Bike running rich

[numark1]

My bike is running too rich because of the exhaust (i don't want to change the jets as i don't know how to) is there anyway else of making it run a bit less rich as it's misfiring a bit with the plugs fouling. Maybe a hole or 2 in the airbox??

[bish777]

What makes you think its the pipe thats the cause?

You could get a bifg spike and smash a hole in the baffles in the pipe?
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GSXR1100J

[numark1]

It only started doing it since i cut the can right down. It does have a removeable baffle in at the moment. Can't think of anything else that is causing it. Just have a full service so should be running sweet bar this

[NSR Mick]

Take it to a dyno centre and they will jet it for you for a price.
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If you dont like the way that I ride.......Stop trying to keep up!!!

[prawny1]

Bikes with after market exhausts usualy run lean which causes backfiring etc. but if your plugs are black and the bikes carbs are standard then i would suspect the choke curcuit more than jetting.

Most bike are a little lean standard and get even more so with a can which can cause plugs to burn out or at least go very white around the electrode.

Is the baffle the curved type and if so is there enough space around the removable baffle for gas to escape since you cut the pipe down? If there is not enough gas flow the bike will be choked and will not scavenge properly causing the bike to soot up the plugs.
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hellkat wrote:

Some people are only alive cos its against the law to kill them.

[Wafer_Thin_Ham]

[TUG]

if you take a look at your carbs you can normally see the balancing screws and the air/fuel mixture screws, if its running too rich then to lean it out turn the screw in (clockwise) if its running lean then turn it out(anti-clockwise) if its running rich then fuel range is poor and takes ages to heat up, if its too lean then your bike will heat up extremely fast.
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Haz ER-5, innit!

[prawny1]

I agree most older bikes are jetted richer, mostly with larger slow jets and smaller mains to give a richer midrange, but modern bikes are jetted with larger mains and smaller slow jets to lower emissions in normal round town driving condition (half throttle riding)
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hellkat wrote:

Some people are only alive cos its against the law to kill them.

[bugsy46]

The mixture screw is for adjusting the idle mixture. It is not to provide an overall LEAN/RICH condition over normal running. To do this you change jet sizes
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Laura - "And where did looks come into this and bugsy leave steven alone. You are not gods gift to women you may think you are but you're not."
Keith - "All the best"

[Kickstart]

Hi

As above. If you don't know where in the throttle / rev range it is running rich then not much you can do yourself. A dyno run with an exhaust gas analyser probe up the exhaust should help.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[bish777]

[TUG]

dunno then but its done wonders for my bike, i also adjusted the needle height. since i changed the mixture of the idle, my bike takes ages to heat up, before i changed it it heated up at a decent rate.
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Haz ER-5, innit!

[bish777]

Idle screw adjusts only the idle circuit. When the engine is cold, if you run the idle mixture lean it will stall alot when the revs drop.

The mainjet and slide needle adjust the off idle, mid and high RPM mixture.

Alot of race bikes did not have any idle circuit at all and required the throttle to be held open.
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GSXR1100J

[TUG]

how would i know if its running lean at high midrange power? stutters? my bike has a slight stutter at 4.000rpm, needle and jet adjustment needed?
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Haz ER-5, innit!

[bish777]

try raising the needle. Put the clip in the next higher notch, this means the needle sits higher in the carb, richening the mixture in the midrange.
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GSXR1100J

[TUG]

wha? you sure that not leaner? i put all the needles up a notch to lean out my mixture as my bike was drinking petrol 16 litres in 140km, i raised the notch and it now does 180-210km to a full tank.
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Haz ER-5, innit!

[Pete.]

[Kickstart]

Hi

Simplest way I can think to describe it, put the clip nearer the pointed end of the needle to richen the mixture.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[TUG]

ye thats correct, thats how i knew to lean out my bike, as it was running stupidly rich, it drank petrol, i think i need to change my float heights but i'm confused on how to measure them. i've read loads of different ways to measure them and its driving me insane.
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Haz ER-5, innit!

[bish777]