Bandit running rich, can't be fixed?

[vindy500]

so my bandits running a bit rich, fouled plugs. So the guy at the shop (had already worked on the bike in the past) sold me some hotter plugs, apparently the bike cant be set to run less rich, does that sound right? Doesnt ring true for me.

[_STAIN_]

I do hope this shop wasn't a bike shop, parts can be replaced to correct rich running, but are expensive

[klyong82]

I think a carb sync. is what we do to tune a bike running rich and i took it to a shop to do that before. Can be done provided the screws/needle in your carb. are not worn....pricey though

[Viscount Montgomery]

Assuming your bandit has carbs, float levels can be lowered, carb needles can be lowered, pilot jets can be down-sized, main jets can be down-sized, air filter can be replaced with freer flowing filter(K&N type), airbox can be drilled, air jets can be enlarged etc.. The 'guy in the shop' is FULL OF SHIT...

[vindy500]

does anyone know what size jets a 92 bandit is meant to have?

[fireliv]

Hey ya.My Bandit always tended to run rich, I'm sure that something probably can be done for it but I do think it might just be a bandit thing...

Anyways good luck!

[Viscount Montgomery]

Well, 'bike runs rich' is a pretty sweeping statement, how was this conclusion made? Removed the plugs and found them sooty? The question should be WHERE is it running rich? Just at idle? screw the mix screws inwards(leaner) to find out.

Running rich at mid-range? Find out by doing a plug-chop at, say, 80 - 90kph in top gear. Dropping the needles one notch will usually cure that. Ditto with one size smaller pilot jets. Running rich at hi-range? Do a plug chop at, say, 120+kph. Plugs usually always run clean at hi revs though, even if the mix is slightly rich.

Trawl thru the myriad of 'plug reading' instructions on the net and try and decide which are bullshit and which aren't. You can drop a size or two on the main jets to lean out the top-end if the plugs really are reading rich up there. P.S. brand new plugs take a fair few days to colour up.

Thing is though, if the carbs are all kosher, set at stock settings with stock jet sizes, then the bike shouldn't be running rich at all. Shitty clogged air filter? Some PO has diddled with the floats and fucked up the fuel levels? Get the workshop manual for measurements or scavenge thru one in the library.. Make damn sure the float levels are precise.

Emulsion tubes worn oval? New emulsion tubes needed if that's the case. Jets are around 12 bucks each, emulsion tubes dearer again.. Don't be suckered by sneaky bikeshop mechanics, it ain't rocket science like they'd have you believe...

[mossy1200]

Has this been on dyno and gas analiser or is it a mechanics best guess method.

[vindy500]

umm well it has idle issues, sometimes idles at 4k, sometimes at 2k sometimes doesnt etc. It also has issues once you get up around 100kmh, if you take the throttle past about a quarter it just gets real noisy and then if you hold it there it dies and i have to pull over, starts again after 20 seconds or so. The mechanic said it was running rich because the plugs were soaking, not starting, just completely black. Has not met a dyno/gas analyser afaik

[motorbyclist]

so my bandits running a bit rich, fouled plugs. So the guy at the shop (had already worked on the bike in the past) sold me some hotter plugs, apparently the bike cant be set to run less rich, does that sound right? Doesnt ring true for me.

he's full of shit - there is shitloads of adjustment you can make, given any two of time, patience and money

hotter plugs just mask the problem, they don't fix it.


Thing is though, if the carbs are all kosher, set at stock settings with stock jet sizes, then the bike shouldn't be running rich at all. Shitty clogged air filter?

weeeeelllllll the vfr400 rear cylinders run a little out using stock jetting and the new GN250 needs to be rejetted on arrival in NZ but some dealers are cheap so it isn't always right....

but the air filter is a great place to start.


Has this been on dyno and gas analiser or is it a mechanics best guess method.

:killingme:

wtf?! when have you ever seen a mechanic use a dyno and gas analyser for anything less than a race bike and/or specifically requested dyno tune?! most shops don't even have a dyno!

that said a gas analyser or atleast just one of those handheld 02 meters would be damn handy around the shed.... plugs are very good indicators but they're far from accurate


umm well it has idle issues, sometimes idles at 4k, sometimes at 2k sometimes doesnt etc. It also has issues once you get up around 100kmh, if you take the throttle past about a quarter it just gets real noisy and then if you hold it there it dies and i have to pull over, starts again after 20 seconds or so. The mechanic said it was running rich because the plugs were soaking, not starting, just completely black.

which shop is this? this is totally unnacceptable from a mechanic and a motorcycle. How many K's are on it?

get a new mechanic

Take it to a reputable mechanic and have a chat - what you need is a real good carby tune including balance. Include a new air filter and new standard heat plugs, and an oil change while he's at it.

shouldn't cost too much over 500 bucks plus the parts:pinch:

what's probably happened is some munter (previous owner) has tried to save himself $500 and took the DIY route without a clue, then sold her off on trademe to some unsuspecting learner who doesn't know any better.

I hope all goes well :)

[motorbyclist]

what's probably happened is some munter (previous owner) has tried to save himself $500 and took the DIY route without a clue, then sold her off on trademe to some unsuspecting learner who doesn't know any better.


I take that back.


What have I done? Bike not starting after cleaning carbs

so my bandits having issues with bogging down at past 50% throttle so the guy at the shop told me to clean the jets with a wire from a wire brush and set the pilot screws, done. 1.5 turns out for a 1992 bandit 250 and scraped out the 2 holes in the jets in all the carbs, put it back together and it wont start, push start electric start and electric start with "start ya bastard" all not working. any ideas?

you have fucked up your jets using steel wire on a brass fuel jet. they are now too big and probably not even round. Reading more of that thread that's not all that's wrong with what you did either.

get new ones. get a new mechanic.

[vindy500]

I take that back.



you have fucked up your jets using steel wire on a brass fuel jet. they are now too big and probably not even round. Reading more of that thread that's not all that's wrong with what you did either.

get new ones. get a new mechanic.

yeah, my bad :cool:

Ill get some new jets for the beastie, when we pulled the carbs apart when we first got it they werent right, one of the springs for example which sit over the needle wasnt even on properly, was only letting the slide go half way up etc. So maybe a combination of a few people not knowing what they were doing (including myself as one of them) I know how to do plugs and oil no problem, its just the more complicated stuff i start to get lost on

[mossy1200]

wtf?! when have you ever seen a mechanic use a dyno and gas analyser for anything less than a race bike and/or specifically requested dyno tune?! most shops don't even have a dyno!



The closest bike shop to JVille that has dyno and analiser is 10mins away and charge $90 for 3 runs plus repairs as required.Motormart.
$90 can be less than the cost of a mechanic($70-$80per hr)to muck around blind on the carbs.

[vindy500]

The closest bike shop to JVille that has dyno and analiser is 10mins away and charge $90 for 3 runs plus repairs as required.Motormart.
$90 can be less than the cost of a mechanic($70-$80per hr)to muck around blind on the carbs.

thats not bad a, i was seeing numbers around $600 for a dyno...

[t3mp0r4ry nzr]

o rings in carbs fail very quickly in these carbs. there are about 20/24 o rings (5/6 each carb). leaky orings can cause fuel to be sucked past into the main jet causing richness. or leaky fuel valve seat o ring can cause fuel to leak pass/by-pass the fuel valve, effectiviely raising the float height and causing richness in the offending carb.

also worn needle and emulsion tubes can cause lowdown and mid range richness.

I would suggest that changing jets should be the last thing to do if they are in fact the standard jet sizes. start with looking at the condition of the o rings and needle and emulsion. check and reset float heights if they are not faulty. messing with jetting when it is not at fault will only mask the condition, not cure it. And besides, last time I brought some, jets were $12 each, and you have 8 of them.

you need lots of patiance and knowledge to fix the richness, or lots of dollars to get a shop to fix.

hotter plugs will not fix the rich condition, just mask it.

[hospitalfood]

i would put off the dyno until you have fixed damaged parts and set everything back to factory settings.

if the muffler is standard....?

start with the air filter, clean or replace ( you can put in a performance filter if your muffler is not standard ).
check for any obstructions in airways.
if they look damaged or you suspect they are, replace main and idle jets with new factory spec.
set neeedles at factory spec position.
reset idle screws to factory spec position ( the ones bottom of carb, not the throttle stop ).
put in factory spec plugs.
give all carbs a visual inspection when doing the above to check they seem the same. check floats etc.
after this it should run well. provided the throttle stop/idle is set right.

is the muffler standard ? if it is not, you will need to dyno it after you have done the above.

[hospitalfood]

check your choke ! make sure it works as it should. is it staying on ?

[vindy500]

check your choke ! make sure it works as it should. is it staying on ?

I dont generally need to use the choke, if i do put it on it makes it rev alot higher, thats about it