Getting my Bandit running after being in storage

[smatheny]

The bike: 92 Suzuki GSF400M Bandit, 4k miles
The circumstance: Battery went dead a couple (5) years back and bike has sat inside w/o fuel in the tank.
What I have done: Installed new plugs, fresh fuel and a new battery.
What it does: The bike turns over freely and sounds as if it wants to start part of the time. Does not fire/sound any better with a shot of starting fluid than without. I pulled a plug and grounded it to the frame and it sparks when engine is cranked. I also noticed it does not seem to spark on every revolution of the engine and when it does spark it sounds like the engine wants to run but when the plug I have out doesn’t spark the engine just rolls over.
My question: Is it possible the ignition is weak and not firing under compression? This seems like an electrical issue to me, am I on the wrong track? The carbs may need rebuilt but it should run for a few seconds with a shot of starting fluid shouldn’t it?

Any help would be appreciated.

Thanks,
Scott

[Clint]

Welcome, Scott. Great first post!

Four-stroke engines don't fire every revolution - only every other.

I'd start by cleaning the carbs. Undoubtedly they have some fuel residue in the jetting that's clogging them. Are the new plugs gapped properly? Check air and fuel filters, too.

[smatheny]

Hey DoubleR,
Thanks for the quick reply. With respect to the 4 stroke comment, I should have stated that when cranking the plug will fire steady for a while and then not for several revolutions of the engine. I have no way of telling where the engine is at within the firing cycle but by watching the plug spark while cranking, it appears as if it is missing a spark for a time that corresponds to the same time frame in which the other three plugs also dont seem to be sparking. I hope this makes sence.
On another note, your comment abouit the air filter has me thinking. It takes fuel (gas), heat (spark) and oxygen (air) to make fire. I have confirmed the fuel with the addition of starting fluid and heat by confirming the plugs are sparking but I just assumed I had oxygen. I know from past experience that this bike wont run (rev above about 3k rpm) without the air filter in place. It shouldnt be dirty with only 4k miles but maybe I should remove it just to make sure I am getting air flow during craking. What do you think?
Thanks for the warm welcome,
Scott

[Clint]

Can't hurt, but you will lean the mixture temporarily. Good luck.

[tlwisner]

My neighbor's Bandit 400 needed new coils - just something to check.

[smatheny]

Originally Posted by tlwisner

My neighbor's Bandit 400 needed new coils - just something to check.

I was kinda thinkin that direction also. Obviously they work but may be breaking down. Is there a way to test them?

[Kaikias]

Originally Posted by smatheny

I was kinda thinkin that direction also. Obviously they work but may be breaking down. Is there a way to test them?

Yeah you can test the resistance in the coils with a volt/ohm meter. have to check a manual for specks.

[smatheny]

I downloaded a manual and tested the coils and the signal generator with an ohm meter and they were within the specification. The only other piece in the ignition system is the "digital igniter." The Suzuki manual references a Suzuki checker for this piece. The pasrt number for the checker is 09931-94430. The three closest Suzuki dealers either want to use an ohms meter, dont know what I am talking about or are backed up for three weeks in the service department. Is there anyone I could UPS my igniter to that could test it and ship it back in the evnt it is ok?
Thanks,
Scott

[Kaikias]

Have you changed out the plugs? I had the same problem now that I think about it, where I looked like it was getting spark but wouldn't run. Changed the plugs and it worked fine. Went through the same steps and was priceing out a new Igniter and figured I would try the plugs just of the hell of it.

[smatheny]

Yes, I installed new plugs, fresh fuel and a new battery before I did anything to the bike.

[Kaikias]

Originally Posted by smatheny

Yes, I installed new plugs, fresh fuel and a new battery before I did anything to the bike.

Gap the plugs? May be time to take her in.

[smatheny]

Turned out to be the digital ingniter that resides under the rear seat. I bought one of the ones made in argentina that is sold on ebay. The bike now runs but lacks power. It also doesn't want to idle very well. I am betting I am going to have to disassemble the carbs and give them a good cleaning.
Thanks for all the help,
Scott

[Clint]

Good work, and I'd bet you're right.