When cleaning up the (fixed) heads on my bike, I notice that they have inserts in the plug holes (this is with 18mm diameter plugs, so, not 14mm reduction inserts).
These are rather tatty and I would like to replace them.
Does anyone have a pair, or know where I can get some?
The plug ferrules can be a swine to remove, but usually respond to a big beefy pair of Stillson type grips, to unscrew them out of the blind heads. If you can’t get new ones and new ring nuts from the Spares Scheme, Roger Moss, Ken Lack, or Richard Blackburn, let me know, and I should be able to help.
Mine look like they have been screwed in by tapping with a hammer and screwdriver (or something similar) and they appear to be quite damaged around the edges ; hence my reason for wanting them replaced.
I suppose that I could remove them the same way.
Is there a special tool for tightening them up?
The ring nuts, with castellations around their edges, are usually found to be chewed up, after idiots have attacked them with hammer and screwdriver in a vain attempt to overtighten them to stop a water leak that is actually rarely due to the ring nuts not being tight enough, and in reality caused by a failure of the sealing washers situated between the plug ferrules and the alloy water-dome casting. These used to be a copper and asbestos sandwich, but asbestos is now banned, and much better alternatives can be used, together with silicone mastic sealant. The flanges on the plug ferrules need to be in good condition if a good watertight seal is to be made, and you also need a good ‘nip’ on the outer sealing rings between the water dome and the top of the cylinders. The way I do it is to put the dome in place with the chosen sealing washer in place on the plug ferrules, but NOTHING on the outer joint. Tighten down the ring nuts with the special tool, (easily made out of an old tube spanner, or length of steel tubing), but not too tight. Then measure the gap between the outer edge of the water dome and the top of the cylinders. Add about ten thou” to that measurement, and that is the thickness of sealing rings that you need. In other words, you are trying to get the same amount of ‘nip’ on both the outer rings and the plug ferrule washers. Finally assemble it with all the packings in place, aided by silicone mastic sealant, and tighten down firmly. Leave at least overnight for the silicone to cure before starting the engine. Before assembly do check carefully that there are no radial cracks in the aluminium around the inner holes of the water dome, or you will never achieve a water-tight joint.
I should also say that the outer sealing packings used to be made of compressed granulated cork. Whilst this is impervious to water, glycol antifreeze seems to be able to come through it very easily, forming a white crust on the outside of the joint, which removes the red paint off the barrel, and turns the metal rusty. So if you can get some, use the black rubber outer packings as this doesn’t let antifreeze through. If necessary, you can buy this stuff in a sheet of the right thickness, mark it out using a pair of compasses, and then cut it out using a craft knife or strong scissors.
Hello Brian the last couple of pairs that I made ( outer water dome seals ) I used a pair of stout dividers the type that can be locked with a wingnut on a slotted thingy . Reduce the legs so that one leg can be stoned to make a small blade re point the other leg keep the blade razor sharp and Bobs yer next set of seals. Regards D F .
Thanks for the info.
Are the ferrules left hand or right hand thread? By tapping them anti-clockwise, I might be simply tightening them (because they are not shifting).
Any one got a good set of 600 long stroke barrells and pistons (with rings and including water dome)? I’ve got a slight bit of piston slap on the RHS, so might as well go the whole hog and replace them.
Both the ferrules and the ring nuts are R/H thread. You shouldn’t really be tapping them as there is a risk of slipping and damaging the water dome casting, and of course it also chews up the ring nuts. It is bodgery ! Get a piece of thick walled steel tubing of about the same O/D as the ring nut, then mark the end to correspond with the castellations on the ring nut, cut down about 3/16″, and then cut and file away the tubing to leave the end with pegs that will engage with the castellations. Drill a hole through the other end of the tube to take a tommy bar, and now you can easily unscrew the ring nuts without causing any damage. When they are off you can put a screwdriver or tyre lever in the gap at the front of the dome, and gently lever up the dome to remove it and reveal the rest of the ferrules. There should be a nice flat ledge around the edges of the ferrules that the sealing washers sit on, but if these are badly corroded the ferrules will need renewal, and can usually be removed by unscrewing, using a pair of Stillson grips. As they are going to be renewed you could take an angle grinder and form a couple of flats on the sides at 180 degrees to one another, and you will then get a much better grip on them. Your ‘piston slap’ may be nothing of the kind…… Typically it will be a gudgeon pin hole that has worn oval due to the pin turning in the piston instead of in the little-end eye in the conrod. If that is the case it will be best to get both pistons bushed in order that both weigh the same afterwards.
Rather than use stillsons which distort the ferrule and can make it oval and therefore grip even harder into the barrel I prefer to mig weld in (put in loads of heat) an old spark plug and whilst it is still nice and hot use a big adjustable or socket to remove the ferrule. I’ve also removed them by mig welding on a piece of flat bar. Just be careful on old barrels on large bore sizes as one day the cylinder top will come off with the ferrule……
When removing corroded old plug ferrules in the past, I have firstly taken a hacksaw blade, wrapped one end with tape to make a handle, and then VERY SLOWLY AND CAREFULLY cut two slots, at 180 degrees to one another down the internal threads. It is a tricky thing to do, as every few cuts you have to check that you haven’t gone too deep and into the threads of the cylinder head. I check by shining a strong light down the cuts, and at the stage when you have got to the bottom of the threads, a row of pinholes will appear at the bottom of the saw cut. Obviously you must stop there ! With the two cuts made some penetrating fluid into them will seep into the threaded joint, and when the ferrule is gripped tightly it will partially collapse into the saw cuts, and then unscrew quite easily. I didn’t detail this procedure in my previous posting as I could foresee people going too far with the hacksaw blade and damaging the threads in the cylinder heads. I cannot overemphasise how carefully the two cuts have to be made, and I have only now explained it for the benefit of those who don’t have access to welding equipment, and wouldn’t trust a local garage to do it !
Rob Frances lent me his removal tool and it removed the previously tapped in (and rusty) ferrules without any problem at all.
Simply screw the central bolt into the plug hole (his is 18mm dia to suit 18mm plugs) which holds a swivel nut (with spigots to engage with the ferrules) against the ferrules. then unscrew the nut. Simple!
I am going to get one made by a local engineer. If anyone wants one, let me know. I should have a price tomorrow.
I am interested!
I am confused ! Surely this gadget is only removing the castellated ring nuts, and not the ferrules ?
Yes. Sorry. The tool is for removing the ring nuts to the ferrules.
I am interested too, please as my water domes will have to come off this Winter. As an aside I have just got back from Denmark with the 2-speed motor that was for sale. The motor seems good, turns over by hand and spark plugs unscrew easily, all complete at a cursory glance. But of course we got stuck in Esbjerg due to the Harwich ferry accident and ended up driving all the way to the Hook of Holland. Denmark was great though. Rather an expensive motor at the end of the day I must admit!