A change of direction
With the IT465 on holiday, some attention is paid to the rest of the editor’s machines.
With the IT465 project having a break, the editor has a chance to do a bit of work on his own bikes.
Due to one thing and another cropping up at various times, my own collection of dirt bikes has been neglected a little recently. Like most enthusiasts I’ve a few bikes in the shed and they’re there for reasons which will be familiar to a lot of readers. Longest standing member of what has been referred to as ‘my fleet’ is the 250 Bultaco Sherpa T I’ve had from new and it was the subject of a rebuild series itself 20 or more issues back. The newest machine – as in new to me not ‘new’ new – is a TY250 Mono Yamaha, similar to the one I had in the Eighties and in between there are a scattering of British and European machines with one thing in common… they all need a bit of spannering. Problems I’m facing include grumbling
main bearings, leaking fork seals, worn gearchange shaft splines and a clutch needing strong hands to operate the lever. Actually this last one is also the tech feature here and involved the help of someone with more engineering ability than me to do the machining. Without spoiling the surprise of the tech feature too much, it involves a Can-am clutch modification aimed at giving the editor’s clutch hand an easier time of it in enduros.
The thing is, while a bike is apart there always seems to be other tasks to attend to. For quite a while the primary case on the Rotax engine fitted to my Can-am enduro bike has leaked oil at an alarming rate and this aspect has been ignored rather longer than it should have been; in my defence the case has been on and off a lot, making sure the standard clutch actuator was lubricated properly so it could perform at its best.
I was just about to give up hope when several suggestions for mods were put my way, one actually included the bits to do the job…
With this task completed I turned my attention to stemming the flow of oil out of the case. Rotax’s disc valve two-stroke engine is a fairly well known unit and comes in a number of specifications, depending on the intended use, but it can be grouped into two main types, these being auto lube and pre-mix. In the former, the primary case has a separate compartment in it which houses an oil pump fed from an external oil reservoir – in the case of my ex-military Can-am this reservoir forms the top tube of the frame – while engines using pre-mix often have a different case with no oil pump and the two stroke oil is mixed in with the fuel. Now, I was advised by no less an authority than Jeff Smith, who actually designed the bikes for Can-am, to retain the auto lube facility on an enduro bike, so I did. The way most of us flatten the mating faces of a case is by rubbing the case on an old mirror which has had some grinding paste spread on it and lubed by a squirt of light oil. All you do then is lay the face to be flattened on the mirror, in the gloop and swirl the case round while applying light pressure. It’s noisy, dirty and boring, but works. The problem with a Rotax case is the auto lube system pumps oil through passages drilled in the case and it is almost a dead cert grinding paste would find its way into the drillings and if not cleaned out would happily destroy the big end bearing when fitted to the bike. So what, I hear you say, wash out the drillings... It isn’t quite that easy as the oil
pump feeds, in the form of two brass tubes, are pressed into the holes too and have restrictor valves inside – a spring and a tiny ball bearing. Still, a method of cleaning the drillings was arrived at and involved squirting light oil down the feed tube so the gloop was pushed out. A further refinement was to put some grease over the end of the drilling to stop any grinding paste going in there in the first place.
I did try squirting contact cleaner down the tube but the restrictor valve was too much for the pressurised liquid and I managed to squirt it everywhere. In the end I used a pump action oil can. Just got to reassemble the oil pump into the casing then apply a light smear of instant gasket, refit the case and then I can put the Can-am to the bottom of the list…
Next on the work bench is likely to be my BSA B40, which managed to shed its gear lever during the Pre-65 Scottish Two Day Trial. The splines on the shaft are worn to the point of non-existence. Luckily, there is a replacement part available which means the gear selector can be saved as the shaft only can be replaced rather than the whole part. It does of course require a strip down of the timing side of the engine to access the internals, but at least with a B40 this can be done without taking the engine out of the frame. No doubt when the case is off there will be other issues to sort too, such is life with a 50-year-old motorcycle. The Beezer does need some work elsewhere too, on the cycle parts or brakes but they are sort of acceptable and work well enough to pass the MOT test, but first water splash and they’re history. Probably the easiest job to do will be the fork seals on the TY and to be honest the new seals are in the spares box but finding five minutes to do the job has proved awkward lately. The biggest job facing me is replacing the main bearings in my 250 Bultaco engine. The bike was rebuilt in 1988 for the Scottish Six Days Trial and internally at least has
remained largely untouched since that day as the rebuild series focussed on the cycle parts. It’s been rumbling for a while and a recent outing at Inverness DMC’S Highland Classic at Alvie and the following weekend’s Bultaco Nostalgia trial in Cumbria are pretty much it until I change the bearings. Yes, it still starts and runs quite well too but there’s always the danger of doing other damage and in any case it’s not ‘right’ and that isn’t the way things should be done.
Thanks to the age and use the Bulto has been through there are other problems to contend with, gear changing has become difficult when the engine is warm. Changing the oil and cleaning the clutch plates didn’t solve the problem and a bit of research – or, more accurately phoning Dave Renham up and asking – gave me a few areas to check when stripping the engine. So hopefully all will be well with my Bulto soon.
There is a danger when several bikes need attention that several bikes are stripped down and I won’t be the only one who has ever been caught out with every bike they own in bits. Thankfully, I’ve managed to avoid that scenario lately but it has happened in the past and if your workshop is large and can have a dedicated work area for each bike then it’s not so bad but, if like me, you’ve to haul everything out in order to access a work area then it is best to keep things as rolling chassis at least. Such is the case with my Can-am and with the case off at least I can still wheel the bike in and out of the workshop. Luckily, I do have some organic shelving which has been added to as time has progressed so I am able to dedicate an area for sub-assemblies at least.
Having too many bikes in bits at one time means more chance of things being lost, misplaced or just forgetting how they go back together. Naturally jobs such as the fork seals are probably an hour from opening the shed door to putting oil in the fork leg, but the clutch case has needed some machining and some fettling to get it right, plus the flattening so it’s been apart for a while. Now it’s going back together I’ll have to refer to the pics I took of it being stripped apart so I can remember where everything goes.
Once the clutch is in place again it will be time to look at other bits of the bike, such as the lights. One of the regulations for an enduro requires a motorcycle to have lights fitted and in order to pass this requirement I jury-rigged some in place. These madeup lights were the broken front one from Project IT – the mounting ears had broken off – which, with some gentle scraping and sanding, slipped inside the Presto Petty front number board/lighting unit. The rear one was one of several original military Can-am units I have and is a truly massive affair. It lasted one lap of the last enduro I did and its demise was written about in my column a couple of issues ago. However, something better is needed and while the front light fits and will work okay, a unit slightly more sleek than the original one, the size of a bungalow, will be sourced.
All the gizmos for sorting lights are in place and long-time readers will remember our prize bike was wired up by Ferret from Ferret’s Custom Electrickery who had the instruction to ‘…provide a white light at the front, a red light at the rear, the front one has to dip and rear one needs a brake light too, both have to work even if I drop the bike in a river…’ “anything else?” joked Ferret. ‘oh, yes, a horn would be useful too and I don’t want a battery on the bike.’
This instruction is pretty much what I want for my own bike too, but this time I shall attempt the dark and mysterious world of motorcycle electrics with wires and connectors and stuff. I know electricians will be shaking their heads and collectively sighing ‘but it’s easy’ which is what all tradesmen say about their skill – I’m as guilty as anyone when it comes to woodworking things – but don’t forget not everyone will have had the benefit of working with others as they learn such skills.
All that’s needed now is to give the workshop a quick clean as it’s not good practice to have engines apart in dirty conditions and it is amazing how soon dirt can accumulate in an average workshop. A ‘clean room’ for engine assembly is an ideal few of us have space to dedicate to, so a sweep of the bench, make sure nothing can drop down from the ceiling and all should be well... )
The two brass tubes are for the oil feed to the big end and the mixture.
While the clutch was being done we did a few other things too as for some reason the oil was determined to leak past the case. The pump was refitted quickly enough and the oil pipes can only go back one way, I still used my pic for reference though. It would be really bad for the oil orifice to have grinding paste inside it, so a light smear of grease to block it off worked a treat. This little cog sits at the back of the oil pump and is prevented from spinning by a flat in the spindle hole…. …which corresponds to a flat on the pump spindle.
Right: Once the return spring was fitted, all the case needed was a light smear of instant gasket… a really light smear. Seriously, I once saw an engine where the owner had, inamisguided attempt to stemoil leaks, used almost a full tube of the stuff. Above: Locking the cog in place is by a Ny- Loc nut. Assembly continues and this time I attached the clutch cable before fitting the case.
Next task is the Beezer gear shaft… no wonder a gear lever won’t stay on. And the task after that is for the Yam’s fork seals. A fiddly job, but hey… Just the oil feed and the pump cable to attach.