NO performance modifications . . just some stock engine servicing suggestions. Click on thumbnails to view larger images.
Service ManualTroubleshooting Flow Chart Guide.
TOOL SUGGESTIONSHOME DEPOT . .
Husky #532135 45-Piece Stubby Set, $13, includes 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17mm (oil drain plug) 6-point sockets. If not in the tool section, look for a display near the checkout counters.
CHECKER SHUCKS KRAGEN . .
Alltrade #836332 8-Piece Metric Wrench Set, $10, includes 6, 7 (carb main jet), 8, 9 (valve lash adjusters), 10, 12, 14, 17mm combination wrenches. Most sets at a comparable price point DO NOT have the 9mm size wrench.
For a smaller
"take-along form factor", most of the metric tools from these sets will fit into a 6.5"Lx4.75"Wx3"H
food container (Wal-Mart thinly sliced meats).
ENGINE & REAR GEARBOX OIL CHANGE GUIDELINESA strainer (Wal-Mart kitchen gadgets or a Goodwill type thrift store) is useful for catching the engine oil drain plug and screen assembly. Change oil several times during the first 1,000 miles (1,609 kilometers) to flush out suspended metal particles. Wal-Mart SuperTech 15W-40 works fine.
While positioned on the center stand, warm engine dipstick oil level should be around midpoint on the cross-hatched tip when placed against the case threads (not screwed in).
To avoid stripping rear gearbox case threads, apply thread compound to bolts and just "snug up".
Using a squeeze bottle (Wal-Mart kitchen gadgets) is one method of refilling the rear gearbox until oil runs out the hole. SuperTech 80W-90 works fine.
A rinsed and air-dried soda pop bottle works well for collecting used oil for recycling.
VALVE LASH ADJUSTMENT GUIDELINESOn a cold engine . . remove spark plug, and valve cover. Apply ArmorAll (or similar) to cover gasket to keep supple. Check that head bolts are tight.
Use kick start lever to rotate engine and align cam sprocket holes with head top surface. Remove right side fan cover inspection plug and verify flywheel "T" mark is aligned with case protrusion.
Manual specifications state .002 inches clearance.
If you have access to compressed air, before installing the spark plug consider removing the right-side engine cooling shroud and fan, then blowing out stator dust from under the flywheel . .
thread link.
If you can access the carb through a hatch in the underseat compartment, also consider removing the top round cover (spring loaded), then lifting out the diaphragm-slide assembly and applying ArmorAll (or similar) with a foam brush to keep the rubber supple. While the needle-slide is out, might also spray a shot of carb cleaner down the main jet to back-flush it.
CARB CLEANING GUIDELINESRotate throttle control plate to disconnect cable. Loosen adjustment nut and remove cable through support slot.
Disconnect enricher (choke bystarter) electrical connector, loosen front and rear mounting bands, and separate carb from manifolds. Remove fuel line and drain to catch bottle. Drain fuel from carb bowl to catch bottle.
While wearing SAFETY GLASSES in a well ventilated area, preferably OUTDOORS, disassemble and spray METAL components with carb cleaner over crumpled-up newspapers in a wastebasket. Flush all internal passageways. Blowing out the passageways with compressed air is helpful, but not essential. Any residual carb cleaner will either evaporate or be mixed with gas. Watch for a miniature spring and O-ring to exit from low-speed mixture screw hole. Verify that the miniature aeration holes at nozzle end of main and low-speed jets are clear by viewing through them against a bright background. For future reference, record size markings at suction end of jets (may require a magnifying glass). The sizes in this stock carb are 35 low-speed and 85 main. Avoid spraying rubber and plastic parts with carb cleaner . . applying ArmorAll (or similar product) will help keep the rubber supple. Jumper enricher wires to a 12 volt source and verify that needle extends . .
video. Reassemble carb components and turn low-speed mixture screw 2 revolutions out from seated. The L-extension on the low-speed mixture screw in these images was
owner added.
Reinstall carb. Refilling carb bowl through inlet fuel line with gas from a
squeeze bottle will aid restarting. Allow wastebasket newspapers to air-out OUTDOORS for several hours while carb cleaner evaporates.
SPARK PLUG TESTING GUIDELINESPull off boot, unscrew with a 5/8" deep socket (perhaps with a universal), and "read" plug electrode color. Black indicates a too rich fuel mixture and very light beige/white usually indicates a too lean fuel mixture.
To free up one hand, bungee cord left brake handle (to enable starter interlock). Ground plug against engine case and energize starter to observe spark (ensure "emergency-off" switch is in run position). Apply anti-seize to old or new plug threads when installing. Consider a NGK C7HSA (or resistor version) gapped to .028".
INTERMITTENT & NO SPARK TROUBLESHOOTING GUIDELINESVerify that the spark plug wire ends are securely twisted into the screw studs in both the plug boot and coil. Check continuity of
CDI-to-coil wires, and engine-to-frame ground wire. Some multimeters have an audible tone continuity feature . .
example.
"i suspect that there was an intermettent spark due to dirt from the stator and flywheel" . .
thread link”that spark plug wire and braided metal hose seem a little chummy” . .
thread link”the wiring harness was getting pinched between the frame and the floorboard!! This was grounding out the ignition or power to the CDI box” . .
thread link”Put some crushed ice in a plastic bag. When you have a no spark situation chill the CDI or the coil, and see what happens. Do them one at a time.” . .
thread link”Pin plugs are jsut holders for individual small electrical connectors, and sure enough one of the connectors had backed itself out.” . .
thread link”The first thing you should try is to disconnect the black/white wire from the CDI connector and then check to see if you get a spark. This test will indicate if the problem is with ignition components or in the scoot wiring. With the black/white disconnected and you still do not get a spark, the problem is within the ignition system component parts. If you do get a spark, then the problem is with the ignition switch, kill switch, sidestand switch, or the wires going to those switches.” . .
thread link.
A miniature flat-tipped screwdriver can be inserted into the plastic housing to bend down the tang for temporary ground wire connector removal.
”The lesson I learned from all of this is that you can't determine anything by measuring voltages out of the stator with the CDI hooked up.” . .
thread link.
Ignition Troubleshooting: No SparkCDI Troubleshooting”Ive tested a stator before that ohmed out fine but after it ran for a while it lost spark because of low quality windings.” . .
thread link.
Replacing the
139QMB stator requires first removing the shaft nut (lefty loosy) with an impact wrench, or securing the flywheel with a strap wrench and using a socket wrench/bar, then attaching a
24mm x 1.0mm right thread puller to remove the flywheel. The scooter panels may obstruct the use of the
combination 50cc/150cc cross puller design, but a 10mm bolt from a hardware store can be substituted.
Stator
pickup only resource.
TESTING CYLINDER COMPRESSIONVerify compression test set includes a 10mm adapter . .
example. Engine should be warm. Removed spark plug must be grounded, or "emergency-off" switch in off position, to avoid "air gap spike" ignition coil damage. Twist throttle to full open before energizing starter for a few seconds duration.
TESTING MANIFOLD VACUUMVerify fuel is visible in the in-line filter. Connect gauge hose to intake manifold vacuum port. Readings will be highest at idle speeds.
