinder head to get a decent sized drill and drill bit at the spark plug hole 100% perpendicular with the hole as I suspect most engineers would want to drill that sort of large hole with one of those proper drill bench press things to ensure 90 degree hole and no movement.

But as I mentioned, I've only done small stuff and have limited knowledge so am happy to be wrong.

[Updated on: Sun, 04 February 2018 22:48]

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Re: 2010 CB600F plug issues [message #298966 is a reply to message #298956] Mon, 05 February 2018 20:33 Go to previous messageGo to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
Yes, it can be done. Pick up the Yellow Pages and look up a shop in your area specializing in old car and bike engines: they are geared and experienced in this kind of thing. No point suggesting you a shop hundreds of miles away.



Re: 2010 CB600F plug issues [message #298971 is a reply to message #298966] Mon, 05 February 2018 23:02 Go to previous messageGo to next message
Kermit is currently offline  Kermit   United Kingdom
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(22) Giacomo Agostini
bang goes my theory then Laugh

But that sounds like good news Bob Thumbs Up
Re: 2010 CB600F plug issues [message #298972 is a reply to message #298971] Tue, 06 February 2018 07:42 Go to previous messageGo to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
Kermit wrote on Tue, 06 February 2018 00:02
bang goes my theory then Laugh

But that sounds like good news Bob Thumbs Up
Helicoil has a product (in several sizes of course) specifically marketed to repair stripped spark plug threads.
To avoid metal shavings falling into the combustion chamber Helicoil suggest coating the tap with grease, but some people stuff a piece of oiled cloth down the spark plug hole before tapping. They must be feeling way more confident than me in fishing it out, especially when heads like that of the old CBR1000F are involved. Laugh
Since the tap has to be worked slowly the grease is usually more than enough to retain any metal shavings and the rest is usually so minute it won't hurt the engine.
The coil that goes into the thread to complete the repair has a tang that has to be broken off at the end and that's another cause of problems because it's stainless steel, obviously of the amagnetic kind, so you cannot fish it out from the combustion champer with a magnet should the worst happen.

I have zero problem saying I am not a Helicoil/Timesert fan and repairing spark plug holes, especially on some four stroke, is one of the things that make me feel most uncomfortable. Confused

[Updated on: Tue, 06 February 2018 07:42]

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Re: 2010 CB600F plug issues [message #298976 is a reply to message #298972] Tue, 06 February 2018 17:44 Go to previous messageGo to next message
anardon is currently offline  anardon   United Kingdom
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Yes, I have seen/heard of helicoiling being done in situ using grease as a retainer. Another trick is oily string in the barrel via the plug hole which then tacks up all the fine stray swarf and gets pulled out on completion.
I think the major problem is actually getting to the damn plug hole as the frame and other random stuff is in the way.
Maybe the only way to resolve this is to get the bike down to the local engineers and let them have a look but how to get it there?!?
Or maybe just drop the engine out and take that?
A busy weekend coming up.
Thanks for the suggestions & help smile
Re: 2010 CB600F plug issues [message #299034 is a reply to message #298976] Sun, 18 February 2018 23:43 Go to previous messageGo to next message
Gragson is currently offline  Gragson   Netherlands
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(2) BSS Racer
If the bike is a keeper, helicoils are not great for something like a plug which you will want to change now and again, even well done they tend to bind to other steel like the plug over the ali head, even with copper slip on thread.
You could say the same of timeserts but they are a better engineered solution. A machine shop worth its salt would want the head off :-(
Re: 2010 CB600F plug issues [message #299040 is a reply to message #299034] Mon, 19 February 2018 19:43 Go to previous messageGo to next message
Quazi is currently offline  Quazi   United Kingdom
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(22) Giacomo Agostini
Ok in a lawnmower not a bike engine.
Re: 2010 CB600F plug issues [message #299057 is a reply to message #299040] Thu, 22 February 2018 12:31 Go to previous message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
Quazi wrote on Mon, 19 February 2018 20:43
Ok in a lawnmower not a bike engine.
My old Transalp 600 had a Helicoil'd spark plug hole.
I don't know when and where it was done (the bike had three previous owners) but it never gave me any problems for all the years I had it, albeit I changed spark plugs only once.
I think the trick is not to overtorque the things, but if you are really really worried there are all sorts of graphite-based thread lubricants you can use.
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