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Discussion Starter · #21 ·
Ok hopefully y’all can help me with this, but I got a carb sync tool and it seems to be syncing but I’m getting a very weak backfire on the left cylinder with it “synced”. I say “synced” because the needles are both pointing in the same direction but idk why it’s acting strange. This is at idle/ 2200 rpm.
 

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yeah they may be almost in sync (but not quite) but clearly out of tune. if the left cylinder is popping it is running weak you need to dial the carbs mixture screws remember each one could be different to get them both in tune. for instance mine runs roughly 2.75 turns out on the right but only 2.25 on the left.
 

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Discussion Starter · #24 ·
yeah they may be almost in sync (but not quite) but clearly out of tune. if the left cylinder is popping it is running weak you need to dial the carbs mixture screws remember each one could be different to get them both in tune. for instance mine runs roughly 2.75 turns out on the right but only 2.25 on the left.
I’m not gonna lie, I’ve just been kids turning the screw for the sync. I guess I’m doing it right😂. I need to grab a screwdriver that’ll fit and then I’ll adjust the mixture screw. They’re both at 2.5 turns right now.
 

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yeah there was a good write up on dialling the carbs from balance to mixture screws. just looked for it and it not there must have been in the old WIKI.
there are 3 adjustments to get them right the idle screw (black knob) balance screw (cross head between the cabs) and mixture screws (under each carb) when I dial them in after a carb job.
it's idle screw up to 2k. balance carbs. set mixture screws. recheck balance. drop the idle to 1100/1200rpm.
 

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Discussion Starter · #26 ·
yeah there was a good write up on dialling the carbs from balance to mixture screws. just looked for it and it not there must have been in the old WIKI.
there are 3 adjustments to get them right the idle screw (black knob) balance screw (cross head between the cabs) and mixture screws (under each carb) when I dial them in after a carb job.
it's idle screw up to 2k. balance carbs. set mixture screws. recheck balance. drop the idle to 1100/1200rpm.
Alright. When I get my screwdriver I will do that and let y’all know how it goes
 

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you know the ones that come with a electric screwdriver, not the short ones but the ones about 2in long I use one of those. the flat medium one.
 

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Discussion Starter · #28 ·
No matter how much I turn the air fuel screw that side still pops. I set the idle to 2000 and it sounds like ****. Almost like it’s redlining but it’s at 2000 rpms
 

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Discussion Starter · #29 ·
I’m also getting a lot more response on the vacuum gauge from the left carb and left from the right. The left spikes when I blip the throttle while the right doesn’t really. They both are balanced when I let off the throttle
 

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have you checked the valve clearance?

FOG
 

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Discussion Starter · #33 ·
Idk, I took a break for today, it’s dark and don’t want the neighbors getting mad. The carbs are synced pretty well, they’re off at idle but when I twist the throttle and hold it they sync up pretty well. Still getting popping, seems to speed up at low rpm’s, can’t tell if it stays that way when accelerating. Like I said, maintenance is up to date, it’s been 2000 miles since a valve adjustment, they should be good. Float height it set, I guess it could just be the air screws and balancing now.
 

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Have you inspected the diaphragm of the carb side in question
Any tears in the rubber?
Seems odd you're making turns on the carb w little change in synch gauge
 

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hi. I think you may be getting lost on the purpose of what your supposed to be doing because one thing effects something else that you don't expect. sort of not seeing the forest because of all the trees in the way. an easy situation to get in (most of us have been there at some time) take a breather relax and reflect on the reason for doing it.

my feeling is either your not doing it right or there is some other issue stopping you from achieving the correct results, if you go through the correct procedure and it still isn't right then some other issue is causing the problem.

first do over from step one. attach gauges release the gauge throttle down valves. attach a remote fuel source with enough fuel to do the test. start the engine.

set the idle screw (black knob) to a raised tick over 2k may be fine I prefer around 1700/1800rpm. then leave that knob alone. (this is going to be your base line) the revs will raise or lower as you do the adjustments.

the needles on the gauges will be wobbling all over the place. so one gauge at a time slowly shut the valve so the needle steadies but not stops (there should be a very slight movement) when it's steady do the other one.

now if the two gauges are not spot on equal make them the same by turning the carb balance screw (middle of the carbs) left or right whichever makes the needles the same. remember if you press on this screw while adjusting, it WILL increase the revs as your pressing on the throttle shaft. you should only need the bite of the head to turn it.

when both are spot on blip the throttle both needles should rise and fall in unison and settle exactly to where they were if they don't you have some other issue. maybe an air leak or something in the carbs changing how they react to each other.

if they do the balance is done. report how this goes. and we will move on to setting the idle screws.
 

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Discussion Starter · #37 ·
hi. I think you may be getting lost on the purpose of what your supposed to be doing because one thing effects something else that you don't expect. sort of not seeing the forest because of all the trees in the way. an easy situation to get in (most of us have been there at some time) take a breather relax and reflect on the reason for doing it.

my feeling is either your not doing it right or there is some other issue stopping you from achieving the correct results, if you go through the correct procedure and it still isn't right then some other issue is causing the problem.

first do over from step one. attach gauges release the gauge throttle down valves. attach a remote fuel source with enough fuel to do the test. start the engine.

set the idle screw (black knob) to a raised tick over 2k may be fine I prefer around 1700/1800rpm. then leave that knob alone. (this is going to be your base line) the revs will raise or lower as you do the adjustments.

the needles on the gauges will be wobbling all over the place. so one gauge at a time slowly shut the valve so the needle steadies but not stops (there should be a very slight movement) when it's steady do the other one.

now if the two gauges are not spot on equal make them the same by turning the carb balance screw (middle of the carbs) left or right whichever makes the needles the same. remember if you press on this screw while adjusting, it WILL increase the revs as your pressing on the throttle shaft. you should only need the bite of the head to turn it.

when both are spot on blip the throttle both needles should rise and fall in unison and settle exactly to where they were if they don't you have some other issue. maybe an air leak or something in the carbs changing how they react to each other.

if they do the balance is done. report how this goes. and we will move on to setting the idle screws.
Ok the balance is done, I set the idle at 2, got the carbs balanced, the idle increased to almost 3 while doing that, and it set it back to 1200, which is when it started to make that noise again. What’s next?
 

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mixture screws. set the idle to around 1350rpm you have the mixtures set at 2 yes . so insert the screwdriver up the hole and engage the screw head. turn the screw 1/8th of a turn out listen to the engine tone if it doesn't change turn it another 1/8th and so on keep doing that each time waiting about 10 or 20 seconds each time all the time listening to the tone of the engine. keep doing that eventually it will sound a bit lumpy the revs may also rise or fall
keep turning the screw out until the engine starts to throb that is the point the setting is a little too rich so then back off the screw 1/8th at a time the opposite way until it runs smooth. it takes some time and practice but you can hear when it right you are looking for the smoothest running at the highest revs out of each carb. after setting one carb readjust the idle back to 1350rpm and do the other exactly the same it should now run smooth (for a EX) and be responsive without popping. reset the Idle to 1200 and your done.
be aware this takes practice you may have to do it a few times until you get used to hearing when the mixture is correct.
 

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Discussion Starter · #39 ·
mixture screws. set the idle to around 1350rpm you have the mixtures set at 2 yes . so insert the screwdriver up the hole and engage the screw head. turn the screw 1/8th of a turn out listen to the engine tone if it doesn't change turn it another 1/8th and so on keep doing that each time waiting about 10 or 20 seconds each time all the time listening to the tone of the engine. keep doing that eventually it will sound a bit lumpy the revs may also rise or fall
keep turning the screw out until the engine starts to throb that is the point the setting is a little too rich so then back off the screw 1/8th at a time the opposite way until it runs smooth. it takes some time and practice but you can hear when it right you are looking for the smoothest running at the highest revs out of each carb. after setting one carb readjust the idle back to 1350rpm and do the other exactly the same it should now run smooth (for a EX) and be responsive without popping. reset the Idle to 1200 and your done.
be aware this takes practice you may have to do it a few times until you get used to hearing when the mixture is correct.
Does screwing out or in richen the mixture? I read that screwing in does. I got the carb to stop popping for the most part, I did that by screwing it in. I will try that technique though
 

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Screwing it out makes it richer. Screwing it in makes it leaner.
 
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