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These are information sheets issued by the distributor, Inter-Trends, Inc., in order to keep our dealers aware of any problems, maintenance or other relevant information on the MONARK 125cc machines. These will be sent out to cover existing or new components and a sheet listing all technical information numbers will be sent out as it is updated. Index #1 125cc GS Model Changes Geoff Burgess #1 125cc GS Model Changes
Using SACHS 1251/6B Engines The above models are basically the same as standad 125cc 6-speed models, the difference being mainly with engine and carburetor changes. The GS models have the following special parts in place of standard components:
Selector Boss #286-317-022 Selector Gear #634-106-201 Carburator #681-007-000 - 28mm Choice Crankcase #687-107-515 Cylinder #687-108-260 Cylinder Head #613-106-007 Piston #686-207-035 Retaining Plate #645-102-000 Gear Changing Device #690-002-003 or 004 Eccentric Bush #647-103-001 Bracket #686-211-000 Spring #639-003-000 Monark 50cc Model Schoolboy Scrambler GS Eng. utilizing 50/6 GS Engines The following is a list of special parts used only on the 50cc GS Engine in place of the standard components.
Geoff Burgess #2 1251/6B Std and GS Technical Information
SEE TIS/1 FOR DETAILED DIFFERENCES IN SPECIFICATIONS
Geoff Burgess #3 SACHS 6-speed G Box Adjustment
Several queries have arisen as to the correct adjusting procedure for this gearbox. Outlined below is the correct checking procedure. First, remove the kickstart and gearshift levers. Remove the outer chain case cover #611-114-100, then remove the clutch by extracting the circlip #245-020-001 and lifting off the hub complete. Refit the gear change lever, loosen screws #1940-144-000 (no. 17 on illustration page 25 of parts book), rotate eccentrick lobes #31, part #647-103-000 away from motion of travel of pawl, it: anti-clock for L.H. lobe, clockwise for R.H. lobe. Retighten allen screws. Engage low gear (1st) ensuring that the selector rod part #619-004-001 (part no. 9 on illustration page 22) is fully home. No check to ensure that there is clearance between selector shoe part #248-135-000 and the slot in the selector rod. In other words, make sure that there is no end load on the selector rod. Next, engage high gear (6th) and repeat the above checking procedure. If any end load exists or if there is very little clearance, adjustment is made by loosening nut, part #642-108-001 and rotating eccentric screw, part #640-110-000 to give the correct adjustment. Now engage low gear again, ensuring the selector rod is fully home and allow gear change lever to return to neutral position. Then observe the position of the selector pawl, part #248-136-000, when the gear lever is depressed into low gear again, under the return spring pressure. A mental note of the clearance between the pawl and the engaging tooth on selector boss part #286-317-021 must be made as the lever is depressed from the neutral position. Engage high gear (6th) and repeat the above procedure. The clearance between the pawl and the corresponding tooth on the selector boss must be equal in both gears. If this is not the case, loosen allen screws no. 17 page 25, and move the selector adjusting plate, no. 16 page 25, part #248-133-001, to ensure that this is the case. Engage low gear once again, and rotate the eccentrick lobe so that it is just clear of the pawl when the lever is held fully down in the low gear position. Repeat in high gear position. The gearbox is now adjusted completely and should function satisfactorily. If the machine is a GS model and has been fitted with the gear locking device, the following additional points should be noted: Before attempting the above procedure the return spring #639-003-000 must be unhooked, allowing the pawl arm #686-211-000 to drop away from the positive stop locations. The above proceedure can then be carried out to correctly adjust the gearbox. To adjust the pawl arm to the correct position, third (3rd) gear must be located. The pawl arm should then locate in the 3rd gear notch on the positive stop quadrant. Select 2nd and 4th gears by lifting the gear changing pawl over the tooth on the selector boss in each case and depressing the gear change lever against the stop. Check to see that the pawl arm moves an equal distance each side of the 3rd gear notch on the positive stop arm. If this does not happen, then readjust the position of the pawl arm by loosening the L.H. allen screw and moving the same. Retighten the allen screw and hood the spring. Tightening torque to allen screws is 8.7 ... 10.8 ft lbs. Geoff Burgess #4 Clutch Chainwheel Problems
Several problems have come to light with new machines being run in the first two or three hours, with this component. It is most important to check that the chainwheel is shimmed to the correct end clearance (.003-.005) on the layshaft, as several complaints have been made that excessive end play exists. This, of course, will damage the circlip groove and cause breakage of end of the layshaft. Four thicknesses of shim are available, #246-015-000, 001, 002 and 003 to take out all excessive play. Another problem that has shown up is the "seizure" or "freezing" of the layshaft wheel bushing #632-113-000, on the layshaft. It would be advisable to check that the wheel is free running and has sufficient clearance for good running; also ensure it is sufficiently lubricated. On the outer side of the chainwheel there is a slot cast into the hub, but after the bushing is pressed in, it obstructs the slot. It is advisable to machine or file away the bushing in this area to create a channel so oil can enter into the bearing area when the engine has stopped. Geoff Burgess #5 Moto Plat Electronic Ignition
Several failures of the generator system have been reported by various dealers. It must be emphasized to the customer that under no condition should the engine be rotated if the spart plug is not grounded out. Severe damage to the diade will result if this does happen. Enclosed is the service bulletin no. 6/1972 (Editor's Note: This is unavailable at this time) concerning the checking of the moto-plat system for condition, etc. Geoff Burgess #6 Wheel Hub Front and Rear
The above component has been known to fail in a number of cases. The customer should be instructed upon collection of the machine to ensure that the spokes are tightened up constantly after each race or run, as the spoke nipples "beds" itself into the rim. After the above procedure has been completed four or five times the nipple has completely bedded down and no further loosening will occur. If the spokes are allowed to loosen and the machine is run, hub damage will certainly occur. The normal lace pattern is of the cross 3 type, however, we will supply a heavy duty cross 4 lace pattern spoke for competitors who wish to build a stronger wheel to withstand severe going. Geoff Burgess #7 GS Porting Specifications
Modification Sheet to GS Specifications Several modifications can be done on a standard 1251/6B alloy cylinder to achieve an improved horse-power output. As can be seen from the enclosed drawing, it is mainly modifications to port sizes and shapes. Geoff Burgess | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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