Hold Onto Your Head

Hold Onto Your Head

Handy tool for working on your head, just weld a piece of 25mm RHS to an old spark plug, screw into the head and clamp in the vice. The first one I made use a bit of 25mm water pipe, and it worked okay until I lost it or lent it to a mate, but RHS grips in the vice better. My son made this one for me, did a good job of it too, funny how you think your ankle biters are just kids when they are actually 30 yr old skilled people. See photo;

Oil Leaks


True surfaces, new gaskets and new oils seals properly fitted can result in an oil tight motor, particularly with the later 650/750 twins.

Nigel Sprocket was working on a revolutionary solution to oil leaks in a secret department at Meriden and recalls – “after years of intensive research we discovered that the polarity of crude oil atoms is reversed in the refining process – thereby creating an attraction between the oil in your motor and the subterranean reserves of crude. Ah yes I can see a few of the more astute TOMCC members taking notice now. Yes that is the reason oil consumption increases as you cross the Taranaki oil fields. We discovered injecting a small amount of uranium into the oil feed changed the polarity back and we all know, well those of us that managed to finish primary school, like poles repel. Simple innit. (At this point Joe Lucas’ nephew, Smoky assures members that kits would have been supplied with a syringe of weapons grade uranium for direct oil line injection in the unlikely event of there being insufficient smoke available to drive the injector pump). Regrettably the project was halted when apprentice Wokey Mills (no relation to current TOMCC president Glenn Mills who I am assured has only two ears at present) Mum complained about the extra ear growing on Spotty’s for’ead. This one still puzzles me, me Mum was always complaining that I had no ears while repeatedly thumping what was patently obviously an ear – wot’s wrong with and extra one I  ask you fellow members? Oh an there’s an opportunity out there for the more entrepreneurial TOMCC members – fit an oil level gauge to the old girl, monitor it while riding around this fine country, and when consumption goes up bingo! No charge for this little gem, just remember yer old mate Sprocket when you hit the mother lode seam.

Right that’s enough of that crap, joints first, I lay a sheet of emery on a piece of plate glass and dress up the surfaces of both components until I have a shiny surface all round. Make sure you wash all traces of grit off with petrol and assemble with a new gasket. The photo on the left shows the head of my 69 Bonnie and the head joint has clearly been leaking.


A very light dress up on the plate glass fixes this, removing hardly any metal, see photo on the right. While this is not a simple oil leak situation the other surfaces on my top end when I took this photo were perfect and the principal is the same. Rocker box joint surfaces are often not true.  Tighten bolts evenly but don’t overtighten. Socket sets are partly responsible for this, the handle has the same leverage on a 3/8” nut as a ¾” nut – a 3/8” ring spanner is much shorter than a ¾” spanner making it harder to overtighten.

Oil seals should all be new, and if there’s a spring around the lip then the spring faces where the oil is. Careful with Hinkely fork seals, some have a lip and spring both sides so note which way round it is before taking the old one out. Smear oil around the seal and fit the components together carefully so as not to damage the seal.

Don’t overdo silicon sealant but I always smear the pushrod tube seals with silicon and that stops the leaking. I just use the standard ‘o’ ring type seals but every time I order new ones British Spares send different types. Last time they sent a rectangular section sealbut it was too big. Always check the thickness of seals by placing the pushrod tubes, seals, head gasket and head loosly in place and measure the gap between the head and barrels/gasket. It should be about 1/32″ (31 Thou”), if it is much more or less than this it won’t seal either by being not tight enough or by crushing the seal , I have heard of ones that needed trimming to fit providing a perfect seal but haven’t used them – anyone out there who can comment?

Timing the 650 Gearbox

Nigel Sprocket “There ye go lad, a flash new selector mechanism for the new 650”

Spotty Stapp (no relation to Grumpy Stapp, TOMCC member) “I was talking to a nip down the pub last night and he reckons we should split the crankcases horizontally so the gearbox can be assembled and tested before bolting up the crankacses.”

Nigel “Come orf it young fella, you know Honda’s haven’t been invented yet”

Spotty “Well what about one like the 500 then?”

Nigel “No 650 riders are more discerning, they’ll enjoy timing and assembling several times to get it to work properly.”

Spotty “Geez wot a wanker.”

There is a method developed by Hughie Hancox where you are not supposed to need to time the gearbox and while it’s a great way to reassemble the box I have no trouble timing it as follows; With the outer cover off and the gearbox in 4th gear four speed or 1st gear five speed box mark the inner casing and selector quadrant see photo. I just use a permanent marker (see photo)

If you’re stripping and rebuilding the box, with a longer restoration project it may pay to physically mark with a punch or die grinder so you don’t have to guess a straight line between the mainshaft and gearshift (see manual). Then on assembly just line up the two marks as you push the  outer cover home.


Hinkley Fork Strip

The only difficulty dismantling modern fork legs is to hold the damper tube while undoing the bolt that retains it in the bottom of the fork lower tube. To make this easy I welded a 30mm nut to a section of tube see diagram. Tube diameter doesn’t matter much, mine is made from a piece of 25mm outside diameter tube. Insert the tube, nut first into the upper stanchion (top tube) and fit it into the socket at the top of the damper tube to stop it from turning while undoing the retaining bolt at the bottom of the forks.



This tool fitted both my Yamaha and Kawasaki dirt bikes as well so must be pretty standard for moderns. Never had this problem with my Meridens, just loosen the bolt at the bottom of the forks before you remove the top nuts and springs.