Can-Am 175 Dirt Bike Build, Part 5

The 1975 Can-Am T’NT 175 project has continued to evolve this season, earning a few more trophies along the way.

The first thing I changed this spring was the offset steering head bearings. I swapped to NOS Can-Am offset bearing cones set to give the bike a 27-degree rake. I was worried this might upset the stability of the bike, but since the first race of the season was an indoor Vintage arenacross I was more concerned with getting the bike to carve.

The front end push was gone with the 27-degree setup, and the bike turned great! I wanted to lower the gearing for the indoor race, going from a 44-tooth rear sprocket to a 50, but the sprockets were back-ordered. The end result at the indoor race was a second-place finish … and a totally worn-out clutch. The tall gearing forced me to abuse the clutch mercilessly in the tight confines of the arena.

Can-Am 175 Project Stories
Part 4

Part 3

Part 2

Part 1

Vintage Parts 4U http://www.vintageparts4u.com/ came through with a new clutch and a 50-tooth rear sprocket in time for the next race, which was held at the former Canadian GP track at Motopark. Motopark is fast and rocky, with lots of elevation changes. Stability seemed ok on my home grass track, but I brought along the 30-degree steering cones just in case, figuring after practice I’d know if the bike was unstable at speed. The other thing I did, I guess because of a premonition, was to run a new o-ring chain, cut to a length that would run the rear wheel near the most rearward point of adjustment. The weather on race day was brutal, with standing water everywhere and the mud was forming footpeg-deep ruts, so the o-ring chain was a reliability bonus!

The start and the hills were like a natural dyno, and while the bike was better with the lower gearing I struggled to keep up to the 250s and 400s. Though I got off the gate first in both motos I was nearly in last place going into turn one. I wrung the snot out of the poor old bike going up every hill and down every straight, riding over my head. It paid off though, with second and third place motos and a third place overall trophy to hang on my office wall. I was proud of my riding but frustrated. I realize it’s only a 175, but still there were times when the 250s would just walk away while I killed my poor bike to keep up. It was time to start looking for more power!

I installed an even bigger 54-tooth rear sprocket, along with a new conventional chain, figuring if nothing else the bike loved to rev. That helped somewhat, and it made third gear starts possible. Titan Cycle http://titanracingworld.com/ offered to put their decades of two-stroke tuning to work to help me coax more beans out of the Rotax engine.

Can-Am MX175 low-pipes are more rare than hen’s teeth, so Titan Cycle broke out the torches and built a pipe using a DG pipe for a 1973 Honda CR125 Elsinore as a starting point. With some time modifying the pipe header length and expansion chamber shape, the pipe fit great, weighed less than half that of the stock exhaust and woke up the powerband at all points, especially midrange up.

While the torches were out, the guys at Titan Cycle also improved the spindly stock footpegs, welding on a bigger platform that was not only more aggressive but placed my short legs a little higher and a little further back to improve ergonomics.

Titan then dug into the cylinder, cleaning up all the ports but spending the majority of their time on modifying the transfer ports. The top-end was still in great shape, so the engine was simply put back together with new gaskets. Even the spark plug was changed to a short-electrode plug that was carefully indexed to align the electrode with the exhaust port.

The bike now ripped! In fact it didn’t even feel like the same motorcycle. It was still smooth but now yanked hard with a crazy amount of overrev. At our home track we blew away modern 250Fs in drag races through the gears and around the grass track. Sweet!

With the Ormstown Vintage Off-Road Festival rapidly approaching I wanted the bike to look pretty, so Vintage Parts 4U stepped up with a Clarke reproduction fuel tank, new graphics and reproduction side panels. The new tank further improved ergonomics because it is much narrower than the stock T’NT tank. Vintage Parts 4U also supplied me the necessary seals to correct an annoying oil leak around the combined kickstarter/shifter shaft.

With the Can-Am running and looking better than ever we loaded it into the trailer for the long drive to Quebec. Ormstown always comes with drama, and for me this year was to be no exception. I was fighting off a throat infection, but the bike developed sniffles of its own during a short pre-race test run. The ignition quit, just like it had the year before. I swapped the spark plug, plug wire, CDI box and wiring harness. Still no spark. The “Dead End Race Team” came through with a spare stator. I installed it, guessed at the timing and once again had a running motorcycle. For the record, vintage Bosch electronics both suck and blow.

In any case, the Can-Am ran great at Ormstown, powering around the high-speed track without giving up an inch to the bigger bikes. I even managed to get a holeshot in moto-two, though it was short lived when I nearly took out the entire field by nearly low-siding in turn one. There were lots of fast guys at Ormstown this year in the 1966-1975 Expert class, so I am quite proud of my fifth-place overall finish. Thanks Vintage Parts 4U, Titan Cycle and all the people I’ve begged for advice from along the way with this project, including former Can-Am engineer David McLean. Most of all thank you Dad for keeping your old bike around for me to race over 35 years later!

The Can-Am project isn’t done yet, though I am very satisfied with how well the bike works now. Future plans include a conversion to a 428 chain to save weight and reduce power loss, stronger billet aluminum triple clamps, lighter aluminum rims with beefier spokes and a more powerful front brake. Plus I’ll be putting effort into making the Can-Am look pretty by bead blasting the engine and getting the motor mounts and swingarm powder coated. Stay tuned!

Can-Am 175 Project Stories
Part 4

Part 3

Part 2

Part 1