Suzuki Gixxer SF 250 Ownership Review

Did you have any kind of fueling issues prior to the Fi warning? Just asking out of curiosity as I would like to document common issues faced in the ownership. I have seen this error pop up in a few Gixxers, on the internet. It seems like an expensive part when I tried to search the part number. Did they give you a quote?

Never. But after the error came, sometimes. Like the RPM wont settle at 1500 rpm after the engine is hot, rather would stay at 1750-2000rpm.
But this occurred very rarely.

The ASC said that it would cost around 2.5k and it needs to be pre ordered.

And this error pops up for multiple reasons. Even personally it has came for me 4 times,
1. Starter coil issue
2. Battery down (fueling was random in this case)
3. Battery down (fueling was random in this case)
4. And now- O2 sensor

I have an idle hunting issue when the bike is warmed up as well. After hearing about your O2 sensor failure I decided to diagnose mine. And the diagnosis was very interesting. I might've found the reason for my engine's poor running and vibes once it was warmed up

O2 Sensor diagnosis
The O2 sensor is placed on the exhaust right before the cat. There is only one. You can find the connector that goes to the ECU right behind the bottom side panel that covers the frame, among other wires. Unclipped the connector and there were 4 terminals.



This is the layout of the O2 sensor connector I got from a Spanish Gixxer 250 service manual. Google translate was of great help.



First two terminals give you the voltage output from the sensor. This is what ECU reads and uses to adapt the AFR in closed loop fuelling. The bottom two terminals are for the heater element inside the sensor. You can also spot them by looking for two similar colored cables coming to the sensor among the 4 that is on there. It was black colored on the Gixxer.

Voltage readings

According to the manual, the voltage reading should be between 0-1v at idle. And it should fluctuate. Voltage reading I got was 0.00V initially and it increased to 0.02V a minute later but it stayed there without any change Even when I revved the engine to 4-5k rpms, the voltage reading was not changing at all.

Heater element resistance readings

The manual says the resistance between bottom two terminals should be between 5.49-6.91 ohms



The reading I got after multiple checks was 9.0 ohm. Again not in the range

Observations after disconnecting the O2 sensor

Disconnecting the O2 sensor basically puts the bike into open loop fuelling mode always. Open loop fuelling works off the default fuel maps coded into the ECU. It doesn't read the o2 sensor values and adapt the fuelling to AFR values that is required for the emission norms and economy. It basically runs a richer map.

It also lights up an engine malfunction light along with an FI error on the console. Because the ECU looks for the sensor and since it cannot read the signal anymore, it throws a check engine light. This can also happen if your sensor has completely failed. From what I've understood, if the heating element has not failed, it won't show a CEL. O2 sensor delete and dongles that trick the ECU into thinking the sensor is still there are popular among aftermarket tuning crowd.

So my bike is now stuck in open loop fuelling after disconnecting the O2 sensor.

• The bike now runs extremely well. Pulls all the way to 9k with no flatspots even when the bike is hot.
• The fuelling woes and hesitation is completely gone. Before, if I opened the throttle slightly from a closed position, the engine used to bog for a few milliseconds. This was an issue when you pick the throttle up after an upshift. Made smooth progress difficult.
• Significant reduction in hand numbing vibes at cruising speeds. I'll run it for a couple of 100 kilometers before I confirm this but there is certainly a huge difference.
• Low end fuelling got much nicer and I could finally understand what the reviewers were praising.
• Smooth rev-matched downshifts. The blips felt lethargic before.
• The unstable idle is gone and bikes idles at a stable RPM when it is hot.

My conclusion from the diagnosis and experiment is that my O2 sensor is shot and it is not giving the ECU the right values and is causing the fuelling in closed loop mode to go haywire. I would like to know the inputs of you guys on this. I was not expecting such an early failure for the sensor. The bike is just 2 years and 17k old. I'll ride the bike with the sensor disconnected for a while to confirm my findings.

Woah. That is some deep research!. Thanks a lot. But I never experienced such fueling issues. And regarding parts going bust, mine would hold the record i believe- Starter coil, sensor, Engine-cyclinder/piston assembly all within 4 years.
One doubt from your inference- How vibrations are related to this sensor issue, can you please detail?
Meanwhile my check engine light went off Let us see whether it comes back or not.

It could be related to the faulty O2 sensor reading making the ECU to set the AFR more lean then required. Too much lean AFR can cause pinging and uneven combustion leading to increased vibrations.

Did you notice any change in the engine heat? A richer AFR will cause less engine heat compared to a leaner AFR.

Castro Gunner, in the name of science, the issues you've faced have been nullified and henceforth will be deemed as "mantle to mankind". I mean, envisaging your issues and reading your posts, there's a stark coincidence between the timing you post about an issue here and the issue automatically corrects itself. Strange!

Vibrations occur in many guises, one of which is improper firing of an engine, weak/loose engine mounts etc. Now, per my understanding, an O2 sensor will never be the prime causal for engine vibrations during running. Idle hunting on both a cold or warm engine can be attributed to either an O2 sensor issue or a faulty idle air control valve mechanism. O2 sensor monitors the amount of oxygen present in the header and adjusts the fueling accordingly.

A comparatively rich mixture means, barring the tailpipe emissions, the engine runs cooler, the engine makes slightly more power and the engine combusts better and overall makes it for a peppier engine.

Most modern bikes of today have a 4 wire O2 sensor with a separate heating element in them so that it can get up to operating temperature faster and perform better. All O2 sensors have a specific voltage threshold of 0.1v to 0.9V or 1V max where 0.9V reads richer and 0.1V reads leaner.

An O2 sensor isn't stuck to one value, it is always constantly fluctuating around decimal points especially at idle. When an engine is connected to the OBD scan tool and revving the engine, one can observe the voltage reach as high as 0.8V to 0.9V which is perfectly normal and a sign of good O2 sensor.

Clogged O2 sensor too can shoot out different values as they just can't fine tune the feedback loop, so try cleaning the O2 sensor and see if it helps as your O2 sensor is stuck at lean voltage rating at 0V to 0.2V. Clean the sensor tip using WD40 and gently clean the innards of the sensor, let it dry and then try to take a reading. In the process make sure your connector pins are free of grime and the sockets of both the male and female connectors thoroughly cleaned.

Coming to the after-effects of an O2 sensor removal, per me is.

1. When the lambda is disconnected, the fuel maps turn to the preset open loop mapping as you've correctly said, but the same map cannot be fine tuned without the intervention of a lambda sensor. The bike will and feel peppy as it's running a default richer map for a particular MSL. Case in point you've observed, but once varying O2 levels and elevation changes are considered you might feel the performance suffer.

I'd be keen to hear your observations from an inquisitive standpoint and would wait for your observations and the after-effects if any, without the O2 sensor. The reason I give this benefit of doubt is many FI bikes run a closed loop system with preset fuel table maps irrespective of the air flow being metered in nor out, so if this experiment can somehow clear the phlegm out of the 250's throat, it might perhaps be another interesting analogy.

Let us know how it goes!

Good luck.

Cheers!
VJ

[quote=VijayAnand1;5632430]Castro Gunner, in the name of science, the issues you've faced have been nullified and henceforth will be deemed as "mantle to mankind". I mean, envisaging your issues and reading your posts, there's a stark coincidence between the timing you post about an issue here and the issue automatically corrects itself. Strange!

Hi Vijay, You are truly the SHERLOCK HOLMES of the forum or more aptly what we call in tamil as THUPPARIVALAN.

What I was able to deduce from the voltage readings is that the sensor is telling the ECU that the engine was running lean. From what I've understood, close to 0V is on the leaner side and close to 1v is on the richer sider. So most probably the ECU was over compensating with fuel to keep the mixture close to the stoichiometric ratio.

I hade these issues ever since the day I picked up the used bike from the previous owner. In fact after 10 minutes of riding, the bike felt like I was riding a generator. But if I went WOT, bike felt alright. That was very confusing for me at the time but makes all the sense now. The vibes and lethargic throttle response was reduced by say 50% when I changed the clogged filter but in all sense, a clogged sensor alone could not have made the engine run so poor on a modern bike. So I assume it had sensor issues much earlier. The vibes were felt particularly in the handle bar and it always felt to me like poor combustion.

I wish I could give you a clear answer. But the ambient temps in KL seem to be hovering around mid to high 20s thanks to the return of the monsoon and these Suzuki 250s don't really run that hot compared to the likes of KTMs. I haven't done any long traffic sessions after disconnecting the sensor to notice a big difference. And I think in my case, the bike was running too rich in closed loop. The sensor voltage nearer to 0V denotes leaner mixture. Assuming the sensor is faulty, ECU should've been throwing more fuel at it to compensate.

Is it really effective Vijay? in case the sensor has went lazy, can we revive it with normal cleaning? From what I've understood, it is difficult to clean the inners of the sensor with regular methods and most of the time it is better to replace. But yeah, I guess it doesn't hurt to try it once.

I'm not quite sure how the sensor got shot in the first place. Unless some contamination has happened somehow, it is not normal for them to go bad in 17k. But the previous owner has told me that the bike had an exhaust replacement done under warranty because there was a crack in it. Is it possible to mess up the sensor while replacing the whole exhaust?

Right now it is not an issue as I'm limited to cities and occasional highways thanks to a back issue. Won't be taking the Gixxy to any high altitudes soon. I do intent to replace the sensor. Hope I don't get too comfortable with the open loop It is nice to finally get a feel of the 250 platform for what it is.

OT

I have completed under 1700kms on the Gixxer in about 5 months. I'm not able to ride it more due to a lower back issue under recovery. Got a set of Maxxis Extramaxx tyres to replace the stock MRFs. Not a fancy set of tyres but perfectly adequate for my current use case. And very VFM. The whole set cost me under 6500. Changed the fronts for now as the rear MRFs have a good 2k left in them. So far haven't been able to run out of grip on these. And feels more feedback rich compared to the old MRFs in front. Also feels softer in construction for some reason so I'm running a couple more PSI from stock. They advertise these tyres for sub 300-400cc motorcycles.

As I said, an O2 sensor mostly outlives the vehicle itself in most cases. There's always buts and just like any other electronic component, failures can occur. As I've reiterated in my earlier post and going by your test procedures, your lambda sensor is faulty.

Secondly, cleaning really work? It's worth the try and if it works, it works if it doesn't, then sadly you'd have to look for a replacement for the better side of things. Cleaning is pretty easy and you'd really need not excavate into those little holes. Cleaning them as normally by allowing them soak for a few mins in kerosene or diesel and then using a toothbrush to clean them works extremely effectively.

Lastly, exhaust crack and replacement does raise a solid red flag. Numerous possibilities; right from mishandling, dropping the sensor or hammering the sensor, the buts and ifs can stretch a list. So, start off by cleaning in the name of science, if comes alive, good. If not, don't think too much about it and get it replaced.

Good luck. Keep us updated.

Cheers!
VJ

I went on a trip on my relatively new 2023 Gixxer SF 250. The second service was done recently.

Impression: This was the first time I really opened up full gas and boy did I enjoy! Surprisingly both the brakes performed really well during high speeds under hard pressure (while doing threshold braking) compared to the same during low speeds. This held my confidence and the way this goes in corners puts a big smile on my face after exiting; I am not an expert in cornering though. I feel like downshifts are smooth without a slipper clutch, but rev matching should be done. Fuelling is awesome in this bike, so revv happy!

is here -

Note: I have used complete armor protection with a good LS2 helmet.

Hello, this is my first post on Team-BHP. I am a proud owner of a 2019 Gixxer SF 250 with the ODO roughly at 26.7k KM. I currently ride to work everyday which is 52km 5 Days a week.

I too observed an increase in vibrations (especially around the windscreen) and idle hunting around the 22k mark and it's something I've been trying to diagnose since. The fact that bhpian b16h22 faced it too gave me some relief that the issue was not isolated to my bike.

What has worked so far for me is:

• A quick restart when the bike is stationary immediately fixes the idle hunting. But the acceleration does still feel rough
  
• The lazy technician squeezed a rubber gasket under the windscreen just behind the numberplate, but that hasn't helped much for the buzzing sound.

The next line of action is hopefully getting the lambda sensor cleaned to see if it is the one causing the issues currently.

I haven't seen a lot of discussion around the experience of replacing just body parts like the fairing on the Gixxer. So I'll add mine here

Background:
I took my SF 250 (BS4) for my 15 day ladakh trip this year in August and the bike slipped on a very muddy shortcut we took while descending the Gata Loops. Due to this, the front brake lever bent and I got a few scratches on the fairing. Possibly, one the locks broke too because the upper fairing would detach from the lower if we drove too fast on the bumpy roads or a big stone on the road occasionally hit the fairing. I decided to claim my insurance on it as I've never claimed it in the last 3 years.

The experience:
I left the bike at Ace Kudale, Wagholi, Pune ASS. The ASS told me they cannot order the parts until the insurance surveyor visits and accepts the claim. I had to register the claim myself as the ASS didn't have tie-ups with Bajaj Allianz insurance. It took whole 7 days, thanks to slow Bajaj. At all points, I had to call the surveyor and the ASS to coordinate between them. After 7 days they ordered the parts and it took 15 days for the parts to come in. In the name of Ganesh Chaturthi, they took another 7 days. I was without a vehicle in Pune for almost a month so that I could have a fairing and a bent brake lever replaced.

I now have the bike without the stickers on one side that's glossier than the other side

All in all, the process is very slow. The total bill was around 3000 for the whole repair + labor. Please be careful with the bike.

We finally managed to locate a nearly oven fresh piece of the CEAT Zoom Rad X1 radial front 110/70-R17 tyre at Tyre Trax. Thanks to fellow BHPian Surja for the contact. The owner Rahul Midha waa really courteous and helpful, and a biker too.

My son and I rode down and got it fitted today evening. Its a 5223 manufacturing, which makes it just 4 weeks old. The only other two available in Poona were 2023 February and August manufacturing. The tyre comes with a 3 year or 25,000 km unconditional warranty.

Got a good price (3000) plus another 250 plus 20 gram weight for the balancing (probably the most advanced and expensive imported 2 wheeler wheel balancing unit in Poona).

Some photos ...

The old MRF Revz front





Wheel removed



The new Ceat Zoom Rad X1 radial







Mounting the new tyre







Wheel balancing











Wheel with fresh rubber goes back on to the Gixxer







The rear tyre, which is running without complaint and has some life in it still (my biker/cycling philosophy ... don't fix something that aint broke)



A BIG thank tou to all you guys who contributed with your on the ground tyre knowledge and real world experience in helping us choose the best rubber fir our bike!

Cheers, Doc

https://www.team-bhp.com/forum/motor...ml#post5709694 (The KTM Duke 390 Ownership Experience Thread)

Link to my post on the replacement of the pretty knackered, hardened and uneven wear-ed scary original MRF Revz on my son's 2019 Gixxer 250 SF with a 5223 manufactured CEAT Zoom Rad X1 radial in the same stock 110/70-R17 size. The bike (and the original tyre) has done about 18,000 kilometres. Mainly college and now commuting, with very few highway or "recreational" miles.

The previous 4-5 pages contain posts discussing options and their real world experiences by riders riding on them.

Cheers, Doc

My personal approach is that always change both tyres unless it's an untimely change. I have experienced the Rad X1 on the rear and it's a pretty good tyre, decent grip and fairly strong as well. Great choice.