Bandit Alley
MODEL SPECIFIC => SUZUKI BANDIT 250 & 400 => Topic started by: Gouraami on April 13, 2015, 04:32:43 AM
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Hi Everyone
I am having a problem where the bike only wants to rev cleanly till 6000 rpm
From there the bike just bogs, feeling like it runs out of fuel.
I have searched the forum, finding two posts that relate to this. One was a 250 where the guy had mixed up the jets while cleaning it. The other, a 400, was due to a dirty carb.
I am currently running the bike from a small extra petrol tank, eliminating any petcock issues. The filter I have connected flows with a good flow rate, so I doubt it is a fuel delivery issue.
I have cleaned the carb very (Very) well, so it isn't a dirt issue in the jets/emulsion tube or needles, and the jets cannot be mixed up on the 400 carbs.
I currently have the needles set on the richest setting, otherwise the engine just bogs if you turn the throttle. On the richest setting it can be revved and driven without bogging till 6000rpm.
When revved in neutral when very light on the throttle it can be revved till 10000rpm where it starts sounding like it runs out of fuel, if more throttle is given it bogs and the revs drop till around 6500rpm.
Any assistance will be greatly appreciated, thank you
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it sounds to me like you have exactly opposite problem as you try to solve - your mixture can be way too rich. you mentioned that your jets are all correct and carbs are well cleaned but you are saying nothing about float heights setup.
if floats are set far too high engine can get too rich if throttle is pulled. mine had heights just 3mm above normal and I got hole under throttle when accelerating around 6k RPM anything faster than by absolutely gentle revving up.
another thing i noticed is that floats tend to bend easilly when carbs are removed from bike and put aside buttoms-up. the weight of floats itself combined with ratio of arm length (float : needle push nose) seem to be enough to bend the nose resulting in higher float height.
so my advice: check the float height; bring needle to their nominal setting, check tightness of float needles AND tightness of O-rings on float mounting cradle. if not replaced since bike was made they may leak fuel into float bowl even if needle is fully closing the inlet.
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Hi ventYl
Thanks for the reply :thanks:
I set all the floats at 14.6mm, according to the manual. The first thing I did when I got the bike was replace all the o-rings + choke rubbers with the Litetech viton replacement.
If I set the needles to the #3 setting it simply bogs when even slightly blipping the throttle. When being VERY gentle on the throttle it will rev up (also to about 6000 rpm before it starts stuttering) It seems to run lean at this setting as it will continue revving a while once the throttle is closed. On #5 it doesn't do that.
It does have an aftermarket exhaust on, but it should surely still run on the std carb settings?
The needles seem in relatively good condition, but I will check how tight they are tonight after work.
I think I will also make a video to help diagnose the problem
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check the hole of the emulsion tube where needle fits while travelling down. they may have slight wear and become much larger than original allowing too much fuel go in. i'm still thinking it is too rich. my experience is that if engine is too lean it revs good at neutral but dies when under load.
also i had similar issue with different motorcycle when it was idling very nice, doing nice job at low RPM but if revved above some limit it bogged completely. the bog was the harder the faster I revved it up. also resulting in huge black smoke from exhaust (not necessary true for you, mentioned bike was two-stroke). reason? main jet had damaged thread and unscrewed itself due to vibrations. fuel was passing into emulsion tube much faster and clogged engine when needle was pulled enough for engine to suck exceeding fuel. i am not saying that your jets are also faulty, but something similar may do that.
you did you also replace the "secret" O-ring sealing main system emulsion tube into slider guide?
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you did you also replace the "secret" O-ring sealing main system emulsion tube into slider guide?
Yip, was part of the kit
I will definitely check the emulsion tubes and needles out tonight.
Thanks again for the assistance :thumb:
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This is either an incorrect main jet, or airbox problem.
At about 6000rpm full throttle, the needles should be open or almost open. Doesn't sound like a needle problem to me.
What is your setup? Airbox?
Sounds like it's getting way too much air.
I tried to run with just the airbox cover off, but stock airfilter and it would also bog down.
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Hi Squishy
For testing purposes I have been running it without the air box... I received the bike in a stripped condition, so it has never had the air box on while with me
I take it these bikes don't like running without the air box?
I will put the airbox on tonight before I do anything else, :thanks: Squishy
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Hi Squishy
For testing purposes I have been running it without the air box... I received the bike in a stripped condition, so it has never had the air box on while with me
I take it these bikes don't like running without the air box?
I will put the airbox on tonight before I do anything else, :thanks: Squishy
What.
:bandit:
No, it won't run even close to OK without airbox. At least mine won't.
I don't think there are many bikes that will, unless heavily tuned.
Like I said, even removing the top cover from the airbox will cause my 400 to run bad..
So u aren't even using an air filter??
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No filter or anything at the moment :duh:, wanted to get it running right before I put the extra bits on. It still needs a lot of work, spraywork etc. I will start a build thread to document what I have done so far
I have been running it as in the picture below:
(http://i258.photobucket.com/albums/hh252/gouraami/200is%20TLC%202015/03022015791_zpsmmmbqydn.jpg)
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Well I hoped you removed the toiletpaper from the carbs before starting it :rofl:
Anyway without any filters I'm surprised it even ran OK to 6000rpm. (well, it should go to 6000rpm in neutral but probably not when actually driving it)
ps. airbox and especially air filter is NOT "extra bits". It's an essential part.
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WOOHOO! Thanks squishy and ventYl! She is pulling well, took her till 10500rpm last night
You are right, turns out the the airbox is an essential part :thumb: I thought it was only essential on two strokes :duh: most my experience is from cars, so I haven't run into this air box problem before.
It ran surprisingly well till 6000rpm, as it does now with the airbox on.
Well I hoped you removed the toiletpaper from the carbs before starting it :rofl:
:bandit:
Due to load shedding I was unable to work any further (I am sure it has made global news due to Eskom's miss management) however I will check the emulation tubes for wear.
Currently it will be running rich, so I will return the needle to #3 and go from there.
The air filter is very dirty, almost beyond washing. seems like a previous owner put grease instead of oil on it. I will try and wash it, if it doesn't work I will buy a new one
Once again, thanks so much guys! You saved me from fiddling with other things that would have made it worse! :bigok:
I have many more questions, but will start new topics accordingly
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:congrats: :thumb:
Yes running on highest needle settings will make it run rich, but I've found it to run way better +1 or +2 (from the middle).
On the stock needle setting, mid range is very weak and has a flat spot at around 4-5k RPM.
Unless you live high altitude you might put it on +1 rich (or keep it as it is if it runs fine).
Good luck.
Ps the airfilter is only €/$ 15, so you might just consider buying a new one
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It has an aftermarket exhaust, so expecting it to run higher than stock.
At Sea level, will see which setting works best.
I must still finish drilling out a pilot screw due to it being abused in the past, so carbs must come off again. Lol, I can probably remove the carbs with my eyes closed by now :rofl:
Thanks!
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after four or five remove - dismantle - rebuild - remount cycle in row each of last two days I can do it in time shorter than average commercial break in TV :P
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after four or five remove - dismantle - rebuild - remount cycle in row each of last two days I can do it in time shorter than average commercial break in TV :P
Hehe... very familiar.
I can't count the amount of times I have removed the tank, air filter or opened the carbs..
I don't even put the screws in the side panels anymore because I'll just take them off later.
I've been looking for a way to quickly connect/disconnect the fuel hoses but only found very expensive couplers.
I wish it had the same mechanism as the SV650 tank where you can just pop the tank up :bandit:
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In such cases I use some thin long barrel instead of fuel tank. spares a lot of time.
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In such cases I use some thin long barrel instead of fuel tank. spares a lot of time.
Yeah me too, when I'm working on the bike..
But everytime you wanna look at the filter, change needles or do ANYTHING basically, gotta remove that tank and disconnect them hoses :(
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Well I hoped you removed the toiletpaper from the carbs before starting it :rofl:
Anyway without any filters I'm surprised it even ran OK to 6000rpm. (well, it should go to 6000rpm in neutral but probably not when actually driving it)
ps. airbox and especially air filter is NOT "extra bits". It's an essential part.
Okay, I think you've just pointed me in right direction to solving the problem with my B4. The airbox, well, I can tell its not the original one because someone had to cut it in half to make it fit under the tank and covered the hole they'd made with gorilla tape. The filter also looks like it came out of a vacuum cleaner and doesn't fit snugly in the airbox either. I'm starting to think it's a bit leaky.
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Well I hoped you removed the toiletpaper from the carbs before starting it :rofl:
Anyway without any filters I'm surprised it even ran OK to 6000rpm. (well, it should go to 6000rpm in neutral but probably not when actually driving it)
ps. airbox and especially air filter is NOT "extra bits". It's an essential part.
Okay, I think you've just pointed me in right direction to solving the problem with my B4. The airbox, well, I can tell its not the original one because someone had to cut it in half to make it fit under the tank and covered the hole they'd made with gorilla tape. The filter also looks like it came out of a vacuum cleaner and doesn't fit snugly in the airbox either. I'm starting to think it's a bit leaky.
Sounds like it. Just google for Bandit 400 airbox pictures and you'll see the original one.
I'd suggest finding a 2nd hand one.
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Already scouring feebay to find one.
She also suffers from the problem of bogging down when you throttle her a little bit just after starting her up. After running for about five minutes it tends to settle down and you can give her some juice, but she can still lose power when you get her in gear and try to pull away. She does not like starting the first time each day either, but once she's warmed up completely she'll start easily for the rest of the day and power feels okay, until you get up into the high revs when she'll start sputtering. Sounds a lot like what you've been describing, which would mean a leaky airbox and given the state of the mine it's a good place to start. I didn't realise the airbox was that important, just thought it was to stop crap getting in the engine.
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First find the airbox and filter. Original is foam-type. There's also K&N aftermarket but considering the price of foam I don't think K&N makes any sense at this stage.
Then we will see if you need to rebuild your carbs (but most probably you will need to do that too).
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First find the airbox and filter. Original is foam-type. There's also K&N aftermarket but considering the price of foam I don't think K&N makes any sense at this stage.
Then we will see if you need to rebuild your carbs (but most probably you will need to do that too).
Yeah, I saw the K&N one and it's just crazy prices.
I already know I'll need to rebuild the carbs, but that did make me laugh. Almost like it's inevitable.
When I got her she was doing about twenty miles to a gallon, which is not great. I've already dismantled the rear-end, cleaned everything up, put some actual grease in the bearings and put it all back together without tightening everything up to breaking point (I don't think the previous owner understood torque settings) and just from that alone I'm now up to 35mpg. I would expect the bike to be getting at least fifty though, so I'll see how much closer a new airbox and filter gets me before hitting the carbs.
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I am glad my thread is helping you out, don't be scared of those carbs, they are relatively straight forward
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So yeah, I got a new airbox, air filter and petcock, plus a new fuel-line. Had to jump start her because the battery was dead and after remembering the new petcock is manually operated got the bike running easy enough. She idled at about 5k rpm! Okay, I figured at least the carbs are being properly fed now, I just need to make some adjustments.
The idle adjustment screw is bang in the middle and after playing with it for a few turns either way I found that turning it in made the engine run faster (which I'm guessing means the mix is richer) and turning it out made it run slower. I ended completely removing the adjustment screw and she still idles at 4k rpm!
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Did you do basic carb setup? It sounds to me like the carb rack is completely desynchronized. Especially if engine is slowing down after being revved in extremely lazy fashion.
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Did you do basic carb setup? It sounds to me like the carb rack is completely desynchronized. Especially if engine is slowing down after being revved in extremely lazy fashion.
I've just fixed it and taken her for the first proper run in I can't remember how long. I am so ridiculously happy to be mobile again!
The problem was the new fuel line was pushing against the throttle adjuster on the carbs, which meant the throttle cable was taut enough to be engaged as if the throttle itself was about a quarter turn. I had an inkling this was the reason and when I turned the handlebars the engine would rev higher turning it to the right and then drop when I turned it to the left, which backed up the theory. I just took the tank off, loosened the throttle adjuster nut to give more play on the cable and after putting her back together I got the expected stalling when trying to start her. Put the idle adjuster screw back in, set it midway and after some tinkering got the idle down to around fifteen hundred. She is running almost perfectly for the first time since I got her and after taking her for a spin to charge the battery now starts on the button first time. I'll see how she starts tomorrow from cold, but I'm hopeful I might have finally sorted out that particular problem.
I'm guessing a little, but the airbox and filter are not just there to stop crap getting in the engine but also to regulate just how much air is getting to the carbs. A leaky airbox can't control the airflow effectively across the range, so you get all manner of weird problems happening. I also replaced the petcock because the previous owner had chopped the filters on the old one and put in an inline filter in the fuel-line instead. That actually ran uphill, so I think the flow of fuel to the carbs was also causing problems, probably because it was only trickling down to the carbs.
I'm going to see what the mpg is like over the next couple of weeks before deciding if I want to rebuild the carbs just yet. I've got a hundred other things to sort out (no headlights, no indicators, retainer missing from rear wheel, no rear brake...) and at least with an engine that runs my time might be better spent sorting those out before taking her off the road for a few weeks to clean up the engine itself. I just want to be able to ride in truth, I don't drive so the bike is my only means of transport and it sucks when I can't wander into town for weeks and months at a time (I live in the middle of nowhere).
I know at some point I'll have to rebuild the carbs and swap out some parts, maybe the needle or main jet because the idle screw is turned out a lot further than it should be to get the bike idling at a reasonable rpm (if I turn it fully in she idles almost on the redline!), but I'm not overly concerned right this minute to start playing with it.
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I'm glad things are going well, it is a good feeling when you are able to fix something yourself :thumb:
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The 35mpg your getting is about as good as a 400 will ever get. It's engine is in a very high state of tune it put out more horse power per liter than the formitable GSXR1100 of the same period. It was never intended to be a fuel sqeazer it is a little hotrod. Want gas mileage get a CB125 lmao :stickpoke:
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The 35mpg your getting is about as good as a 400 will ever get. It's engine is in a very high state of tune it put out more horse power per liter than the formitable GSXR1100 of the same period. It was never intended to be a fuel sqeazer it is a little hotrod. Want gas mileage get a CB125 lmao :stickpoke:
Uhmmm what? :stickpoke:
My GSF400 averages 1 liter per ~20KM (=55 MPG) for about 45000 kms and 6 years. Cruising, highway, or very sporty riding in the mountains. Always between 1:18 and 1:22.
And I have the 59BHP version, even with bigger main jet... and it does 215km/h on the speedo.
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For quick fuel line disconnect:
https://www.amazon.com/Motion-Pro-System-Disconnect-Coupling/dp/B000WJ3FUQ/ref=sr_1_4?ie=UTF8&qid=1466997760&sr=8-4&keywords=motion+pro+fuel+line+quick+disconnect+couplings
Tusk make one too in 3/8.
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I am the same with the consumption. It ranges from 4,5 l/100 km to about 5,5 l / 100 km. The only weird thing is that when I was riding more aggressive on curvy roads chasing brother's 600cc Hornet I had smaller consumption than when cruising on freeway at legal limit.
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For quick fuel line disconnect:
https://www.amazon.com/Motion-Pro-System-Disconnect-Coupling/dp/B000WJ3FUQ/ref=sr_1_4?ie=UTF8&qid=1466997760&sr=8-4&keywords=motion+pro+fuel+line+quick+disconnect+couplings
Tusk make one too in 3/8.
$22 for a coupling?
No thanks.
Btw I did a 250km trip last week, (245.3km on odometer). It was a perfect mix of highway, city and b-roads.
Added 11.42 Liters to the brim, topped it off a couple of times. So that's 245.3/11.42 = 21.48 KM per liter or 50.52 MPG(US)