Hi all,

Not too long ago, I went to a Sparks X6 exhaust, converted to a ProDesign airfilter setup ( K&N), and rejetted etc etc. I
set the carbs up with a DynoJet kit,and Sparks/Dynojet recommendations. With the lid on, but snorkel modded,
it called for stock pilots, 146/148 mains, dyno needle on 4th clip, and 3 turns out on each air/fuel mix screw.

At first I thought it was spot on, ran like a raped ape. And it still is running strong, but at very low rpm or low throttle, I
get the ever so slight feeling of being rich perhaps. When I am negotiating a slow trail in the woods, in 1st - it almost
feels like its loading up a bit too much fuel and gets a bit sluggish on the throttle response. A quick hammer down on the
throttle brings it back to life, but it feels a little boggy when chuggin slow. During the slight boggy times, I can really hear
the feedback in the exhaust sound. It gets really brap bap bap bap bap with noticeable time between "baps". Unlike a full
rev sound.

Anyways - its rideable and all, and most people probably wouldnt think anything was off... but I just feel it could use a little fine
tuning. Should I attempt to mess with the mix screws a bit ? It idles fine, starts fine and runs fine other than the certain situation
above. (sometimes the idle does seem a bit weak, but always stays running)

Ready for any advice available. Im not gonna mess with it unless someone can convince me that I should [img]i/expressions/face-icon-small-smile.gif[/img]

 

If you are really rich at idle to about 1/4th throttle turn your air/fuel mixture srews about a half a turn in at a time and this should fix it if it is rich but with your set up I would tend to think you may need bigger pilots; its hard for me to say. Do a proper plug check at 1/4th throttle and see whether you are lean or rich then take it from there. With my stock air box with lid removed I had to go to 27.5 pilots because of similar type problem. Hope this helps. This should be a simple fix unless something else is going on. Slim

 

I am having a similar problem......

if I go from WOT to idle.....and it dies.....do you think that is rich or lean?

 

Sounds like it may be lean. You may need bigger pilots. I you have the stock pilots and are currently 3 turns or more out on then its may be time for bigger pilots. Before anything else check your idle it may just need to be idled up. Another thing it will do if you need bigger pilots a lot of the times is when letting off of the throtlle from WOT the bike will pop almost like a backfire. Slim

 

I have 27.5's now
2 1/8 & 2 3/8 turns out

The idle was kinda low, but now it is too high and it still does it sometimes

 

BigScary, Its really a hard call for me to make just from the details but I would do a plug check at 1/4th throttle just to see what it looks like and take it from there. I am running the k and n filter with no air box too and i'm just over three turns out on my pilots which are 27.5's. Depending on your alltitude it is also a possibility you could be rich causing your problem. If the plug is looking good in all areas 1/4th, 1/2 to 3/4 throttle and full throttle start checking all of your lines and hoses. If all checks out maybe someone will have some other suggestions. Slim

 

Hey PipeIt660 I had the exact same problem your mentioning to a T about a month ago! I run a similar setup, GYTR Carbon fiber silencer, FMF Hi-Flo header, Pro Desing K&N Intake W/No lid, And a DynoJet Jet Kit set at 146/148 Pilots, 3 turns out, and the clips on the 3rd or 4th position from the top, whatever setup the instructions say for 800FT elevation... What elevation are you at? Mine did this when I forgot to move the air/fuel mixture screw from 2 1/4 to 3 turns out, and was running 148/150 Pilots, instead of just adjusting the air/fuel screw when I took it apart, I went back to the jets I had started out with, 146/148 and turned the screws to 3 turns out as well... I did this because in winter I ran fine off the bottom in tight technical first gear maneuvers and idling during winter but encountered the results you did in summer when I jetted up, which was too much! It would have been fine to run 148/150 in winter as I was too lean on the header pipe and idle as it would idle a tad too high to the point the idle screw was completely backed out to just idle right and the header would glow on idle! Now since this, I tested it, as I was having problems in creeks and hillclimbs that if I wasn't WOT it would bog or stall out, as well when I started it back up I had to hold it WOT to clear it out and slip the clutch bad to get up the obstacles... Since then, going back to 146/148 mains and 3 turns out on the air/fuel screw I tried it in technical half hill starts and take offs and run so wicked! Even better than before! I had problems racing a stock Pred in winter(possibly due some to traction) but just raced one with pipe and K&N filter just two weeks ago with this setup and blew his doors off at least 2-3 quad lengths and heald him at 75MPH in 5th with a 12 tooth countershaft sprocket! That says enough about being jetting right, bottom to top revs! Try that setup if you run anywhere between 0-3000FT in elevation.. Remember, the higheryou go/warmer it gets outside, the leaner(smaller) the mains you go, the lower the elevation/colder it is outside, the richer(bigger) on the mains you go... It's the difference between goin' and slowin'... In the mountains it meant the difference between going up a hill, or not even coming close to making it on sleds... It's quite the huge difference to be spot on then nowhere near close! I think I'm the closest I've ever been right now to perfect jetting on my Raptor with my setup...

 

Im between 500 - 1000 Ft elevation.

I think I understood your post, but it seems like what your saying, is that my current jetting is the exact same as
where you ended up. 146 / 148 3 turns out on air screws, 4th clip on the needle, stock pilots.

When I think about it, when I noticed it acting this way, it was very very humid and probably 80+ degrees out. I
will get to give it some more testing in cooler temps now as its cooling down here in PA. Ill report back if it
clears up.

My question is this. If the 1/4 throttle performance clears up when its cooler out, but acts up when its hotter and humid..
could I simply make air screw corrections to alleviate the trouble, on a situational basis ?

I just know its really close to perfect. Im also running my airbox lid "on". Would adding some ventilation to the airbox
have any effect on idle - 1/4 throttle performance ? Thats always something I could do as well.

Anyways, the situation you described Sparxx is exactly the same as mine. Tight technical trails, usually uphill, at very little
throttle is where it happens. Gets chuggy and poppy and MUCH clutch slipping is required to even make it up.

 

I did a plug check and the base ring was brown almost black, the arm(whatever it is called) looked good and tan........but the porcelian was WHITE as heck.........
I went up to the 4th clip and it still does it.......maybe worse.......I dunno what to do........cause it runs perfect everywhere else........

 

Hey PipeIt660, the big difference between you and I are that you run with the lid on and I don't! That would be just as big if not bigger difference than the over fat(rich) jetting setup I had! So try going somewhere clean if your too worried about water getting in your intake and try it out, and if so, you need to cut back on your jetting... The symptom I had, you have now is due to running too rich, it's just too much fuel off the bottom... If you put some vents in the airbox sure, it'll help it and most likely fix it if you put at least I'd say 4-6 holes bare min 1 1/2 to 2" wide in the lid, but if you do that, I'd say you might as well run with the lid off, a water resistant outerwear that you should have gotten with your Pro-design intake and pull the plug on your airbox for any water that may have entered to drain... Trust me, I go through water over the tires and as long as you don't stop or don't jump in and splash it that bad you won't have a problem at all... I never did.... I now run a outerwears airbox lid cover instead of the filter to deflect any water completely around the airbox.... It works wicked! You shouldn't need to alter your jetting just for the cover, but just run one or the other, not both, I found it choked it out like a lid did and was part of my problems when I was bogging like you did back a month or two ago... So try it out without the lid, and if it runs good, which it should like mine, cause your at similar altitude, keep that setup, or run to 144/146 mains with the lid on and try that, stepping it down one step at a time till it clears up... I know it's alot of work to keep tearing apart your quad and then putting it back together again, but that's the joys of jetting... The air/fuel mixture screw is too difficult to reach when the quad is together to try that... Let me know how you made out...