Short Story: I got a new exhaust and since ive put it on my bike is popping when i close the throttle at 7k and above rpm when at a stand still. and sometimes if im up above 7-8k when riding and im decellerating the pop is there as well. Since the pop is a sign of running lean I adjusted the mixture screws out until i saw signs that it was running rich but the popping was still there. It doesnt happen as much when im riding but it definately happens when im at really high rpms and let off the throttle. Can i just find the right adjustment of the screws to get rid of it. I do not want to buy a new jet kit.

I didnt notice any signs of it running lean other than the popping. It doesnt run hot and it doesnt have any noticable flat spots or anything like that. Just the pop after the rev.


Long story: Hey guys i have a k&n and i used to have a vance and hines. Now i have a shorty devil exhaust which is much different than the vance nd hines and i was getting some popping when i close the throttle when im at high rpms. If i rev the bike to 7k there will be some popping out of the pipe. Classic signs of running lean. It wasnt really lacking accelleration at all or any other signs of running lean other than the pop and its kind of funny sounding but nothing outrageous around 4-5k rpm.

So last night i did half turns out on the adjustment screws to richen the mixture, still popping. then i did another half to make 1 full turn out. But i still had popping and it even got a little worse. So now i started to wonder if something was up.

so i messed around with my idle under 1k removing the air filter and blipping the throttle she went up and came down and stayed running. That told me based on my research that it was now too rich.

I couldnt justify wasting any more time fiddling around with the bike last night so i threw it together with the screws at 1/4 turn out from where they were originally and its idling fine. i blip it under 1k and for most of the time goes right back without any fidgeting. But when i ride it in 2nd at 4k it runs fine but i feel like its not exactly the way it should be.

im thinkin about bringing them out another quarter and leaving them there kus im not really sure what else to do. I dont know why whether the bike is running lean or rich the pop is still there. I also really do not want to spend money on a new jetting kit.

 

Hey there,
Before you go and spend what could be a pile of time and money... Verify your ignition timing and check your plugs, so you are absolutely sure that what your feeling is a lean condition. I would suggest getting a fresh set of plugs if possible and pull a few "throttle chops" to get a reading. Unless of course you have access to a dyno! If the a "throttle chop" sounds scarey (which they can be, lol), head to your favorite straight away and do a few very hard pulls with those fresh plugs in. I suggest having the fairings of for this, as the plug readings will be more accurate the less those plugs cool off. IMO, this is the surest way to see where you are at, before you make any wasteful or even worse, irreversable adjustments to your carburetion. I hope this helps out. Keep us posted.

 

I have her running smoothly again at 2.5 turns out sounds great above 5k. Runs good 4k and below, still pops when the throttle is closed quick tho. The money spot is some where in between 2.25 and 2.75 turns out because it sounds kinda funky and doesnt ride very smooth around 4k. When my idle is under 1k and I rev it, it hangs up just a tad so im thinkin its on the lean side. was thinkin about tryin an 1/8 turn out from 2.5 and seein how it is.

I was thinkin about putting fresh plugs in and doing some test i just dont want to put fresh ones in and screw them up so i have to buy more. My bike also never ran bad in the first place its just a tiny bit rough when i ride in 2nd and hold it at 4k. Im just tryin to make it run as good as possible without spending more money becasue im movin up to an rr next season.

 

Since you r familiar with the screws, would you please answer this question? Is one turn on screw=360 or 180 turn of screwdriver . Thanks , hope youget it tuned up!!!

 

1 turn = 360.

 

Do you really understand what the pilot screw does? This controls fuel mixture at idle and very low throttle openings. Changing the pilot screw won't have an effect on your main jetting.

 

yeah i understand dude.... im talking about minor issues with my bike maintaining a steady speed at 4k rpm and the moment i close the throttle... My bike runs beautifull in the high rpms above 5k as i mentioned.

Are you trying to say the popping is a result of my main jets not being right? because all the research ive done says main jets are tuned by riding the bike hard. My bike rides hard fine until i close the throttle. or if im at low rpms it runs a bit rough. I dont mean to be redundant but i suppose im just clarifying. I really more or less want to know what the poppping is about.

and yes 1 turn is 360 degrees my friend i guarantee it

 

I'm not suggesting that the popping is a problem with the main jets. What you describe definitely sounds like the pilot circuit which is in effect at idle and something less than <1/8th turn of the throttle. Which makes me wonder if this applies to your issue at 4-5k rpm. Finally, stock idle speed is 1200RPM (1400 for CA bikes).