Suzuki Bandit 1200 — The Old School Hooligan Tool.

Bigger cubes!
Part of the reason for putting the GS550 on the road was to take things at a gentler pace. While the CBR600RR is amazing — compliant, smooth, light, quick — probably too quick, you need to be a bit careful where the constabulary are concerned.

Ambling round on the GS is great, it's happy mooching round and gives you plenty of time to take in the scenery. I absolutely love being on old stuff too. Points and condensers, carburettors, air-cooled engines... they just have more soul. The smell in the garage after they've been for a run is awesome too.

But then you hit that steep hill, loaded with hairpin bends, and she struggles in first gear just to make it round. It starts me thinking about GS1000's, GSX1100's, something a bit bigger, torquier. Something that will go two-up with ease, trundle around all day on the sniff of fumes and sit at 3,000 to 4,000 RPM.

Mmm... nice but too expensive nowadays. 

So, it got me thinking. What about the first of the Bandits? 1157cc, oil/air-cooled monstrous fours that ooze torque and charisma, and will wrench your arms off just off idle. Basically the detuned engine out of a GSXR1100. Always wanted a GSXR1100. Mmm, here we go again!

Gumtree.
Such a visual feast of all things bargain, if you look properly. There were lots on there, later 1250S models with the water-cooled engine, but all were runners and commanding large sums of money. I prefer a project for much smaller sums of money. And I found one. But it was a thirteen hour drive, for a non-running Mk1. It looked in reasonable fettle (obviously in photos) and Murray, the guy selling it, seemed pretty legit, in fact an absolute legend. So transport was organised...

In all the years of riding, I'd never taken much notice of the Bandits. I was too busy riding big sports bikes, and left these in the commuter bike bracket. What was my first thought? It's comfy (I'm obviously getting old).

My second thought... this bike is all about Suzuki showing off that fantastic engine! And it looks awesome. I like engines (I am old!).

Now it was time to work out why it didn't run. Murray assured me it was an electrical issue and that the engine sounded fine. Big risk? That's why you need to work out if the guy is legit, or not. 

First issue, not even the starter motor was working. Quick look, fuse blown, boom!

Check all the others, clean out fusebox and connections with WD and an airline.

It now turns over on the button, though the engine compressions sounded a little "out" for a few seconds, but then she sorted herself out. So although it sounded pretty good on the starter motor, she still wasn't attempting to fire. 

Next step, plugs out. All of them wet. Dried them off, put them all back in bar no.1 and checked for spark. Spark visible, a couple of cylinders fired. Put the plug back in an tried again. Nothing.

Plugs back out, dried them, swapped the leads to be on the safe side. She fired up on two. Reversed two of the leads back and BOOM, she was running beautiful for about four seconds when it then suddenly sounded very retarded. CDI issue?

While it was still running, I also checked the charge rate — 15.2volts!

Overcharging!

Now be very careful here, I went online to check if this was a common problem on the Bandit, and if you could get regulators for them (they have a car-style alternator instead of the more common stator on the end of the crank).

A lot of people were saying that Suzuki say it's ok to charge up to 15.2v — it isn't.

Coming from the the car world, anything above 14.2v is getting sketchy. Maybe 14.4v as long as it stays there. If it continually climbs with revs and goes above 15v, components will melt.

The bike ran for a short time before cutting out, and then there was a fizzing noise coming from around the battery. But it wasn't the battery boiling, it was something inside the CDI unit itself! The casing itself was hot to the touch. 

So I had two issues. Time for some more online investigation, and eBay for a CDI unit.

The good news is the engine ran, and sounded nice, albeit for a few seconds.

Regulators.

I soon found the aftermarket alternative to the original regulator housed within the alternator. For a hundred bucks this will fit in the same spot, so worth a punt.

Wemoto supplied that with their usual great service, and I got to work.

The black cover is easily removed from the back of the alternator by removing three nuts, but disconnect the battery first.

The regulator is the small round metal "cap" that is screwed to a black plastic bracket at the bottom of the alternator.

And that simple little device is what replaces the original. The bracket is held on by two screws, and one of the wires inside needs to be unscrewed too.

Once the bracket is off, the regulator is held by two screws and the solder needs to be removed from the contacts. 

Assembly is as per diagram supplied, although one screw wasn't long enough to do the job so I cut down another to suit. Once hooked up, the outer cover was cleaned of dust and refitted.

I then tried it with the original CDI to see if it would start — it did — and checked the charge rate. Still going straight up to 15.2v before levelling off, and the CDI was still getting hot. 

Oof!

On further investigation, i found out that a voltage drop between battery and the signal wire into the alternator could fool the alternator into thinking that the battery wasn't as charged as it actually was.

So, if the battery was reading 12.5v, as mine was, by the time the alternator was receiving this signal, it could be as low as 12.1v. So I checked it, and they were right. The wire runs through the loom, via the ignition switch, through various connectors and back. Old wiring and connectors can build up a resistance over years and it appeared that this was my issue. 

In the first pic I'm taking the reading direct from the battery.

This is into the back of the two-pin plug with orange and red wires, which changes to two red canvas-covered wires going down to the alternator. The orange wire is the ignition feed to the alternator.

A substantial voltage drop, and enough to cause overcharging.

The Cure?
Great band (is that a dad joke?).

Ok, the cure: Simply to take a feed direct from the battery positive terminal to the alternator signal wire. 
Now, if you were to do this with a wire directly, you would end up with a flat battery overnight. For this, we need a relay to switch it all off when the ignition switch is turned off.

As mentioned, the orange wire is the ignition feed and will be cut to provide a signal to switch a relay on. 
The other "cut" side of the orange wire will be provided with a 12v supply direct from the battery when the relay is switched on. 

A basic four-pin automotive relay will have numbered terminals: 85 and 86 are the triggers (the coil), 30 and 87 are joined together when the coil is energised.

For our purpose, we will wire it as follows:

86 will join to the side of the orange wire that comes from the ignition switch. 
85 will go directly to earth, either the battery negative terminal or the frame.
87 will go to the other side of the cut orange wire (that goes to the alternator).
30 (with inline fuse) will go to battery positive.

At this point, it should be time to check it.

Perfect.

You will notice the rev counter isn't working in the video, I'm hoping another CDI will sort that nonsense. Unfortunately, the secondhand one that arrived also took a beating from the overcharging before I realised.

However, to look on the bright side, it is now charging efficiently and I've covered over 500 km's in the last few days. It's running beautifully!

Lots more to cover in the next posts...