I have tried to make up a complete checklist for both ignition and carburettors. Work down this list systematically, then there's a good chance you get your bike running
Invitation to forum members, if you can add to this list, please do!
Note: never connect the transducers to 12V, as it will destroy them permanently.
1) Spark on the sparkplug? Yes, sparkplug shows a spark, but engine won't start.
a) Check the ignition timing with a strobe (timing of the spark at tdc).
b) Set the gap between the electrodes at 0.5mm. Standard gap of 0.7mm of new sparkplugs is too big for black transducers.
c) Take off the magnet of the pickup, turn it 180 degrees and put it back.
d) The red pickup cable with the markering "1" should be connected to the transducer of the front cilinder (see picture 1 below).
e) Pickup housing mounted the wrong way around (hardly possible). The arrow in the plastic housing should be at the down lhs corner (see pictures 2 and 3 below).
If this does not work, check the flow of petrol, part II.
2) No spark!
a) Coil of the ignition blown. Should measure app. 220 Ohm or more (max. 300 Ohm), but no less than 180 Ohm.
b) Transducer(s) blown or bad connections.
c) Please pay attention to all earth conncections. The earth connections on the frame should be bare metal. Make sure of this after a frame was painted or powdercoated. Also the earth connectors of both transducers should be bare metal.
d) Make sure the earth wires of both transducers are not broken. Use fine sandpaper on the connectors for a good earth connection.
e) Black earthwire of the pickup should also have a good connection to earth.
f) Magnets of the flywheel too weak.
g) Sparkplug cable oxidised on the side of the transducer, or on the side of the sparkplug.
h) Sparkplug cap broken.
i) Sparkplug broken.
j) Electrodes of the sparkplug should have a 0.5mm gap.
k) Mess-up electric connections.
l) Check the ignition switch. From the ignition switch 1 green cable goes to the fusebox. Take off only this green wire from the fusebox and try to start the engine.
Note 1: Only thing in this case: if the engine starts, you cannot switch it off with the key. Instead take off a sparkplug cap, or both.
Note 2: When you use the ignition key to switch off the engine, you connect the ignition coil to earth. So if the ignition switch is broken, the connection to earth is kept and you won't have a spark.
: Flow of petrol/gasoline
3) Engine won't start
Sparkplug does have a spark, all possible problems with the ignition have been investigated.
a) Old petrol/gasoline in the fueltank. It has been standing too long. Take out this stuff and use fresh petrol/gasoline. Also take off the float bowls of the carburettors and throw out the petrol/gasoline.
b) Check the electrodes of the sparkplug after start attempts. They should at least be wet of petrol/gasoline.
a) At the bottom of the fueltank dirt, rustparticles block the flow of petrol. Clean out.
b) The venting hole of the fuelcap is blocked. This blocks the free flow of petrol.
c) Filter of the fueltap is blocked with dirt. Clean out.
d) Filters of the Dellorto carbs are blocked with dirt. Easy to find. Take out the bolt of the cover on which the fuel line is connected. Below these covers there is a small plastic filter.
a) Water in the carburettors/floatbowl. Empty out the floatbowls.
b) Old fuel has turned into a kind of gum and has blocked the jets. First indication: thick green layer of gum stuff in the floatbowls.
c) Clean out jets.
i) use compressed air (never use sharp tools),
ii) clean out in an ultrasonic device,
iii) leave soaking in diesel fuel for a while.
d) Level of fuel too high or low, check out the floatlevel. Float could even have a leak. If there is fuel inside a float (hold it against light), replace it for a good one.
e) Float does not cut-off the flow of petrol due to a poor fitting float needle. This "drowns" the engine.
f) Engine sucks "false air". Check rubber parts between the cilinderheads and carburettors on cracks etc.