Surge between 2000and 2800 rpm in lower gears

Hey guys ,

Just bought Gsf  1250Sa and love it ,just has an annoying surge at roughly 2000 rpm throught to 2800rpm most noticeable in the lower gears .

Its a pain in traffic cause that's where you are most of the time .

Havent checked Air element yet ,but the owners manual has a not to say kn filter fitted at 12000k ,its now done nearly 18000

May be revisting old info but its all new to me .

Thanks Tony

Ps do these things have an easily replacable fuel filter ,cant see anything in the owners manual ?

Fuel pump fix here: https://nswbandits.forumotion.net/t1379-fuel-pump-fix

Not sure that that will be the issue though. Could be that the throttle bodies need to be synchronized?

I normally sit between 2800 and 3500 rpm in traffic, not usually an issue at these revs.

Thanks mate ,

I'm gonna check air element tomorrow and have booked for a couple week's time for dyno and Throttle body synch so see wat comes of that .

How may kls on it?

its done 18000 k Kn filter ,Yoshi pipe and had plugs changed at 12000 k .How dose valve adjustment affect these things .?

Check to see if has had a TRE fitted. If it has, there's your surge.

The surge is usually due to the lean air/fuel ratio at the lower part of the rev range resulting from the factory mapping being lean to pass Euro 3 specs.  Fitting a less restrictive air filter like a K and N or a better breathing pipe doesn't help, although the bike will adjust to a certain extent.  It seems to affect some worse than others.  I had the issue with mine and have tried all sorts of things as it is bloody annoying.

Some people feel it differently too.  If you drive at moderate speeds as a cruise you will notice it more than someone who wrings its neck.

What helps in my experience is ensuring firstly the bike has fresh plugs.  Ensure the throttle bodies are balanced as this will have an impact on smooth running.  There's a good how-to on the site.  Some advise that you want to ensure the TPS shows -C00 and not _C00 (or the cursor in the upper position) but personally I don't feel it makes much difference.

Some swear by a Timing Retard Eliminator (TRE or ATRE).  I have a GiPro ATRE and other than being a good gear indicator can't tell the slightest difference if it's there or not, or off or on.  A dodgy one can affect running, but otherwise they don't make much difference on a Bandit in my opinion.  (Others may have different experiences).

Some swear by replacing the o2 sensor with a resistor, but that didn't in itself fix my bike's surging.

If a good tune makes no difference, the best thing in my experience is a TFI or Power Commander (PCV).  There's a range of options, and all add fuel where it is needed.  I have a Dobeck TFI as part of a Dale Walker Stage 2 kit and have converted four 1250s now.  The Dale Walker setup is plug and play, and the Stage 2 setup removes the secondary butterflies and a lot of the airbox lid.  The results are amazing - surging eliminated (in fact from Stage 1 onwards), much more power (last bike I did with a Stage 2 yielded 130.8 hp with Dale's headers fitted) and no loss in drivability. All gains.

PowerCommanders, Juice Boxes, all work similarly with differing levels of adjustment, although dyno time is often needed to get the best out.  What I like about Dales is he gives you the settings and has massive experience in the Bandit and it all works well without messing about.

So - if you want to keep it fairly stock - plugs and balancing the TBs helps but won't fix it.  If you want to spend a little more, look at www.holeshot.com. Worked for me.

I tried a while ago taking the bike back to stock settings (was tempted to sell briefly), and removing the TFI brought the  surge back straight away

Check out http://www.sportrider.com/bikes/146_1201_project_suzuki_gsx1250fa/viewall.html

Would suggest a tps reset and TB balance before any further attempts at diagnosis/rectification.

Fuel system issues typically occur higher up the rpm range and once they start (at some given throttle opening/rpm) they do not go away.

I agree.  This sounds like the ubiquitous Bandit lean surge - not a fuel pump issue

Yeah sounds like my bike. around 2800 rpm it surges when cruising. I just ride in a lower gear(third instead of 4th around town) so its cruising at about 3200 or so.

Kaupy1962 wrote:Check to see if has had a TRE fitted. If it has, there's your surge.

I'll check but first whats a TRE ?

,I'm gonna check air element and tps and tb adjustment and go from there .

Will keep yáll posted .

New ground here first injected bike I've ever owned .

Tony

Timing retard eliminator. A fair few of us have it included with our aftermarket gear display. I've turned mine off. I'd recommend a decent tune along with removing the secondary butterflies

reddog wrote:Timing retard eliminator. A fair few of us have it included with our aftermarket gear display. I've turned mine off. I'd recommend a decent tune along with removing the secondary butterflies

So the latest is ,I now realise that my obvious after market gear shift indicator (GI pro /atre) is also   a tre .How do you turn it off and I have a 80mm round hole cut in the cover of my air cleaner box .

To turn off the TRE, assuming it's a GiPro, on the bottom is a small hole for a switch.  Turn on the ignition and press that switch.  It will display the map (probably 5). Keep pushing it till it says "0", then turn off the ignition.
You can download a guide off the Healtech Electronics website.

The hole in the airbox, K and N filter and pipe are all contributing to a leaner running situation, although they surge when absolutely stock.  Cover the hole with some duct tape if you want, but I don't think it will change things.

kewwig wrote:To turn off the TRE, assuming it's a GiPro, on the bottom is a small hole for a switch.  Turn on the ignition and press that switch.  It will display the map (probably 5). Keep pushing it till it says "0", then turn off the ignition.
You can download a guide off the Healtech Electronics website.

The hole in the airbox, K and N filter and pipe are all contributing to a leaner running situation, although they surge when absolutely stock.  Cover the hole with some duct tape if you want, but I don't think it will change things.

Hello Kewwig and all involved ,

I went through the process and turned the TRE off then went for about 100k ride .Should I mention the view ,the steak sandwich at the Mapleton pub or the cold beer or the sex when I got home ?
No you don't want to know about that .

The surge is miraculously gone all through the rev range and in every gear ,

Thanks all Tony

Tonyw3 wrote:Hello Kewwig and all involved ,

I went through the process and turned the TRE off then went for about 100k ride .Should I mention the view ,the steak sandwich at the Mapleton pub or the cold beer or the sex when I got home ?
No you don't want to know about that .

The surge is miraculously gone all through the rev range and in every gear ,

Thanks all Tony

The sex doesn't count if you were on your own  

Fantastic.  Pushing that little button helps............then there's the bike:lol!:

reddog wrote:Timing retard eliminator. A fair few of us have it included with our aftermarket gear display. I've turned mine off. I'd recommend a decent tune along with removing the secondary butterflies

I took mine off as it was driving me nuts around 2800 - 3000 rpm. Surged like a bastard until I took it off.

Results with those vary a lot. I have a theory that the gear position switches play up and the gear linked maps can vary as the bike thinks its in neutral (when the switchneeds cleaning my bike thinks its in neutral in gears 4 to 6)

What is this surge you speak of?
Mine must have missed out on that "option"
I'm usually up over 3,500rpm these days I have done city commutes and never felt it.
Quality fuel (not talking octane rating) probably goes a long way to help too.

I had the same thing, as did almost everyone I guess. When I went stage 2 it went away. You really need a fuel box like a Power Commander or a Dobeck TFi when you go the K&N route I believe. Like others have mentioned,simply adding a K&N will make the bike even leaner.

All you blokes with your TRE's, TPS's, TFI's, PCV's, GPI's, WTF's . BTW I'm going to KFC ASAP on my GSF & I don't care or know how retarded my timing is, or if in fact its eliminated. LOL.