Can-Am Dirt Bike Build, Part 3

Aug. 26, 2010 By Dan Paris
In part two we left you hanging at the 11th hour, with the bike sort of' ready and only a day to go before we made the long drive to the Ormstown Vintage Offroad Festival in Quebec, Canada. Since Bombardier's Can-AM motorcycles were the featured make, along with former research and development rider World MX Champion and ISDT medallist Jeff Smith as the guest of honor, we wanted to make a good impression!

The project was moving along, but we were learning lesson number one about vintage motocross. Patience. You can't just zip around the corner to grab a part for a motorcycle that hasn't been made in well over three decades! Still, the guys at Vintage Parts4U and Cycle Improvements were burning the midnight oil to help get our bike ready in time. Vinylocity came through with some reproduction tank graphics two days before we were to leave. The new rear shocks, from Progressive Suspension, arrived the same day, as did throttle cables. The bike was still geared absurdly tall for ice racing, and we were scrambling to find a suitable gearing combination for motocross. We eventually borrowed a 13-tooth front sprocket to replace the 14 that was on the bike. Still not ideal, the small change in gearing was better than nothing and much appreciated!

The petcock began leaking, causing a last-minute scramble to find a replacement or rebuild kit locally. Yeah right. Luckily a  rebuild kit from a Harley Sportster was eventually modified to work in the Can-AM petcock. We still hadn't ridden the Can-AM with one night to go, but the bike was coming together nicely if not ideally. Then we did something stupid; a tiny 7mm ¼” drive socket was knocked down the top of the carburetor while installing new throttle and oil injection cables. It was 11 p.m. Sometime around 2 a.m. the socket was finally fished out with the help of gravity, a magnet on a long hunk of mechanics wire and a whole lot of cursing. Some things still weren't right, for example the homemade foot peg return springs were cheesy at best, and several smaller items were unfinished. But by and large we had a 175 Can-AM race bike ready to strap to the bumper of the motorhome to head North.

The drive to Ormstown stunk. A veritable symphony of broken toes, blown automatic transmissions and sketchy GPS advice accompanied us into Quebec. But we made it, as expected, on Friday the 13th long after dark. Come sunrise we had a look around at the sea of Can-AMs and other vintage bikes assembled in the Ormstown pits. It was beyond cool! A bit of fiddling with the bike and a few runs through the gears had us reasonably confident we could actually race the cross country race at 11 a.m. One of the former Bombardier engineers walked by, taking a look at the bike and remarking, “You've still go the snail muffler on there!” I explained I had no time to try others and that my dad had sworn up and down that it worked best. “He's right!” the engineer told me. “If we could get one more horsepower by ditching that muffler we would have. But we couldn't. We only stopped using it because it didn't have a spark arrestor.” So there you go, maybe our lack of prep and test time was going to pay off after all!

That morning the bike started every time we tried with a wimpy, half-heated kick. On the second row of the cross country race, lined up next to stuff like Hodakas and Maicos and Hercules and who knows what else, the bike didn't start. The pack roared off while I struggled to figure out why it wouldn't go. I frantically poked the kill switch, fondled the carburetor and twisted the petcock. Nothing. Then, about the fifth or sixth kick, the bike fired and ran just fine as I chased the cloud of dust into the forest. The bike surprised me by being comfortable to ride immediately, with good ergonomics and a nice, smooth powerband. The clutch worked well and the bike shifted nice under power. It even tracked straight through the rock-infested trails, and I quickly caught and passed the second row guys and chased down the front runners. It was a riot, the bike ran great and I quickly forgot I was on a 35-year-old motorcycle and it became just another woods race. Until the bike quit. It started with a couple kicks like nothing was wrong and I took off again, but a few minutes later it quit again. And then again. By now I had tried loosening the gas cap, thinking perhaps there was a faulty vent. I'd ripped off the kill button wires. Removed the fuel line to check for gas flow. Nothing. Then it started and I took off again, running hard for half a lap until it died completely. I checked for spark. None. Installed a new plug. Still no spark. Luckily the bike was light since I had to push it a few miles through the forest to get back to the pits, feeling quite dejected I might add.

Ormstown was full of Can-AM experts who helped me diagnose the problem as a bad CDI “Black Box,” the same component that had failed and left my dad with a DNF the first time he raced this bike back in 1975. I scrounged the pits for a replacement, but my motocross class was coming up fast. I heard it take off for practice while I worked ...

World Enduro Canada honcho Lawrence Hacking came running across the pits pushing his beautiful CCM, yelling at me to race his bike. Without thinking I put my helmet on and together we ran to the line while he told me important CCM stuff, like, “The brake is on the left. This thing here is a compression release, blah blah blah starting ritual broken leg ...” His words drifted away as we reached the line just as the big rubber band was pulled tight. I hadn't even walked the track yet, had never even looked closely at the big BSA engined CCM before, and what was that he said about the rear brake?

I was in mid thought when the rubber band snapped and instinctively launched down the front straight. By turn two I was in second place, and by the end of lap one I had checked out and ran away to the victory circle. It was an amazing ride, at least by my standards, and the CCM was awesome and easy to ride, but since this is a Can-AM story lets get back to business.

That night at the trophy presentation, I was awarded my first-place trophy by Jeff Smith, which was the highlight of my riding career by far! But the Can-AM was sitting with the ignition system spread all over our pit area, and I had resigned myself to spending Sunday watching instead of riding. Sunday morning a new Bosch CDI magically appeared, thanks to another racer who had taken pity on my dilemma. Did I mention vintage racers are the coolest folks on the planet? Anyway, the bike ran and ran well. I elected not to ride the morning hare scramble but to instead focus on the motocross race that afternoon. Putting my dad's bike back on the podium is a dream I've had since the first thought of this resto-racer project!

Wide open, in second gear on the line, the little 175 got a massive holeshot. It beat all the other bikes in the 1966 to 1975 class to turn one, and by turn two I had checked out and was pulling an ever-increasing lead. The engine was fairly easy to keep on the pipe, the suspension worked well and the brakes were adequate.

But my endless late nights and the exertion of pushing the bike so far out of the forest on Saturday before racing that big CCM were taking their toll, and by the last lap I was pooped and making mistakes. My lead slipped away with about three turns to go and I finished second to a guy on a Hodaka Combat Wombat no less! Oh the humility ...

So what'd we learn? The Vintage Parts4U engine was tight and ran great, so no issues there. The oil injection worked great, if only because we had the only two-stroke on the line not belching clouds of smoke. We will be installing a bigger rear sprocket and improving our homemade chain guide. Cycle Improvements did a great job on the forks. The bike was stable to the point of being too stable, and we'll be trying different steering head bearing offsets to sharpen up its cornering habits. We'll be updating the foot pegs, lacing up some aluminum rims and trying to find a lighter aluminum seat base. We'll also be carrying a spare Bosch CDI to races in the future, but overall this resto-racer project has been a huge success and dad's old racer is back on the podium where it belongs!

Thanks to the companies who made this possible:
Vintage Parts 4U
Cycle Improvements

We'd also like to thank Dennis Paris for not only keeping his old bike all these years but for spending so much time in the garage getting it race ready again! Paul Waterhouse and Helmut Clasen for digging up sprockets. The Ormstown Vintage Offroad Festival organizers for putting on an awesome event! Our next race with the Can-AM is Oct 24, so stay tuned for part four! Newsletter
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