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known problems of the suzuki dr 350

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Known Problems Of The Suzuki DR 350

Oil Overfilling

The Suzuki DR 350 is easily and accidentally overfilled by even the most attentive owner.  The DR contains engine oil in it's engine crankcase.  This oil is not confined to the crankcase but is actually pumped through oil hoses and is pumped and routed through the motorcycle frame.  The location for checking this oil level is at the oil level dipstick which is at the top of the frame and right behind the headstock.  This factory determined location for checking the oil level is actually at a high spot in the oiling system.   When the DR is at rest the oil tends to drain and collect at the lowest point within the engine crankcase.  At startup the engine begins to push this oil through the hoses and through the frame passages.  It takes more than a couple of minutes of engine run time for the oil to be dispersed throughout the entire system and then stabilize to a normal running level.  So if the dipstick is checked without the bike being run long enough then you will get a false low oil reading.  Typically when you change the oil you drain the oil in the crankcase, you change the oil filter, and you drain the oil from the drain plug on the front of the lower frame.  This normally will require 2 quarts of oil to refill the bike properly.  If you haven't just completed an oil change you must rely on the dipstick to determine if the level is low and needs more added.  Be sure to give your bike plenty of time to warm up before you check the oil level on the dipstick or you may not get an accurate reading.

  

Difficulty Finding Neutral

Many Suzuki DR 350 owners have complained of this phenomenon.  Typically the bike may exhibit the symptom in several forms.  It maybe difficult to shift into neutral with the bike running, sometimes it is more noticeable as the bike warms up.  You also may notice the bike trying to lurch forward with the clutch pulled in with the bike in gear.  You may also feel a dragging sensation as you do not feel the clutch completely release while changing gears. 

There are many causes of this problem that have been discovered to date. 

Often times, the clutch basket is not machined at the factory to allow sufficient end play when the clutch basket nut is tightened properly. 

Another cause can be just normally worn clutch components such as grooves worn into the basket fingers, or worn out thrust washers, etc. 

Also, other components can effect the clutch operation such as weak, binding, or stretching clutch cable, loose or moving / flexing brackets that do not hold the cable rigid enough. 

The aftermarket extended clutch lever can cause this problem if you do not have the appropriate levers and lever mounts that will allow sufficient movement and therefore sufficient pull against this longer lever which is designed to make clutch pull easier but at the same time it releases the clutch by a lesser amount due to the shortened length of the arc. 

Additionally, aftermarket clutch disks have been known to create these problems and often times o.e.m. replacement discs are a cure. 

Last but not least, it is possible that the type of oil you are using could cause some clutch engagement issues. 

This is a fairly deep subject and I just wanted to mention the basics of the known problems here.  The in depth repair procedures for these known DR clutch problems can be found here on THIS PAGE 

 

Kick Stand Rubbing The Swing Arm

The DR kick stand may rub on the swing arm when in the up position.  Since the kick stand is metal and the swing arm is aluminum, over time, the swing arm can develop a substantial groove in it's side which is quite bothersome.  Be sure to keep an eye out for this before you damage the swing arm.  If you notice that the kickstand is beginning to rub simply have someone hold the bike for you , and with the kick stand in the down position, use the kick stand as a lever and slightly pull it away from the bike, bending it ever so slightly.  Put the kickstand in the up position and check your clearance.  Re-bend as necessary and keep an eye on it.  If you really wanted to get fancy you could always adhere a small piece of protective metal onto the side of the swing arm where it is in danger of being rubbed by the kickstand.  

 

Tank Decal Failure And Bubbling on Plastic Off Road Fuel Tanks

This is a flaw of the DR which seems to be more severe in the later model years.  My 1999 Off Road Model was very effected by this problem.  On the Off Road Models the gas tanks are plastic.  This plastic apparently allows a great deal of gas vapors to escape through it's porous composition.  These gas vapors become trapped behind the factory graphics and the graphics bubble and fail.  There is really no know fix for this problem unless you went to the trouble to always drain the gas tank completely any time the bike was not being ridden.  Aftermarket tank graphics are available that have a lot of holes punched in them.  These holes allow the decals to have a better capacity to accommodate the escaping gas vapors. 

 

 Suzuki DR 350 S Dual Sport Model Acting Up On Rough Terrain, Either Cutting Out Or Surging

Two Separate Problems effect the Suzuki DR 350 S Dual Sport Model when riding aggressively on rough terrain. 

The first problem is associated with the safety mechanisms that are unique to the dual sport model.  The kick stand safety switch on the dual sport model can cause the engine to cut out on rough terrain.  Some owners disable this safety switch during aggressive off road riding to avoid the engine cutting out on rough terrain.  A simple shunt is sufficient. 

The second problem is associated with the CV carburetor.  This carburetor problem is only found on the dual sport model.  This problem will cause the bike to surge, stall, or run erratically, when riding aggressively on rough terrain.  The procedure to correct this problem is relatively simple and inexpensive.  The procedure is called the T- Vent Mod and it involves putting a Y into the vent line thereby creating two paths for the air to flow and thereby eliminating the CV problem when riding on very rough terrain.

 

Catastrophic Engine Failure Due To Counterbalance Failure

The first thing I want to say is that this happens very rarely among a very large number of motorcycles.  Some of them with tens of thousands of miles on the odometer. 

Nonetheless, it has happened in the past and it will happen again in the future. 

The DR 350 engine has a counterbalance shaft located in the front part of the crankcase.  This counterbalance shaft spins in the opposite direction that the crankshaft spins in.  It rotates opposite the crankshaft and it's counterweight goes in between of the crankshaft weights.  The connecting rod also occupies this same space.  Thus the counter balance shaft must pass between the crankshaft weights when the connecting rod is not in the way.  Therefore, the counter balance must rotate in a specific timed relationship to the crankshaft rotation.   

 

This Is A Picture Of The Actual Balancer Assembly

 

This Is A Picture Of The Balancer In The Engine Case

This counterbalance shaft is driven by a gear that times it's rotation in sequence with the rotation of the crankshaft.  The gear that drives the counterbalance shaft is located by a metal dowel pin that slips into a hole in the crankshaft.

This is a Picture Of The Drive Gear And Pin

 

The hole in the crankshaft is supposed to have a smaller inside diameter ledge machined into it.  This ledge would prevent the pin from moving deeper into the crankshaft.  Some Suzuki's were inadvertently manufactured with the hole in the crankshaft drilled completely straight through and with no ledge. 

This Is A Picture Of The Hole And Ledge

This flaw has been known to allow the locating pin to recede into the crankshaft.  When this has happened the gear that drives the counterbalance shaft has become disengaged from the crankshaft and has become out of time or out of sequence.  Within a split second the rotating crankshaft comes into a fatal high speed collision with the oppositely rotating and out of sequence counterbalance shaft.  The carnage is horrific as the counterbalance shaft weighs several pounds and the crankshaft is even heavier.  They may collide with extreme force if the engine is rotating and high r.p.m.s' when the impact occurs. 

 If You happen to own a DR effected by this problem it is possible to correct it.  You can machine a new pin that will press fit into the crankshaft hole and the drive gear.  With a .002" interference fit the pin will not be able to recede into the crankshaft hole.  You can also machine a new pin that is threaded on one end and machined to press fit the gear with a .001" interference fit.  The crankshaft is then tapped and the newly machined drive gear pin is screwed into the newly tapped threads in the crankshaft hole.  Install the pin with high strength loc-tite and then gently press the drive gear and drive gear pin back together. 

 

 

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