Retarded Busa?

[OB_kiwi]

My Hayabusa seems flat in first and second gear ( especially compared to my GSXR750)

It seems that the timing map in these gears is retarded to tame the bike.

My information suggests that each gear provides a different resistance reading to the ECU

and that the 3rd gear register provides the best advance.


I have cut the "pink" wire and it definitely performs better in second, but I suspect the ecu will then run in the neutral mode which will probably lessen top end power.

I have read the post regarding timming changes on the PCII having no effect on the dyno, I suspect that this because dyno runs are in the higher gear and the ECU is already on its best advance., and further advance lessens power.

Does anybody now how modify the wiring so that the best timming map (I suspect that 3 gear ) applies???

 

[Guest]

FROM SUZUKI:
Disconnecting this wire to increase performance is a common misconception.

If you were to disconnect the gear position (pink) wire on any Suzuki EFI motorcycle, poor performance and possible engine damage will result.

This rumor started because earlier model carbureated GSX-R1100's used a pink wire to retard ignition timing in first gear to improve traction. Some tuners discovered that disconnecting the wire increased engine HP output in first gear. The motorcycle did produce more engine output with the wire disconnected, but it became more difficult to accelerate from a stop and actual acceleration and traction was reduced. But riders liked the "feel" of increased engine performance.

The Gear Position Switch wire is also colored pink on the GSX1300R Hayabusa, as it is on previous Suzuki's. Like the TL, this switch provides transmission gear information to the motorcycle's Electronic Control Module (ECM).

Some mechanics and consumers have experimented with disconnecting this wire to improve performance or drivebality (especially during the very early TL1000S driveablity problems before Suzuki released the improved, revised ECM).

As the rider selects higher gears, the ECM changes the injector duration, usually longer, producing a richer mixture to compensate for the additional air provided by the SRAD ram air system. Without the additional fuel, the mixture will become lean, performance will deteriorate and engine component damage is possible.

Since a disconnected gear position wire will make the ECM think the transmission is in neutral, the injector duration is longer than it might be in the first couple of gears.

This is why the customer might feel a "seat of the pant" driveablity improvement".

A mechanic using a Dyno may see different, or improved HP with the wire disconnected.

BUT, since the dyno is testing a static motorcycle without a pressurized air box from the ram air system, the results do not indicate real world performance. A fully operational EFI system on a dyno will indicate lower peak power as the mixture is slightly rich. Disconnecting the "pink wire" will lean the mixture to a better level for a non-moving motorcycle.

Once again, leaving the wire disconnected will reduced on-the-road performance and could lead to engine damage.



[This message has been edited by Todd (edited 08 December 1999).]

 

[Frank Adams]

Todd, nice to see you took the time to print all of that!

i thought everyone knew about the "Pink" wire by now.....

 

[OB_kiwi]

Thanks for the info re the pink wire.

I do understand even though I'm from down under.

Ive actually fitted a switch into the wire so I can do a direct comparison.

For wheelies and twisty roads I have the pink wire off, for high speed I run with it on.

I looked at a PCII but it seems to have 2 problems

First I don't think it will let me modify the map in individual gears ( PCII owners may correct me if I'm wrong)

The result is that to add enough timming for the lower gears the higher gears would be over advanced.

Also as pointed out it wont add timming below 4,000.

I want to improve performance down low because the GSXR750's give me a hard time until I get up to about 130 to 140 KPH (80-90MPH). After that its not even a race.

I understand Suzuki NZ run their race Hayabusa in the third gear map, and that the 750 race bike in the states do as well.

What Im not sure about is how they achieve that.
I presume that the gear position indicator provides a different resistance reading in each gear to tell the ECU which map to apply.

My next step is to investigate the wiring diagram and start measuring the imputs to the ECU in the different gears......

If anybody has done any work a long these lines I'd appreciate any tips.


I suspect the maps in the first 2 gears are retarded to stop the bike flipping over backwards on unsuspecting novice riders
as well as helping the bike pass the
standard noise tests.

This probably doesn't concern those riding
the freeways at speed .

But the roads in NZ are full of tight turns and up and down hill.

 

[OB_Bob]

I do not believe many people have toyed with the timing much yet.(at least not on this site
0
The power commander II locks you out of the timing at 4000 rpm and below because they are concerned about knuckleheads detonating their motors. This means that the timing adjustment only applies in the upper map of the ECM's dual map set-up.
I want to work with this more, but have not found the time or motivation yet. I would assume that increasing or decreasing the timing on the map would provide a net increase or decrease in timing regardless of what gear you are in unless there is some sort of limiter in the ECM.

I would hope to be able to run some higher octance fuel and increase timing. Remember the bike was released to run on 87 octane minimum. If there is a chance to see any gains higher octane would probably be needed.

Bob

 

[OB_KawAbuser]

Glad to see you didn't shorten the wheelbase and paint it yellow.

(then it would be "the short Bus")


Disclaimer: It was a joke, nothing more. I am proud to say Connecticut is the home of the Special Olympics.
This was a Hayabusa Joke only!

DynoJet finally released some new maps for the Yoshimura pipes, one of them has ignition timing changes - M304-005 upper rpm changes of -2.

[This message has been edited by KawAbuser (edited 10 December 1999).]

 

[OB_kiwi]

I knew I'd get some good ideas from this site...

Thanx for the advice