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Discussion Starter · #1 · (Edited)
Hey there all,
i have been working on making this 91 bandit 4 reliable for years now and im about at wits end.
I just finished rebuilding the top end ( gaskets valve seals cyl hone ect.) and went for the test ride, i made it about 5 miles and thankfully about a mile and a half from home when at a stop it dies on me. it would start but would not take any gas. it would rev on the choke but would not take anything from the throttle. when i got home i diagnosed that it had weak spark. but was getting fuel (edit)( i had checked the spark that morning before the test ride and it had a nice good spark so what ever happened fail within a few miles)
so i think it could either be the coils or the ignitor
is there anything else i could be missing as both of those bits are rather expensive and im a bit broke at the moment.
thanks again
RW
 

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Check your plug wires and boots first. Make sure they aren't loose or decayed. See if you get spark out of them. Since you had spark earlier, my assumption would be coils first. See if you are getting spark on the 1/4 or 2/3 coils (assuming your bandit is the same firing as my gs). If you get spark on one bank, switch plug leads and see if the problem also moves. If you get no spark at all, check your wiring connections to the coils and grounds. If all else fails, test your ignitor.
 

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check all HT conections first ,also battery conections. How long has tha bike been laid up while you was working onit?
 

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Discussion Starter · #4 ·
ehh i might as well tell the whole damn story
i bought the bike 5 years ago as a non runner as a first bike for my gf at the time. i brought it home popped in a new (used) ignitor p/o had opened the original one up and it was just a circiut board sitting under the seat. i was fairly new to bikes at the time so i paid a big shop to rebuild the carbs( which they didnt they just cleaned the passages) and she was running for a few months. at the end of that season i was riding her about 200 miles to my parents house and she was running like crap no power had it pegged the whole time just to stay at 55 and about twenty miles left to go she died out and wouldnt restart.
then school got in the way and she sat at my parents house while i rode my other bikes. for about 2 years. my fiance got interested in learning to ride so i dug it out popped in a new to me still old as crap coils. battery and rebuilt the carbs myself. and balanced them. and she ran for a few months ok but still not perfectly dialed in.
i started hearing some valve tick so i pulled off the head and cleaned the valves replaced the seals and cleaned everything else up with new gaskets. she had last run in november last year ( we bought a house so havent had a whole lot of time to work on her)
thats where im at as far as history
when i was checking for spark last time all seemed to be consitantly weak i will double check this tonight. the coils are pretty bad i was saving for some accel coils to replace them but we are getting married in a month so funds are a bit lacking. the ht wire are a bit loose on some but if the spark is bad across the board then it seems hard for me to accept that all of the plug wires are bad.

also any idea how to test the ignitor the manual specifys a special machine that i doubt anywhere round my small town would have.

i will play around a bit more tonight thanks for all the help
RW
 

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ehh i might as well tell the whole damn story
i bought the bike 5 years ago as a non runner as a first bike for my gf at the time. i brought it home popped in a new (used) ignitor p/o had opened the original one up and it was just a circiut board sitting under the seat. i was fairly new to bikes at the time so i paid a big shop to rebuild the carbs( which they didnt they just cleaned the passages) and she was running for a few months. at the end of that season i was riding her about 200 miles to my parents house and she was running like crap no power had it pegged the whole time just to stay at 55 and about twenty miles left to go she died out and wouldnt restart.
then school got in the way and she sat at my parents house while i rode my other bikes. for about 2 years. my fiance got interested in learning to ride so i dug it out popped in a new to me still old as crap coils. battery and rebuilt the carbs myself. and balanced them. and she ran for a few months ok but still not perfectly dialed in.
i started hearing some valve tick so i pulled off the head and cleaned the valves replaced the seals and cleaned everything else up with new gaskets. she had last run in november last year ( we bought a house so havent had a whole lot of time to work on her)
thats where im at as far as history
when i was checking for spark last time all seemed to be consitantly weak i will double check this tonight. the coils are pretty bad i was saving for some accel coils to replace them but we are getting married in a month so funds are a bit lacking. the ht wire are a bit loose on some but if the spark is bad across the board then it seems hard for me to accept that all of the plug wires are bad.

also any idea how to test the ignitor the manual specifys a special machine that i doubt anywhere round my small town would have.

i will play around a bit more tonight thanks for all the help
RW
Alright, good background info.

Carbs: Did you take out all the jets and run some wire thru them. New orings? Did you sync up the carbs and set the float height correctly.

Valves: did you check the valve clearances, too tight valves will make you lose power and worse.

Ignition: I'm going to regurgitate some info;
Easiest check is to see if the voltages on the coils are correct. The plus side should have +12V all the time with key on and kill switch activated. If not you have a wiring issue.

The negative sides should go alternatingly up and down +12V and 0.5V as the engine cranks (1-4 and 2-3 are also out of phase). If it doesn't then the ignitor is probably bad.
volt meter on the negative side of the coil, the voltage should go between 12V and 0.5V as your crank over the engine.

If there is no 12V then there is something in the harness, if there is no 0.5V then there is something wrong with the ignitor.

The ignitor will alternate between the two coils.
On a coil ,remove plug caps - measure plug wire to plug wire (stick probes in wires)- should be about 12 kohms. It's tricky to measure over plug cap to plug cap due to corrosion and caps' resistance, but a decent reading might be 24 to 34 kohms.
Taken from http://www.thegsresources.com/_forum/forumdisplay.php?f=133

If you don't have the service manual for the bike you can find it here for download;
http://carlsalter.com/pdfs/Suzuki_GSF400_Bandit_91-97.pdf

If your coils are bad, cross ref the part number on a parts site and see if they also fit the larger bandits or katanas or gs500's. If so, I may have a spare set of used but working coils you can have. Assuming you are in the states.

ALSO, what Rob said. Check your grounds first. Might as well start with the simple.
 

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Discussion Starter · #6 ·
thanks for the info
carbs
i rebuilt the carbs completly im a goldsmith so i have an ultrasonic. i took everything out jets floats if it could come off it did. new jets new needles new floats and new gaskets i was having problems with the carbs and i wanted to start fresh. i balanced the carbs then but i havent since i rebuilt the engine.
valves i set the valves at the loosest spec that was still in range so good there.

i got a tin of contact cleaner im gonna clean all of the contacts and make sure every thing is tight then test the coils
Thanks for all the info
RW
 

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Discussion Starter · #8 ·
well i got a chance to work a bit tonight.
i tested the coils just on the sparky end and got a consistent 12kv so that test was good. however i was cleaning every connection i could find earlier and i noticed the low voltage side of the starter solenoid was held on by a strand so i went out to get a bullet connector and when putting it together i accidently touched one of the low power sides of the starter solenoid to the high power side big sparks everywhere wooo....
well i get everything connected and i thumb the starter and nothing not even a click.
i go to check the fuse and i notice that there is a 25 amp fuse in the ignition side where a ten amp fuse should be! i can jump the solenoid to turn the engine but it figures it is the wire that connects the ignition key, thumb switch sidestand switch clutch switch ect all together.
any ideas before i start tearing everything apart? or am i missing something right in front of me?
can you tell electrocity is not my top mark
thanks RW
 

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well i got a chance to work a bit tonight.
i tested the coils just on the sparky end and got a consistent 12kv so that test was good. however i was cleaning every connection i could find earlier and i noticed the low voltage side of the starter solenoid was held on by a strand so i went out to get a bullet connector and when putting it together i accidently touched one of the low power sides of the starter solenoid to the high power side big sparks everywhere wooo....
well i get everything connected and i thumb the starter and nothing not even a click.
i go to check the fuse and i notice that there is a 25 amp fuse in the ignition side where a ten amp fuse should be! i can jump the solenoid to turn the engine but it figures it is the wire that connects the ignition key, thumb switch sidestand switch clutch switch ect all together.
any ideas before i start tearing everything apart? or am i missing something right in front of me?
can you tell electrocity is not my top mark
thanks RW
a 25 in place of a 10 is a big no-no! likely high draw on that wire. look for bad corrosion or a short.
 

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Discussion Starter · #10 ·
I had a few mins to play with it today. its been crazy here getting married in a week now and still havent made my ring!
anyway i made up a quick set of jumpers and went straight from the battery to the low power side of the solinoid and nothing happened. does this mean my solenoid is bad?
also i have been trying to trace this circuit in my manual and it appears to never enter the fuse box am i missing something?
RW
 

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If the siloniod is bad you can still jump it by putting a screw driver across both sides of it. From what you're saying it sounds like the solenoid. You can get them cheap on eBay just make sure you find a working one. Assholes on eBay will sell a bad solenoid and list for parts.
 

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If u r in the states. Go to a tractor supply or farm n fleet and grab a riding tractor solenoid. Same solenoid as any bike.
Congrats on the pending marriage.
 

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Discussion Starter · #13 ·
hey guys
so i finally got a new solinoid in and it works perfectly now im back into checking out my coil and such
Question when checking the circuit as described in

Originally Posted by posplayr View Post
Easiest check is to see if the voltages on the coils are correct. The plus side should have +12V all the time with key on and kill switch activated. If not you have a wiring issue.

The negative sides should go alternatingly up and down +12V and 0.5V as the engine cranks (1-4 and 2-3 are also out of phase). If it doesn't then the ignitor is probably bad.
Quote:
Originally Posted by posplayr View Post
volt meter on the negative side of the coil, the voltage should go between 12V and 0.5V as your crank over the engine.

do i just ground one side of the volt meter and connect the other side to the low side terminal?
when i do this i get about 8 volts and that drops when i crank the engine to about 5-4 volts and stays low.
am i doing something wrong?
sorry for my stupidity
RW
 

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Discussion Starter · #14 ·
Ok so I have determined that I don't get the 12v from the ignitor but I get the .5 volt so this is a wiring issue any idea where to start looking? Would this be a loose connection issue or maybe I burnt out a wire when I fried my soilinoid
Thanks
RW


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Discussion Starter · #15 ·
Ok I think I I have a bit more sorted I have power going into the ignitor and have tested the signal generator and that is fine but coming directly from the ignitor. So leaving out any possibility of a bad wire I get only 12 v going to one coil and halve a volt going to the other coil. They never alternate. So to me this means I have a bad ignitor. Does this seem right for anyone else. I could really use the help before I pay 400 bucks for a new ignitor
Thanks RW



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incoming pm,easier to diagnose via email or phone
 
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