Jetting

[Rastus]

Well, i checked my plug today after about a 3 hour ride and its a light red color. This is with a WB E-series, with the stock headpipe.
I had a DG close circuit racing exhaust, and it was jetted right, and I still have the same jets.
I do have the White Brothers headpipe, i tried running it, but it just runs worse.
Could i be running lean? It back-fires on deceleration. Would i have to go bigger to an even bigger jet if i put the White Bros. Headpipe on?

Thanks in advance.

[Rastus]

Any help would be helpful.

[BornOnFire]

If you are back firing on decelleration, you are definately lean. try a bigger jet or turn in the fuel screw on the carb 1/2 turn.

[Rastus]

Thanks.
I tried running my WB headpipe, and i checked the plug. This time it was a black color on the threads, and a dark brown on hte electrode.
Does that make any sense? Seems like a bigger headpipe would increase the flow.


Stock Headpipe+ WB E-series Pro-Meg = lean

WB headpipe +WB E-series Pro-meg = rich

(these are on the same jetting.) Weird?
Ill be taking the carb off tomorrow, and checkin to see what the main jet is.

My problem isnt with the needle jet, or the slow jet, its the main thats running rich, because it acts like it has the choke on. The Low to mid power is great, but the topend sputers.It only does this at 3/4 to full throttle.

Thanks for the help guys.

[BornOnFire]

You may be having a problem with the back pressure created by the new head pipe and the silencer. You can try removing a few discs from you silencer and tune it that way or mess with the fuel screw a little. Don't depend on that spark plug too much. It can give false readings depending on the brand of gas you are running. Also, you should be using a fresh plug for these tests as well. A fool proof method to use would be to go up on the main jet size incrementally until the engine begins to make a "warbling" sound while accellerating. At that point the engine is telling you that you are rich and you should be able to go down one jet size and be right on the money. Good luck

[Rastus]

Thanks, it already does that when i have it full throttle.It acts like I have the choke when the throttle is 3/4 to full. So just try getting going down a jet size?

Thanks

[spliffy]

hey man... You Can Change The Main Without Taking Off the carb... On The Bottom Of The Bowl... There Is A large Nut... Take That Off & Ur Main Is Right There... Takes 5 Minutes To Change It That Way Instead Of Taking The Tank, Carb & Bowl Off Seperately.... Let Me Know What You have in There... im Running a 150 Main Right Now & 40 Pilot... Im A Little Rich On the Low End .. But Top End I'm Good At That.... We Have Similar Mods Except For The Pipe.... Im Just Running A Stock Pipe With The Welds Ground Out On the Head Pipe..... I am thinking Of Going Back Down To The 38 For Pilot Cuz When I Give It Gas On the Lowend She Kinda Sputters But On The Mid Up... She Takes Off Like Crazy..... I have Some New Scratches On the Bottom Of the Back Grab Bar... If you Know What I mean hehe

[BornOnFire]

I would go down on the jet size until it stops "warbling". Then put in a new plug and test it out by getting into a large straight away. Open her up into 5th gear for at least ten seconds and then pull the clutch while you hit the kill switch at the same time. Coast to a stop and let her cool a little. Then check your plug. It is important that you kill it while in the WOT position otherwise you will not get a "pure" main jet result. Good luck.

James

[Rastus]

Im running a 130 main right now.
So jsut try a 129 main and see what happens?

[Blake24]

sometimes bumping up the pilot will help backfiring during deceleration