Wednesday morning and a week and a day to departure. Time to stop the weeding and complete the spannering . Today’s weather is not gardener friendly with 90% heavy rain but could be the opportunity to button up the last mods and improvements for the Cub which is this year’s weapon of choice.

For those more interested in bike maintenance and ongoing work on trials machines rather than the joys of pulling weeds lets review what has been done since last year.


Leaks from the rocker shafts copper washers ran round the head and appeared to be leaking from the exhaust valve cover

I wanted to ride the Cub at Sipapu NM but on start up it started leaking oil ? Then going up some of the climbs she was decidedly unhappy and lacking power big time. On return from a less than perfect weekend new jets were ordered for the Del Orto which had arrived jetted from the UK several years ago and had performed flawlessly at all altitudes up to 7000′ without any changes. 9000′ at Sipapu was a different story!

Consultation with Ray over in CA  who suggested the change to a hi comp piston in a fresh barrel which he would supply FOC. He also wanted the head to redo the valves.


Hi comp piston


Time for some new valves


Boyhood memories of the Cub from 1963 revealed only the highlights and few of the engineering frustrations of piston rings and getting the bloody piston back in the barrel and the even more frustrating game of pushrods and cylinder head assembly.


If its giving you problems try it this way on the bench then transfer back to the motor


Pushrod fun!

Finally all back together and a refabricated Whitworth wrench later the machine gets started …….. still leaking oil and a nasty “ticking” noise until the oil gets round.



Whitworth gets slimmed down to go between the fins

Much annealing of the rocker shaft copper washers and some new domed nuts that had stripped. Gurus advice followed and generally it seemed that the “crush” copper washers don’t! These all being made in China and having a large nickel content make them as hard as a rock. More annealing and double banking this time round and the oil stops leaking.


The annoying “ticking” continues and there are “witness marks” inside the finned exhaust rocker cover. Well they could have been over tightened and “dished” slightly. Ray sends another set! Still “ticking” yet more frustration.


Tick, tick, tick

Another set of “double thickness” gaskets for “finned” covers is found and fitted but now I have another issue I don’t like in the form of the fuel cross feed which is too close to the head. An experiment is done by blanking the system off to see if it will get enough fuel from internal splash in the tank. Seems it will so the underside of the tank is closed off.


Blanked off



Recently changed the bars over to Pro Taper with some bar risers and it feels good so far.


Bar change to Pro Tapers


Bar risers give room to get at fork nuts

I would like to change the footrests that I originally fitted to the Apico ones I have on the Yam but this will take a fair bit of radius filing as the shank length is shorter.


Apico pegs on Superglitz


Will need a bit of filing to make them fit!

So, the objective for Casper is a pleasant two days of trialing with no oil leaks and no ticking. Footrests on the back burner for the time being.






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