GS 1000 ST on the dyno

[John Kat]

I went to my local Suzuki dealership today and the guys proposed to measure the power my GS 1000 ST makes
Needless to say that all the local Hayabusa's and other BMW S 1000 RR's have been through this test
My bike is the European version with the 30 mm carbs, the special OEM cams and a 4 into 2 Kerker exhaust.
The result is : 93.6 HP at 8167 rpm and 9.3 m.kg at 6551 rpm.
The absolute values are not too important but the diagrams are interesting.

[posplayr]

if I'm reading that correctly you are very lean at redline?

[John Kat]

No, I believe the AFR ( on the second diagram) is spot on, oscillating between 12.8 and 13.
The engine goes through a rich spot between 4700 and 5500 rpm.
Apparently this could be fixed by lowering the needle?

[mrl1000l]

Any idea why you're so lean at 3-3.75k rpm?

[posplayr]

No, I believe the AFR ( on the second diagram) is spot on, oscillating between 12.8 and 13.
The engine goes through a rich spot between 4700 and 5500 rpm.
Apparently this could be fixed by lowering the needle?

Sorry, I could not even see that line till you pointed it out.

Looks good

[John Kat]

Any idea why you're so lean at 3-3.75k rpm?

I was told that the data at low rpm was not valid
Two reasons maybe:
The AFR is measured through a probe that goes into the exhaust and not through a welded O2 sensor.
The engine is fed by slide type VM 30's and it can't digest the sudden WOT at 3000 rpm.
What worries me more is that after that the mixture goes very rich then relatively lean until it settles around 13 A/F ratio.
I wonder if it's not due to some resonance in the exhaust?
There must be a good reason for Suzuki to place a tube between headers 2 and 3 before joining 1 and 2 on one side and 3 and 4 on the other?

[49er]

I dynoed my 850 in 2008 and recorded it here. Can't find the post at present.

Your power curve is similar to mine, with a few more ponies up top end. My max torque was at 6750 and max Hp at 9200 rpm.

The AFR's were quite close too. Mine richened significantly just after the throttle was wacked open at 3000. It dropped to 11.8 by 5200 and then rose to 13.2 from 6900 to 9200 and dropped to 12.8 by 10,000 rpm.

I run the VM26 carbs with a modded airbox, a 4-1 Cycleworks slash cut pipe and stock cams.

Incidently, GS850 cams are the same grind as the stock GS1000.

Comparing the data, it doesn't look like the balance tube between #2 & #3 primary exhaust pipes makes too big a difference to the AFR variances.

Are you running an aftermarket electronic ignition? I'm using a Boyer Bransden unit on mine.

[John Kat]

A French magazine " Revue Moto Technique" published the power curves of all the 8 valve GS's.
Clearly, the European ( including the Australian) GS 1000 ST was the most powerfull of all due the special camshafts and the 30 mm carbs.
The engine with the broadest torque curve was the GS 1000 G.
Here they are:

[John Kat]

Incidently, GS850 cams are the same grind as the stock GS1000.

Comparing the data, it doesn't look like the balance tube between #2 & #3 primary exhaust pipes makes too big a difference to the AFR variances.

Are you running an aftermarket electronic ignition? I'm using a Boyer Bransden unit on mine.

The cams on the " European" GS 1000 ST were different from those on the other GS's as you can see below.
I'm running the OEM electronic ignition.

[mrl1000l]

I was told that the data at low rpm was not valid
Two reasons maybe:
The AFR is measured through a probe that goes into the exhaust and not through a welded O2 sensor.
The engine is fed by slide type VM 30's and it can't digest the sudden WOT at 3000 rpm.
What worries me more is that after that the mixture goes very rich then relatively lean until it settles around 13 A/F ratio.

That makes some sense, it's probably just some clean air contamination. I've heard similar reading issues when welding a bung to the collector of a 4-1 header instead of welding a few inches down from where the header connects to the head, which is supposed to provide the best readings.

When you're AFR dips to 13.5:1 I'd hardly call that lean. Looks great!

[850 Combat]

That power is impressive.

[posplayr]

There is an attachment to this post that shows my final "hill pull" tuning run. It also shows the AFR climbing way up when the throttle was shut off.

I did not have a bung welded into the pipe, but I use a sniffer that is about 3 foot that extends from the tail pipe up past the collector to a void sniffing air.

I think this effect is just characteristic of the WB02 sensors and is to be expected.

http://www.thegsresources.com/_forum/showpost.php?p=1303763&postcount=12

I looked up the conversion to Hp for anyone interested.

100 horsepower = 74.5699872 kilowatts

50 ft-lbs = 67.7908975 N-meters

[John Kat]

I would love getting an AFR data acquisition system
Would you still go for the Innovate system today?
I saw the ZT-3 system from Zeitronics that looks very professional and pretty affordable.

http://www.zeitronix.com/order/order.htm#SECTION_ZT3_BDISPLAY

Any experience with this system?

[posplayr]

I would love getting an AFR data acquisition system
Would you still go for the Innovate system today?
I saw the ZT-3 system from Zeitronics that looks very professional and pretty affordable.

http://www.zeitronix.com/order/order.htm#SECTION_ZT3_BDISPLAY

Any experience with this system?

I would go with the zeitronix. The Innovate has good software but the LM-2 is problematic and not well integrated as I needed two boxes. You can get the

Zt-2 Wideband Controller and Datalogging System - Model 2010 for just $279

and what ever display you want that will work with it. Like

NEW ZR-3 AFR Gauge $89 (double check if this actually works with the Zt-2)

You won't be able to log Speed unless you can get a frequency to voltage converter to work with a proximity sensor off of your wheel.

I spent a lot of time on the Innovate LM-2 working around design defects; The LMA-3 is reliable but it would have been nice for it to all be in one box. I have not seen an major upgrades to the software since I worked with it back in 2010 and I know the hardware RPM input was defective but I figured out a way around it.

Unfortunately our GS's dont have OBDII as then the innovate product that outputs OBDII to a smart phone display would be kinda ideal.

[49er]

The cams on the " European" GS 1000 ST were different from those on the other GS's as you can see below.
I'm running the OEM electronic ignition.

Not sure what visual differences you are referring to.

What are the timing figures for the OEM European grind? The GS850GN figures are 28-68/66-26. The 850GT and onwards had their inlet timing advanced by a further 10 degrees.