1983 Suzuki GS750E/ES running real bad.

[Bikeman982]

My bike started acting real funny today.
It would stall and then not start right away. I did get it running and at different times it would start to die. It took awhile but I got it started and then it died when starting out in first gear. I got it going again and started out and it acted like it was running out of gas. It had over 1/4 of a tank, but I barely made it to a nearby gas station and filled it up. It ran the same - barely. I can't tell if one or both of the plugs are bad, the coils are bad, the fuel is blocked, or if something else is causing it to be very erratic on running. At times it would be great, then all of a sudden stall or act like it was not getting spark or gas - skipping and the engine would stop. If I was going along I would downshift and then pop the clutch after it stalled and it would run again. It was bad at stop signs and at red lights. Sometimes it would start up and then stall when I started to go, other times it would be dead and would not start for a minute or two. I would push it to the side of the road, then start it up and try to go again. Other times it ran normal and would idle fine. What could possibly be causing this kind of intermittent problem? I am almost afraid to try and ride it again. I don't want to be stranded somewhere. I don't have any way to get home, if it fails to start up or run again. Should I just start by replacing the spark plugs, maybe the coils, or check all the carbs for bad jets or clogged lines or bad fuel?? What could it be? It really has me baffled. Anyone have any ideas??

[Mark whiz]

definitely sounds like an electrical situation. My '85 GS700 acted similiarly and it finally took an igniter box to solve the issue.

In your case I would start with checking the battery and charging system. Check the charge of the battery (specific gravity check of the electrolyte) and the voltage with the ignition switch off. Voltage should be at least 12v, then get it running and check the battery voltage with it rev'd up to at least 3000 rpm - you should see anywhere from 13 to 15volts.....................anything above or below that indicates that your charging system ain't up to par. For troubleshooting that, you can search the forum here for the "Stator Papers" for good info on finding charging issues.

[Suzuki mad]

Sounds like a CDI/ignitor unit failing to me. Somethings getting warm and then letting go.

Suzuki mad

[Billy Ricks]

Did the bike sit for any length of time with fuel in the carbs?

Here are some tests you can run on the ignition.

Remove spark plugs 1 & 2 and ground them to the motor so they will fire when they get power. With the ignitor facing you, the plug on the right side of the ignitor is where the signal generator plug fits. The two terminals on the right side of that portion of the ignitor will be pin 1 at the front and pin 2 at the back. The two left pins will be pin 3 in front and pin 4 at the back. Turn the ignition switch on. With a multitester set a the X1 ohm range put the + probe on pin 2 and the - probe on pin 1. Plug number 1 should fire. Next put the + probe on pin 4 and the - probe on pin 3. Plug number 2 should fire. If this happens the ignitor is good and the signal generators are suspect.


As for testing the pickups, signal generators, measure the resistance between the two wires on each pickup. You should get somewhere around 130-200 ohms. If the resistance is infinity or less than spec they are shot.

To test the coils put one probe of the multitester on each of the terminals on the primary side of the coil. You should get 3-5 ohms. Check the secondary windings by placing one probe into each of the plug wires coming from one coil. Those would be 2 & 3 from one coil and 1 & 4 for the other. You should get 30-50,000 ohms for stock coils and 15-20,000 for aftermarket.

[Bikeman982]

Igniter box bad?

What does the igniter box do and how do I know if it is bad?
Can it work intermittently?
Can it be tested, or do I just need to try another one?

[Pearson]

Is it electrical or fuel?

When you say it wouldn't start right away, what was going on? I had similar problems to what you're describing with my '78 750. I don't tighten the fuel cap as tight anymore.

[kingofvenus]

Had a battery short out on mine and it would hardly run, but the lights would also dim. So, I'm betting it's an ignitor issue. Run a full set of tests first tho.

[Steve]

What does the igniter box do and how do I know if it is bad?
Can it work intermittently?
Can it be tested, or do I just need to try another one?

The igniter box is just an amplifier. The signal pickups that are located on the right end of the crank will send a pulse of current that is triggered when the crank reaches a certain position. The igniter box amplifies that pulse and sends it to the coils, which then amplify it enough to show up as a spark at the plugs.

Since it is ALL electronics, yes, it can operate intermittently. Things that can make it intermittent include heat and vibration. The transistors inside can do flaky things when they get warm, and the solder connections can sometimes come apart due to vibration. Guess what our bikes have plenty of? Yup. Heat and vibration.

Yes, it can be tested. Billy Ricks gave one way to test it. I did it another way that was quite a bit more involved, but showed me what I needed to know. There are two basically similar amplifiers in the igniter. One is for cylinders 1&4, the other for 2&3. I was only getting fire on two plugs, so I swapped the input leads, then the spark plug leads, and found that I was now getting fire on the other two plugs. This told me that one half of the igniter was not working, because now the other coil was working, as was the pickup.

Good luck just "trying" another one. You might be able to find one on eBay for a reasonable price, but be aware that a new one from a dealer is over $400. :shock:


.

[geerhead]

Try this.....

http://cgi.ebay.com/ebaymotors/1985-SUZUKI-GS700E-GS700-TESTED-CDI-BOX-IGNITER_W0QQitemZ270124144670QQihZ017QQcategoryZ35594QQrdZ1QQcmdZViewItem

I managed to pick up a spare ignitor last week for $15. Good luck.

[Bikeman982]

When I said it would not start, I meant that when I pulled in the clutch, with the kickstand up, and the bike in "neutral", and pushed the "start" button - nothing happened. I could take my finger off the button and try it again several times. After some attempts it would start right up. I could also keep my finger pushing the button and after maybe ten or twenty seconds it would start right up. Sometimes I turned the ignition key conterclockwise to "off" and then turned it back to "on" and tried the "start" button. Sometimes it started and other times it did not. There were times it started up right away, and other times I had to physically push the bike over to the side of the road (cars behind) before I got it started. Sometimes it would start and run fine, other times it would stall immediately and I would go thru the process again.
I don't have a tightening gas cap, just one with the key that opens or closes it. I don't know that I could put it on any looser, or tighter.
I will get an igniter from e-Bay and then see if it makes a difference. I don't have the time (or the technical expertise) to get a meter and check for voltage/current, etc. I know how to swap out parts and how to remove and replace electrical components. Thanks for the suggestions - keep them coming. I will keep you posted.

[chef1366]

Clean the kill switch. Clean the ignition switch with WD-40. Clean the starter button. Bypass the clutch safety switch by following the wires into the headlight bucket and remove the male and female ends and connect them together.
Check battery connections and clean the main ground off the battery to the engine case.
If these don't work change your petcock with a new one.

[Bikeman982]

You don't think it is the igniter?
Maybe it is the sidestand switch? It was on one time with the sidestand up.It is only supposed to be on when the sidestand is down, but that should not affect starting or running, since it can run/start with sidestand up or down.

[chef1366]

I don't know. I would just do the basics before forking out mucho dinero.($$$)

[moto_dan]

I will get an igniter from e-Bay and then see if it makes a difference. I don't have the time (or the technical expertise) to get a meter and check for voltage/current, etc. I know how to swap out parts and how to remove and replace electrical components. Thanks for the suggestions - keep them coming. I will keep you posted.

Removing and replacing components without thouroghly troubleshooting the problem can lead you to unnecessary expenses and frustration when after R/R components the condition still persists. Bottom line if you're gonna work on these old bikes either you need to have deep pockets or obtain the tools and knowledge to DIY. Members on this board have literally hundreds of years accumulated experience and have assisted many with even the most complex of problems. Be patient and your bike will once again live.

[Bikeman982]

Still running badly

Today I took the gas tank off and drained out the fuel. I removed the petcock and cleaned it. I took out the CDI to get the numbers off it. The CDI looks new. I put the petcock back together and back on the gas tank and then put the tank back on the bike. I put the fuel back in and the CDI back on and started it up. I was going to take it for a ride, but after warming it up and letting it run for a few minutes, it stalled when I put it in gear. It did not start immediately but eventually it started up again. I let it idle for a few more minutes and it just suddenly quit while idling. It happened a couple of times like that, so I put it back in the garage. I can tell it is not running any better and I may need to get another CDI, or maybe the carbs need cleaning?

P.S.
When I took off the gas tank I noticed two wires (orange and a white one) for the front brake switch were not connected to anything. I checked the schematic and it showed an orange/green and a white wire for the front brake light switch. I could not find any connection for the two wires - is it supposed to have them?
Is there a front brake light on the instrument cluster somewhere??