Ron Sutton
812 Brown St.
Alton, IL  62002

I have entered these in text format so they can be searched for "key words".

I noticed when I got all of these Bulletins together that there a two different types, Service Bulletin and Procedures.  The Service Bulletins seem to be addressing things that go wrong, whereas the Procedures bulletins are about modification to the Rokon 340's.  The Service Bulletins and Procedures are numbered separately, so I have divided the Indexes.

I now have some Sales Bulletins that I have added under the Sales Bulletins.  They are not really relevent to maintaining Rokon Motorcycles, but I thought they were kind of neat background.

Some leaky cup seals, PN 13-02116, have been located in the Kelsey Hayes foot master cylinders as used on RT-340 Enduro motorcycles.  Kelsey Hayes has now corrected this problem.  At the request of Kelsey Hayes Rokon is requiring holders of motorcycles with serial numbers between RT340.17 and RT340.189 and from RT340.700 to RT340.723 to make this change also as the defective cup seal may without warning fail to work, leaving the operator without a foot brake.

Proceed as follows to change the cup seal:
(Page 33 of the Parts Manual can serve as a guide)

1.  Remove two, 5/16 screws holding the cylinder to the frame.
2.  Pull the brake push rod out ot the boot and pull the cylinder away.
3.  Remove the boot.
4.  Holding the cylinder with piston facing up, push down on the piston and remove the snap ring with snapring pliers.
5.  Slowly let the piston up out of the cylinder.  If it sticks, gently pry it out.  Don't scratch the piston.
6.  Remove the defective cup seal.
7.  Install the new cup seal.
8.  Reassemble the piston and snap ring.
9.  Reinstall the boot with a new cable tie.
10.  Reinstall the cylinder of the bike and seal the boot to the rod with a cable tie.
11.  Refill and bleed the brake.

Experience has shown that when the exhaust system is rigidly fastened to the frame brackets that the forces involved eventually break off the frame brackets.  This kit provides a simple method of soft mounting these points.  It is applicable to bikes with serial numbers from 17 to 189, and 700 to 776.

INSTALLATION:

1.  Remove the seat.
2.  Remove both 5/16 screws from the rear brackets.
3.  Look to see if the holes in the frame brackets are large enough and located so as to leave room in all directions around the mounting screws.  I there is not, remove the exhaust system and file or drill out the holes until there is.  Replace the exhaust system.
4.  Reassemble the mounting bolts as follows:
   a.  Clean, prime, and Loctite the threaded holes in the expansion chamber brackets.  Prime and Loctite the bolts.
   b.  Put a rubber washer between the pipe and frame brackets.  If there is a boss on the rear bracket, use a metal washer under the rubber washer.
   c.  Put a metal and a rubber washer on each screw and screw them in so as to just lightly clamp the frame bracket.
   d.  Let the Loctite dry.
5. Install the seat.
6.  Parts List - The parts required are as follows:
   a.  Screw, 5/16-24 x 1           #100210  (2 required)
   b.  Flat Washer                     #101380  (3 required)
   c.  Rubber Washer                #101382  (4 required)
   d.  Loctite and Primer

Keeping the Sachs SA340R engine properly timed is important to its performance, life and smoothness.  Following is a simple procedure for timing the engine.  To follow the procedure you will need a sensitive ohmeter or a proprietary timing light or buzzer to indicate point opening, a top dead center gauge reading in millimeters or inches, a .016 inch feeler gauge, and a screwdriver.

1. Remove spark plug, junction box cover, starter, and starter pulley.
2. Check and set the points to .016 gap.
      Be sure to re-check the gap after final tightening.
      Replace the points if they are worn or pitted.
3. Install top dead center gauge and connect ohmeter across points by connecting one lead to kill button terminal and other to ground.
4. Ignore any timing marks on the flywheel.
5. Advance spark fully by moving advance weight all the way down with finger through hole in flywheel.
6. With spark fully advanced rotate flywheel clockwise until points just open.  Release spark advance.
7. Read top dead center gauge and rotate flywheel clockwise to top dead center.  The distance should be 3.0 to 3.5 mm (.118 to .137 in.)
8. If timing is incorrect, loosen the 3 stator locking screws and rotate stator clockwise to retard, or counter to advance.  Recheck the timing until it is within specifications.  Tighten up the three screws.
9. Recheck everything for tightness, cleanliness and accuracy.  This is a good time to clean and lubricate the starter.
IMPORTANT NOTE:  To avoid extensive damage make sure that the 4 coil mounting screws are tight.
10. Reassemble starter pulley, starter, junction box cover, and spark plug.  Silicone rubber seal the starter on.

No. 5

It has been found in some cases that the above four screws, (particularly the two for the ignition coil) part no. 0640 009 000, (Item 40, Catalog page 20), are prone to loosening.  Eventually, this will cause complete destruction of the magneto generator unit with resulting ignition loss.

To prevent this failure, during your initial set-up of each 340, remove the pull start unit and the rope pulley, part no. 3656 005 001.  Through the flywheel openings, one at a time, remove each of the four #0649 009 000 coil mount screws, clean them with Loctitle Primer or some other solvent, Locktite and then throughly re-tighten these screws.

In case either coil moves slightly during this operation, the coil-to-flywheel magnet gap should be .013" to .016".

We recommend using silicon sealant around the flange of the pull start unit when re-installing it to prevent needless water ingression into the magneto.

This job will take about 15 minutes per 340 and should be done at the time of the initial set-up or as soon as possible for any 340's you may have in the field.

The Rokon warranty system will not cover the damage caused by loosening of these screws.  This Service Bulletin is intended for machines Serial No. RT340.1 to RT340.925.  All Rokons should be checked periodically.
 
 

There have been instances where the 340 when running emits a loud rattling or knocking sound from the bottom end of the engine.

We have found that this sound is probably caused by a loose ramp cover, part #601486, catalog page 23, item 9, on the torque converter drive assembly.

If you have an RT-340 between the above serial numbers, remove the drive guard (primary cover) and check the torque converter drive pulley assembly for an "Accepted" sticker.  If this is not present the torque converter drive pulley assembly must be partially disassembled and the cause of the loose cover remedied.

Remove the torque converter pulley assembly from the engine using puller #101050 from the tool kit.  Remove the ramp cover nut #703208, lock washer #703245, and washer #703200.  Remove ramp plate cover and pull the movable face assembly apart from the fixed hub #703253.

The knocking sound is caused by the fact that the end of the fixed hub shaft is too long.  This holds washer #703200 away from the cover ramp so that the washer cannot perform it clamping function.

The end of the fixed hub shaft should be filed so that when the cover is assembled the end of the shaft is below the cover, and the washer will bear on the cover.

When this end is correctly flat, reassemble the torque converter drive pulley assembly.  The chamfered inside edge of #703191 bearing goes toward the fixed hub #703253.  Clean the top surface of the #703194 retractor plate, ramp cover and washer.  Then Loctite all flat surfaces on these parts.  Clean and Loctite the

--- Sorry, I didn't get page 2 of this Bulletin.  Check out the Service Bulletin No. 6 (Amended) below, it also covers loose ramp cover on the Torque Converter too. ---

There is a possibility that some of the 1975 RT, MX or ST-340s may have a loose ramp plate.  It would be advisable to check all of the bikes in this time bracket for this problem.  The procedure to follow is listed below.

Remove the torque converter pulley assembly from the engine using puller #101050 from the tool kit.  Remove the ramp cover nut #703208, lock washer #703245, and washer #703200.  Remove ramp plate cover and pull the movable face assembly apart from the fixed hub #703253.

The loose ramp plate is caused by the fact that the end of the fixed hub shaft is too long.  This holds washer #703200 away from the cover ramp so that the washer cannot perform it clamping function.

The end of the fixed hub shaft should be filed so that when the cover is assembled the end of the shaft is below the cover, and the washer will bear on the cover.

When this end is correctly flat, reassemble the torque converter drive pulley assembly.  The chamfered inside edge of #703191 bearing goes toward the fixed hub #703253.  Clean the top surface of the #703194 retractor plate, ramp cover and washer.  Then Loctite all flat surfaces on these parts.  Clean and Loctite the #703208 nut and tighten it to a torque of 100 lb. ft.

Clean the taper on the engine crank shaft and torque converter drive pulley assembly.  Install the torque converter drive pulley assembly.  Clean and Loctite the #101107 mounting bolt and tighten it to a torque of 80 lb. ft.  Then give the head of this bolt a shat rap with a hide of plastic hammer, retorque to 80 lb. ft.  Repeat this procedure one more to fully seat the tapers.

When reinstalling the drive guard (primary cover) be sure to Loctite the two #100848 bolts that hold it on.  Also check after tightening these that the cover clears the rear drive pulley properly before running the engine.

All RT-340 & MX-340
May 14, 1975
No. 16

The alignment of the rear brake torque arm is critical to the effectiveness and puck wear of the rear brake.  Improperly adjusteing the chain will misalign the disc to the torque arm.

Pictured below is the sequence and techniques to align the torque arm to the disc.

1. Make sure rear wheel adjusters are both adjusted the same.  See Photos #1 and #2.

2.  Disconnect brake line and remove screws that hold caliper to torque arm and allow caliper to swing down out of the way.

3. Torque arm might be so far out of alignment that it does not even sit on brake disc.  See Photo #3.  The torque arm in a relaxed manner should sit on the disc.

4.  Take a monkey wrench and bend torque arm so it will rest on disc.  See Photo #4

5.  Torque arm must be parallel and perpendicular to the disc and might require about 3 or 4 different bending operations to get correct alignment.  Photo #5 shows the torque that still needs to be bent.

6.  Putting a straight edge on the disc and torque arm reveals the alignment of the torque arm.  See Photo #6.

7.  Reinstall caliper to torque arm and brake line to caliper.  Pump brakes several times to get the piston and puch in proper place.

8.  Never align torque arm and assemble a puck that is worn at an angle and expect brakes to have a good pedal feel.  Always use a new puck after alignment.

Testing and troubleshooting the Moto-plat ignition system for a problem will require the use of an OHM meter.

The reading to the internal coil (stator) from the blue wire to ground is 178 - 165 OHMS.  If the OHMS reading is low (below 165 OHMS) it is shorted.  If the reading is infinity, it is open.  The stator may test out okay, but during operation will exhibit irratic spark.  The OHM meter test will show infinity but the stator is defective.

Checking the secondary coil (ignition coil) is also done with the OHM meter.  The reading from the plug wire to ground (strap) should be 9000 - 7000 OHMS.

The ignition coil must have a red spark plug wire.  An ignition coil with a black spark plug wire will not work on a Cobra with the Moto-plat ignition system.

Contrary to may peoples belief, running the Moto-plat with a brown ground wire or the spark plug wire will not damage the unit.  Do not use resistor type spark plugs with the Moto-plat unit.

The Moto-plat stator has two rectifier diodes.  If there is a failure in the unit, there is a 50% chance that it can be fixed.  The rectifier diode that is semi exposed on the stator plate is the only one that can be replaced.  Remove and replace this rectifier diode with a good quality 400A 1V rectifier diode.

If the unit cannot be repaired, then it can be directly replaced by the standard RT-MX-ST340 ignition system part #1483008300.

No. 19

Sometimes due to improper alignment of the drive and driven  pulleys, the ROKON 340 may not push easily.  This can be solved by removing the drive guard cover, and then removing the screw and large washer that hold the rear driven pulley in place.  The driven pulley should then be checked for ease of sliding movement on speed reducer shaft.  Using (2) two 3/8" spring lockwashers or a 1/4" spacer between the end of the speed reducer shaft and the inside of the large washer, start and tighten the driven pulley  mounting screw.  You will notice the driven pulley will now move back and forth on the speed reducer shaft approximately 1/4"  This allows the driven pulley to self center at any speed with the drive pulley.  The result will be an easy pushing ROKON.

Some ROKONS produced after January 1, 1975 had this mocification done to it at the factory.  If your rear driven pulley moves freely back and forth, then nothing more should be done.

This modification will not effect belt life or give any problems with key life on the shaft.

Some of the above-mentioned ROKONS have fork caps that always spit oil from the breather holes.  To prevent this from occurring, make a baffle from a piece of plastic.  A source of this plastic is a plastic bottle that was used to package oil, or a Clorox bleach bottle.

Cut a disc slightly smaller in O.D. than the I.D. of the fork tube.  Cut a notch in one side to accommodate one turn of the spring.  Slip this disc in between any coil of the spring near the top and re-assemble.  This baffle will prevent oil from hitting the fork cap with a high velocity, and will prevent the cap from spitting oil.

   It has been brought to our attention that there may be a possibility that the rear brake puck holder may contact the rear hime joint of spherical rod end.  It may be necessary to file or grind the top of the pad holderr approximately 1/8" down and 1" back from the top front edge of the pad.  This will ensure that the pad holder will not contact the hime joint and cock it out of shape, which causes the brake pad to wear incorrectly.

A.    STARTING PROCEDURE
The Sachs RT340 engine is normally quick and easy to start.  Proceed as follows:

1.  Go to the left side of the parked bike.

2.  Reach across and check throttle operation with your left hand.  Make sure of free operation with your left hand.  Make sure of tree operation and some slack in the cable.  Remember, this is an automatic.

3.  If the engine is cold, set the choke lever to "on" by pushing down on the choke lever at the top front of the carburetor.  If the engine is hot, omit the choke.

4. Turn on the gas by pulling out the petcock knob.

5.  Hold the front brake lever on with 2 fingers of the left hand and control the throttle with the same hand.  If the choke is on, use no throttle or you will bypass the choke.  If the engine is warm, give a little throttle.  Be careful to regulate the throttle so the bike doesn't start off.

6.  Grab the starter T-handle tightly with your right hand.  Pull carefully until the pauls engage and then pull strongly and quickly.  Repeat if necessary.  Two or three pulls should start a cold engine, and one pull, a warm one.  Lead the starter rope back in and seat the handle in its socket.

7.  If the choke is on, let the engine run a half minute to warm up and then put the choke off by pushing down on the right side of the choke lever.

CAUTION

a.  Don't pull the starter rope to its bitter end.  You may well pull it off the pulley.
b.  Don't let the rope snap back in.
c.  Don't wrap the rope around your hand.
d.  Regulate the throttle carefully.

B.  STARTING TIPS
These tips will help assure quick starting.

1.  Keep the ignition system clean and in good condition so electrical energy is not leaked off before the spark is made.

2. Keep the engine properly timed.

3.  Keep the spark plug clean and properly gapped.

4.  Pull the starting rope quickly to make a hot spark.  One or two fast pulls are better than many slow ones.

5.  Fine wire spark plugs like the L2G and new spark plugs with sharp-edged electrodes fire at lower cranking speeds.

C.  TROUBLESHOOTING
If the engine fails to start with the above procedure after half a dozen pulls, there is probably something wrong.  Proceed as follows to find out what and correct it.

1.  Too much fuel - flooded engine.  Flooding may be caused by choking a hot engine, tipping the bike over, leaving the petcock open, a misadjusted carburetor float, dirt in the carburetor inlet valve, or the inlet valve stuck open.

a.  Open crankcase drain and pull the starter to check for excess fuel in the crankcase.
b.  Pull the spark plug and see if it is wet with fuel.
c.  If flooding exists, put a plug in the spark plug wire and ground it on the engine so the insulation in the spark coil is not stressed.  Close off the fuel supply.  Open the crankcase drain valve, open the throttle wide, and pull the starter through fast until no liquid comes out and the engine is aired out.  Close the drain valve.
d.  Put a new or dried spark plug into the spark

plug wire, ground it on the engine and pull through to check spark.  If okay, install the plug.
e.  Use first the warm engine starting procedure, and if too lean, then the cold engine procedure to start the engine.

2.  Lack of fuel.  A mixture too lean to fire may be the result of petcock not opened, clogged fuel filter, stuck inlet valve, choke not used, or throttle opened when choking, no fuel in the tank.  If leanness is suspected, proceed as follows:

a.  Check the spark plug as before to see if it is dry.
b.  Pull off the fuel line on the downstream side of the fuel filter and check for good fuel flow.
c.  If necessary, remove the carburetor float bowl and check for a stuck inlet valve.
d.  Reassemble and choke to start.

3.  No spark.  No spark or inadequate spark may be caused by a shorted or fouled plug, defective coil, points not opening, too slow a cranking speed, shorted kill button wire, electrical leakage through worn or we high voltage leads, defective capacitor.  If you suspect spark problems, proceed as follows:

a.  Remove the plug, connect it to the high voltage wire, ground it to the case and pull the starter.  Check for a fat blue spark.
b.  Pull out the kill button wire from the terminal at the engine and check for spark.
c.  Try a new spark plug.
d.  Check for point opening by removing the starter and emergency starter pulley and rotating the flywheel.

TUNING UP THE 340R SACHS ENGINE

  1.  Raise exhaust port .060 by radiusing.

  2.  Raise cooling ports .060 and deepen.

  3.  Raise piston skirt on inlet side 2.5mm width of inlet port.  Radius corners.

  4.  Clean and match all over.

  5.  Compression ratio should be 13:1

  6. DO NOT WIDEN PORTS!

All RT, MX, and ST 340

If you find it difficult to pull-start your Rokon, there is a hole that can be drilled in the side of the cylinder, exiting in the exhaust port, to help this problem.  This hole will not affect the performance of the machine.  Due to its location, the hole will only cause loss of compression on slow engine speeds, as when statring.  Much care should be taken when drilling the hole, as to its correct location and angle.

It will be necessary to remove the cylinder from the engine to do this mocification.  First apply machinists' Dykum-blue to the area to be drilled, and scribe a line .600" down from the top of the cylinder.  The hole can, and should, be started with a Dremal tool or an end mill in a milling machine.  After a good flat spot is stated at the proper angle, which is 20 deg., a .082" drill is used to drill the hole into the exhaust port.

REMEMBER:  The 20 deg. angle is important, as it is very easy to mistakenly drill into the finned area.  If machine shop facilities are available, we strongly recommend the entire job be done on a milling machine.

February 23, 1976

You may have noticed that the fork tubes have been extended through the upper triple clamps approximately 1-1/16 inches.  This was done to lower the front of the bike for better rider comfort, not for shipping purposes.  This was also done to ensure the correct rake and trail of the front forks.

Remember, for every inch you raise or lower the fork tubes in the triple clamps, the rake angle changes approximately one-half inch.

If you have any questions relating to the front end, please call the Service Department at Rokon.

As a Rokon products dealer, you are well aware of the number of ROKON 340s in your area with spacers in addition to the head gasket between the cylinder head and the cylinder.

At this time, we wish to make a special off on the following cylinder haed which would enable your customer to eliminate the head spacer and use only a head gasket.  This cylinder head normally retails for $17.27 and carries a dealer cost of $12.95.  The special dealer price to you will be $8.40 which represents a wholesale savings of $4.55.  For your customers, the savings based on an $11.20 suggested list price would be $6.07.

We strongly urge you take advantage of this special offer immediately as orders will be processed as usual on a first cime first serve basis.  This will also give you as a dealer, a reason to call a customers vehicle in for a general servicing which could generate additional profits.

Simply circle the quantity desided below and return this handy order form for your 1487-037-000 Cylinder Head.

DEALER NAME____________________________________________

ADDRESS_________________________________________________

CITY__________________STATE___________________ZIP_______

ORDERED BY____________________DATE____________________

SALES BULLETIN
May 24, 1976

As a result of successful factory testing, ROKON will now offer Silicone Brake Fluid as an inventory item.  This fluid has a higher boiling point than automotive brake fluid, and will extend brake life.

We highly recommend this fluid for all owners who compete in enduros, hare scrambles, motocross, etc.  It can be used in all ROKON motorcycles with hydraulic disc brakes.

Please note the following information for future reference:

Part #              Description          Dlr. Cost

103092          Silicone Brake Fluid       $ 7.45

Please detach the handy order form below.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Circle quantity desired below and return this order form for #103092 Silicone Brake Fluid:

2    3    4    5    6    7    8    9    10       @ $ 7.45 each      Total $ ____________

DEALER NAME____________________________________________

ADDRESS_________________________________________________

CITY__________________STATE___________________ZIP_______

ORDERED BY____________________DATE____________________

Terms will be as on your statement in the past.