Derestricting Suzuki Bandit GSF 1200.

Bandito

I am hoping that somebody can help me work out how to derestrict the Suzuki Bandit 1200. I have the model which was imported from an EU country which legally requires a restriction at 180/200 kmh or thereabouts. What happens is that the bike pulls normally, in fact it goes like hell, up to approximately 6500 rpm in 5 gear and then goes into "splutter" mode.

I have done quite a bit of surfing for the subject and have found that some Suzuki (and some other makes) are restricted by retarding the timing ever so slightly to "restrict" sudden or unexpected responsiveness. (Dont ask my why!) In the case of the Bandit the restriction on top speed.

I have found quite a number of sites which present explinations on how to get rid of the 187mph restriction of the Hyabusa and a lot of helpful information on sites discussing the 1000 TL. It would seem that the answer is a modification called a TRE (Timing Retard Eliminator) which is a simple device changes the resistance on the "pink" wire fooling ignition system into thinking that it is in a different gear. Much of which is probably fuel injection specific. I may add that I could buy a TRE almost anywhere but its a rediculous price.

I have put together such an arrangement but it would appear that I have the resistances wrong because, with it in place, the bike is restricted to 6500rpm in every gear. (sux) Since I have been unable to find any information specific to the gsf 1200 bandit I have put the TRE together using the TL, GSXR specs which seem to be wrong for the bandit. eg I have tried 2,7Kohm which is the value for 4th gear, 1,5kohm (3rd gear) 0ohm (neutral) and with all, the "splutter barrier" can be found at 6500rpm in all gears.

I will greatly apppreciate it if somebody can help me break the "splutter barrier"!!

bushy...

Bandito wrote:

.
I have done quite a bit of surfing for the subject and have found that some Suzuki (and some other makes) are restricted by retarding the timing ever so slightly to "restrict" sudden or unexpected responsiveness. (Dont ask my why!) In the case of the Bandit the restriction on top speed.

Restriction on power in lower gears is there to help stop some lads flipping the bike after buying it.Your bike is like Jap. import stuff , limited to ~180k.

Bandito wrote:

I have put the TRE together using the TL, GSXR specs which seem to be wrong for the bandit. eg I have tried 2,7Kohm which is the value for 4th gear, 1,5kohm (3rd gear) 0ohm (neutral) and with all, the "splutter barrier" can be found at 6500rpm in all gears.

You are nearly there , what you need to do is get hold of a multimeter and measure the resistance in each gear on your own bike.

Bandito

Hi there Bushy,

I have a multimeter but Im not sure how I would do that and end up with the correct reading. As Im typing this I realise this may sound a bit dim witted of me but measuring on either side of a resistor gives the resistance of the resistor. So if I place the prongs on either side of the (cut) pink wire, one leading to the ignition unit and the other coming up from the sensor on the engine, the measurement will be the resistance of the complete circuit?

I then take the the resistance of the highest "unrestricted" gear and place a resistor of that value on the Ignition unit side of the pink wire bridging it onto the neutral (black)?

Bandito

Humm, tried to measure the resistance. When the ignition is switched off its open circuit. Obviously when the ignition is switched on ,it is impossible to measure resistance because the current in the circuit messes with the multimeter's current that is induced to measure resistance. I tried measuring voltage and current with the hope i can calculate resistance using ohm's law but alas..... the values are not static and fluctuates as soon as I turn the back wheel. This is starting to work on my tits.

Hotblack Desiato

You're doing it wrong and if you're not careful, you can damage a circuit (or your meter) by trying to measure resistance on an energised circuit.

Ignition OFF.
Disconnect wire from gear position sensor (I am presuming there is only one wire coming from it)
Connect meter between the wire coming from the sensor (NOT the wiring loom) and a good earth, measure resistance. Select different gears (ignition still OFF) and the resistance should change. The value for 3rd or 4th gear is probably what you want.
Connect a resistor of that value between a good earth and the wire coming from the LOOM, and bob's your uncle.

Hotblack Desiato

Bandito wrote:

the values are not static and fluctuates as soon as I turn the back wheel. This is starting to work on my tits.

Sure you've got the gear position sensor, not the speed sensor? The speed sensor resistance fluctuates as the rear wheel turns, which can be used to calculate road speed for your speedo (assuming the B12 doesn't have an old-fashioned speedo with a mechanical cable.) The gear position sensor resistance will not change unless you change gear.

Bandito

Hey Ninja, thanks for kicking my brain into gear. You were right, I was on the speed sensor circuit. I traced the gear position sensor, put in a 1.5k ohm resistor in and it works like a dream. Power wheelie on hard acceleration. Thanks for the help!

Portege

Hi Bandito
I am in the same position as you where . My bandit will not rev , I think it is timing , but having read your fight to free your best I put my noose away ( cos I was sick of trying stuff , I could now strip my carb in my sleep).
My problem is my bandit is a 95 ( early ) 1200 is great up to 6/7 thuo then just burbbles /splutters , it has no speed sensor ( I can see )no TPS switch . So I do not think my ECU does not know which gear I am in , it simply works out how fast engine speed is by pulse width and caps my rev at about 6500. HELP .
You and Ninja 99 looks to know whats what so any help would be greatfully excepted.

bushy...

Compare the numbers/codes on the cdi to an unrestricted one of the same year or do a bit of research with the codes and check that the slides in the carbs don't have extra holes in them in unusual places.

Portege

Hi Bushy
when I stipped the carbs I did not see any holes in the base of the slides ,but have been informed of code numbers for the cdi box.
ie
Standard UK 132900-27e10 ( or 23e20 )

Mine is 13900- 27e00.
But at £99.00 second hand I was hoping somebody would know if a simple change of CDI will free the monster .....
cheers