Suzuki GSX650F Forum - www.GSX650F.biz

Hello everyone,
I have owned a GSX650F for 18 months and for the entire period I have experienced what I think is a fuel management problem. When cruising between 80 to 100 kilometers per hour without any stress on the motor the bike seems unable to make up its mind whether it wants extra fuel or no fuel at all. It surges quickly and violently causing the bike to lurch back and forwards so that the ride is like a bucking bronco. Once the throttle is either opened or closed the problem is fixed but it just doesn't like to cruise on neutral throttle. I have had the bike to the mechanics three times without success as they claim not to be able to replicate the problem I experience. Does anyone else have the same problem?
Greyrider
Queensland, Australia

I would check a throttle position sensor (if there is one). I had a car that would do the same thing and that turned out to be the problem.

Murphy's Law.....it will only malfunction in the absence of the mechanic

Hi greyrider and welcome.

What gear are you in when doing between 80-100 .and what RPM.
I ride a local freeways in 4th to 5th gear on 80-100 ,if im in 6th its does what you say.

I had a 800cc V twin before this bike and would ride in top gear from 50-150kph and it was smooth.
Once I got the inline 4 ,I soon realised and was told to keep it over 5000+rpm and don't have the surge.

Not saying its your riding ,just what I felt and learn how to ride my bike with out the surge.

Is this your first bike ???

Read thisand ewither do it or get someone to help you do it.

disconnect the Gear postion sensor and go for a ride (there is a post somewhere around about it)

make sure your chain is adjsuted properly.

Check your fuel filter (big job)

reprot back on how things go.

BTW, Common prob that effect some bike but not others.
Suxzuki Oz will say tehre is nothing wrong

I'll post more when I get time.

Thanks for the response, everyone.

I am riding in 6th gear when I experience the problem around 3000 rpm which seems to fit the comment from Sleddog. I guess I'm just coasting and that is contributing. I do experience the surge when decending hills when backing off the throttle.

I have returned to riding after many years absence and this is my first bike since that absence.

I am throughly enjoying the experience of the GSX650F except for this idiosyncrasy.

I will try keeping the revs up to see what the effect is.

Cheers,
Greyrider

this indicates there is a problem.
I've sorted mine and can putter around in top at 60 kph then accelerate to any speed and cruise without surging

this indicates you are riding "around" the problem not getting it fixed
If your car behaved like this would you be happy to be told this is how you must drive so it doesn't happen or would you want it fixed. The suggested way to ride is exactly (to the letter) what Suzuki told me about my bike. Total BS

this is about where the problem is when on cruising type throttle. Usually happends in 4, 5 and 6 gears. Not as noticable on the 650's tho due to lower torque in the lower part of the RPM range

Reading grey riders post again, he said he can't cruise ,I can cruise on any gear and no problem ,if I start to slow or go faster in a higher gear at lower speed ,then I might get a surge ,like your chopping the throttle wide open or fully shut.

When I say I was told to ride in a lower gear then I was used to and higher RPM..... ,it was in the words REV IT ,its not a V twin {referring to my cruiser} and can sit on 2000 rpm ,like I used to.
Not so much as a way to fix the problem {I don't think there is a problem with my bike },just the way in line 4's or "sports bike" are ridden in general.
I was still going into 50kph corners in 6th gear at 3000 rpm when I got my 650F and this is where I felt the "surge" ,not so much a fault ,more rider error IMHO ,and the way I realised I was not on my V twin and had to learn to REV IT and ride it in the higher RPM.

I think my problem is my rider error and may not be the same problem as Grey rider ,like I said I can cruise in any gear and any RPM.

But 3000 rpm and 6th gear ,is the wrong gear IMHO....ride in a lower gear then your used to and see what it feels like after a week.

Sleddog's comments are correct.

3000rpm is way too low to be cruising on in 6th gear. Our bikes engines are not designed for low rpm use and it can damage the internals if constant and consistent. You need to select the right gear to suit the rev range.

On average I keep my RPM limit at around 6000rpm and generaly do not let it drop below 4000rpm. Quite often I am cruising in 4th gear at 100km/h which is around 7000rpm. The in-line 4's can handle sitting on 10,000rpm all day long without any problems. They are high reving engines and should be used as such.

Keep your revs up, see how it goes over the next few days and keep us posted on the results.

Forum Member


Joined: Sun Feb 15, 2009 7:53 am
Posts: 611
Location: Melbourne, AUS Sleddog's comments are correct.

3000rpm is way too low to be cruising on in 6th gear. Our bikes engines are not designed for low rpm use and it can damage the internals if constant and consistent. You need to select the right gear to suit the rev range



OK now i know he does not know anything about motors do not listen to this guys advice

Making comments against a member like that on this forum is not going to get you very far at all.
The members here do not tolerate it.

Actualy, although I am not a mechanic and never claim to be one, I do know a bit about motors
and have helped out many members here before. I'm not always right but more often than not
I've been able to help out.

Rather than just shoot your mouth off and make a negative remark about another forum member at least
use the opportunity to explain why you think that, and provide the info as to why I am so wrong.

Show some respect gsxrider
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edit: GSXRider is not the one having issues with the bike. That part removed.

Said more respectfully than I would have.

Uh-oh, here we go

I've never found bikerboy to say anything incorrect or without reason in my time on this forum and will continue to value his advice and experience.


I agree the F feels much more comfortable in a slightly higher RPM range and tend to keep it up higher to be able to evade all the idiot drivers in this city. In my limited experience so far I've seen Dhula's suggestion of a throttle body sync work wonders for friends on a ducati st3 here and an 07 hayabusa. I'm not sure I've ever seen a rider more scared than when the busa motor had a few hiccups going into a switchback

When cruising, keep the rpm at or above 4K. If the problem still occurs, try dropping down a gear and see if that fixes the problem. If it does then perhaps the problem you are referring to is the EFI's tendency to cut off fuel supply when at very low throttle, presumably to reduce emissions and save the planet from destruction. If this is the case then you are experiencing a problem that appeared on this forum in it's early days. Some riders have learned to live with it, others have found ways to fix it. But if this is the problem you are experiencing then it is nothing to panic about, it's just a result of Suzuki pandering to the eco-terrorists.

But ignoring your problem for a moment I can at least offer the following advice : don't ride the bike below 4K rpm unless you are in first or second gear. Any other gear wants the engine to be above 4K to avoid lugging the engine.

3000rpm is way too low to be cruising on in 6th gear. Our bikes engines are not designed for low rpm use and it can damage the internals if constant and consistent. You need to select the right gear to suit the rev range.


You said " our bike are not desigend for low rpm and it can cause internal damage" well thats bull #1 these bike peaks at 10k rpm witch is low for a bike of this nature. 2nd it will in no way cause damage to your engine is you run it at low rpms the bike has almost equal torque to horsepower so it can be ran at low rpms.

6th gear around town at 2500 to 3 k is nice and ok for the bike with no problems at all.

As long as the engine is not pinging, knocking, or lugging, use any gear you want at low rpms.
If you want to have power band available for instant response and motivation use a gear lower to keep rpm higher.
DOES EVERYBODY THINK JUST BECAUSE YOU RIDE A MOTORCYCLE YOU ARE RACING ALL THE TIME OR SOMETHING?
Race to work, race home, race to the grocery store, race to walmart, race to gas station...
or can a motorcycle be used as transportation to work?
Now riding around in the redline portion of tach is not recommended....
I bet my tach has never even seen 7000 rpm and never will.
Just my opinion, bla, bla, bla , bla, bla.