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Idle got the best of me!

7K views 74 replies 8 participants last post by  bgballin26 
#1 ·
Some of you may know i have been fighting an idle issue for awhile now, i did sync my carbs and they were not that bad out of sync. My symptoms are bouncy idle, i have to keep it idled at 1800 rpms because when it drops, it drops down to 1200, the other symptom is when it is idling, if i crack the throttle and rev it to say 7k and let it fall, when it drops back down to idle it almost dies and sometimes it does die. I think that would mean the bowls are running out of gas? But i really don't know so i'm asking for some opinions. My settings are:

Factory Pro 155 & 150 mains
Factory Pro #40 pilots
OEM airfilter
OEM needles with 2 shims (1mm)
screws 2.5 out
elevation is 875' above

I pretty much rode with it like this all summer, but i'm about to tear it apart for the winter and would like to know what i should change or check.
 
#2 ·
Tear down the carbs and clean them well. I swear that fixes 90% of the problems, haha. Check the float levels and look for any vacuum leaks. Also make sure you buy new gaskets for the float bowls, you don't want them leaking after you put all that work into cleaning and rebuilding them.
I never had a bouncy idle on my '01 so I never had to diagnose that problem.
 
#3 ·
sporadic idle is usually an indicator of vacuum leak.
 
#4 ·
I have had the carbs off 5 times trying to get them tuned right, it seems like when i went to the bigger pilots is when i developed the idle problem. I'm about to take them off again, i will check all my vacuum lines, i'm sure they are hardened and could be cracked.
 
#5 ·
Make sure you get the boots that hold the carbs to the bike tight bro. They are so hard to get to, it's easy to have a loose one, and the bike may run good when on it, but lope or have a shitty idle. Infrared gun indicated I had a cooler cylinder and then I realized it was the boot making that one cylinder suck at idling.
 
#6 ·
Ok, one thing i have not checked was the temp of each header tube, thanks for the info
 
#7 ·
Here is a crappy video taken from my phone, the idle was not bouncy here, it comes and goes. I did notice the tip of my exhaust has turned black, so i'm thinking it's a tad rich.

http://youtu.be/RHnNg0YFaDI
 
#10 ·
It has always had that choppy sound since i cut the exhaust, and also the sound quality of my phone makes it sound worse then it really does. Last time i checked the plugs they looked alittle rich, but no sign of a cylinder not hitting. I will check the temps of each header tube tomorrow. Like i said the bike runs amazing, runs hard all the way to red line, just the bouncy idle, which is not consistent. I'm hoping santa will bring me a Go Pro so i can get some good video's of my bike in action, i have some nice twisties around here where i can get wfo in between curves.

It's 40 degrees outside when i shot this video and the bike was not warmed up all the way. Before i turned the choke down it was idling right at 2000 rpms
 
#11 ·
Bro, sounds like your not firing on all four or one isn't getting good enough spark, or too much fuel in one cyl. What do your plugs look like?

I just went and took a vid of mine for comparison. Its idling about 12-1300 w/o the choke and it isn't fully warmed up (about 140ish). I'll link the vid when it's done uploading.
 
#12 ·
So should i start by checking my plugs?
 
#13 ·
#14 ·
Well hell, for sure a difference in sound, i will tear it down tomorrow :mad:
 
#16 ·
Ya the bike looks awesome!
 
#17 ·
What, this old thing?


Thanks guys :cheers
 
#18 ·
Your exhaust is so much quieter than mine, i like that sound, i think all the packing is gone on mine, i changed my plugs last February and they were all the same. I'm anxious to check them out tomorrow to see what i'm dealing with. I'm going to get inside the carbs as well and make sure everything looks good, and make sure my boots are still good shape. I think i will turn my mixtures screws to 2 turns. I think i will also try out the Dan Moto Exhaust, for the price it's hard to beat.
 
#19 ·
Its actually pretty loud when its rev'ed up. Packing is solid though. I found that out when I swapped the polished sleeve for the CF one. It has a real deep throaty sound at low revs, but screams like a mofo up high.

I don't really think the screw setting is the issue with yours. Sounds like something else. Maybe 1 of your float needles isn't closing all the way off and flooding out a cylinder...... then when you get on it you are able to burn the excess fuel so you don't really notice the issue. Plugs could tell the tale, and checking the temps of each cyl like Chief mentioned could pinpoint which one quicker.

I spent countless hours reading, re-reading, and reading again, the carb tuning information on FactoryPro's site. Took it one step at a time, and didn't give up until it was butter smooth. Its a real pain for sure, but the end result is worth every minute. I've heard more than one of these bikes sound like crap and remembered how bad mine ran when I got it 2 1/5 years ago.
 
#20 ·
Here are the plugs, 1 through 4 (left to right)
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The burn marks look even, but the white part in the center of the plug is whiter or plugs 3 & 4? I don't know what that means.
 
#21 ·
It means 1&2 are rich, or they are out of sync. When was the last time they were sync'ed?
 
#22 ·
I synced them a couple of months ago but i had trouble with the gauges (old home made set up). They are a pain to get to the vacuum ports to sync them! But i guess i will order a motion pro sync tool and try that, should i bother pulling the carbs apart or should i sync them 1st and see how it reacts?
 
#23 ·
Definitely sync with a real sync tool, makes a big difference.
 
#24 ·
I picked up a Motion Pro sync tool, a guy i ride with had it, he used it once and sucked all the fluid out, so i have to order the fluid, he said he didn't calibrate it. I took my carbs apart and cleaned them real good, inspected everything, put them back together, i turned the screws to 2 turns just to see what happens, and now it hangs around 2500 rpm for a split second, it will not run at all with the choke on which is bizarre. I think i will go back to 2.5 turns and hope the sync will smooth it out.
 
#25 ·
Pulled the carbs back off, set them at 2.5 turns out, noticed the boots on the airbox were pulled halfway out, so i pulled the plate off, put them back in place and put it all back together, it's back to normal now, except the idle isn't bouncing around that bad, i can actually idle it at 1500 rpms instead of 1800 rpms, now the waiting game for the fluid so i can refill this sync tool. I'm ready for a F.I. bike..
 
#26 ·
Should idle around 1250-1350 when its all good, this is where it needs to idle when syncing too. These things always bounce a little at idle, but yours sounded abnormal. When you get it sync'ed right, you'll probably be much happier. I check the sync on mine every 3 months just because I'm that anal about my bike. I remember reading in a manual somewhere that it should be done every 4000 miles.
 
#27 ·
Does it take a special tool to get in between the carbs to adjust the screw? I tried my skinniest screw driver and it didn't fit?
 
#28 ·
Its a pain in the azz, but a skinny phillips is what you need. You just have to find the right place to get at it from.
 
#29 ·
Does it matter which carb i use to calibrate my motion pro sync tool?
 
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