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General GL1000 Troubleshooting Guide

You might consider this item: Randakk's GL1000 Carb Rebuild Video

Note: You should do a valve adjust and compression test (in that order!) before doing ANY ignition or carb tuning. GL1000s will run poorly when valve lash is not set exactly to spec. Fortunately, valve lash stays "in spec" for a long time once properly set.

Note: Valve timing on a GL1000 is critical. Verify that your cambelts are installed correctly. The "match marks" on the flywheel and the cam pulleys must align perfectly. The GL1000 is an interference design engine. If your belts are off by 1 tooth, your engine will run like crap. If your belts are off by 2 or more teeth, serious engine damage will occur immediately.

Note: Keep in mind that all ignition issues must be perfect before carb work is undertaken.

This includes coils, plug wires, plug caps, spark plugs, ballast resistor, breaker points, condenser, ignition advance mechanism, ignition switch, kill switch, main fuse, battery and all associated wiring harness components.

Ignition performance and timing is critical on GL1000s! Ignition problems often mimic carb problems to an untrained ear.

Potential Ignition Problems:

Faulty coil and / or spark plug wires. Check using the method here
Dirty, pitted or poorly adjusted points
Problem with Ballast Resistor and/or it's wiring
Spark plug caps...check for for excessive resistance (should be about 5,000 ohms max). This should be a secure, screwed - in connection...you shouldn't be able to easily pull it out of the cap.
Problem with wiring from coils to points. Typical problem areas include the junction with the condenser assembly (to the left of the battery) and the "pigtail" which connects to the actual points assembly...very easy to have a short or partial short here.
Bad condenser ...did you replace? Put the old one back as a test.
Weak battery - one classic sign of a weak battery is a tendency for a the engine to fire right after you release the starter button.
Bad ignition switch, kill switch and / or associated wiring
Bad main fuse ... these can fail without "blowing"...results in intermittent high resistance to entire wiring harness.
Timing advance mechanism not operating freely.
"Dead" cylinder is usually an ignition problem. Can be a carb problem...especially if it is rpm-specific.
Faulty stator, rectifier or voltage regulator. GL1000s require full function of the charging system for the ignition to perform as designed. If charge voltage is substandard, ignition performance will suffer dramatically.
Electronic ignitons (like Dyna) are typically powered throught the turn signal circuit. If the fuse for this circuit blows for any reason, you will lose your ignition. Yet another reason to carry spare fuses!

Potential Carb Problems:

Implement the "off idle" fix (recommended for '75-'77 models only).
Simple problem of carbs out of synchronization. Did you sync properly?
Idle speed set too high (at a certain rpm level the ignition advance is activated which can cause an oscillation in idle speed).The correct idle speed is about 950-1000 rpms (measured with a real tach...not the one on the bike). Some bikes perform better with curb idle of 1050 rpms or so. Don't go beyond that idle speed or you will begin to activate the progression circuits in the carbs.
Big vacuum leak (did you use new intake o-rings?Did they move out of position?)
Check intake rubbers for cracks?
Sticky" vacuum throttle slides - did you polish the slides and carb bores?
Binding throttle linkage, not enough slack in throttle cables, missing or broken springs in throttle linkages.
Binding choke linkage or shafts ... choke butterflies are controlled by spring pressure...not direct mechanical connection.

Overly rich mixture for any number of reasons:

poor synchronization (causes rich idle and plug fouling at idle due to premature involvement of progression circuits on 1 or more cylinders)
worn jet needles or needle jet holders
clogged jet holders (emulsion tubes)
clogged secondary or primary air jets
clogged pilot air jets
secondary and primary air jets reversed
aftermarket jets poorly sized
jets modified by previous "mechanic"
deteriorated internal o-rings in carbs
bad central plenum gasket
float levels too high or poor alignment
floats "fouling" on side of fuel bowl.
floats "hanging" due to bent float pivot pins
floats "hanging" due to pivot bores on floats that need reaming / alignment
defective floats saturated with fuel or other bouyancy problem causing them to ride "low" (rare)
dirt in float needle valve
"sticky" throttle vacuum slide(s)
leaking float valve assembly (seat and/or needle valve worn out)
aftermarket float needle valve and seat assemblies (notorious for leaking!)
idle mixture screws set incorrectly
aftermarket jet needles - incorrectly sized
dirty or aftermarket air filter
deteriorated or missing rubber blanking plugs (over idle jets)
aftermarket exhaust
high fuel pump pressure
faulty carb bowl gasket
loose carb-to-plenum bolts

Overly lean mixture for any number of reasons:

vacuum leak
clogged primary or secondary main fuel jets
clogged internal fuel passages
clogged idle fuel jets / circuits
clogged idle by-pass transfer ports in throttle bore (3 in each carb...under "puck")
clogged idle nozzle jet
clogged jet holders (emulsion tubes)
secondary and primary air jets reversed
aftermarket jets poorly sized
jets modified by previous "mechanic"
bad air cutoff valve or leak where air cutoff attaches to plenum
clogged vacuum signal port for air cutoff valve (on carb #1)
cracked vacuum hose(s)
crack in intake rubbers or defective intake o-rings
float levels too low...or floats "fouling" on side of fuel bowl.
idle mixture screws set incorrectly
"sticky" throttle vacuum slide(s)
air filter missing, perforated or aftermarket air filter
aftermarket jet needles - incorrectly sized
aftermarket exhaust
low fuel pump pressure
clogged internal fuel screens (at float valve assemblies)
clogged external fuel filter
defective gas tank cap
obstruction in fuel tank pickups
dirty or stale fuel
loose intake runner clamps
loose / missing sync port screws
faulty carb bowl gasket
exhaust leak
"popping" sound can be from sticking intake valve

Weird loss of power with no other explanation:

Collapsed header. These headers are dual-wall construction which are notorious for internal disintegration. This can cause a partial or compete blockage of exhaust gases.
Choke linkage / return springs installed incorrectly. Can cause choke to be closed at all times!

REPEAT: ALL IGNITION ISSUES MUST BE PERFECT BEFORE CARB WORK IS UNDERTAKEN. This includes coils, plug wires, plug caps, spark plugs, breaker points, ignition advance mechanism, ignition switch, kill switch, main fuse, battery and all associated wiring harness components. Ignition timing is critical on GL1000s! Ignition problems often mimic carb problems to an untrained ear.

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