SK3 TRE and TPS Mod, My experience...

Hi Guys,

Thought I'd do a quick write up on my experience with these two mods, for which I was certainly skeptical about them doing much.

The reason I decided to do these mods was purely curiosity to see if it made any improvements.

I found the default settings on the bike to me adequate, though I did notice that it always was a jerky engine in low RPMs, and did notice a lack on power in low gears. (Please note: Before these mods, my bike was entirely stock).

So, I did both mods at the same time...

First was soldering a 6.8Kohm resistor inline on the pink wire on gps connector, fooling the ecu into thinking I'm in at least 5th gear due to additional resistance always adding up to more than 6.8Kohm.

I did this mod, and checked for any issues/errors displayed in dealer mode.

Sure enough, no errors. So I was happy even if it did nothing to benefit.


Next... I proceeded with TPS adjustment. Turns out that injectors pumped more fuel after approx 4Krpm, so I managed to adjust the sensor to around 1800rpm. didn't want to go lower and risk lean mixture at idle or just above.

So these are the settings I went with.


The outcome...

WOW!

I really didn't expect this, and people may get different results, but this isn't purely based on thinking or being fooled into feeling it has made a difference, But after doing both of these mods, a few things have certainly changed...


1. Smoothness: The bike is definitely smoother in lower RPMs throughout the gear range. With jerkiness pretty much completely eliminated. And a much more pleasant experience for my partner on the back.

2. Low gear power increase: Now I know many are skeptical about this one, and many don't feel a difference. But I got a noticeably significant increase in pulling power in 1st-3rd gears. I know this for sure because I had a hard time pulling short wheelies on this bike vs the Curvy. Not sure why the curvey was better at this because I was sure that the curvy also had a Timing retarder.

So, I did feel an increase in acceleration at full throttle 0-70mph. But I feel that the torquey pull of the engine is definitely more noticeable than acceleration. But both have been positively affected.

It's easier to pull up the front wheel in 1st and second gear, and i've noticed yanking the throttle tends to make the back wheel more prone to slipping on wet roads vs before the mod. definitely an increase in pulling power.


In summary: I can't believe this worked so well! I was expecting slightly increased smoothness, and that's about it.

But I got way more, for a mod done with a single resistor and the adjustment of a single sensor. I can't believe the outcome.

The bike now feels how it should have done from factory.

Bonus: I run the stock exhaust, and have reasons to believe the Suzuki did do this partly to reduce noise in those gears, because I also noticed an incremental increase in exhaust volume at full throttle. Not a lot, but definitely enough to notice. But I do have a particular sensitivity to changes in sound.

Leave your comments on whether you think I'm full of ****, if you experienced anything different, or are looking to do this yourself. I won't bite

Im happy you had a positive experience with these mods, im yet to try the TRE mod, but I did do the TPS. I think I need to do it again then though as it feels snatchy again. I got mine close to 1800rpm IIRC, but it feels as though it has slipped.

One thing I will say (Which im sure you have heard before) Dont do long wheelies as the front cylinder becomes starved of oil and then you'll be in the for sale section asking for a new engine :P

1-3 second clutch ups will probably be fine though.

Definitely give the TRE a try. Can't hurt.

And yes I am aware of the V-Twin wheelie rules :-p

I never wheelie more than 3 seconds and never too high.

Also, always in an appropriate area

Originally Posted by isutty5

And yes I am aware of the V-Twin wheelie rules :-p

I never wheelie more than 3 seconds and never too high.

Also, always in an appropriate area

Good man, I can neither confirm nor deny I too enjoy the odd clutch up in first/second

[Bibio]

great you like the outcome.

just a little word of warning about resistors. if you have used any form of carbon resistor it will loose its value very quickly being outdoors it might go up or down, i would use a metal film resistor and seal it with silicone. while a TRE is going to make a difference its very very little on a 650 v-twin and i doubt that a rider will feel a difference. the TPS if set correctly makes a huge difference.

Don't worry, I am using a metal film resistor, I have 1000's of them.

Either way, it has made a huge difference and am loving it.

[Bibio]

Originally Posted by isutty5

Don't worry, I am using a metal film resistor, I have 1000's of them.

Either way, it has made a huge difference and am loving it.

send me some then... lol

Originally Posted by isutty5

First was soldering a 6.8Kohm resistor inline on the pink wire on gps connector, fooling the ecu into thinking I'm in at least 5th gear due to additional resistance always adding up to more than 6.8Kohm.

Next... I proceeded with TPS adjustment. Turns out that injectors pumped more fuel after approx 4Krpm, so I managed to adjust the sensor to around 1800rpm. didn't want to go lower and risk lean mixture at idle or just above.

So these are the settings I went with.

:

Can you supply a more detailed explanation of what you did and how you did it. I'm tempted to give it a go!
Rich

Yeah I wouldnt mind a write up on the TRE Mod if possible, I found one but its not amazing tbh!

As requested I will do I write up.

(Text for now, photos to follow shortly)


For the TRE mod:

A brief explanation before instruction...

The GPS (Gear position sensor), is a simple sensor determining voltage sent through circuitry in the gearing electronics. Not sure of the exact range but know its between 4v and 5v.

When you select a gear, there are resistors inline on each contact for each gear.

See diagram below:



As you can see, 1st gear has a resistance of 560omhs, this results in a voltage reading sent to the GPS/ECU which can then work out what gear you are in.

The TRE trick works as follows... By adding a 6.8kohm resistor inline on the gps, you are setting a minimum of 7.36Kohm resistance, referring to the diagram above, 6.8Kohms+ = 5th gear. Therefore, no matter what gear you are in, the GPS will always be subject to a minimum of 7.36Kohms, making it think you are always in 5th or 6th gear.

In first to 5th gear, it will think you are in 5th gear. in 6th gear, it will know you are in 6th.

Neutral is not affected.


So, how to do it.

remove the seat, lift the tank.

Underneath the tank, left hand side of the bike, you will see a white connector with three wires.



Now from here, there are many ways of modifying this connection, but this way is the simplest and most effective...

on one side of the connector, any preference, cut in the middle of the pink wire, this should give you a good amount of wire on each side to enable easy soldering of a resistor inline.

take a 6.8Kohm metal film resistor 1/4w or above, and solder one end to one end of the pink wire.

Ideally, slip over some heat shrink tubing before joining the resistor to the other end of the pink wire.

Then simply solder the other end of the resistor to the other end of the pink wire. You should now essentially have re-joined the pink wire as it was, except you now have a resistor in-line. Slip the heat shrink over the resistor, ensuring you cover all metal contacts, and carefully shrink it with a lighter.

You may want to also add electrical tape for better insulation and water protection.

TRE Done!

TPS will follow soon, knackered! ha!