Stock Bulbs  

For my GS850GT, and most other GS bikes, the stock bulbs are as follows:

Headlamp (recommended): Sylvania Silverstar H4ST - a high performance halogen headlamp, maximum 55w/65w with 7" round headlight.  Can be found at just about any auto store.

Stop/Brake lamp: Stanley 1034 - 12v, 23w/8w Turn Signal lamp: Stanley 1073 - 12v, 23w Gear Indicator Bulbs: 12v 35mA, 5mm dia. available from Parts Express.

Licence Plate lamp: Stanley 67 - The full Stanley part number is A41B 67, 12v/8w. Instrument lamp: #194 or #158 (miniture w/wedge base) is close enough. (OEM 12v/3.4w is hard to find.)

In many cases, a generic 2-prong FL-522 or 552 flasher can be used in place of the stock turn signal flasher. Note that this will disable the auto-canceling feature of your turn signals.

Tridon, Bussman, and others make 522 and 552 flashers.

Wiring Color Chart/Usage

Compatible Stators and R/R Units:

CLICK HERE for a list of compatible stators and FET regulator/rectifiers for the GS850 and other bikes.

A wiring diagram for 6-wire Honda r/r units:

Here is what I tried to do in modifying it [Phase A of the Stator Papers Fault Finding Chart]:

• Highlight with a table what you are doing in each step. I think this helps provide focus. I know when I was going through the table, I was not real clear what I was doing at every step in Phase A.

• The first step is to insure that the is some charging going on when you raise the idle up to 2500 RPM the battery voltage should increase. If it doesn't then you should still test and clean the connections in Step 2 and 3 but if the stator is bad, then you will get through all of Phase A and still have low output.

• Modify the voltage drop tests which are specified at idle to be less than 0.2 volts to perform the test at 5000 RPM and be less than 0.25V. This is critical as you could easily have less than 0.2 volts at idle and the have that voltage rise to 0.5-0.75 at 5000 RPM when the system is trying to push current to the battery. Depending upon the variability of the GS idle you might even be discharging and so the voltage drop will not even show up. This is probably the biggest issue in the diagnosis table.

• Modified the table to show an explicit 14.0-14.8 Battery charging range at 5000RPM. The is somewhat narrower than the Suzuki specificed 14.0 - 15.5V range. Regardless of the manual 15.5V at the battery is too high.

• Modified the table to insure that all three steps in Phase A are done even if you pass the output voltage range. This is important as the output voltage range is quite wide and it is not hard to com in with a 14.0V charging level due to some bad connections and in 2-3 months that corrosion has gotten worse and you are now charging at 13.5V. You would not really know this if all you did was look at the battery voltage. It is absolutely critical that the R/R is connected across the battery with low resistance and measuring the voltage at 5000 RM when charging is near maximum is a fool proof way of confirming proper operation.

[The following paragraph is somewhat speculative. I'd have to check a wiring diagram to be sure.] Some coil relay mod diagrams show that one of the o/w wires going back into the loom is left unconnected. While this doesn't affect the operation of the relay mod on the coils, it would seem to disable the kill switch. My kill switch still works.

Then I ran 2 wires (both red in my case, you may want to use different colors) all the way back to the relay next to my battery box. I had to be careful to label the wires correctly so that I know which one goes to the coils and which one goes back into the wiring harness.

I took a Sharpie and wrote on the plastic covers of the spade connectors (you've seen them on my r/r replacement guide and such). I came up with a little mnemonic to remember what goes where.

There are 4 connections on the standard relay; 30, 85, 86, 87. The power from the battery gets connected to #30. Then, like the car Mazda made years ago - Mazda GLC, the Great Little Car - I think "G-L-C" for the rest of the connections. G for ground. L for loom (another name for the wiring harness), and C for coils. (+)=30, Ground=85, Loom=86, Coils=87.

In this manner I used my Sharpie to write "+", "G", "L", "C", on the connections at the relay. The connections at the relay are all female spade connectors since the relay has the males. If I ever want to take the relay out of the circuit I can...

1. Pull the fuse on the hot wire to the battery.

2. Disconnect the "C" and "L" connections from the relay.

3. Use my short jumper, with male connectors at each end, to reconnect (C and L) the coil wires back into the harness.

My clutch interlock was not affected at all. I still have to pull the clutch in to start my bike even if it is in neutral.

If everything else is well-maintained in your engine, then even if you have some loss at the coils, there is enough spark to start combustion. But a good, fat spark gives you the most efficient burn. It's usually when the voltage falls below 10v that you really start having problems, especially if there is anything else wrong with your motor. These engines are so well designed that they can take a LOT of abuse before they quit running.

Here is a diagram I did for somebody doing the same thing some time ago. It only shows the lights, not the wires that come from the controls, etc., but it shows the original setup with a standard bulb, then how to wire in two LEDs that will allow the use of a single LED in the instrument panel.

Originally posted by Mr. Matchless

I pulled the tape off the wiring loom, removed the two redundant wires for the third phase charging and cleaned each wire full length with benzine.

Sprayed out all connectors and bullet connector boots with brake cleaner. Then dipped contacts in hydrofluoric acid for 5 minutes to clean the brass, dipped in clean water, sprayed with brake cleaner and finally sprayed with contact cleaner, left overnight and again cleaned each connector and conector block with brake cleaner. All connectors are now bright brass and the bullet connector boots look close to new.




(Optional) Next step is to add new wires for coil and horn relay mod as well as a 12v accessory point and then wrap the loom up.

As the most problems on these old bikes are usually electrical or fuel related I am trying to do this properly.

When you unwrap use "benzine" to clean the old glue and dirt of the plastic wires. It will not harm the plastic.

If you decide to rewrap use a well known brand of insulation tape, the cheaper types have the adhesive loosen in hot weather. The types without adhesive becomes a headache when it unwraps at the ends.

Stay away from wrapping with "rubber" tape, that usually is the expensive type with no adhesive and is stretched and bonds into itself. You will learn new words if you ever have to open the loom sometime in the future!

If you decide to use the split sprague type conduit for the wires, just note that it is going to be much wider in diameter at the head (due to the ridges) and coils area and may cause problems. Where you have enough space it will look very neat.

Also note stationary wires are OK in a loose tube, but in areas such as the head they are pulled and moved and may chafe individually against each other, when wrapped they bend and move together as one. Wires loose in a tube may feel better on the steering, but it is not really a good idea.

If rewrapping the complete loom, pull it out, put it on a large wooden board and put some nails at the ends and junctions. Take a few photos.

Unwrap and use cable ties to hold them together at intervals and at the branches. Clean the wires with a benzine soaked cloth. Inspect the wires and replace if too short or damaged. Decide if you are replacing all connectors and connector plugs and have them at hand. Remove wires such as the 2 stator 3rd phase wires that is not to be used again. Add you coil, headlight and or horn relay wiring. Relace any wires with heavier gauge if this is required.

Now make sure that your wires are clean, straight without any kinks and nicely laying alongside each other and eleiminate any crossovers. Keep them in place with a couple of cable ties.



Some looms have a split sheathing around the wires under the tape to protect the wires, especially in areas where there is movement. Replace this or reuse, but fold it over as tightly as possible to keep the diameter down. Pull the wire tight at each end of the tubing and wrap the wires for an inch or so and over the tube.

Now start wrapping from the center moving towards the ends, so as to eliminate any slack and crossings causing bulges being trapped, At the end overlap the wrapping a few times and move back a bit so as to not leave an end that can start peeling back. Always stretch the insulation tape so that it just starts stretching as you wrap. Try to keep the wires parallel with each other, crossing over is untidy and makes the bundle thicker. Remove the cable tie as you get to it.

Finally make sure you have wrapped the complete loom and the branches as it was done originally. This will keep out water grime, protect the wires and make the loom look good again.

Mr. Nessism adds:

Deoxit works well to clean electrical contacts...CLICK HERE for a source and more info. 
There are different formulas. I think the D100S version has the strongest cleaning power.

1. Basic test, remove spark plugs. Fit them to the plug HT leads and ground them to the engine. Turn engine with starter and see if plugs spark. If any one spark plug does not spark swap it out. If the spark seems good on all 4 plugs, the ignition system is very likely in order. If spark is not present or very weak proceed with the following tests.
2. Remove the tank, left side cover, seat and signal generating unit (pickup) cover at bottom right of engine.
3. A good habit is to check the coils and igniter to see if they do not get very hot once the ignition is switched on, as this will most likely be the indication of a failed component of faulty connection or wire.
4. If the spark is weak but present, inspect the HT leads and plug caps. Suspect coil wires and spark plug caps, or voltage at the coils and thus the battery condition. It could also be due to coils with partially shorted windings, but do not jump on this cause immediately, and they may get hot.
5. Overheating coils with no spark may also be due to them getting a permanent full ground either from a faulty igniter or a grounded and pinched wire. Disconnect the coil plug connectors and proceed with tests.
6. Measure the battery voltage directly across the battery terminals. If lower than approximately 12.6V first charge battery fully before proceeding.
7. Next measure voltage over the coil connector plug, orange/white wire and the battery negative terminal. If lower than 12 Volt inspect the wiring for poor contacts and localise cause of voltage drop.
8. Again measure directly across the battery, but pull off the spark plug leads to prevent engine from firing and swing with starter. While starter is turning the voltage should stay at least above 11 Volt. Also swing the starter with the headlights on to see that the voltage does not drop significantly at the coils while the starter plus headlights load the battery, which could prove that even if your battery is fully charged, it cannot give full or sufficient current and is on its way out or your starter may be drawing excess current (usually unlikely if starter is spinning at full speed) and pulling the battery down. If it drops much lower, charge battery fully or have it load tested and replaced if faulty.
9. If all is well up to here you can assume your battery and the positive feed to your coils are in good order.
10. With the coil plug connectors disconnected, use an ohm meter and measure the resistance of both windings on each of the coils. Exact resistance measurements are not too important, but continuity of the windings close to the approximate resistance values given indicates that the coils are in good condition. It must be noted that it is possible for the coils to only show up a fault when at higher operating temperatures, but this does not happen frequently.
    Ignition coil resistance:
    Between the two HT plug caps of the same coil, secondary HT winding, approximately 30 - 35 K ohm
    Between the orange/white and white on the first coil and orange/white and black/yellow on the second coil, primary winding, approximately 2-5 ohm. If this test is within limits you likely have two good coils.
11. Locate the igniter and disconnect the plug with the blue and green wires coming from the signal generator (pickup) at the right bottom of the engine. Test the resistance across these wires coming from the signal generator pickup coils, it should be approximately 250 - 360 ohm. If this is in order you have proved the pickups and the wires to be good.
12. The little back box or igniter is now tested as follows. With the ignition on, kill switch on, test for 12 Volt DC between the orange/white and the black/white wires in the plug going into the igniter. This proves that it is getting the correct voltage.
13. The next step is to prove whether the igniter is powering your coils. Remove all 4 spark plugs and connect the HT lead caps to a spark plug #1, #2, #3 and #4 which is grounded and located to enable you to see the spark. Ensure all the connector plugs are back in, except the one with the green and blue wires from the signal generator.
14. To simulate the small voltage generated by the pickup coil, prepare an ordinary 1.5V dry cell with two wires red for positive and black for negative. Connect the negative black wire from the dry cell to the blue wire on the connector plug going into the igniter. Switch on the ignition and kill switch to power the igniter and briefly touch the red wire from the dry cell positive to the green wire connector going into the igniter. You should see a spark on plugs #1 and #4 when you touch the wire and on #2 and #3 when you remove the wire. If this works your igniter is in a working condition.
15. One other check that is often overlooked. Run the bike at night with all lights off in a dark area and check that no sparks are jumping from the HT leads to the frame or tank. If so they may need replacing.
16. At this stage if all tests have passed you MUST get a spark at all the plugs when everything is reconnected and the engine is turned with the starter.
17. If a spark that was previously missing has mysteriously appeared, have a very good look at your wiring and connectors, as something may be making intermittent contact and corrected itself temporary when you moved the wires.
18. If there is a spark, but the engine will not fire, it could be due to ignition timing, valve timing or fuel problems. Ignition timing and valve timing problems are more likely on a bike that has not run yet after being disassembled and more unlikely to be the cause if the bike was not taken apart and was running before.
19. A quick test with a few drops of fuel directly into the cylinders before replacing the spark plugs and then trying to start will prove it to either the fuel system or ignition system.
    1. If the engine then starts and runs for a few RPM's the ignition is correct and you need to look at the fuel and carburettor side.
    2. If the engine does not fire, but occasionally gives one load pop through the carburetors or even exhaust, it may be igniting when the valves are open, the valve timing may be a problem, cam chain or swapped wires from pickup - plugs firing at wrong time.
    3. Other reasons could be extremely low compression, too tight valve clearances, thus not closing fully (usually unlikely on all cylinders at the same time, but plausible), carburettor faulty or dirty, fuel line, filter or petcock faulty. Filter can cause an airlock if not positioned properly to allow free gravity feed.
    4. Then finally the ignition timing must be set properly. At less than 1500 RPM connect a timing light to #2 or # 3 spark plug and check that the timing marks line up for 2-3 on F, then move to #1 or #4 spark plug and check that marks line up for 1-4 on F. Check the advance by pushing revs up to 2350 RPM and the timing marks should both line up on the 45 mark behind the signal generator mounting plate through the sight hole at the top. The three mounting screws can be loosened and the mounting plate can be moved slightly in the elongated holes to meet this.

for those of you who might be building a new wiring harness for your bike:
http://livetorideridetochurch.blogspot.com/2010/09/i-love-these-types-of-diagrams.html

Right-click and save this diagram:



Here's a diagram drawn up by the GSR electrical guru, Jim (posplayr) for a GS550 but can be adapted for other bikes:
550_Schematic.pdf (about 350kb)