Sonya the money pit...

[IanZW95]

So guys, I have a 92 bandit 400. Her name is Sonya and she is the most frustrating thing I've come across in my entire life, and one of the most expensive. I got her for 1k back in about October of last year, and about a week and a half later she broke down. Since then I've spent a couple of months and about $1300 trying to get her back running. So far I've replaced the entire electrical system, and removed and cleaned then tank, installed an inline fuel filter, and most recently had the carbs professionally cleaned and rebuilt. And yet, she's still having the same issue. The bike will start and run just fine on the choke, and after about 10 minutes will isle with no choke, but as soon as I try to give it throttle, it dies and won't start again. So gentlemen, any ideas what I may be dealing with here?
  in advance for your help.

Ian

[interfuse]

I'd try removing the inline filter and see if it improves. I'd also try running the bike on prime to rule out problems with the vacuum line on the fuel tap.

[Nickelodeon]

Hey Man,

I just bought my bike last March. If you're ever near the Columbia area PM me.

Anyway, here's another thing to check:

When I first got my bike I did a bunch of stuff(including carb rebuild) and then rode it for a couple of weeks sorting out issues. The bike only had 18k on it when I bought it, but it spent time outside "rotting" before I scored it and was a little rough in some ways as a result....

After 2 weeks of riding it alot after most the work was done it was starting to act funny after it was warmed up...it started with it skipping @ high RPM and then eventually became more severe to close to what you're describing.

I checked both the coils and plug wires. Mine is a 91'. So all this ignition stuff is starting to get up there in age(20 years plus).

I found two things:

1. The plug wires were in horrendous shape, specifically where the plug boots on the engine side thread into them. To the point where the insulating material was brittle and falling out in small clumps. Being cheap, I tried to clip the plug wires back(they are integrated with the coils) to get to "good" material....to no avail. It turns out after a little investigating that I found out the insulating material in these types of wire actually gain resistance as they age...which leads me to point 2.

2. I checked the coils(cold at first, big mistake) and they tested fine resistance wise(I can't remember the ohms off hand, do a search here). But after clipping the wires back it still didn't stop the bike from running on two cylinders(or cutting out) after warming up...so I warmed it back up and quickly put my meter/ohms tester on the bike right after shutting her off...one of the coils was WAY out of spec.

So here's the deal, I don't know if the wires being so old, with such high resistance caused the coil to temporarily overheat...or if the coil was bad...or a combination of both....but I replaced both coils with nology coils and bought the cheapest set of accel solid core ignition wires I could find(on amazon) and clipped them to size.

Problem solved.

It might be something for you to take a look at if the carbs were rebuilt and you have fuel flowing well to the carbs.

[phoenix]

What all have you replaced on the electrical side and who did the carb rebuild? 

Huh, 3 Bandit 400s in SC, who would have thought.  Which one of you bought the grey one that was on craigslist?

[Nickelodeon]

Not me, I got mine off ebay from a boys home in Wisconsin. It needed a ton of work. If you are ever in the area on a Sunday morning PM me. 

[IanZW95]

What all have you replaced on the electrical side and who did the carb rebuild? 

Huh, 3 Bandit 400s in SC, who would have thought.  Which one of you bought the grey one that was on craigslist?

I've replaced the battery, the starter solenoid, the voltage regulator, the cdi box, and the plugs. I had the carbs cleaned and rebuilt at L.A. motorsports in Summerville (lamotorsports.net)

[IanZW95]

Once I get this sorted out we should do a group ride sometime

[IanZW95]

Huh, 3 Bandit 400s in SC, who would have thought.  Which one of you bought the grey one that was on craigslist?

I haven't gotten a close enough look to see if its a b400 yet but there's a guy pretty close to me that I see riding around on a grey bandit.

[IanZW95]

but I replaced both coils with nology coils and bought the cheapest set of accel solid core ignition wires I could find(on amazon) and clipped them to size.

Problem solved.

Do you have a part number for those coils?  If not do you know the ohmage that I need?

[phoenix]

Factory test has 2.5-3.8 ohms between + and - on the primary side, 30-50 Kohms on the secondary side.  Might try checking them after it's run a few minutes and dies. 

Are you getting spark at all after it dies?

[Nickelodeon]

My coil info:                                                                                                                                                 152 051 350 ProFire PFC-30D (3.0 Ohm System)
dual high tension tower
(Electronic Ignition - 2.4 Ohm Actual)                                                                                                                                                                                                                                                                     I had to make my own mounts, I used 1/2 or 5/8" aluminum square stock(cant remember) (need 2 coils for 4 cyl)

[AlanDog]

The bike will start and run just fine on the choke, and after about 10 minutes will isle with no choke, but as soon as I try to give it throttle, it dies and won't start again.

When I was getting this symptom on my bike, it was due to the idle mixture being too rich. Do you know what they're set at? Screw them in clockwise (all 4 carbs at once), maybe start at 1/2 a turn and see if the idle improves hot. But don't try any larger adjustments, they are very touchy. I think my bike can go from not running cold to not running hot with a single turn. Are your four cylinders running equally hot? (check this by spraying water on the exhaust pipes). This will help diagnose if a cylinder is 'bad'... but doesn't distinguish between ignition or carb problems... 

[TJS]

I hate electrics! They are expensive and take time to chase problems! I hope it's just you carb air mixture screw. mMine are set at 3 turns out.

[AlanDog]

Regarding replacement coils, there is a thread here about replacing the stock coils with "stick coils" which are on newer supersport bikes. The coil is integrated into the top of the spark plug cap, so each spark plug has it's own coil. Since only low voltage is fed to the spark plug cap, this eliminates the potential for problems with ignition wires. Here is the thread: http://forums.banditalley.net/index.php?topic=12808.0

I did buy this setup on ebay (like $33 on ebay for the harness and coil sticks) but never installed it because my bike is running fine without it. At the time I figured I could install it and that would at least rule out my coils and wires.