Project Can-Am

Tim Britton of Classic Dirt Bike is taking on the conversion of military Can-Am for use in vintage enduro events.

It started as one of those conversations that you often have with mate at an event; “I was thinking of buying a DT125” you say, “No! exclaim your mates, you really need a Kramer 500 fitted with lights”, without you noticing the evil gleam in their eyes.

Tim called me (and Jeff Smith) and asked if we thought he could buy and rebuild a Can-Am for a £1,000?. Obviously both Jeff and I had the same evil gleam in our eye and encouraged Tim to undertake the project. So I provided Tim with rolling chassis, an engine and all the bits to form a complete bike.

But Tim has had the last laugh, throwing himself into the project and doing everything the proper way. From acid cleaning the oil tank to fully rebuilt wheels with stainless spokes and alloy rims, Tim is doing a super job of the project.

Tim now has plans to show how versatile the bikes can be and has lined up Steve Saunders and Mick Andrews to do some other competitions, including an enduro and trials event.

You can follow the full story in Classic Dirt Bike and Old Bike Mart, of which Tim is the editor of both. The project was announced at the February Off Road Show at Telford and outlined in issue 19. The full story is continuing in the current issues. Check it out at www.classicdirtbike.co.uk

Project Can-Am is Complete!

Fair dues to Tim, he hung in there and battled through all the problems and has produced one cracker of a bike. The bike is now up as a competition prize, so if you’re a Classic Dirt Bike subscriber, then it could be yours.

The full details of the competion and rebuild can be found at : http://www.classicdirtbike.co.uk/news/win-a-can-am-250cc-enduro-bike

Not steal any thunder (or readers from Tim), here’s the highlights of the rebuild:

So, there I was, in the office after doing Vinduro last year and spouting forth to anyone who would listen – or couldn’t escape – about how fabulous the event was. And that the twinshock enduro scene was sure to be a growth area, combining the speed of MX with the skill of trials but without the intensity of the former or the technicality of the latter.

As eyes started to glaze over, group editor Rose chucked “could you use an enduro for lots of things like riding to work and scrambling?” into the conversation.

“Ha! of course, almost the ideal type of bike for fun and a reasonable chance of success too,” I countered.

“Good,” he said, “there’s a small budget available to buy, do up, use, then give away, a bike… so what’s out there?”

Hooked, I now needed to know just how much of a budget was available before I could ‘see what was out there’.

Getting serious for a moment, the bike we’ve got is a 250cc Rotax engined Can-Am military model built for the British Army. Depending on your viewpoint it is either a 1974 model, 1978 model or 1980 model. The reasoning there is all the military machines were made in 1978 but issued in two batches – 1978 and 80 – but based on the 1974 enduro bike. It’s only confusing if you want it to be and we’re going to claim the bike as a 1974 machine. This allows us to enter it in a lot of events, get it seen and have a lot of fun before one of you gets your hands on it.

The finished bike will be road legal, eligible for Circa 74 scrambles – or the pre-77 class of their events – Vinduro ready and a lot of fun.

I’d decided at the start all I would do that night would be to slacken off the fasteners and leave everything in place until the weekend when I could attack the bike from all sides. OK, so it never works like that and before I knew it, thanks to the WD-40, many of the Allen bolts were slackened. The front wheel was straight out and the forks dropped from the yokes.

It was obvious that the front wheel spindle was bent beyond use, that there were no brake shoes on the back plate and the wheel rims, fork seals and gators were beyond use. There was also a lot of corrosion on the alloy parts so these will have to be inspected to see if they are serviceable as I’m not used to dealing with magnesium castings.

Next I will pull the yokes off and free the steering head bearings. Speaking of which, the bearings are of an eccentric design that allows tweaking of the head angle and wheelbase to suit your riding style. It’s likely the bearings are beyond viable repair so will have to be replaced and, no doubt, as the work progresses many more such things will come to light.

With the bike in bits, clean and spread out everything could be checked over and either saved or discarded. Starting from the front, the wheel bearings were beyond saving as were the head stock ones. The fork oil seals were okay for the time being and, probably most surprising of all, the chrome on the stanchions was good too – okay, there was a bit of rust at the top but where the seals run was fine. Checking the frame showed a bit of surface rust here and there but apart from a bullet shaped dent in the damper mount on one side, it was okay and will, for the time being, be rubbed down and painted.

The swinging arm too had a bit of surface rust but the bushes were good. The back wheel bearings were even worse than the front ones – which could at least turn if not spin. The rear ones were solid. One of each set was cleaned up to take the bearing numbers off and new ones will be ordered. Also seized were the original rear dampers, which will have to be replaced. Also to be replaced is the petrol tank as I’ve never seen a more rusted one still in one piece.

As this magazine is quarterly a lot can happen as it’s being put together and there were a couple of offers of help and parts following publication of last issue. Pete Hillidge sent along a sprocket and a set of brake shoes and added he might have a few other bits. A new pair of Renthal bars came our way and Paul at Military Can-Am sorted some new head bearings, other brake shoes, a swinging arm spindle to replace the destroyed one. Chris Marsh, who sourced the bike in the first place, provided a spare set of wheels, a petrol tank and a kick-start so there’s a chance to build the bike up to a rolling chassis.

Unfortunately the top tune oil tank has a foam filter in it which breaks down and has to be fished out. Former Kawasaki works racer, TT winner and now arch trials enthusiast Mick Grant lives not far away, though the amount of times I’ve been there with Can-Am bits he’s probably planning on moving and not leaving a forwarding address. He said: “The best thing is cut an inspection hatch in the tube, fish out the muck then you know it’s right.” So, we did and even though I was expecting a lot of crud in there I still got a shock. Next stage was to mix up a concentrated de-rusting solution and fill the tube with it. It was so concentrated that the rust almost jumped off and now, with the hatch welded up, I’m happy to put oil in there, certain that no crud will reach the engine internals.

This is the sort of thing anyone who has ever rebuilt a bike will be familiar with. It’s difficult enough when the machine in question is one you’re used to working on but when it’s new to you, the potential for getting it wrong is quite high. An example of this was the throttle cable. As the Rotax engine is on autolube and I’ve been advised to keep it that way by those familiar with it, the cable is a three part item. Part one goes from the twistgrip to a junction box, then parts two and three go to the throttle slide and the oil pump. All well and good so far… right up until I came to fit it and found that I didn’t have quite enough room to lift the top off the carburettor thanks to the exhaust pipe, so off it came. A shame as I’d spent ages threading it through the frame tubes and mounting the rubber bushes but it had to be done.

With the bike up on a lift, the engine unit was slotted in. It is possible to do this on your own but when the time comes to fit it after the prettying stage I’ll ask for volunteers to be on hand as the frame was clunked a time or two during the process. Once the unit is in place there are three fixing points to line up. The rear one is the biggie as it involves the swinging arm spindle going through the back of the engine. This bit caused major problems during the strip down as it was seized solid. On the assembly I used loads of copper based assembly paste, it still took a bit of lining up though with bits of wood and persuasion with a rubber mallet.

Once in, the lower engine mount slipped in easily, then came out again to slip in the alloy distance pieces… yes, we’ve all done it. The front mounts are two small engine plates bolted to the frame and then the engine. Keeping them slack allowed the four bolts and one stud to slip in easily, then a quick check all round to make sure everything was in place before tightening the nuts up.

Once this stage was arrived at, it was just a case of adding parts, things went relatively quickly and the bike started to take shape. There were minor obstacles to overcome such as the front mudguard mount. The guard fits under the bottom yoke by being bolted to tapped holes and there are some smart alloy bobbins to keep the distance correct. Three of the tapped holes are M6, the other is M8. Why? Because the Army wanted a steering damper fitted and this was the way one end was mounted. The steering damper is being abandoned and one of the alloy bobbins was opened out to accept an M8 bolt. It goes against the grain to have two different sizes like that. In an ideal world I would have helicoiled the hole back to M6 but that would have bumped the cost up a little. This method works and if I want to save a bit of weight, then I’ll drill out the length of the bolt.

There has been some discussion lately as to the colour scheme we’re looking at for the Can-Am and current favourite is the blue and silver ‘look’ that is very 1970s. Problem is the plastics on our machine are army green, well, NATO green to be exact, and won’t sit well with a silver frame. There are replacements available in white but naturally we want blue to add a bit of colour to the machine. Plastic is tough stuff to paint as traditional stuff won’t adhere to it. Luckily there are modern paint types available that are more suitable for the hard plastics that are a feature of modern cars. Most people in the UK will have a Halfords superstore near to them and it has a small range of paints suitable for the colouring of car bumpers, they also work well on plastic mudguards.

One of the colours available was a rather nice blue. So, we got hold of a tin and tested it out on the old shabby rear guard to see what it would be like before we started to spray new plastics. Given that the base colour was a dull and faded green and that often this can affect the way the top coat looks, the result was very impressive. When coating a white guard and side panel the results should be even better.

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