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[Les H]

Hi Norm, You highlight a nasty possibilty, but that possibilty exists at all times when one is trying to remove the head from the barrel by any other means apart from levering the head and barrel apart with a crowbar type tool which can break fins off the head and barrel (not a nice thing to happen) The same exists when tapping the head upwards, which is the recommended method, or by using the rope trick. Your experience shows the breakage can happen and thanks for the warning. SO, the nut on the bottom bolt should be removed every time the head is removed, just in case the worst happens. As the barrel will now be completely free to move apart from stiction on the base joint and its own weight and thus inertia, I would recommend that the head nuts are loosened equally to give about 2-3mm open clearance. As the standard barrel is very heavy, sharp tapping conventionally or by rope trick should break the stiction of the head joint at the barrel but excessive or accidental upward movement of the barrel limited by the partially unscrewed head nuts should the initial impacts not separate the two components. As the two components seperate, the nuts can be further loosened or removed completely.

[PeteF]

If you are using a copper gasket a smear of sealant is a good idea. I would choose Wellseal rather than Hylomar as I belive it stands the heat better. It's the one Hitchcocks recommend for this job. I've certainly found it excellant stuff.

[Alan R]

Hello M1ks -------- I would ask that you re-consider about not removing your barrel and checking the piston assy. etc. To have got this far and not checked on what, in these engines is probably THE one item that gives the most cause for concern, does seem a real lost opportunity to say the least. Please don't "spoil your ship for that H'porth of tar" ?? Also you mentioned in your first post about "hopefully that and not the piston rings"----so how are you going to be sure ?? Unless you check ---------. Have a look at a current thread headed }---"500 Piston failure". You'd be looking for any tell-tale signs of immanent failure as per those postings, plus a fresh set of rings. No great extra cost, very little extra time but at least that would complete a Top-End overhaul properly. I'd forgotten about those hardened washers--again,well worth the money I spent ( There you are---a definitive statement from Mr Miserly himself that I spent some money !).Remember to anneal the copper gasket to ---"Cherry red"---ie a dull red, not as some seem to do, a bright, sparkling colour !! Finally, a note to LES H & Co. }----Like Mike I also resorted to the leverage, only because all others had not worked. What made the fin snapping-off so galling was the head had loosened and was on the move--damm-it ! Anyway, it's back on now. The problem with either the lifting bracket or the rope trick is it asks the gasket to "give" equally all across it's area in one go. This is ok if the sealant is of the normal type eg Wellseal etc but what Mike and I had was just as I said, like cement and in my case applied at the factory. I must look on E-bay again---according to that T/V programme a while back you CAN buy old rope on there !! Best regards to all-------

[Lone Wolf]

Wotcha.

Hmm - Alan R said . . .Incidentally there was a thread on here a while ago where someone posted a bolt-on lifting bracket design.Looked quite effective too . . that would be something like THIS --> http://www.moonshiners.org.uk/bulletheadgone.htm

[Thomas]

Had the same problem years ago when I opened my engine for he first time. The washers were heavily locked in the threads, I couldn’t get the head off, even broke a fin of the barrel. Came then up to this:
http://666kb.com/i/c4cqpumbp9zqljai9.jpg
The plate is locked to the head with the rocker and cover studs. The four screws are pressing down on the cylinder studs. There is a ½ inch brass cylinder under each screw to avoid damage to the studs. By tightening the screws crosswise a half rotation each the head comes off very easy and evenly. Anyway, I think the problem is not the sheer force that is needed but to execute the force even and to avoid to tilt the whole thing.
With hard washers the head now comes off more easily, but I still use the plate as I find it much more comfortable than working with hammer and mallet.

[m1ks]

Fair comment Alan, just that when you're a Yorkshireman living in Scotland tight fisted is a given,

I know the barrel isn't leaking, (drastically anyway), as I had a quick test idea pop into my head yesterday, i wrapped a piece of double cling film over the barrel lip, wrapped with a rubber band, in top gear, rotated the rear wheel backward and forward checking that the film was drawn down and stayed and inflated and stayed accordingly, worked quite well but was a fiddle round the studs.
I may well whip it off the while it's in bits.
Thanks for the image links of the alternative removal methods LW and Thomas.

[Alan R]

Hello again matey ----I've deliberately left this to later----after most of the postings have been on. Now I hope we're still going to be friends ? Well, here goes----sticking my neck out and putting it on the chopping block I'm going to say something controversial ie }-------You don't need to take the head off to achieve a helicoil in the plughole. --------------------------------------------------------Hello,it's all gone quiet !!! It depends on what equipment you have available and it requires the use of a "helper". An industrial vaccumm cleaner with a small nozzle, say 2" diam.---that's for the helper to use, is called for. With the piston at half stroke (to avoid the incoming drill) follow the usual instructions for Helicoiling, plugging, whatever except use the drill in light applications and allow the hose to suck up the bulk of the drillings.(Like at the Dentist?). With Aluminium and a standard-angled drill, these are usually curly turnings and LOTS of them. It is possible to modify a drill bit into producing "chips" but we DON'T want that. Some swarf will drop into the bore--move the piston to almost TDC on the exhaust stroke, insert an HP air gun with angled, lance-type end and give a good all-round blasting. Anything left after this will be blown out upon starting. Remember this IS Aluminium, not tool-grade steel and wont do any damage. Now Helicoils have a "Tang" across the centre at the input end which allows the "Special fitting tool, Sir!!" to rotate the coil when fitting and then counter-rotate to break it off. Use a pair of stubby, long-nosed pliers for this. IF it drops in then a flexible magnet does the trick----don't ask me how I know that----But I now use the INSERT type---they don't have that little tang problem and are a heap stronger. Take a look at this }----------http://www.specialty-fasteners.co.uk/up ... ---------I used these on a daily basis and can personally vouch for them. Are we still friends???? Seriously though, when working on vehicles and equipment that has a short turn-round time eg required "yesterday" then conventional thinking goes out of the window and a little "Risk-assessment" enters the scene. Glad I'm not there anymore. Be seeing you-----------

[m1ks]

Not a problem at all Alan, indeed several people have told me this and in fact i have done this very thing on a Kawasaki Z750 chop I had a few years ago.
Despite judicious vacuuming with a modified nozzle I made, (large bore high pressure fuel hose, lots of gaffer tape and the Vax, shh, don't tell the missis, it was more powerful than the crappy old thing I use in the shed) after a couple of weeks I developed a weep from the very area of the cylinder i'd helicoiled, it may have been one of those things but it pressed my paranoia button and i'd rather have the thing in bits and make sure it's spotless when it goes back together, with an engine like this, it's easy enough, OHV so no cam timing to worry over, single cylinder, air cooled, etc
I was taking off and stripping the carb anyway to return the jets to stock when I do the same with the silencer and airbox assembly, I was removing the header pipe to fit a cooling / fin ring, (when I order it)
It also means I know after decoking, giving it a scrub up and re-lapping the valves and decompressor it should be well sealed.
A fella I know had a Timesert kit which he offered to loan me, sadly the largest insert was an M12, I do like the look of those you linked, the little keys once tapped in place obviously lock the insert then, clever stuff, are they readily available? are they a self tapping insert?
I've yet to get the helicoil kit as I'm waiting on asking a friend, (i borrowed the kit from the last time) to see if he still has it.

[Alan R]

Hi matey--------Oh good, that's ok then. I can't comment of their ready availability as the MoD stores had them in stock as standard kit ( we were after all dealing with Aluminium, Duralumin and Armour plate, 24/7 with a "customer base" of several Armoured Regiments). There is a dedicated tap for the outside thread and, as this is partly tapered, I would sometimes only part-tap to ensure a really tight fit. There are a range of different inside threads for any one given outside size. The insert is applied with Loctite 270 High Strength threadlock and then, as you say finally those 4 little tangs also keep it in place. Have a look at this}----------http://www.specialty-fasteners.co.uk/ca ... ---------- and follow it up. They are designed with the regular removal/fitting of the threaded item cocerned and for use in materials such as aluminium so are ideal for spark plug use. My main dislike of Helicoils is that the application tang I mentioned doesn't always break away cleanly---leaving a small protrusion at the bottom. Any thread coming into contact will therefore be slightly damaged----not a good thing for a spark plug. You could always make your own using the threaded shank of an 8.8 high tensile bolt as the outer. I've had to do this on many an occasion when the standard item couldn't cope with the location, material thickness etc. Best wishes---------- Alan R

[Les H]

Just an extra note as regards the barrel moving upwards when removing the head. I had forgotten that the bottom barrel extension that enters the barrel is, or should be, pinched and held by the two crankcase nut and bolts at the top of the crankcase mouth, this will obviously restrain any up ward movement quite a bit if they are left tight....removing the small bolt at the top of the tappet adjuster box still seems a good idea though before knocking the head upwards just in case the barrel wants to move with it.