Friday, 31 July 2009

Cut Me Some Slack

CB Special ownership frustration levels have reached bursting point. Local scrap dealer calls at Diplo HQ once a month and I've been contemplating loading the bike onto his truck ! Shocking mal-combustion issues at anything over 1/2 throttle have been causing grief. Compression ? Balance comp test is holding 90 psi (as much as I could hold against the kicker) for more than a minute with no drop off. Carburation ? Complete carb overhaul X2 including comprehensive clean, float checks, new jets, needles, etc etc etc including up and down main jet sizes. No fix. Ignition ? Timing set, new coil, plugs, condenser, points, leads etc. NO FIX !!!!. Valve adjustment or timing ? Comp test rules out adj but re-set just in case, slight miss-time could be enough to cause trouble at big revs without kissing a valve - Off With His Head then.
Upon initial inspection camshaft is timed perfectly - BUT - cam chain looks a bit slack !?%&@? Could this be enough (low tech variable valve timing) to cause grief at high rpm ? With the head off I'm beginning to suspect the chain tensioner wasn't engaged following some earlier re-build (it locks up out of harms way for assembly and is released post-build.
Very un-honda looking grooves machined in the front of the timing tunnel happen to fit the profile of the timing chain perfectly !!!!!!! WOW - to cause this wear (and so quietly) the cam chain has been centrifugally flung about 25mm from its intended route ! I'm working on the assumption that this "adjustment" is greater at higher revs and is sufficient to advance the valve timing a fraction and give me an open exhaust port when we're really not ready for it.
You can see from the state of the uncleaned piston we've acquired a bit of carbon en-route which can't help. Damage to head indicates earlier valve or piston issues but should clean up ok. Variable valve timing Indeed ! MORE ALUMINIUM SWARF !

Thursday, 30 July 2009

Exhausting Repairs

General principal for running a series seems to be - carry spares and tools equal in weight to the fuel you propose to use on a given journey. Forthcoming trip to Inverness (and, hopefully, back again) is 1000 miles. At 15 mpg-ish that should take around 65 gallons or 482 lbs of fuel. Uncannily, my estimated stash of gear required (prop shaft, one road spring, several UJs, water pump, wheel bearings, hub, brake drum, assorted hub and pinion seals, steering idler, couple of shocks, equal quantities of EP90 and 10-50, large tool kit etc etc) could easily run to 4 or 5 cwt as the formula suggests. Perfect ! Is this why the military classification for the 88 inch series is "1/4 Ton Truck" ?
Failed exhaust system has been getting worse with use and I have succumbed to a complete new outfit (£30.00 from Paddock). Needless to say the three studs in the bottom of the manifold have been only two for some time and the old outfit was blowing here as well as in the pipe. An obvious opportunity here to fix this problem at the same time. To affect a satisfactory repair there is really no shortcut and the manifold needs to be removed. Once on the bench, a steady hand on the centre punch and 1/4" drill will see the old stud removed, hole reamed to 17/64 and tapped to 5/16 unf ready to take a new stud.
As you can see I very rashly splashed out a couple of quid for a new manifold gasket ! All's well that's finished etc etc. Start to finish about 4 hours work, couple of Izmir smokes, many cups of Yorkshire Gold and a huge amount of swearing - oh, stopped off for a couple of pints of Topaz on the way home. MORE PADDOCK SPARES !

Monday, 27 July 2009

Buffalo Bill

More recent shot of Diplo Jnr's workbench. The knife blank is one of those rather pricey hand forged steel pieces from Scandinavia favoured by Ray Mears and his followers. When it arrived in the post I couldn't quite believe how beautifully made it is or how sharp ! The plan is to make up the handle with a brass hilt and a collection of bits to be bonded and shaped as one, probably finished with a turned piece of aluminium for the butt. For the main shaft of the handle we have a very fine and extremely hard piece of Box we turned up on the lathe. We've an assortment of Buffalo horn, Red Deer antler, Rhinoceros hide (from and old pair of boots) and some Ivory to make up the laminated pieces. Finished product should be great and certainly unique. MORE LAMINATION !

Wednesday, 22 July 2009

High Speed Comfort

Travelling at speed in this country is becoming more difficult with increased traffic levels and a shocking prevalence of toady driving. Comfort is, of course, paramount and the Raleigh Police Issue from the '60s combines cycling luxury with awesome speed.
24" frame and 26" wheels leave the pedalist with a commanding view of his surroundings and a confidence inspiring presence on the road. Unmitigated discussions on the other chanel have driven me to haul the machine out for a photo shoot. A couple of months back a twelve mile, pre-pub, jaunt around the Eyebrook proved no problem for machine or rider and many a modern Disraeli geared hi-tech cycle was left for standing. This particular bike was bought new by my dad in the mid sixties in an effort to get fit, it spent most of the next thirty years gathering dust and a wholesome patina before being shocked back into life about fifteen years ago. Whilst I don't pretend to be a regular cyclist, this is definitely my machine of choice when required and no amount of marketing will see it replaced with a "modern". MORE SWEAT !