Bandit Alley
MODEL SPECIFIC => SUZUKI BANDIT 250 & 400 => Topic started by: Vested on May 16, 2011, 05:23:08 PM
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Hello! Glad to finally be a part of the board after going here so many times for various bits of info about the bike and possible mods.
Before the winter set in I bought a running GSF 400 from (August or September) 1992 and brought it to my apartment, where I disassembled it and moved it piece by piece into my house for a thorough cleaning and inspection. I've reassembled the Bandit after a long winter and nearly everything is working (sans "braking" light and the tachometer lights).
Now though it refuses to produce a spark. The coils (switched to stick coils, wired in series) read the correct primary and secondary resistances, as does the signal generator. 12V is getting to the CDI as well as both of the coils. Still though, while the engine freely cranks with a fully charged battery I can't get a single spark.
What are the steps to be taken to determine the cause of this issue?
Thanks for any help you can offer!
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Hi Vested,
I don't know if I have an answer for you, I'd just say that I would want to change one thing at a time. It looks like you changed a lot at once, then it didn't work. Is it possible to say go back to the original coils and see what happens, then try another component, etc? Take it from its last known working configuration and work towards the end goal?
Other than that, I really popped up to say :welcome: to the Alley.
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Hi there
Have you D/Led the service manual yet? It's probably the best place to start with electrical troubleshooting. Reading from section 8-6, it says under "No spark or poor spark" to check for defective plugs, coils, and signal generator/ignitor unit. Since I presume your plugs are new, as well as the coils, and everything is getting power except the plugs themselves, I'd guess, with my admittedly feeble and diminished knowledge, that the problem lies between the signal generator and the CDI. Maybe it's just a wire or a plug, maybe not.
Of course, I have bounced off my skull a few too many times, so maybe just get the manual!
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Thanks for the warm welcome!
I haven't tried switching one of the old coils on yet actually. Just waiting for a warm day and some time to give it a shot. As for switching components, really the only swapped components in the ignition are the battery and the coils. Everything else is as I received it.
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If you have access to an oscilloscope you can check if there are pulses being supplied to the coils from the igniter.
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Trying to borrow a friend's quite old oscilloscope soon, hopefully that turns up. However, as a short term test tonight could I just jumper a LED between ground and the signal generator lead to see if that's the problem? I'd think it should blink as the generator gets some current going in the circuit, proving weather it's faulty.
(as an aside, I did check the resistance of the signal generator and found it to be in the correct range per the manual. does this not always relate to a good generator?)
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Stormi wins! I misunderstood the coil wiring and had both coil sets wired backwards, with + to - and vice versa. While trying out the old coil packs I noticed they gave spark, at which point I switched the spade connections in the new stick coils and they gave spark too! Duh.
Now I just need to get the fueling down and all will be well!
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Stormi wins! I misunderstood the coil wiring and had both coil sets wired backwards, with + to - and vice versa. While trying out the old coil packs I noticed they gave spark, at which point I switched the spade connections in the new stick coils and they gave spark too! Duh.
Now I just need to get the fueling down and all will be well!
Yay!! go girl power!! :penguin:
I'm glad you got it figured!! Did you download the service manual? The wiring diagram should help you out with the brake and tach lights, etc if you don't have those sorted yet.
What's wrong with the fueling? Maybe I can go for 2 out of 2. :thumb:
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Haha! Glad that made you so...well...glad! Well deserved!
I've been using the service manual all along, though it seems a mite tricky. Some of the wires aren't matching up exactly, and I can't for the life of me figure out where the oil pressure sensor hooks up to the wiring harness...
As for fueling, I do need to make sure I'm getting spark to all four cylinders first, but as of this moment it's coughing without picking up, even when I spray a bit of starter fluid into the intake. Before I put the bike back together I did mess with what I now know to be the idle control, so I'm thinking that might be an easy cause of this. I also drilled out the stopper plugs for the A/F screws and screwed them in all the way, backing them out 2.5 turns.
So, thoughts? Want to make my life super easy? :grin:
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I've been using the service manual all along, though it seems a mite tricky. Some of the wires aren't matching up exactly, and I can't for the life of me figure out where the oil pressure sensor hooks up to the wiring harness...
Damn,.. without access to a bandit anymore, I don't know if I can help with that anymore. Perhaps someone else will chime in on that part.
As for fueling, I do need to make sure I'm getting spark to all four cylinders first, but as of this moment it's coughing without picking up, even when I spray a bit of starter fluid into the intake.
I'm pretty sure this still points to a spark problem. The thing should be able to fire on the starter fluid regardless of your A/F mixture position...
Other than that, it could be that the motor is just having trouble getting started after the work you did to it... That's what happened when we did similar work to Dita a few years ago:
http://forums.banditalley.net/index.php?topic=5277.0
Before I put the bike back together I did mess with what I now know to be the idle control, so I'm thinking that might be an easy cause of this. I also drilled out the stopper plugs for the A/F screws and screwed them in all the way, backing them out 2.5 turns.
So, thoughts? Want to make my life super easy? :grin:
I know that there are definitely posts in the 250/400 forum about the air mixture and stuff. Depending on where you're located, I wouldn't be surprised if there's someone who'd posted "optimal" settings for your bike already. Give a quick search, and see what's out there.
Let me know if you can't find anything and I'll have another look around.
hint: great names to pay attention to when you're searching:
thief400, gsxr400racer, interfuse, pitterb4. There are others, but I didn't make a proper list before they called my name for the academy award,.. sorry about that, and sorry to anyone I left out. It wasn't intentional. :stickpoke:
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theres a fair chance that the a/f screw you talk about are just the idle mixture screws.
they are pre set at factory and shouldnt be touched.
when its "coughing" are you using no choke,part choke, full choke?
if it sounds like its more likely to start on no choke than full choke, its prob to rich and is wetting the plugs.
if its trying to start at full choke, you are prob to lean and cant light it up.
to richen it up, wind the screws out half turn at a time. i've always found 4 turns out to be a better starting point for just about any motor, car or bike.
had one motor that needed 7 turns out to idle properly.
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The mixture screws have springs that keep tension on them. This is to keep them from moving due to vibration. The Mikuni tuning manual says that beyond 3 turns out the springs won't work. A lot of people have 4 turns out so that's probably conservative. If you needed 7 turns though you may consider changing the pilot jet.
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Arg, so it's definitely a spark problem. I've been taking the plugs out and grounding them on the frame to check for spark. Every once in a while I'll turn it over and the plug will healthily arc away at a steady rhythm. I even got it to fire up after which it ran fine outside of a lean issue. But today it once again refuses to consistently spark/fire.
As for the a/f mix screws, given the mods I've done (filter, exhaust) I figured it was better to set them up in the base condition and be able to modify them on the fly as opposed to having to take the carbs off and drill the plugs out after the fact.
So, what are the thoughts? Given that it fired and ran healthily on all four, I'm assuming it isn't a coil issue as that should be isolated to one bank. The signal generator as well is reading a happy 100 ohms.
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Hey Vested,
Any more progress on this?
I would agree about the A/F mixture, set it to stock and work from there. Just don't run it too long if it's really lean.
Couldn't be bad wires could it? I think it's Interfuse or PitterB4 who's had more than his share of headaches with the wires themselves. Original wires by now could be rather suspect.
If not that, I would still swap the original coils in and see if it runs right. Otherwise, you're sort of down to Signal generator / CDI....
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Progress yes!
I threw the original coils on to no effect, at which point I figured out hacking the cdi apart is probably the best answer. With a little soldering done I plugged in the box and tried starting it with a bit of starting fluid. Voila! Running bike. It wont start without the fluid though, and is slow to return to idle. The second I'll attribute to running lean thanks to the new exhaust and k&n, and the first maybe to the 7 month old gas? Thoughts?
Either way, thanks all and I'm sure I'll be around with more questions!
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Sorry to disappear on you like that, it's been a busy week!
So the CDI had some issues eh?? Well at least you got it sorted. :bigok:
I'd say your starting issue and your lean condition are related. Engines like to be rich when starting. That said, usually we flood the b4s quite easily by pulling too far on the choke ,... what's the position of your choke lever when you're starting? (ideally, we'd not be past about 1/4 - 1/3, but this may be different for you while you're running lean.....)
I'd say 7 month old non-stabilized fuel is definitely not helping at the moment. If you can drain and replace, that would be a good idea.
Our bikes, because they're stored for up to 7 months of the year are stored with full tanks, but we use seafoam to help the gas not go stale.
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No worries, I've been in the same boat with a move! Also, yes, the CDI was the missing link in the chain of sparking, and thankfully took well to some new caps!
My choke was at full out while starting. I'm moving the bike to my new place tonight, and then will hopefully be able to drain/swap the gas and see what that does.
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Yay!! A lot of people here have had to do a similar surgery, I'm glad it worked out for you.
K,.. if it was full out, and still sounds like it was lean, you may want to look at the cable and see if it's actually pulling at the carb end. Sometimes they break / seize / who knows and stop doing what we expect. I would think that at full out you should still have been able to flood the bike,... what happens once the bike is running and you move the choke lever? does the idle change? Because at full choke, it should have been racing...
Also check your idle speed setting. The two of these together can cause some really strange starting / initial running issues.
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I'll double check the cable, but before I remounted the gas tank it was working fine in terms of pulling the little slides out. As for idle speed, I have that pretty well set up, idling around 1300 rpm.
So, today. I get the bike fired up, finalize the seat mounting and such, and strap on my helmet. Clutch in, bike in neutral, and I click it down into first, at which point it instantly stalls. I tightened the clutch cable, unscrewing the set screw at the clutch lever until it was pretty tight, and tried again. Again, it stalled the second I went into first, holding the clutch all the way in. Both times it stalled I felt a tiny bit of a forward kick, which makes me think it's catching even though the clutch is in.
One note: I did have the clutch lever pulled tight for about 3 weeks with a ziptie while I was trying to diagnose the spark problem. It allowed me to try to start the bike while having a hand free. Obviously I had it untied while starting it today, but I could see possibly fatiguing a spring through that period?
Thanks for any help!
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If I'm reading that right, the kick is pretty normal. I feel it all the time when throwing the VFR and 919 into gear. Heck, even the KTM for that matter.
K, first question is - what was the position of the sidestand while doing this? Because what it sounds like is one of the safety switches.
If the stand was down, it did exactly as it was supposed to.
If the stand was up,Check the proper operation of the clutch safety, neutral safety, and sidestand safety switches.
Otherwise, you really need to look at your jetting. A lean condition can cause stalling issues when throwing it into gear. You can test this by giving her a small blip on the throttle as you throw it into gear.
A lean condition will respond to this favorably, switch problems won't care.
There's a good chance that you can get your jetting into a reasonable zone without needing to change the jets, just by adjusting the air or fuel screws (check the service manual to see which one you have. It escapes both of us at the moment as to which one the b4 has.)
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Well, I feel like an idiot now. I actually pulled the sidestand switch because it was giving me some troubles (as was the clutch switch) when I was initially working on the bike. The manual made it appear as if you only needed it for starting, but apparently it's a requirement for running as well? I'll throw it back on and, if it's being a pain, just solder a jumper in before the switch.
As for the screws, the B4 has the air screws on the airbox side underneath little plugs. And as always, thanks! :)
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It goes something like this:
If the sidestand is down, the bike must not be able to take off under its own steam. So when the stand is down, it can be started, if in neutral and of course with the clutch all the way in, but if you throw it into gear, it will kill the engine (as you had happen)
I actually use that feature to my advantage. When I come to a stop, and am about to get off the bike, I throw the sidestand down with the bike in gear to stop the engine. That way (because of my process) I should never be able to forget to put the sidestand down and get off the bike, which is how a lot of bikes get dropped at the end of a long ride.
Of course it make r_outsider a little crazy I think, because he's hardwired to expect a bike to be in neutral if it's on the sidestand. So if he goes to move a bike that I've ridden last, he has a bit of a false start each time. :trustme:
K,.. so for the air mixture,.. I'd say turn them in a little, til the mixture richens up and the bike wants to start up better for you. (Then adjust your position of the choke lever accordingly)
Are you off the starting fluid yet?
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Double checked the manual and it's indeed on the engine side of the carb, not the airbox side, and the screw meters the flow of air/fuel through the fourth pilot hole. Given that, I should be screwing those out to give the engine a bit more fuel, correct?
As for the starting fluid I'm still definitely hitting it for starting, but that's with the old gas still in.
My overarching theory is generally one that aims for simplicity, so I might have to take r_outsider's point. :) The sheer amount of time I've spent with a multimeter checking switches in the bike has me ready to jumper out the sidestand and clutch contacts next time I have the bike apart!
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Correct, turning them out (counterclockwise) will richen the mixture. Mine are at 4 turns out, a quarter turn either way gives very noticeable acceleration problems for me.
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Hey awesome!! Thanks for piping up. r_outsider and I were trying to remember and were going to take a look through the manual to see if we could refresh our memories on which screws he was talking about, but didn't get very far last night. It's a lot harder sometimes when you don't have the bike anymore so you can run out and check something, or recent experience working with the bike.
I can't believe it's been almost a year since we let her go. I still miss her too.
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Everyone I've talked to that 'used' to have a B400 wishes they still had it. I am planning on keeping mine.
I took a ~3,000 mile trip on mine last week over the Rocky Mountains in Colorado. Since I'm adjusted for sea level here in San Diego I had to lean out the mixture using the above mentioned screws to keep it from stalling out (too much) in the high altitudes like Independence Pass at 12,000 feet.
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Plugged the sidestand switch back in, fired the bike up, and off I went! The bike sounded a bit off under low throttle, but the note firmed up nicely once I cracked the throttle a bit more. I do want to play with the fuel screws a bit, just didn't have the proper bit at the time. How will I know when I'm hitting the sweet spot, fuel wise? What's also the best way to spot detonation? I'd rather not explode the engine, you know...
To-do list:
Wire up resistors for turn signals
Figure out why speedometer isn't working
Get lights in tach working
Fuel screws for days
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For my mixture screws the initial acceleration gets worse when the idle mixture is too lean or too rich. So the sweet spot is the best throttle response. Engine must be hot and float levels must be correct before doing this or it's wasted time.
If you mean load resistors for LED turn signals, they are a big waste of power. They just shunt current so the flasher sees the same load as bulb turn signals. This gives you the same power draw as bulbs and less brightness so it's a net loss. If you want LED's then get the flasher made for them rather than load resistors.
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And again troubles. I've tried to run it a few times since I replaced the capacitors, and it's only fired up once. Though the signal generator is giving good resistance, I did want to pull the clutch cover gasket and make sure it was positioned close enough to the rotor to get a good pulse. Should I be able to pull the starter clutch cover without draining the oil, or is that a "wet" part of the engine?
I started unbolting it as I had thought it was a "dry" section but a couple drops started coming out so I quickly resealed the cover. I want to know whether this might be just an ounce of spillover from somewhere or whether draining the engine/tilting the motorcycle is required.
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OK,.. when you say it's not firing up,.. what -is- it doing? coughing? firing but not catching? do you smell fuel?
As for the clutch side of things,.. I know someone will pipe up here,.. but I'd say check the service manual. it will give you an order of disassembly. if one of the steps is "drain oil", it's a good indicator there should be oil there.
In a quick look online, it looks like it is a wet side (which was my first guess.)
I just can't help but think that you're going a long ways in, it seems like there should be a simpler solution... the bike was running before, you didn't crack any of this since, and now it's not running well. I really want to say it points to something external to the engine...
Speedometer: check the cable on both ends. On my Kaboom, it was a busted cable at the wheel end of things. Simple fix: Honda cable.
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It wasn't coughing or picking up at all. I swapped the ignition capacitors out for some higher quality Rubycon units and checked for continuity this weekend and, finding all to be good, threw the CDI back on and tried again. Right as the battery was dying out it caught and fired up and, not giving up the opportunity, I went out for a nice hour long ride. The next day I got it running with just a bit of starting fluid and choke.
I was thinking it might be the signal generator just because it has such a hard time starting up but no issues when running, when the signal generator will be generating the largest pulse. I was also worried about the signal generator alignment as the bike was knocked over a couple times while sitting in the street over the winter.
I'm taking her in to the local shop to check out the cable, as both the cable and housing are busted. If they don't have anything on hand I'll just order a new cable in.
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Side note: Are the valve clearances correct? Adjusting mine made a world of difference in start-up ease and idle smoothness.
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The other thing that might help is balancing the carbs.
It looks like you've got it largely sorted now! :congrats:
Don't forget to check out if the bike is running lean. A lean bike is also harder to get running, and you should long have been off the starting fluid by now.