Troubleshooting 
1- 
The engine doesn't start
| Problem | Possible 
cause  | 
The 
starter doesn't work  | - 
Flat battery - Rusty or loose battery cables (battery terminals and starter 
terminal) - Loose ground main wire onto the engine - Cracked bakelite insulator 
onto the starter body (+ battery) - Dirty or worn starter brushes - Worn 
starter relay - Dirty starter button connection  | 
The 
starter works but doesn't drive the engine, there is a noise to the RHS of the 
engine  | - 
Worn/broken starter flywheel  | 
The 
starter works, the engine turns but it doesn't start  | - 
No fuel in the tank, fuel taps on "off", blocked air vent onto the tank 
cap, blocked fuel filters - Choke system doesn't work (blocked plungers, broken 
cable) - Kill switch on "Off" or moisture inside the kill switch - 
Blown main fuse - Worn main switch (no current to the ignition module) - 
Points too tight (650/750) - Worn engine stop relay (1000/1200) - Worn ignition 
module (1000/1200) - If detonation in the exhausts while trying to start, worn 
ballast resistors (1000/1200 equipped with Bosch BTZ)   | 
2- 
The engine misfires
| Problem | Possible 
cause | 
Misfires 
occur at any speed  | - 
Points too tight (650/750) - Worn condensers (650/750) - Wrong electric 
insulation of the points (650/750) - Pick-ups set incorrectly (1000/1200) - 
Worn resistance ballast (1000/1200 with Bosch BTZ) - Bad connections to the 
main fuse - Worn or damaged ignition module (1000/1200) - Bad current supply 
or ground connection to the ignition module (1000/1200) - Bad fuel supply - 
Too cold plugs  | 
Misfires 
occur only when accelerating  | - 
Too much ignition advance - Fuel accelerator pumps uncorrectly set (750 SF2/SF3/1000/1200) - 
Ignition points uncorrectly set (650/750) - Worn condensers (650/750) - 
Mixture too lean - Mixture really too rich  | 
Misfires 
occur when decelerating, with detonations in the exhausts  |  | 
3- 
Lack of power
| Problem | Possible 
cause  | 
Lack 
of power  | - 
Ignition points uncorrectly set (650/750) - Blocked ignition advance centrifugal 
system (650/750) - Pick-ups uncorrectly set (1000/1200) - Bad current supply 
or ground connection to the ignition module (1000/1200) - Uncorrect advance 
setting - Worn or damaged ignition module (1000/1200) - Bad fuel supply 
(blocked cap vent, blocked filters) - Bad carb setting, notably too rich - 
Worn piston rings - Valve clearance too small - Worn valves - Bad fuel 
supply on race engines, use the same fuel suplly system as the RGSs - Blocked 
or dirty air filter - Air leak - Bad timing setting  | 
4- 
The engine doesn't idle
| Problem | Possible 
cause  | 
No 
or unstable tick over  | - 
Ignition points uncorrectly set (650/750) - Pick-ups uncorrectly set (1000/1200) - 
Worn or damaged ignition module (1000/1200) - Valve clearance too small - 
Bad timing setting - Worn valves - Spark plugs too cold - Blocked choke 
system - Worn piston rings - Air leak  | 
5- 
The engine pinks
| Problem | Possible 
cause  | 
Pinking  | - 
Ignition points uncorrectly set (650/750) - Too much ignition advance - 
Air leak  | 
6- 
Smokes
| Problem | Possible 
cause  | 
Smokes  | - 
Exhaust gaskets (copper) not sealing - Worn valve guides - Worn piston rings - 
Black smoke: Fuel mixture too rich  | 
7- 
Noises to the top and the bottom
| Problem | Possible 
cause  | 
Noise 
to the top  | - 
Broken or damaged amshafts druff key (650/750) - Loose assembling nuts of the 
camshafts (650/750) - Loose or damaged cam bearing (1000/1200) - Worn timing 
chain - Worn timing chain guide and tensioner. In case of leaking head gasket 
near the cam chain tunnel, the tensionner wheel can be melted and destroyed.  | 
Noise 
to the bottom  | - 
loose R and L crank nuts - Locker whasher (to the sprocket on the LHS of the 
crank) too thin - Worn clutch drum silent-blocks - Worn primary chains - 
Worn chain tensionner - Worn mainshaft bearings - Worn clutch drum bush - 
Worn crankshaft bearings  | 
8- 
Vibrations 
| Problem | Possible 
cause  | 
Excessive 
vibes  | - 
Unbalanced carbs - Wrong ignition advance setting - Loose engine fixing 
points (650/750/1000 180°) - Worn engine silent-blocks (1000 120°) - 
Damaged or incorrectly rebuilt crank  | 
9- 
Fuel mixture too rich or too lean
| Problem | Possible 
cause  | 
Too 
rich  | - 
Dirty or seized choke plungers or cables too much tightened - Jets too big - 
Dirty air filter - Wrong cut of the throttle slides - Worn float valvesPointeaux 
non étanches - Sunk float  | 
| Too 
lean  | - 
Air leak - Jets too small - Worn throttle slides or wrong cut - Uncorrect 
float level | 
10- 
Impossible carb balance
| Problem | Possible 
cause  | 
Impossible 
balance  | - 
Worn or damaged top part of the carbs - Worn throttle slides - Setting screws 
too loose  | 
11- 
Fuel overflows of the carbs
| Problem | Possible 
cause  | 
Fuel 
overflows  | - 
Worn float valves - Sunk float - Blocked float bowl vent
   | 
12- 
Oil overflows from the crankcase breather
| Problem | Possible 
cause  | 
Huile 
sort par le reniflard  | - 
Worn piston rings - Oil level too high - Occurs at very high engine speed: 
Fit a second breather to the cam cover or to the oil dipstick place  | 
13- 
The clutch is slipping
| Problem | Possible 
cause  | 
Clutch 
slips   | - 
Wrong oil type, 100 % synthetic with automotive additives, automotive oil. It's 
necessary to come back to a specified oil after having cleaned or changed the 
clutch discs - 1000 120°: insert a extra steel plate between the two friction 
plates that usually run against each other  | 
14- 
Excessive clutch stiffness
| Problem | Possible 
cause  | 
Excessive 
stiffness   | - 
Cable is not routed correctly (no sharp angles) - Cable and levels are not 
lubed correctly - Worn balls and/or rods inside the mainshaft - 1000/1200: 
Wrong clutch drum type (several lenghts were available)  | 
15- 
Problems with bearbox selection
| Problem | Possible 
cause  | 
Selection 
is imprecise, wrong neutrals, one or several gears don't run  | - 
Eccentric screw incorrectly set: Adjust the eccentric screw for equal up and down 
movement with the gears shifted into 4th gear (not neutral) - Washers between 
selector case and selector spring incorrectly set or missing - Worn selector 
drum spring - Worn selection system (too much play)  | 
|  
Gearbox blocked on only one gear | - 
Selector spring incorrectly fitted: Curved end should be to the top. | 
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