GSXR 400 GK73A Help plz

oil change, engine rattle, cut out

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12/05/2009 at 22:00
Hi, and thankyou for taking the time to read my problem.

My GK73A was a little low on oil, so my friend topped her up with 2 litres i believe.
She started fine and rode a good ride for 15 miles, but after arriving on my driveway, she developped a rattle and then cut out...

She would not start again, but the following morning she started and ran fine lol but since that, she has not run since.

Every time the electric start was hit, there was a Click noise, So i replaced the battery, but still has the clicking sound.

My next mission is a starter solonoid.

But i would just like a little wise word about what could of caused the rattle, and would i need to replace my engine if the new solonoid dont work?

Many regards

13/05/2009 at 00:25

2 litres is NOT a "top up". The sump in one of those is probably a bit above 3L, so if it swallowed 2L happily, then it was running so low as to be doing damage. If it didn't need 2L and is now far too full, then it may be building up enough crank case pressure to do a spot of damage also.. So your first thing to do is check the oil level properly, and see where it is, and work out where it was.

The rattle could be the big ends (tho' they tend to knock / hammer), balance shaft, or cams, or any number of other bits. The fact it wouldn't start when hot but would when cool the next morning doesn't bode well - it may have been seizing. Does it have an oil pressure warning light? Was it lit?

The lack of starting could be a dodgy starter solenoid, starter motor, wiring etc, or a siezed engine.

Check the easy things first. Is it a rapid clicking? Or just one big click? Or even just a very faint click?

Can you turn the engine over by hand? Either pop it in 5th or 6th gear and try to turn the rear wheel, or take the timing cover off and use a suitable socket on the crank end. Ideally you should take the plugs out too to release the compression, but even then it's going to be a bit of a judgement call as to whether the engine's too tight.

16/06/2010 at 22:00
my gsxr 4001986 has a warnig light comming on at70 but i dont know what it is its a red dim light but in japaneese can eny 1 help
16/06/2010 at 22:16

Japanese spec bikes have a light that comes on at 50mph / 80kph.

If the speedo has had a converter fitted (to turn the kph reading into mph) then possibly the accuracy's a bit out so it's coming on at closer to 70mph instead of 80?

17/06/2010 at 10:03
thanks ma man that takes a lot of my mind knowing that thanks again
07/09/2011 at 09:32
hi i have a gsxr 400 GK73A can anyone tell me if there is a coil on the righthand side of the bike behind the magnito, and what coil it is? Cause i've traced 3 yello wires coming out there, and im buzy checking al the coils resistance cause she doesnt want to start! The ignition coils is fine, and the coil at the lefthand side of the bike measures 101 kowms! Plz i need help. Thanx
08/09/2011 at 00:28

Go here for a wiring diagram for the GK76, or here for a 1985 GSXR400.

I'm not sure which is most applicable to your bike but:

BOTH have 3 yellow wires for the output from the alternator. This is pretty standard on Japanese bikes and these wires only provide current to power the electrical system and charge the battery - they're nothing to do with ignition signals. 101 killo-ohms is an enormous resistance for these wires if measured correctly, but as they're nothing to do with the ignition I'll leave that for now and you can always come back to me on that.

The 1985 diagram shows the ignition pulse generator as separate - I'd expect it to be on the right-hand end of the crank, but I don't know the engine. Look for a bundle of 3 wires - 1brown, 1 green & white, 1 blue (or black?) & white. I'd expect these to have a resistance of about 350 to 600ohms when measured between green/white - brown and blue/white to brown.

The GK76 also has a set of pulse generators - red, blue & black wires I think - which I'd expect to be for ignition timing because they generally use a pulse each at the fully retarded & fully advanced angles BTDC.

It also shows a signal generator in with the alternator - a pair of brown and blue wires, but I'm not sure what this is for. Could be a tacho signal or something but might also be in some way related to the ignition...

SOOO, the 3 yellow wires are just alternator power - ignore them for now.

Both versions of bike should have another set of 3 wires which time the ignition. If you tell me what colour they are, and how you're measuring to get the 101K-ohms we can go from there. It doesn't sound right, but it depends on what/how you're measuring.

Ta ta for now. 

Edited: 08/09/2011 at 00:35
18/09/2011 at 12:22
i`ve got a 84 model gsx-r400 gk71b ,, can someone tell me from the coils which plugs the leads go to,, Hoping to get this thing going
24/09/2011 at 16:05

Generally one coil will have 2 leads the same length - these go to cylinders 2 & 3.

The other coil will have a short lead & a long lead - these go to 1 & 4.

In my experience the coil for 1 & 4 generally sits to the left whilst the right one does 2 & 3.

Getting this wrong doesn't matter from an HT lead point of view - swapping between 1 & 4 won't do any harm, and swapping between 2 & 3 won't do any harm either.

Where it does make a difference is in the low voltage connections to the coils. If you accidentally cross-connect the power for  2&3 to 1&4 & vice versa then the bike won't run. It might make a few pops and hisses instead, but shouldn't do much damage.

Referring to the wiring diagrams I posted up earlier might help.

28/06/2012 at 17:43
Can u tell me the best oil to put in my gsxr 400 1990. Iv put high performance synthetic ester engine oil 10w-40 witch I was told t use but it seems to be using alot of oil and I don't no y it doesn't really smoke or leak any were so im abit puzzled.
30/06/2012 at 14:50

An engine that old may benefit from using semi-synthetic instead which tends to fill gaps better. You should notice less oil use and slightly quieter running.

I don't *think* it will want 20w50 but if you call a decent suzuki dealer or Suzuki GB they'll be happy to tell you.

How much oil is it using?

03/08/2012 at 11:06


Edited: 03/08/2012 at 12:14
03/08/2012 at 22:15

Have a look at these wiring diagrams for GK76 and '85 GSXR400. I'm not sure how the GK73 differs, but given how similar those two diagrams are I'm expecting it to be pretty similar - if you know different then let me know.

Each of the coils is fed from the switched ignition live. The red battery live runs up to the ignition switch, and the orange switched live runs both to the fuse box and to the ignition coils. So with the ignition on and the gearbox in neutral, check that you've got a full, constant, healthy 12V feed at the orange wire connected to each coil.

The signal that triggers the coil is the CDI switching the coil's earth on and off. With the ignition OFF, disconnect the plug from the CDI unit, and disconnect the White and Blue/Yellow wires from the coils. Check the resistance along the Blue & Yellow wire from the coil to the CDI plug, and check the resistance along the white wire from the coil to the CDI plug.

Come back with your answers

15/08/2012 at 06:18

i have a gsxr 400 rr sp 1990 model, the bike has a clutch problem, the bike will start in neutral but cuts out when u try to engage first gear. is this a simple problem like replace the clutch cable or is it more serious?


16/08/2012 at 22:29

Sounds like the interlock circuit, most probably the side-stand switch in this case.

There's an electric circuit that prevents you from engaging the starter motor with the bike in gear and clutch engaged (lever released), or running the engine with the side-stand down and in gear.

To do this is uses the neutral switch, clutch lever switch, and a side-stand switch.

As it's starting, it's probably not the clutch switch. As it happens when leaving neutral, it's probably not the neutral switch. SOOO, I reckon the side-stand switch isn't telling the bike that's it's not up.

This is either because the side-stand isn't up, or 'cos the switch is goosed, or 'cos it's disconnected.

Try disconnecting the wires from the switch, and if that doesn't work, try bridging them together. If that cures the problem, then sort out the side-stand switch.

30/08/2012 at 13:17

hi there i have a 1991 gsxr 400 .i have a prom with spark when i keep the starter botton pushed in i have no spark and if i tap the botton i have spark some times .iused a tee bar to work the pick ups back and fort manuely but got notting what do you think thanks tony

30/08/2012 at 22:20

That actually sounds to me like a weak battery. If it's struggling to hold charge or deliver current then it can still supply enough power to turn the engine over, but will drop its output voltage so much that it can't trigger the ignition system.

Try connecting a much bigger, known healthy battery or jump-starter in parallel (+ to + and - to -) and see if it improves.

If you can't do this, measure the voltage across the battery with the ignition and all the lights off etc, then measure it with the ignition on, and measure it again as you're cranking the engine over, then come back here with the results.

25/09/2012 at 23:24

hi hhere back agin when i chequed the voltage it was 12.37 i have used a second battery with jump leads but i am getting te same thing i looked at your wiring loom diagram but it does not tell me what colour wires goes to the plus side of the coiles and what goes to the minous side when i tap the button i have no spark and when i get a spark i keep the button pressed and it only stays for about 20 seconds only what do you think thanks tony


25/09/2012 at 23:38

Unloaded voltage is a very poor test of a battery. 12.37 isn't great, and if the battery's knacked then this will plummet when the starter motor is fired. Did you do as I suggested and measure the battery voltage with everything off, and then with lights on, then with the starter motor turning etc?

You did use a second battery, but maybe the earth connections are in a bad state? Using a second booster battery wouldn't necessarily help this.

Both those wiring diagrams show that the live feed to the coils is orange (or orange and white, depending on the model). This is evident because it's the orange wire that's common to both coils and is fuse protected - i.e. it's simply supplying the same quality of power to both coils.

The diagrams also show the "earth" side of the coils - going to the CDI unit - as "B/Y" for one coil, and "W" for the other. These wires are not fused, and are colour coded differently. This shows that the signals in these wires are not the same for each coil - i.e. they're the triggers. In this case the triggering cannot be done on the live side (they're both the same colour, same supply etc) so the CDI must be working by earthing.

SO, go measure the voltage at the coil end of the orange wire on each coil. If there's a decent voltage there then measure it with the lights off, lights on, battery turning over etc and see what it drops to. If the voltage there is a bit pants, then you're on your way to finding the problem.

Hope this helps - it's a bit late and I've rambled.

26/09/2012 at 09:43

hi tappy i checked the voltage in the battery and i got 12.37. i am using jump start leads off a heavy duty battery and i am still getting the same problem. when i get spark and keep the button pressed the spark stays for 20 seconds and if i start tapping the button again the spark come back again for 20 seconds and when i let it alone it gives 1 single spark after 30 seconds. i looked at your wiring diagramme amd i could not tell which wires go directly to the coils just incase there wired wrong, on 1 side i have a white and an orange and on the other i have a black and yellow and an orange i have power in the 2 orange wires when i turn on the ignition, does that mean they go to the plus side of the coils

waiting for your reply..Tony Goggin.

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