72 replies to this topic

[JBX]

I confirm this is 2 & 3.

 

On the next pic the gear position sensor as I received it :

 

 

 

And here is a pic from another 4TX owner taken on his own bike :

 

 

 

 

That said, many people on the French TDM forum removed the white wire going to the TCI giving a better acceleration in 2 & 3 gears.

(removing means blanking it, not connecting it to the chassis/ground)

Edited by JBX, 28 November 2016 - 01:26 am.

[fixitsan]

I confirm this is 2 & 3.
 
On the next pic the gear position sensor as I received it :
 

 
 
And here is a pic from another 4TX owner taken on his own bike :
 

 
 
 
That said, many people on the French TDM forum removed the white wire going to the TCI giving a better acceleration in 2 & 3 gears.
(removing means blanking it, not connecting it to the chassis/ground)

 

 

 

That all tallies with my findings. Thanks for confirming.

 

Now, I forget which bike forum I read (might have been about a Suzuki if  not a Yamaha), but it seems that if a similar limiter is in place in the 900  that disconnecting the speed sensor will make it impossible for the ECU to derive gear position . Of course a sensor error will be declared, but I keep meaning to try it on my 900......I'll share what happens with everyone !

Edited by fixitsan, 28 November 2016 - 07:11 am.

[JBX]

There will be no error code given with a disconnected speed sensor, only no speed display.

 

That seems to show the ECU does not need the speed sensor as a vital sensor, and it does also not use it for any gear position computation.

 

I made the test some years ago and I don't remember any engine behavior change with the speed sensor disconnected.

If any change occurs, it seems to be very light but maybe it's worth the time spent to check.

Edited by JBX, 28 November 2016 - 07:25 am.

[fixitsan]

There will be no error code given with a disconnected speed sensor, only no speed display.
 
That seems to show the ECU does not need the speed sensor as a vital sensor, and it does also not use it for any gear position computation.
 
I made the test some years ago and I don't remember any engine behavior change with the speed sensor disconnected.
If any change occurs, it seems to be very light but maybe it's worth the time spent to check.

Interesting, it sounds like I would need a rolling road to check ! I also have +4 degrees timing advance on my 9er so i don't know if i could feel much more of a difference


Samos Motorsport claim to be able to remove low gear limiters of TDM900, and there are screenshots of ignition timing maps which seem to show they are extant.

I'm quite happy with +4 degrees I already have for now though

Edited by fixitsan, 28 November 2016 - 08:30 am.

[JBX]

At the time I did not have any GPS to get the actual speed, so testing the max speed should have been VERY difficult with the speed sensor disconnected !

 

That said, I don't think the engineers really need a speed sensor to limit the max speed on a bike with a limited engine horsepower as the TDM.

[fixitsan]

True, but i dont think its a speed limiter, but a torque limiter. Suzuki have used it in gear 1,2 and 3 on a few bikes.
You get a different reason depending who you speak to but a common reason is that it makes the bike easier to handle for novice riders, it helps reduce wheelspin in poor riding conditions.
Another reason is that it helps with emmissions ( but not relevant to a carburetted mk2)

Another reason is that it helps save the drivetrain. This is interesting because i have had a few bikes which jumped out of gear under hard acceleration due to early life thrashing. Mostly 2nd gear but i had an early xj600 which would jump out of 3rd if pushed to the limit too...most of them jump out of 2nd gear eventually

Edited by fixitsan, 28 November 2016 - 09:23 am.

[TYREDNGRUMPEE]

I confirm this is 2 & 3.

 

On the next pic the gear position sensor as I received it :

 

 

Ah bollocks.

Clear photo JBX   . Thanks. Can't argue with that.

I will check my arrangement (will have to wait for chain and sprocket time though), to confirm my earlier position/statements - modify and then disconnect white wire too.

 

Question. JBX

Why not disconnect/blank the Green/White wire also?

[fixitsan]

 

Ah bollocks.

Clear photo JBX   . Thanks. Can't argue with that.

I will check my arrangement (will have to wait for chain and sprocket time though), to confirm my earlier position/statements - modify and then disconnect white wire too.

 

Question. JBX

Why not disconnect/blank the Green/White wire also?

 

 

According to Haynes the green/White, and the white, are both connected in the harness to the single white at the CDi

 

JBX may know different

[JBX]

Both wires from gear position 2 & 3 are connected together inside the connector and then the common White wire goes to the TCI.

So  the TCI receive two infos : gears 2 or 3 engaged / gears 2 & 3 not engaged.

 

edit : san was quicker !

 

 

FS : torque limiter may be the right reason because the TRX (same engine/gearbox, no "white wire") have a longer final transmission ration and therefore it is less sensitive to wheel spin / gearbox jump.

Edited by JBX, 28 November 2016 - 11:57 am.

[RolfieB]

Been giving this some thought. Perhaps the used sensor I bought had been tampered with.

I post after completing the mod that it was 1 & 2, then that would have been what I found, not 2 & 3.

Still worked without any issues hooked up the way it was.

Wonder if the Mk2a is wired up different? But then, surely the sensor would be compatible across the Mk2 range.

Suitably perplexed  .

[Studley Ramrod]

Hmmm, well, some of the changes made to the mk2a were for euro compliance so maybe it is different.

[JBX]

Been giving this some thought. Perhaps the used sensor I bought had been tampered with.

I post after completing the mod that it was 1 & 2, then that would have been what I found, not 2 & 3.

Still worked without any issues hooked up the way it was.

Wonder if the Mk2a is wired up different? But then, surely the sensor would be compatible across the Mk2 range.

Suitably perplexed  .

 

4TXa & 4TXb are in the same boat about the gear position sensor.

If I had an MKII (God forgive me) I would remove that wire at once and stop worrying !

 

Hmmm, well, some of the changes made to the mk2a were for euro compliance so maybe it is different.

 

Euro compliance didn't start with the 900 ?

Never heard of car / bike with carbs and without catalytic converters being Euro compliant !

[Studley Ramrod]

Prolly just malicious gossip then.   Seem to recall either reading, or hearing that the electric fuel pump and upgraded carbs were introduced to help meet eu regs.