GSXR250 really thirsty.

[dynamite9585]

My GSXR uses alot of gas. one tank is getting me about 150k down the road (12.7k to the litre)
this is atleast double what my g/f's CBR is getting.

now i understand that not all bikes are created equal, but i did think that 250's would have atleast a similar fuel consumption.

it has new plugs, but i suspect my carbs are in dire need of a clean, before i take it to the shop for a bloody good service (and a bloody big hole in my wallet) if there anything i can try first (fuel additives ect)

[onearmedbandit]

It needs a tune, mainly a carb balancing and tune up. Adding a fuel additive won't do anything beneficial. Spend the money now to save more over the long term.

[dynamite9585]

It needs a tune, mainly a carb balancing and tune up. Adding a fuel additive won't do anything beneficial. Spend the money now to save more over the long term.

thought so, any ideas on how much i should be paying the shop for this (guess-timates)
what about valve clearances?

[onearmedbandit]

Yep valve clearances are a must as well. The biggest part of your bill will be labour, including stripping the fairings off the bike and putting them back on. Save yourself some money by taking the bits and pieces off that you can yourself. For one it will save you money, and secondly it could save any potential damage done to your fairings in their workshop.

[boman]

My GSXR uses alot of gas. one tank is getting me about 150k down the road (12.7k to the litre)
this is atleast double what my g/f's CBR is getting.

now i understand that not all bikes are created equal, but i did think that 250's would have atleast a similar fuel consumption.

it has new plugs, but i suspect my carbs are in dire need of a clean, before i take it to the shop for a bloody good service (and a bloody big hole in my wallet) if there anything i can try first (fuel additives ect)

I had a GSF 250 Bandit. That is about what I was getting. 160km to a tankful. Similar engines I think, Mine was a VVT.

[dynamite9585]

I had a GSF 250 Bandit. That is about what I was getting. 160km to a tankful. Similar engines I think, Mine was a VVT.

gave me a hell of a shock, my 2L car had fuel economy of about that. hence the feeling that something is a miss.

[slofox]

My GSXR uses alot of gas. one tank is getting me about 150k down the road (12.7k to the litre)


Hell, my 600 does better than that - even when it gets the gentle nudge...

[dynamite9585]

so... the real question is, can this be done in the shed by someone with average mechanical ability?? (more than just an oil change in the experience list)

[onearmedbandit]

There might be shortcuts but ideally you will need a carb balancing kit and the ability to use it. Checking valve clearances is easy enough to do with a manual handy if you have the right tools. However, unless the person doing it is competent then save yourself the hassle of taking a bike that won't start at all to the mechanic on the back of a trailer. Then you pay to fix what was stuffed up on top of the tune up.

[boman]

Hell, my 600 does better than that - even when it gets the gentle nudge...

Yea well, the thou does about 240 till empty. And that is riding reasonably quickly too. That took some getting used too. Big bike good fuel economy.

[dynamite9585]

was thinking more the carb clean rather than the balance, will take it down for a balance, just trying to save a penny

[SS90]

I have posted about this several times before, but here it goes again....

ALL (and I mean ALL) 250cc SUZUKI 4 cylinder sports bikes (GSXR and Bandit) have an issue with the carbs.

The slide needles and emulsion tubes (the tubes that the slide needles go up and down in as the slide goes up and down in response to throttle opening) are made of basically cheese..... when these fuel metering needles wear, they let too much fuel in, same as if your jets where too big, or your choke was stuck on......

Over time, the emulsion tubes and needles wear (think of how many times your slides go up and down in 100km), this is, generally an acceptable "wear" thing on high mileage carbed bikes, (100,000km), but with the 250 4 cylinder suzuki carbs, they would only last about, say 20,000 km.

Just now, you get sad gas mileage, but, soon your bike will start running rich, be hard starting, and blow black smoke under acceleration.

This is common on ALL 4 cylinder 4 stroke Suzuki 250cc....... with-out exception, and includes osme of their early LT250 single cylinder 4 wheel farm bikes (they had the same cheese like material used on their slides and emulsion tubes..... it caused such a problem in the early ninties, that federated farmers threatened to take them to court for selling an inferior product..... the fix was to send out stainless steel emulsion tubes and new needles to all the dealers and fit under warranty...... I remember it well.

The fix (as a few on to it bike shops in NZ know) is the same for the GSXR and Bandit 250...... make stainless steel emulsion tubes, and fit new needles.

Contact R1madness on here, he is the owner of "Just Motorcycles" in Christchurch, and they make the stainless emulsion tubes, and can supply new slide needles, you just need to send your carbs to them.

Ask him for a price..... they are not bad, and you only have to remove, send away, then later refit your carbs.

Not hard at all.

[Juzz976]

About the economy of my old FZR250 160k to the 12L Tank.

Just sitting at 100kms uses alot of gas on a 250 as its pumping alot of air and gas to provide a small amount of torque. Round town at low revs your economy improves alot.

Tyre pressure and wrist action makes a big difference too, I even noticed I got a few extra kms when I had the shocks & wheel bearings done on my first 250. Mates bike lost its economy when he put aftermarket exhaust on without re jetting.

[Gibbo89]

as with the aboce comment about the fzr, mine is the naked version and i have got 230k's before the bike wants the reserve turned on, then its time for a top up. (on a 15 litre tank)

in regards to ss90, just motorcycles are a good bunch on guys. ian (R1madness, or whatever it was that ss90 said is a good guy and he'll pm you back with the right info for what you need)

250 iline 4's are not cheap on fuel, but... they are a lot of fun :yes:

[Juzz976]

as with the aboce comment about the fzr, mine is the naked version and i have got 230k's before the bike wants the reserve turned on, then its time for a top up. (on a 15 litre tank)

The Zeal is similar to FZR but detuned a bit something like 40hp instead of 45hp.
Of course the way you are riding will affect your economy, my current FZR can do 220k on a tank b4 reserve.
However that was the week I was in auckland (round town riding) and didn't exceed 70k and almost no hard acceleration. The ride up tho was on reserve by 160 km, tauranga to akl following some bigger bikes so was hard on the gas.

[dynamite9585]

got the carbs off today, taking them to a place in town for a clean and a rebuild, $300 (estimate) will tell them about the needles and tubes and see what they say, if no joy there i will be on the phone to the guy in CHCH to see what he can do, not sure how i can manage without my bike for over a week tho.

[dynamite9585]

small update:
had them at the carb shop today, he stripped them down and is giving them a clean, tubes and needles look ok to him, but one of the main jets was blocked completely :S also mix setting were "all up the piss" suspect it started running rough on last owner and he just fiddled the mixes to make it sound/go right.

[Juzz976]

Sounds like your problem is solved, cheaper than buying a set of carbs and getting them balanced and tuned.

[neels]

small update:
had them at the carb shop today, he stripped them down and is giving them a clean, tubes and needles look ok to him, but one of the main jets was blocked completely :S also mix setting were "all up the piss" suspect it started running rough on last owner and he just fiddled the mixes to make it sound/go right.
Yep, that happens, had to replace a bleed screw in a carb because it had been wound right in and snapped the tapered end off in the hole when someone had fiddled with them.

You'll probably find it goes a heap better after a clean, if all 4 cylinders are getting some petrol instead of just 3. :Punk:

[Juzz976]

Although $300 is a bit steep as rode my bike in to shop with fairings off and had same work done, cost me $300 and they replaced 4 spark plugs too with carbs fitted back on bike.

rode home sweet as.

[onearmedbandit]

Yep, that happens, had to replace a bleed screw in a carb because it had been wound right in and snapped the tapered end off in the hole when someone had fiddled with them.

You'll probably find it goes a heap better after a clean, if all 4 cylinders are getting some petrol instead of just 3. :Punk:

Even better, I think the GSXR250 engine only uses 2 carbs.

[dynamite9585]

Even better, I think the GSXR250 engine only uses 2 carbs.

correct.

will be back up and running tomorrow by midday.
been googleing ect when it come to fine tuning the air fuel mix, is there a sound or anything in particular i should be loooking for so i know i'm on the money? and should this be done before or after i balance them?

oh yea, cost for strip and clean: $80

[Juzz976]

thats your idle air mix screw, probably find its all the way in (not too tight) then something like 2.5 turns out <--- not actually 2.5 but ya see what ya do.

Should say in a workshop manual but would have though bike shop would have set for you.
Only other way to tune is to set needle height or rejet which I don't recommend.

I use an old o2 sensor from a car and put in exhaust and tune that way but only because I can.

[nadroj]

CV carb tuning info

A usefull guide I've had for a while - Emphasizes correct order of adjustments.

CV Carb Tuning

Follow steps in order....First, dial in:

1. Top end (full throttle / 7.5k to redline - Best Main Jet be selected before starting step 2!
Select Best Main Jet
To get the best, most even top end power (full throttle/after 7500 rpm), select the main jet that produces the highest top speed / pulls hardest at high rpm.
If the bike pulls harder at high rpm when cold and less hard when fully warmed up, the main jet is too large. Install a smaller main jet and retest until you find the main jet that pulls the hardest at high rpm when fully warmed up. This must be done first - before moving on to the other tuning ranges.

If the bike doesn't pull well at high rpm when cold and gets only slightly better when fully warmed up, the main jet is too small.
In order to properly tune the midrange and low rpm carburetion, THE MAIN JET MUST FIRST BE PROPERLY SELECTED after 10 to 15 minutes of hard use! Do not pay too much attention to the lowend richness when you are changing main jets - you still need to be using the main jets that produce the best power at high rpm. You will deal with the lowend / cruise later - after step 2.

2. Midrange (full throttle /5k-7k)
Select best needle clip position
To get the best power at full throttle / 5k-7k rpm, after you have already selected the best main jet.
If the engine pulls better on a full throttle roll-on starting at <3k, when cool but soft when at full operating temperature, it is too rich in the midrange and the needle should be lowered.
If the engine pulls better when fully warmed up but still not great between 5k-7k, try raising the needle to richen 5k-7k.
If the engine pulls equally well between 5k-7k when cooler as compared to fully warmed up, the needle height is probably properly set.
Do not pay too much attention to the lowend richness when you are changing needle clip positions - you still need to be using the clip position that produces the best full throttle / 5k-7k power in conjunction with the main jets that produce the best power at high rpm. You will deal with the lowend / cruise next.

3. Low end (full throttle / 2k-3k)
Float height (AKA fuel level & how to..)
To get best lowend power, set float height so that the engine will accept full throttle in 2nd gear from 2.5k to 3k rpm at minimum.
Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring.
If the engine has a "wet" rhythmic, soggy area at full throttle / 3k-4k rpm, that gets worse as the engine heats up, lower the fuel level by resetting the float height 1mm greater (if the original was 13mm - go to 14mm). This will lower the fuel level, making full throttle / 2k-3k rpm leaner.
If the engine is "dry" and flat between 2k to 3k rpm, raise the fuel level.
Example: change float height from 15mm to 14mm to richen up that area.

REMEMBER, since the main jet WILL affect low speed operation, the MAIN JET has to be within 1 or 2 sizes of correct before final float setting.
Warning: If the engine is left with the fuel level too high,, the engine may foul plugs on the street and will be "soft" and boggy at part throttle operation. Adjust Floats to raise/ lower the Fuel Level.
Base settings are usually given if a particular application has a history of fuel level
criticalness. The Fuel level height in the float bowl affects full throttle/low rpm and, also, richness or leanness at cruise/low rpm.
Reference: a bike that runs cleanly at small throttle openings when cold, but starts to show signs of richness as it heats up to full operating temperature, will usually be leaned out enough to be correct if the fuel level is LOWERED 1mm. Check out and RESET all: Suzuki (all), Yamaha (all) and Kawasaki (if low speed problems occur). Needless to say, FUEL LEVEL IS EXTREMELY IMPORTANT!!!
If there are lowend richness problems, even after lowering the fuel level much more than 1.5mm from our initial settings, also check for needle wear and needle jet (part of the emulsion tube). See Worn Needle and Worn Needle Jet diagram. It is VERY common for the brass needle jets (in the top of the"emulsion tube") in 36mm, 38mm and 40mm Mikuni CV carbs to wear out in as little as 5,000 miles.
Check them for "oblong" wear - the needle jet orifice starts out round! Factory Pro produces stock replacement needle jets / emulsion tubes for 36mm and 38mm Mikuni carbs.

4. Idle and low rpm cruise
Fuel Screw setting (AKA mixture screws)
There is usually a machined brass or aluminum cap over the fuel screws on all but newer Honda. It's about the diameter of a pencil. Cap removal details. Newer Honda carbs use a special "D" shaped driver, usually supplied in the carb recal kit.
Set for smoothest idle and 2nd gear, 4k rpm, steady state cruise operation. Set mixture screws at recommended settings, as a starting point. For smoothest idle, 2nd gear 4000 rpm steady state cruise , and 1/8 throttle high rpm operation.
Pilot fuel mixture screw settings, float level AND pilot jet size are the primary sources of mixture delivery during 4000 rpm steady state cruise operation.
If lean surging is encountered, richen mixture screws (turn out) in 1/2 turn increments.
Alternative pilot jets are supplied when normally required.
Pilot fuel mixture screw settings, float level and pilot jet size also affect high-rpm, 0 to 1/8 throttle maneuvers. Too lean, will cause surging problems when the engine is operated at high rpm at small throttle openings! Opening the mixture screws and/or increasing pilot jet size will usually cure the problem.
NOTE: A rich problem gets worse as the engine heats up. If the throttle is lightly "blipped" at idle, and the rpm drops below the set idle speed, then rises up to the set idle speed, the low speed mixture screws are probably set too rich: try 1/2 turn in, to lean the idle mixture.
NOTE: A lean problem gets better as the engine heats up. If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!
Carb tuning is a combination of science, art, intuition and a lot of wizardry.

[Techno]

Just now, you get sad gas mileage, but, soon your bike will start running rich, be hard starting, and blow black smoke under acceleration.


Ok so from this I have questions:
1. Roughly what should the mileage from a 250 Bandit be normally then?
2. Hard starting? like having to twist the throttle right round then hit the go button?

Awesome answer by the way, a fair amount of info there :yes:

[nadroj]

Start with full choke & no throttle.

[dynamite9585]

wow!!! fantastic information there!!!!! thanks.

as for Techno's issue, imo sounds like it's dumping fuel in the carbs and flooding.
but that just my opinion based on that your having to give it all the air you can to get a combustable mix.

[Techno]

Start with full choke & no throttle.
Yeah that used to work but over the last couple of months I've found that I need to crank the handle more and more, I only really noticed it a couple of days ago (as with all things that build up slowly you don't notice straight away). Once it's been running it's ok, but the next morning back to the same.


wow!!! fantastic information there!!!!! thanks.

as for Techno's issue, imo sounds like it's dumping fuel in the carbs and flooding.
but that just my opinion based on that your having to give it all the air you can to get a combustable mix.

So your thinking is that it's just pouring fuel in but it's not getting enough air until the throttle is opened? Are we talking a job for my local friendly bike store :)

[dynamite9585]

possibly, but thats just my inturpretation of it.

i THINK bandits have the same carbs as the gsxr, so could be the wearing that was mentioned earlier

[dynamite9585]

will this ever end??!!!!

got it all back together now the carbs are in desperate need of a tune, but i can't seem to find anything on it that screams this is the screw your looking for. down to the bike shop tomorrow i think..... sigh

[Gibbo89]

will this ever end??!!!!

got it all back together now the carbs are in desperate need of a tune, but i can't seem to find anything on it that screams this is the screw your looking for. down to the bike shop tomorrow i think..... sigh

did you buy the bike cheap? i just wonder as you are having a few issues with it at the moment. is the cbr going well?

[dynamite9585]

ogot the bike for 2k.

the main problem is my OCD for perfection and my compulsion to tinker.

my dad had a saying as he wandered off to the shed. "if it ain't broke..... i'll fix it anyway"

CBR is going great. GSXR isn't bad, i felt it needed a carb clean and got that done. the "is it ever going to end" is more frustration from other things. like gatting everything together to go down and put the GSXR back together and locking myslef out of the house, then the airbox being a prick to get on (took over an hour. turns out it's much easier to sttack the carbs to the air box then attach them to the bike). that and it has been harder to find the bits and bobs for my carb balancer than i expoected today (took half a day to come home practically empty handed)

tomorrow i will get a grease monkey to have a crack at tuning and blanacing then i'll be set, happy and on my way....

[neels]

but i can't seem to find anything on it that screams this is the screw your looking for.
There are screws on the engine side of the carbs, one next to each throttle where they go into the intake rubbers. They are the bleed air screws, to start with these should all be set the same number of turns out, I think I read 1.5 turns for a GSX250F, don't know if this is right for a GSXR

To balance the carbs there is a screw on the linkage between the carbs which adjusts the shafts relative to each other.

The idle adjust is a screw on a stop for the throttle cable, it might have a length of rubber hose attached to it, you might need to adjust the cable adjusting nuts as well.

[Jonno.]

Er didn't you say the mech fixed the screws and commented on how they were "on the piss"?

[dynamite9585]

Er didn't you say the mech fixed the screws and commented on how they were "on the piss"?

the carb guy, he didn't have the rest of the engine.

[mikemike104]

so you guys up for a ride this sunday maybe ? :scooter::scooter:

[dynamite9585]

put the bike back together fully (fairlings and all) today and just got back from a bit of a ride.

what a difference the tune does!!!!!
as for sunday, unlikely. she is working.
tomorrow we are going down to tokoroa.

[Gibbo89]

put the bike back together fully (fairlings and all) today and just got back from a bit of a ride.

what a difference the tune does!!!!!
as for sunday, unlikely. she is working.
tomorrow we are going down to tokoroa.

good to see the suzuki is going hard now.

[dynamite9585]

yea it's good now, but what i want to know is:

WHO THE BLOODY HELL THOUGHT IT WAS A GOOD IDEA MAKE YOU REMOVE THE EXHAUST TO DO AN BLOODY OIL FILTER CHANGE!!!!!?!?!?!?!?!

spent ages trying to get at the bloody thing, ended up un bolting the exhaust from the smokey end and using a jimmy bar to give me the 5mm i needed to get the old filter out and the new one in.

managed to get alot of those niggly jobs done in the mean time tho. like the rattle i could hear and not find, turns out someone had taked the radiator off at some point and hadn't put a bit of steel back in the right place.

[dynamite9585]

WOOT WOOT!!!

went to tokoroa today, filled up in camebridge and made it down there and back with plenty of gas to spare.

trip meter is about to tick over 200km, and i'm still not on the red marking of my fuel gauge.

last trip down (when i realised something was wrong) i had filled up in hamilton and was having to goto the gas station before i was even ready to leave tokoroa.