Troubleshooting Common SSR Bison 400 Issues

SSR Bison 400 Issues

Riding a dirt bike on the trails can be an incredibly fun and freeing experience. The wind in your face, the vibration under you, carving through berms and sending roost on a wide open straightaway. However, that feeling of freedom quickly fades when your trusty Bison 400 starts sputtering, leaking, or worse – leaves you stranded miles from home.

What are the most common mechanical problems with the SSR Bison 400, and how can you diagnose and fix them yourself?

By properly maintaining your Bison and learning some key troubleshooting steps, you can often resolve issues quickly and be back riding in no time.

In this detailed guide, we’ll cover the major problem areas reported by SSR Bison 400 owners and arm you with the knowledge to tackle repairs yourself.

Specifically, we’ll discuss:

  • Starting and engine problems
  • Loss of power
  • Overheating issues
  • Electrical gremlins
  • Clutch and shifting problems
  • Excessive vibration

Follow along and you’ll gain the tools and confidence to keep your Bison healthy for thousands of miles of dirt riding.

Starting Issues with Bison 400

Nothing kills the riding buzz faster than turning the key and getting nothing but a click or weak turnover from your starter motor. Thankfully, most starting problems can be narrowed down to a few common causes. Here’s how to troubleshoot and get your Bison 400 firing again.

Do you have spark?

The first thing to check is whether your Bison is getting good spark at the plug. Remove the spark plug cap and insert a plug tester. Then try to start the engine while watching for solid blue spark (be sure the plug is grounded).

  • No spark means the issue could be a faulty CDI unit, bad ignition coil, or problem with the stator. Testing the stator and replacing the CDI box are good starting points.
  • Weak, intermittent spark can be caused by a bad plug cap, worn spark plug, or loose wiring connections. Replacing worn components may restore normal spark.

Is fuel reaching the cylinder?

Next, verify fuel is actually entering the combustion chamber. Remove the air filter and spray a short burst of starting fluid into the carburetor throat while trying to start.

  • If the engine fires briefly, fuel delivery is likely the culprit. Inspect the fuel petcock, lines, filter, pump and carburetor for clogs or damage.
  • No change after spraying starter fluid indicates an ignition problem rather than fuel related.

Is the idle speed set correctly?

An improperly adjusted idle screw can prevent starting. Turn the idle screw clockwise to raise the idle speed. If the screw is already all the way in, the throttle cable likely needs adjustment.

Is the carburetor gummed up?

Over time, varnish and residue inside the carburetor restricts flow and affects starting. Remove the carburetor, spray all jets and passages with carb cleaner, and blow it out with compressed air. Adjust the idle screw after reinstalling it.

Could the CDI need replacement?

The Capacitor Discharge Ignition (CDI) unit generates spark and times ignition. If the stator and coil test good, replacing the CDI box may be needed to restore hot, consistent spark. OEM and aftermarket CDI units are affordable fixes.

With basic tools and testing, you can isolate the no-start issue to the ignition system or fuel delivery. Replacing worn parts or cleaning carburetor passages usually has you back on the trail quickly.

Loss of Power Problems

A lack of top end speed, sluggish acceleration, or weak power at high RPMs is frustrating. But don’t park your Bison just yet. Here are tips for regaining your lost power:

Is your air filter restricting airflow?

Check the air filter element to see if it’s overly dirty. An excessively clogged filter starves the engine of air, reducing power. Also ensure the airbox ducting isn’t cracked. Replace the filter annually or clean it more often when riding in dusty conditions.

Are the fuel lines obstructed?

Examine the fuel supply lines from the tank to the carburetor for cracks, pinches or debris blocking the flow. Soft fuel line can degrade over time and collapse under vacuum. Replace suspect sections and ensure clamps are tight.

Do the valves need adjustment?

Improperly adjusted valves reduce performance and economy. Check and reset the valve clearances to factory specs. This requires feeling gauges, a valve adjustment tool and service manual guidance.

When were the spark plugs last replaced?

Inspect the spark plugs for heavy carbon fouling or erosion of the electrodes. Worn plugs lead to weak sparks and power loss. New OEM or NGK plugs restore performance and make for easier starting.

Is the timing still in spec?

Incorrect ignition timing hampers power generation. Check and reset the stator and pickup coil air gap and rotor timing according to the service manual procedures. Use a timing light if available.

Getting on top of maintenance items like filters, valves and spark plugs will help keep your Bison running crisp. Testing electrical parts and monitoring fuel delivery ensures optimal performance.

Overheating on Bison 400

Left unchecked, prolonged overheating can seriously damage your Bison’s engine. Here are some common reasons for overheating and how to diagnose the root cause:

Is the radiator blocked?

Check for mud or debris clogging the radiator fins or blocking air flow. Use a garden hose to flush the radiator clean. Bent fins can also be carefully straightened with pliers. Avoid blasting the radiator with high pressure water.

When was the coolant last changed?

Old, degraded coolant loses its heat protection and cooling properties. Flush the system once a year and refill with a 50/50 mix of antifreeze and distilled water. This improves heat transfer and prevents corrosion.

Are the water pump seals leaking?

Inspect the water pump shaft and housing for leaks indicating worn seals. Continued loss of coolant will lead to overheating. Resealing or replacing the water pump resolves the issue.

Is there a radiator or hose leak?

Closely inspect radiator seams and all hoses for signs of leakage. Even small leaks reduce coolant volume over time leading to higher operating temps. Patch or replace leaky radiator sections and replace degraded hoses.

Is the cooling fan operating?

The fan switch activates the electric cooling fan when needed. If the fan doesn’t come on, test the switch and circuit. Replace the switch and check the wiring and relay if necessary. A working fan prevents hot idle overheating.

Monitoring your coolant level, flushing yearly, and inspecting components for leaks helps keep temperatures in a safe range while riding. Never ignore warning signs of overheating that could lead to expensive repairs.

Electrical System Issues

Like most motorcycles, the SSR Bison 400 ignition and charging systems can suffer glitches and failures over time. Here’s how to get the electrics back up to par.

Are the battery posts corroded?

White powdery corrosion on the battery terminals inhibits power flow. Remove the battery and scrub the terminals to expose clean metal. Apply dielectric grease to prevent further corrosion. Charge or replace the battery if needed.

Is the stator output normal?

The stator produces electricity to charge the battery and power the bike. Test its AC output using a multimeter. Compare to factory specs. If out of range, stator replacement is required.

Could a short be draining the battery?

Parasitic battery drain is caused by electrical shorts and damaged wiring. Test for a current draw with the key off using an ammeter. Inspect wiring for bare spots, fraying and shorting to ground. Repair or replace faulty harness sections.

Is the CDI unit causing problems?

As mentioned for starting issues, CDI problems can arise over time. Test or swap in a known-good module. CDIs often resolve chronically hard starting or weak running situations when ignition is suspect.

Did you check the fuses?

Burned out fuses interrupting power are simple to overlook. Verify main, ignition and CDI fuses are intact. Carry spare fuses in various amperages on rides to enable quick troubleshooting and repairs.

Don’t get stranded with dead electrics. Battery maintenance, charging system testing and inspections for shorted wires will help avoid being left in the dark.

Clutch and Shifting Problems

The Bison’s clutch takes repeated abuse when riding off-road. Problems like slippage, drags and poor shifting can ruin your day. But repairs are straightforward once the exact issues are identified.

Is the clutch cable adjusted properly?

The clutch cable and lever freeplay need to be checked and adjusted to specs. Too much play causes disengagement and slippage issues under power. Insufficient play prevents complete clutch release when pulling the lever.

Are the clutch friction plates worn or warped?

The stacked friction and steel plates that engage and disengage the clutch are wear items. Inspect plates for excessive thinness or warping. Replace the plate set to restore solid hookup and avoid slippage.

Have the clutch springs weakened?

The pressure plate springs lose tension over time leading to poor engagement and release. Replace worn springs along with friction plates to renew clutch clamping force for positive operation.

Is the shift lever bent or loose?

Severely bent shift levers can prevent smooth shifting and even lead to missed gears. Also check for loose shifter peg mount bolts. Replace or realign components for crisp, precise shifter action.

Does the shift mechanism need lube?

Dry shift mechanism linkages and pivots hinder shifting. Disassemble the shifter and lubricate the pawl, spring and detent plate with lightweight oil to regain smooth shifting.

Clutch tune-ups and shifter fixes are fairly quick and affordable. Don’t ride with a slipping clutch or poor shifting and allow further damage.

Excessive Vibration Problems

Vibration taking the buzz out of your Bison 400 ride? Harshness and shaking problems usually arise from just a few areas:

Are the wheels balanced and aligned?

Inspect the wheels for damage and runout. Out-of-balance or bent wheels induce vibration. Also check rear wheel alignment and chain tension. Realign the axle or replace damaged rims/bearings to smooth out your ride.

Do the engine mounts need replacement?

Cracked or deteriorated engine mounts allow excessive engine movement. This transfers vibration to the chassis. Inspect mounts and replace worn parts to isolate the engine movement.

Could wheel bearings be compromised?

Worn or grit-damaged wheel bearings allow play and wobble while riding. Test bearings by rocking the wheels and feeling for clunking. Replace rough bearings before they seize up completely.

Is crankshaft runout in spec?

Excess crank runout due to damaged main bearings transmits vibration. Checking runout requires partial engine disassembly. Rebuild or replace the bottom end if runout is excessive.

Isolating the source of vibration helps determine the proper fix. Wheel and bearing maintenance along with monitoring engine mounts reduces harshness.


While the rugged SSR Bison 400 is built to handle tough off-road riding, it’s not immune to mechanical problems. However, diagnosing issues methodically helps identify the often simple repairs needed.

Knowing the common failure points related to starting, power loss, overheating, electrical and drivetrain allows you to troubleshoot smartly. With basic tools and parts sourcing, you can tackle many repairs yourself and avoid costly shop visits.

Riding is more fun when your bike is running properly. So stay proactive on maintenance, monitor behavior closely and be prepared to troubleshoot problems. With the above guide, you have the knowledge to keep your Bison healthy for many more miles of fun on the dirt.

Now get out there and send it!

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