(A bit long post, but it might be useful)
A few days ago, I was out with my bike, stopped at a kiosk and the bike wouldn't start...
For good (?) luck, at the opposite side of the road there was the garage that I'm going for servicing my scooter.
A quick look from the mechanic was unsuccessful. We both hear the click of the relay, but the starter motor didn't start. So we start the bike by pushing, and get back home.
I remove almost all the plastics to have access to all the relays and I noticed that the one that I heard, was the fuel pump relay. The starter relay (it's actually a solenoid) it's located next to the rectifier-regulator. No sound at all.
A small hit with a hammer and ..voila! The bike is starting again.
But still, it looks like it's getting stuck.
Quick remove from the bike, back home to check if can be repaired.
Bad luck. It can't. It's fixed, can't disassembled.
The service manual has all the information needed to check the solenoid. By applying 12V on the solenoid electromagnetic coil terminals, you can check if it's armed or not (you can hear the click or check with a multimeter). Also you can check the coil resistance using a multimeter (It's possible that the coil has shortened/damaged/cut).
First, note that the service manual is wrong! Yeap! It has a big error.
The starter relay contains also the main fuse (30A). You have to check that too by the way. For me, that was not a problem.
At page 381/478, on the second photo, there are two terminals that are marked as "A" and "B". Manual says that you have to apply 12V there.
DON'T DO IT. These terminals are bridged and are the one side of the fuse!
The correct terminals are the terminals marked on the relay as "M" & "B" (from Motor & Battery, they marked to show which cable to connect. B to connect the positive from battery, M to connect to the starter motor positive). The are also marked as "+" and "-" on the third photo. Note that these are terminals that are both positive. The B has always positive voltage, the M is positive when you press the start button, otherwise is bridged to ground.
The "B" and "M" actually is marked for the large terminals down of the two marked as "-" and "+".
The "-" and "+" are the terminals that you need to connect to 12V to check if the solenoid is armed.
Also these are the terminals that you have to check first for continuity (to check if the coil is ok) and it's resistance (it should be between 3 to 6Ω as manual says).
By the way, the typical low priced multimeters have not so good accuracy on low ohm readings, so if it's 2.X or 6.X I guess it's OK.
Anyway, I found that my relay is getting stuck at sometimes. So I have to order for a new one.
Suzuki Greece hadn't that part number in stock! They say that they have to order it from other country. The cost is ~20€ + taxes. Nothing pricey, but you can't start the bike without it! FAIL.
I checked with other part shops, noone had that in stock. Also checked almost all the suzuki's motorcycles, and it looks like the Inazuma uses a unique relay. Unique as for the direct fit, ofcourse if you want you can replace the jack on the wire harness and use any kind of solenoid (at least that it can handle the amperage to start the bike).
The good news are that I have already ordered the part and after some high-technology repair Greek techniques (a.k.a. hitting it with a hammer) it now starts without a problem. I don't know for how long, and I hope that it will be ok for 10-15 days.
By the way, you can also bridge the B+M terminals by hand, and bypass the solenoid. You have to use either a VERY thick cable or something like that. The amperage/current/load of the starter motor is very big and can melt the wire in tens of second. Also you need someone to press the starter button and clutch at the same time. But you can start your bike with no problem if that happened.
The funny thing is that the relay failed exactly 1 month after the warranty period...
The part number is 31800-48H00-000.
I attached some photos.
PS Check also that the terminals are screwed tight.