[Cbcanada]

My bike is a 2005 s2r 800

I recently had the catalytic convertor removed so now its a straight pipe running into my termis

I figured i would have the ecu flashed

I find after the ecu reflash, i have lost the lower rpm torque.. The mechanic says now it has more top end but i miss the torque however the bike is much more friendly to ride in traffic and lowered speeds an rpms now

Anyone have any insight or experience on this subject ?

 

[tye1138]

Yea, midrange is generated from a smaller pipe. A lot of manufactures build mid range into performance pipes by doing a 2-1-2 design, where the mid pipe is short and the same diameter of the incoming pipes. So that way, there is better back pressure built up. Straight pipes with less back pressure, will make the motor FEEL like it has less midrange. The catalytic converter and silencers, both add back pressure, which helps mid range.

Solution? Smaller pipes!

 

[Cbcanada]

But the termis look and sound sweet i wouldnt want to lose them. I figured it had to do with back pressure.. How about i try one tooth less on the sprocket

 

[tye1138]

But the termis look and sound sweet i wouldnt want to lose them. I figured it had to do with back pressure.. How about i try one tooth less on the sprocket

No, just the opposite. Want more torque, add a tooth.

 

[Cbcanada]

Thats what i meant . So in general an open exhaust results in loss of torque due to loss of back pressure. Fair to say? So how do i know or can tell if my ecu was reflashed?

 

[tye1138]

Thats what i meant . So in general an open exhaust results in loss of torque due to loss of back pressure. Fair to say? So how do i know or can tell if my ecu was reflashed?

Yep, thats right.

You shouldn't be able to tell if the ECU was reflashed. The bike should run like it always did before. If it wasn't flashed, it may stall or stutter on you when running.

 

[jduke]

You could download Guzzidiag for free and make a backup of the map. Most DP maps start with the number 9.
The engine sounds like it's running right so get your grunt from gearing. Either drop 1 at the front or add 3 at the rear.
Count the teeth on both the front and rear sprocket and let us know what it is. Google your bike model and see what stock gearing is so you know where you are.

 

[Cbcanada]

You could download Guzzidiag for free and make a backup of the map. Most DP maps start with the number 9.
The engine sounds like it's running right so get your grunt from gearing. Either drop 1 at the front or add 3 at the rear.
Count the teeth on both the front and rear sprocket and let us know what it is. Google your bike model and see what stock gearing is so you know where you are.

Okay i counted
I got 15t front and 40t rear

The google search shows stock as
15/42

So this means my bike before i purchased was geared to be more tamer at low revs.. And since i took out all the back pressure by going straight pipes and did the ecu flash now its even more tame on low revs

Is my thinking correct?
If so i should start out by going to factory gearing at 42t, right?

 

[Cbcanada]

Update.

Found another page on google saying stock is 15/41. So i am either one or two teeth short in the back from stock gearing

 

[tye1138]

Ahh, so if you have 15/40 and its suppose to be 15/41 or 15/42, that could easily be your problem. Someone geared the bike different for some reason, who knows. But I'd go to 15/42 and see what happens, can't hurt!

 

[Cbcanada]

Ahh, so if you have 15/40 and its suppose to be 15/41 or 15/42, that could easily be your problem. Someone geared the bike different for some reason, who knows. But I'd go to 15/42 and see what happens, can't hurt!

Yeah thats the plan. I am thinking if i should go bigger then 42 rear. Since 42 is stock. Maybe 43 or 44 is an option

 

[devimau]

But the termis look and sound sweet i wouldnt want to lose them. I figured it had to do with back pressure.. How about i try one tooth less on the sprocket

That's correct for the front, I'd go for a 14 front, its cheaper and will increase wheelbase.

 

[tye1138]

Yeah thats the plan. I am thinking if i should go bigger then 42 rear. Since 42 is stock. Maybe 43 or 44 is an option

You could try a smaller front sprocket which only looses you 1 tooth there, but its equivalent to a 3 tooth change in the rear.

 

[Cbcanada]

That's correct for the front, I'd go for a 14 front, its cheaper and will increase wheelbase.

Increase wheel base because my rear tire will move back? What are the advantages

 

[Cbcanada]

You could try a smaller front sprocket which only looses you 1 tooth there, but its equivalent to a 3 tooth change in the rear.

Yeah i will consider. But i am thinking of putting the quick change carrier in the back

 

[devimau]

Increase wheel base because my rear tire will move back? What are the advantages

Yes, it'll make it more stable specially @ high speeds, a bit more tranquil.

 

[jduke]

If the bike is the least bit twitchy then you want a longer wheelbase, but if it feels sort of slow or just a little lazy in the tight curves then you want a shorter wheelbase.
I can't imagine a 14 versus a 15 tooth front sprocket making any noticeable difference.
I would go with the 14 tooth for cost reasons alone, make sure you have some room in the swingarm to adjust the chain after the sprocket switch.
If you want to play with the steering response, adjust the ride height rod.

 

[Tom1198]

No, just the opposite. Want more torque, add a tooth.

One less tooth in front sprocket or a few more to the rear. Depends on the sprocket being discussed.

 

[Tom1198]

It's also possible to go 1 down in front and 2 up in the rear while using the same chain to save on cost.
I did it to my gsxr-600 and it made a big difference.

 

[Cbcanada]

It's also possible to go 1 down in front and 2 up in the rear while using the same chain to save on cost.
I did it to my gsxr-600 and it made a big difference.

How wAs that set up on the highways? Revving high?