DEAD BANDIT AGAIN...

[SoEazy]

If you've seen my previous posts, you'd know I've been in the process of transforming my barn find 91 Bandit 400 into a runner. I've rebuilt carbs, upgraded the fuel valve, repaired the CDI (so I thought), put in fresh plugs and battery and thought I should have a ride-able machine.

Not the case.

After adding the new fuel valve, and swapping out the caps in the CDI... the bike ran beautifully but briefly. After starting and letting it warm up, I was able to rev the engine smoothly and even took it for a ride to the end of my street and back. But the engine bogged and died on the way back. I thought maybe there wasn't enough fuel in the tank since it seemed fuel-starved. A couple of days later, I added a gallon of gas, put on my helmet and tried to start the bike and... nothing.

I've since pulled and re-cleaned the carbs. I thought maybe I had a clogged pilot jet? Nope. The bike's got no spark again. So, I'm wondering where do I go from here? Should  replace the CDI with one from Wiel Tronics? Is there something I'm overlooking here? It seems strange for the engine to run perfectly, then loose fire again.

Any thoughts are appreciated. BTW, below is a design I did of what I'm hoping the finished product will be like.
 


Truly, there is no such thing as a free bike.   

[TJS]

Electric issues suck!
Get your manual, power tester, multi-meter, and coffee!

[B4Ben]

+1

and make that 2 coffees.

Firstly does the bike crank, or do you hit the button and nothing happens?
Does the ignition even come on?
Can you hear the starter relay "click" when you turn the ignition on?
if it does turn over but you have no spark at the plugs then you know you can work back from there

HT leads, coils etc etc

[Nickelodeon]

I actually had an intermittent starting problem, getting worse as time when on....it ended being the safety interlock via the clutch.

I had to start from the coil wiring and work my way back to find it....

Electrical issues suck.

I actually just chucked the switch entirely(one less thing to go wrong) and skipped the wiring in the headlight assembly(went straight from the sidestand switch to where ever the next wire went and removed the clutch switch circuit).

I don't think there's anything more dreary that chasing down electrical issues. That's the one down side to owning/running older bikes.

[tomacGTi]

My bet is on the ignition pickup: it's by the LH crankcase IIRC.

The wires break from the vibration or if it were me, the pickup cracked and oil got in shorting the reed switch. The manual will show you how to ohm it out.

I think it's $30 new from Bike Bandit if I remember.

[SoEazy]

+1

and make that 2 coffees.

Firstly does the bike crank, or do you hit the button and nothing happens?
Does the ignition even come on?
Can you hear the starter relay "click" when you turn the ignition on?
if it does turn over but you have no spark at the plugs then you know you can work back from there

HT leads, coils etc etc

The bike does crank over, it just has no spark. I've since reinstalled the side stand switch, so that doesn't appear to be a problem. I've removed/bypassed the clutch switch... So that can't be it. I am getting no spark from either coil, so I assume the problem is somewhere else. What are HT leads?

My bet is on the ignition pickup: it's by the LH crankcase IIRC.

The wires break from the vibration or if it were me, the pickup cracked and oil got in shorting the reed switch. The manual will show you how to ohm it out.

I think it's $30 new from Bike Bandit if I remember.

 I'm going to recheck this. I'm hoping it's the culprit. I would seem strange for new caps to blow in the CDI 30 seconds after starting. XXFingers CrossedXX

[B4Ben]

If it was any of the kill switches: clutch, side stand etc it shouldn't even crank.
As these are there to stop it starting in gear.

The HT leads go from the coils to the spark plug cap.
If you have no spark at the cap then you need to move back to the HT leads, then coils etc etc.

Checking random components in a random order will only ever equal random results.

What's the condition of the battery like? If its crap, it might be able to crank the starter but nothing more.

[SoEazy]

I got out the tester yesterday, tested the signal generator and wanted to make sure I'm reading the results correctly. The manual says the resistance should be between 80-120 ohms with the tester range set to x10 ohms. My tester showed a fully closed circuit with no resistance.

Does this mean the generator is bad? I've added a picture of the tester screen when on the signal generator leads. BTW, the battery is almost new and strong. Also, I am getting no spark from any plug. The bike ran and then next day it was dead. I assume this has to be a single component failure. Thanks for any help guys.

[tomacGTi]

It's bad. It's reading infinity so there's no resistance.

Pull it off and check the wires and inspect the sensor itself. If the sensor is broken, get a new one. I've soldered the wires together before and had it work.

When it fails, it's a no spark condition.

[SoEazy]

That was my assumption. There doesn't appear to be a place to test directly from the unit, it pretty well sealed up.  I guess I'll try and locate a replacement....

[wario]

The CDI systems are notoriously bad on these bikes... I recommend getting a new one off eBay.

[SoEazy]

Well, a new signal generator fixed it. I put my meter on the new one and got the same infinity reading? Anyways, it fired up after turning over for a couple minutes. This thing is blast to ride. Thanks for the help gents.

[erict716]

Glad its running.  Let me know if you ever want to cruise around the charlotte area, I'm out in the denver area.

[SoEazy]

Abs

Glad its running.  Let me know if you ever want to cruise around the charlotte area, I'm out in the denver area.

Absolutely. You should come to the Distinguished Gentleman's ride this Sunday. My buddy and I are in charge of the Charlotte ride. Here's the link if you're interested...

https://www.facebook.com/events/129589117252062/

[erict716]

Looks like a sweet ride but I have a prior obligation with the lady friend and I am pretty sure I would wake up with slit tires if  I bailed on her for the motorcycle