FAQ’s

So what’s happened to the Forum? Constant spam attacks have resulted in the Forum being taken down and replaced with an FAQ section. If you have any questions about Can-Am or have anything to say or share, please email me at canamchris@gmail.com and I will will post an answer here.

Frame

  • Engine changeability – the external geometry between the 125, 175 and 250 motors are all generally the same (premix and oil injection), between the front and bottom bolts and the swing arm, therefore any motor will fit into any frame.
  • All Can-Am’s have chrome moly frames which are strong but the tube wall is very thin. It’s best repaired or altered by TIG welding. When checking a bike over check at the bend just behind the foot pegs as the later MX and Qualifier models often crack at that point.
  • MX1 and TnT frames were painted, MX2 and onwards they were powder coated
  • Very early MX1 and TnT models have a number of unique features, including fiberglass seat bases, air boxes and fenders. The engine mid-cases are also aluminium
  • Frames generally do not change between the 125,175, 250 and even larger engine models.
  • When working on early MX and TnT models, check that the original foam block in the oil reservoir has been removed. Due to age they have all deteriorated and now clog the oil injection system.
  • If you want improved handling of your early bike, switch the cones in the steering stem to change the
  • fork angle from 30 to 28 degrees. Turn both cones to towards the rear as this gives 28deg steering and also gets the handlebars slightly closer to you. Can-Am produced steering cones in four different offsets: 0,1,2,and 3 degree allowing a wide range of steering angles
  • Bikes having the original down pipe (MX-1 & 2 and TnT’s) have a flattened section on the cross member between the foot pegs
  • Front hub’s off the early model MX1′s and TNT’s had aluminium hubs

Motor

  • For the pre-’84 model bikes Rotax engine codes are: 125cc – 50000′s, 175cc – 60000′s, 250cc – 70000′s and 80000′s
  • Military engines have 6 digit serial numbers. They are oil injection with a detuned disk valve, simple porting and a 5 speed box, generally the same as a TnT.
  • No oil filter: Rotax motors do not have an oil filter of any kind, so change regularly.
  • Stick with the oil injector for auto lube motors. Don’t be tempted to change to premix as the Mikuni pump is designed to change the oil ratio as the throttle opens up more.
  • ATF – automatic transmission fluid about a 5wt oil – is ideal for gear box lubrication
  • Gaskets – Rotax engines generally do not have any, with exception of the barrel to crankcase. The mid cases are best sealed with a smear of oil or silicone. The head to barrel connection uses shims to adjust for squish dimension only. The shim acts as the gasket.
  • Oil injection engines use 1200cc of oil – use auto or lightweight gear oil such as ATF. The small bolt near the end of the gear shift lever is the level indicator. Check the level after each hard race to see if the engine is burning oil or sucking in in through the disk valve o-ring.
  • Quick motor identification: 125’s have notched barrel fins, 175’s don’t. Orange engine? – it’s a 370 or 400.
  • Sticky clutches – Rotax motors are notorious for clutches sticking if the bike isn’t run for a while. Although the clutch will free up once started and run, best to remove the clutch plates and clean with fuel, before re oiling and putting back in.
  • Car oil in your bike – don’t do it – car oil has friction reducers that will cause clutch slippage
  • Not all clutches are the same between motors. They have different thicknesses and wear plates – if you change clutches make sure you do a like for like change as it can cause problems
  • Later clutch houses had the three ball easy system. The clutch lever arm in the cover rides on three ball bearing allowing easier clutch movement. Or extend the length of the existing actuating arm as well for even easier and smoother clutch action.
  • Want more power out of your early 250? – put a bigger pipe on from a later model and with a more free flowing exhaust.
  • Don’t paint the head or barrel as this can reduce heat dissipation by 80%
  • Slipping clutch? Check the adjustment and set EXACTLY as the manual
  • Trouble shifting? Change oil, if it persist it is probably a bent or worn shift fork
  • Slight miss or poor running at higher RPM’s? Tried everything to resolve the problem? Check the disk valve o-ring has not cracked or deteriorated. And when you undo the screws on the disk cover use an impact screwdriver to loosen them.
  • Changing bearings out of engine cases is best done by warming the cases to about 100 deg C, but making sure all magnesium filings and oil traces are removed first. Then use thick grease and pack into the centre of the bearing. With a tight fitting dowel or similar over the grease, give a short but strong tap with a hammer forcing the grease down. The hydraulic action of the forced grease should pop the bearing out. Or a buy a blind bearing puller
  • All disk valves are interchangeable but there are two different teeth patterns for the gear that drives the valve. As long as you have the crank drive gear that matches the valve you are using they will all swap.
  • Check squish whenever rebuilding engine. Adjust by using the shims as it must be correct for the engine to run properly
  • Short and long stroke motors. Generally early oil injection motors are short stroke with later premix motors being premix. Both produce the same level of power, but the long stroke is considered to have a smoother and linear power band

Suspension / Wheels / Gearing

  • 125 Marzocchi forks have short helper springs on the end of the main spring
  • Girling shocks on early TnT and MX’s are now remade as NJB’s in England – www.njbshocks.co.uk
  • Sprockets – front sprockets are the same on any Rotax engined bike such as an SWM. Rears are pretty specific to Can-Ams. Aftermarket sprocket companies such as Talon make them
  • Marzocchi fork legs are magnesium (early) and aluminium (later)
  • ATF fluid can be used in forks to soften the ride, its equal to 5wt oil
  • Forks not smooth or binding? Try loosening the axle bolt and top yoke bolts. Bounce the folks a couple of times and starting with the yoke, tighten to the correct torque, then tighten the axle. Occasionally forks are just binding or twisted, this little manoeuvre removes it all
  • Forks sagging? Time for new springs
  • Want more suspension? 35, 38, and 40mm Marzocchi forks – generally 125/175, 250 and 370/400 respectively – yokes and wheels bolt straight on although there is some difference in spindle sizes.
  • Stuck swing arm. My experience is that tightening the swing arm bolt to the factory settings will lead to a binding swing arm. I therefore use an equal amount of spacers on each side, tighten the swingarm to the point that you can feel a small amount of drag when moving the swingarm. If the bolt is not fully tight, then I just wire it on. Chain alignment can be checked with a straightedge or take the front sprocket nut off and spin the rear wheel to see if the sprocket moves on the shaft. If it tracks straight then job done.
  • Magnesium wheel hubs do not like sitting in damp conditions. If you’re buying a bike or going to lay yours up for a while, check the wheels. Ideally a bike should be stored on a stand with the weight off the wheels
  • Marzocchi fork upgrade – a popular swap is to use later model forks with longer travel, but this upsets that steering angle. Therefore you need to raise the rear of the bike with longer shocks to compensate and return the steering head angle back to 28 degrees

Electrical

  • Lights; most were made by Rotax or Bombardier directly and are unique to Can-Ams. With the exception of TnT side reflectors which are Stanley item from Japan as used on early Hondas
  • Make sure engine is grounded to frame. Whenever experiencing electrical problems or if the frame has been painted, don’t rely on the grounding between the frame and engine through the bolts. Run a thick wire between the engine and frame, I normally bolt a wire through the top case saver bolt and up to the CDI holding bolt.
  • Replace HT spark plug wire if its more than a couple of years old. It simply screws into the CDI box
  • Headlight bulbs in Qualifiers are standard items – off the shelf at Halfords
  • Rear taillights the same, there are just generic trailer running lights
  • 3 and 4 pin Bosch ignitions? There is generally no difference between them and do not need any change in wiring, with the exception of the kill switch which needs to be wired directly to the fourth pin on the unit

Finishes / Plastics

  • Paint Codes: RAL 2002 for red Qualifiers, RAL 2004 for the MX5/6 orange, and RAL 7035 for the grey MX4
  • Paint finish on early motors is a special rubberised aircraft type finish. It can only really be removed with blasting. I paint all my motors with PlastiKote BBQ paint
  • Orange fuel tank bungs can be replaced with John Deere part M149638 as used on Gator golf machines
  • For early model bolt on petcock gaskets I just use 3mm gasket cork
  • MX-6 air box is sealed by the seat, but if the sealing foam is old the seat sits down too much restricting air flow causing poor running. Drill some holes in the rear of the upper filter box to allow the engine to breathe better
  • MX 4 , 5, 6 plastic are all interchangeable
  • Fuel tank plastic restoration by Edward Pinzel http://www.4strokes.com/tech/plastic_restore/
  • All wheel bearings and seals on all models are standard generic items and can be bought from any bearing supplier.

Brakes

  • 1980 MX6 and Qualifier rear brake shoes are unique to those models. They have a ridge on the cam seat.
  • Brake performance can be dramatically improved through modern race linings. If your shoes are more than a couple of years old, have them relined.
  • To get a stronger rear brakes use a front brake arm from a post ‘77 model, as they are about 35mm longer and provide better leverage

Carbs

  • Carb choking up? Check that the air filter is clean, the exhaust has got gunked up with oil and that the carb is sealed and not sucking in air
  • Mikuni carb swap?: Use a Bing. Tony Murphy, holder of multiple Rotax records, says so

General

Sourcing Can-Am parts can be a problem, but most parts are interchangeable with other Eurpoean bikes, such as SWM, Portal, Moto Gori, Puch and Kramer. For Rotax you can always look for kart parts!

  • Levers – all bikes had Magura – still made today and easily available
  • Forks – early MX and TnT had Betors, all others had Marzocchi – Seals and springs readily available from aftermarket suppliers
  • Brakes – Grimeca, but unique to Can-Am and can be relined by a specialist
  • Wheels – Sun, Akront etc, apart from the 40 spoke issue, all available from aftermarket suppliers
  • Cables – aftermarket such as Venhill
  • Engines – all Rotax – spares still available from Rotax. Only exception is the Hiro trial bike which have some availability through Aprilia
  • Electrics – Bosch – parts not available, but the stators can be rewound and things like regulators etc can be aftermarket. There is no easy replacement for CDI’s, but you can replace the whole system with one from Power Dynamo www.powerdynamo.biz/eng/systems/lists/overview.php
  • Plastics – aftermarket only – DC Plastics and RTR
  • Seats – can be aftermarket from various suppliers, but I just normally have them redone by a normal motorcycle seat guy who does a better job and allows me to use different coverings etc. I prefer a grippy type cover for enduro
  • Shocks – Ohlins, Marzocchi, S&W, Girling etc. Some can be rebuilt, but the aftermarket selection is huge
  • Tanks – Clarke are now remaking the early tanks and they are first rate. Later models can be fixed with second hand tanks which are regularly on EBay

 

Comments are closed.