4 MOTORCYCLE COMPONENTS CHECKING AND ADJUSTING

As the motorcycle had been adjused and tested before delivery, there is no need to make any readjustment. In case there is any fault with the motorcycle, trouble shooting should be performed as the following:

4.1 Spark Plug Gap Adjusting
4.2 Mixture Valve Opening Checking and Adjusting
4.3 Distributor Platinum Contact Gap Checking and Adjusting
4.4 Ignition Angle Checking and Adjusting
4.5 Carburetter Adjusting
4.6 Foot Gear Shift Lever Adjusting
4.7 Front and Rear Brakes Adjusting
4.8 Main Body and Side Car Connection Adjusting

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When new spark Plug is used or after the motorcycle has been driven for1000 km, spark plug gap should be checked with feeler gauge. If necessary, adjust the gap to 0.6-0.7mm.When the spark plug is needed to be cleaned, it should be cleaned in gasoline with brush (use of metal wire brush is not allowed).

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4.2 Mixture Valve Opening Checking and Adjusting

Inadequate valve opening will directly affect the engine power, which will cause difficult starting, unsteady idling, high fuel consumption and poor acceleration. So the valve opening must be properly adjusted.

4.2.1 Open the valve chamber cover (Item 4 in Fig-7 )

4.2.2 Apply kickstarter to operate engine crankshaft so as to make the cylinder to be adjusted be in final compression position, i.e.inlet valve opens fully and comes down completely.At this moment, the pisiton has gone through a complete operating cycle (from upper limit point to lower limit point and then from lower limit point to upper limit point) .
4.2.3 Move the adjusting screw (Item 2 in Fig.7) with screw driver and check the opening, which should be 0.06mm for hot cylinder and 0.1mm for cold cylinder.
4.2.4 If opening does not meet the requirement, loosen nut (Item 1 in Fig.7) and readiust the opening.
4.2.5 Check repeatedly according to para.4.2.2 and 4.2.3 and then tighten the nut.
4.2.6 Refit the valve chamber cover.
4.2.7 If the opening is still too wide , which can not be adjusted, the relative parts such as tappet should be changed.
NOTE: The mixture valve opening for engine CJ-750D can be checked and adjusted as follows:
a. Open the valve chamber cover ( Fig.7) remove rubber block (Fig.10) from observation hole in crankcase, apply kickstarter to operate the crank shaft. When inlet valve of left cylinder opens, apply gently kickstarter to make the "O" scale line on flywheel be in the center of observation hole.
b.Loosen the locknut, adjust the adjusting screw to make the gap between end of adjusting screw and inlet (outlet) valve be 0.07mm for hot cylinder and 0.1mm for cold cylinder. Then tighten the locknut and recheck the valve opening with feeler gauge.
c. Apply gently kickstarter to rotate the flywheel for 360 when the O scale line of flywheel appears again in the center of observation hole, check and adjust the right cylinder mixture valve opening with the above method.

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4.3 Distributor Platinum Contact Gap Checking and Adjusting

The distributor should be kept clean. The platinum contact should be free from dust and lube (oil) contaminaton. The contacting area of the contact should not be less than 80% and the centers of upper and lower contacts should align with each other.

4.3.1 The distributor of engine CJ-750, installed in the front end cover of crankcase, is of FDQ-1 type, whose contact gap is adjusted as follows (see Fig.8).

4.3.1.1 Remove crankcase front cover and distributor cover.
4.3.1.2 Rotate camshaft to a certain position by applying kickstarter and take off distributor disk.
4.3.1.3 Rise camshaft by applying kickstarter to separate platinum contacts.
4.3.1.4 Loosen the securing screw, adjust platinum contact gap to 0.4-0.45mm by turning the platinum contact adjusting screw, and then tighten the securing screw.
4.3.1.5 Turn cam 180 more by applying kickstarter and check contact gap at the other end to see whether it meets requirement.
4.3.2 The distributor of engine CJ-750D is of FDQ-5 type, which is an automatic and centrifugal ignition advance distributor. It can automatically change ignition angle with the change of engine RPM to get optimum ignition time for the engine.It is installed on top left of front crankcase. Its adjusting methods are as follows(see Fig.9).

4.3.2.1 Remove distributor cover.
4.3.2.2 Rotate ignition camshaft by applying kickstarter to push the movable arm of platinum contact to upper most position.Use feeler gauge to check max gap between upper and lower platinum contacts, which should be 0.35-0.45mm.
4.3.2.3 If the gap does not meet the requirement, loosen the securing screw, adjust the gap to 0.35-0.45mm by turning the platinum contact adjusting screw. Then tighten the securing screw.
4.3.2.4 Turn cam by 360 more by applying kickstarter and check the contact point gap with the above method.

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4.4 Ignition Angle Checking and Adjusting

4.4.1 Ignition angle checking
4.4.1.1 Remove distributor cover and cylinder head.
4.4.1.2 Operate the crankshaft by applying kickstarter to make piston be in upper limit position of compression stroke, measure distance from piston top to cylinder end face and write down the value. Then operate the crankshaft again to make the piston be 0.5-1 mm to the upper limit position. The ignition angle is proper if platinum contacts are just setting apart. Otherwise the ignition angle should be adjusted.
4.4.2 Ignition angle adjusting
4.4.2.1 The followings shall be followed to adjust the ignition angle of engine CJ-75OD:
a. Loosen slightly the securing bolt in the distributor bottom plate (see Figs 8 and 9 ) and connect parallelly an indicating light across distributor capacitor. Turn on ignition switch, apply gently kickstarter to operate crankshaft to make piston reach the point 0.5-1mm to its upper limit in cylinder. Rotate the distributor till the indicating light just comes on. Then tighten the securing bolt, reoperate the crankshaft to make the indicating light on. Check to see if the piston is 0.5-1mm to its upper limit in cylinder. If it is not, it shonld be readjusted.
b. Loosen slightly the securing bolt in the distributor bottom plate, insert a sheet of thin paper between platnum contacts . Apply gently the kickstarter to operate the crankshaft to make piston reach the point 0.5-1mm to its upper limit in the cylinder. Then rotate the distibutor till the inserted paper can be pulled out from contacts.
4.4.2.2 The ignition time delay or advance problem of engine CJ-750 with distributor FDQ-1 can be solved by adjusting the eccentric screw at upper left of platium contact bottom plate. The ignition time advance can be obtained by adjusting screw to rotate the bottom plate clockwise and vice versa.
4.4.2.3 CJ-750D engine ignition angle adjusting (see Figs 9 and 10).
Fig. 10
a. Remove the rubber block from observation hole in crankcase, apply gently kickstarter to make mark "6" on flywheel be in the center of observation hole (see Fig. 10) . Loosen distributor pressing nut (Item 1 in Fig.9 ) and turn the installation plate to make the scale align with the center scale on front crankcase and then tighten the pressing nut.
b. Remove distributor cover and connect parallelly an indicating light across distributor capacitor. Loosen securing bolt (Item1 in Fig.9), turn on ignition switch, rotate distributor till the indicating light just comes on (at this moment the platinum contacts are just setting apart to the extent of a paper-thick clearance) . Tighten the securing bolt, operate the crankshaft for 360. Check to see if the mark "6" on flywheel is in the center of observation hole when the indicating light just comes on. Otherwisie, it should be readjusted. The ignlion angle of the two cylinders should not exceed +/-2.
NOTE: If it is felt in operation that ignition is too much advanced, loosen the pressing nut and rotate, the distributor counter clockwise to move installation plate scale against front crankcase scale ( moving one graduation varies 2 of ignition angle) . If it is felt in operation that ignition is in delay too much. rotate the distributor clockwise, and tighten the pressing nut after adjustment.

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4.5 Carburetter Adjusting

Two carburetters are used on left and right cylinders (one for each) in operation . Since two carburetters are used in operation simultanously they must operate in same state. Otherwise, engine power , fuel consumption, starting performance and low speed stability will be poorer. So the carburetters should be adjusted one by one . The adjusting methods are as follows:
4.5.1 Adjusting at idling
4.5.1.1 Start the engine, carry out the following steps after the engine warms up to normal temperature.
4.5.1.2 Turn outwards throtte twist grip fully home.
4.5.1.3 Screw in the idling adjusting screw (Item 6 in Fig 11) clockwise to raise the throttle valve, increase slightly the engine RPM so that one cylinder can operate continuously with throttle at minimum operating state. Remove the high tension cable from the other cylinder and ground it .

4.5.1.4 Turn slowly idling mixture adjusting screw (Item 5 in Fig 11) to increase the engine RPM to maximum and to make engine operate stably at that speed .
4.5.1.5 Screw out gradually the idling adjusting screw to reduce the throttle valve to mininum engine RPM and to keep engine operating stably and continously at that speed.
4.5.1.6 Repeat the steps of para .4.5.1.4 and 4.5.1.5 to make the engine operate at min. stable RPM.
4.5.1.7 Tighten lock nuts (Item 4 in Fig.11 ) of the two screws.
4.5.1.8 Adjust the other cylinder at idle speed by using the above methods. Improper adjustment at idling will result in uneasy starting , unstable operation, even if it is started and single cylinder operation is impossible when a high tension cable is removed from the other cylinder and checking its operation.
4.5.2 Adjusting at intermeidate speed.
Turn inwards the throttle twist grip for about a quarter stoke. Alternately remove high tension cable from cylinders , and listen to the operation sound of the other cylinder. Remove rubber cover from carburett er upper cover of lower speed cylinder , adjust the steel cable connector ( Item 2 in Fig11).
Check carefully the two cylinders for identical operation and then tighten steel cable connector nut.
To check the carburetter operation turn the throttle twist grip rapidly to center position. At this moment , engine RPM should increase sensitively.
If it increases sluggishly , adjust it as per the above method. The two cylinders should operate in balance when the throttle twist grip is turned outwards fully and rapidly . If flameout happens, adjust it as per the method for adjusting at idling.
If acceleration is not satisfactory when two cylinders are operating in same state . In this case, lean mixture or rich mixture can be checked by closing the air valve narrower or opening the air valve wider . If its power performance becomes better after closing the air valve narrower, it is the lean mixture eausing the problem , which can be solved by checking fuel line for being unimpeded or by raising needle in throttle, valve for 1-2 grids . If exhaust sound is heavy, it is rich mixture, which can be solved by dropping appropriately needle in throttle valve .
For the well-adjusted engine , the surface of spark plug insulator skirt should be dry and brown .

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4.6 Foot Gear Shift Lever Adjusting

Gear shift is realized by applying foot gear shift lever or hand gear shife lever. If trip stop happens in operation by applying foot gear shift lever, hand gear shift lever can be used to shift the gear to proper position . If trip stop still exists after using hand gear shift lever, joint sleeve , driving fork and sector plate should be repaired or replaced . If trip stop disappears after using hand gear shift lever, the cause is that the foot gear shift lever is not properly adjusted.
Then adjust it as follows:

4. 6.1 If trip-under stop happens in shifting from lower to higher gear position, screw out the lower adjusting screw (Item 2 In Fig.12).

4.6.2 If trip-over stop happens in shifting from lower to higher gear position , screw in the lower adjusting screw.
4.6.3 If trip-under stop happens in shifting from higher to lower gear position, screw out the upper adjusting screw ( Item1 in Fig.12).
4.6.4 If trip-over stop happens in shifting from higher to lower gear position, screw in the upper adjusting screw.

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4.7 Front and Rear Brakes Adjusting

The front and rear wheels are equipped with mechanically controlled and unbalanced shoe brakes, which are driven by cams. The front wheel brake is applied by hand. The suitable steel cable free stroke is so adjusted that brake rocker end can move 10-15mm before brake begins to function. The steel cable free stroke can be adjusted by adjusting hollow screw in front hub cap and the rocker position.
The rear wheel brake is applied by foot. Its suitable free stroke is so adjusted that front end of foot brake pedal goes down 25 mm before brake begins to function. The free stroke can be adjusted by adjusting the butterfly nut on rear brake rod.

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4.8 Main Body and Side Car Connection Adjusting

The side car is connected to main body with two ball couplings and to upper frame with two rods. In order to have a smooth and steady travel. a 2inclination and a 10-12mm toe-in are provided for motorcycle. Inclination can be adjusted by adjusting the front and rear rods(Items1 and 2 in Fig.13) and toe-in can be adjusted by adjusting rear pipeconnector (Item 3 in Fig.13).
The inclination and toe-in can be checked by test run. The inclinnation, and tod-in are suitable if the motorcycle only deviates one meter after traveling on smooth for 10-15m with hands off the bars and gear shifted to lowest RPM position.

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