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Bob KellyIII · August 29th, 2021, 05:30 PM

to answer the original question, symptoms of a bad fuel adjustment (screw)
I would have to say this, most times it is difficult to tell if their out of adjustment with one another, But in extreme cases, it's fairly easy... you can hear it as it idles
in the case of my 250R it was very apparent as it would not idle on both cylinders when the engine was cold... In most cases though you can hear it as one cylinder will be heavier than the other, the boom is a bit louder or stronger than the next boom.... in most cases this is all you have to go by until you put the wrenches to it.
keep in mind the fuel air screws do Not effect the running of the engine above an idle
if it's idling at 800RPM the most it will effect the running is about 1200 rpm
lean Fuel air screw adjustment will result in a Sogg when cracking the throttle open.
if they are too rich in adjustment it will smoke black smoke at idle. which is bad as it will foul the spark plugs quickly.... You are supposed to adjust the air fuel screws when the engine is warm and ready to go... not cold !
and you adjust then to the fastest idle you can get by continuously dropping the idle speed ( knob on the side) to as slow an idle as you can get, say 500 RPM ... no lower than that. if you adjust the left cylinder to max RPM then you need to drop the idle to 500~800 RPM and adjust the right cylinder the same way, once your sure you have the maximum RPM on each air screw then you should turn them out about 1/8th turn each More... this will set the Fuel/Air adjustment just right for Idle. it should take any throttle change with out stumbling , it will grab the RPM's fast and without hesitation if it's done right....
this of course assumes the carbs are clean and in good working order, if the bike has been setting all winter with gas in it and it doesn't want to idle like it did before you parked it chances are real good you have to clean the carburetors to get it working properly again... using a gasoline stabilizer is a real good idea in the winter but better yet I like to shut off the fuel and run the bike till it is out of fuel in the carburetors as well... but with the vacuum petcock that is impossible to do...you can't shut off the fuel if you wanted to. only by pulling the vacuum line to the petcock and plugging it
can you actually turn off the gas... but if your vacuum diaphragm leaks gas to the carbs like mine does anyway, that isn't going to help at all.
Up to this date I have always just started every motor on the property at least every 4 to 6 weeks during the winter, I also like to add a little chainsaw gas ( gasoline and 2 cycle oil mix) to the engine's gas tank to help stabilize the fuel, this has never failed me
and I've not had to clean the carbs on anything in the 5 years I've been here. but I do start the motors about every month and run them till their good and warm then turn them off. this is what I do... I don't buy fuel stabilizers, I just add chainsaw gas to the tank.... if your worried about a catalytic converter perhaps you shouldn't do that !!!!
because chainsaw gas and catalytic converters don't mix well, it'll plug them up fast !
....
But the Fuel Air screws under the carb are for Idle Only, they don't adjust the speed of the idle, they adjust the Fuel / Air mixture, the speed is adjusted by changing the butter fly stop screw ( the knob on the Ninja.)
....
Bob...

August 29th, 2021, 05:30 PM	#19
Bob KellyIII Retired motorcycle Mc. Name: Robert Location: Weed, California. Join Date: Jul 2021 Motorcycle(s): 2012 Kawasaki Ninja 250R, 2021 CSC TT250, 1977 Triumph Bonneville 750cc,2001 Honda XR650L. Posts: A lot.	to answer the original question, symptoms of a bad fuel adjustment (screw) I would have to say this, most times it is difficult to tell if their out of adjustment with one another, But in extreme cases, it's fairly easy... you can hear it as it idles in the case of my 250R it was very apparent as it would not idle on both cylinders when the engine was cold... In most cases though you can hear it as one cylinder will be heavier than the other, the boom is a bit louder or stronger than the next boom.... in most cases this is all you have to go by until you put the wrenches to it. keep in mind the fuel air screws do Not effect the running of the engine above an idle if it's idling at 800RPM the most it will effect the running is about 1200 rpm lean Fuel air screw adjustment will result in a Sogg when cracking the throttle open. if they are too rich in adjustment it will smoke black smoke at idle. which is bad as it will foul the spark plugs quickly.... You are supposed to adjust the air fuel screws when the engine is warm and ready to go... not cold ! and you adjust then to the fastest idle you can get by continuously dropping the idle speed ( knob on the side) to as slow an idle as you can get, say 500 RPM ... no lower than that. if you adjust the left cylinder to max RPM then you need to drop the idle to 500~800 RPM and adjust the right cylinder the same way, once your sure you have the maximum RPM on each air screw then you should turn them out about 1/8th turn each More... this will set the Fuel/Air adjustment just right for Idle. it should take any throttle change with out stumbling , it will grab the RPM's fast and without hesitation if it's done right.... this of course assumes the carbs are clean and in good working order, if the bike has been setting all winter with gas in it and it doesn't want to idle like it did before you parked it chances are real good you have to clean the carburetors to get it working properly again... using a gasoline stabilizer is a real good idea in the winter but better yet I like to shut off the fuel and run the bike till it is out of fuel in the carburetors as well... but with the vacuum petcock that is impossible to do...you can't shut off the fuel if you wanted to. only by pulling the vacuum line to the petcock and plugging it can you actually turn off the gas... but if your vacuum diaphragm leaks gas to the carbs like mine does anyway, that isn't going to help at all. Up to this date I have always just started every motor on the property at least every 4 to 6 weeks during the winter, I also like to add a little chainsaw gas ( gasoline and 2 cycle oil mix) to the engine's gas tank to help stabilize the fuel, this has never failed me and I've not had to clean the carbs on anything in the 5 years I've been here. but I do start the motors about every month and run them till their good and warm then turn them off. this is what I do... I don't buy fuel stabilizers, I just add chainsaw gas to the tank.... if your worried about a catalytic converter perhaps you shouldn't do that !!!! because chainsaw gas and catalytic converters don't mix well, it'll plug them up fast ! .... But the Fuel Air screws under the carb are for Idle Only, they don't adjust the speed of the idle, they adjust the Fuel / Air mixture, the speed is adjusted by changing the butter fly stop screw ( the knob on the Ninja.) .... Bob... __________________________________________________ Its too late when you've gone too far !