How to set your pilot screw adjustment.

[AbnMP13]

That's great info, I appreciate it. I found the tool listed in the Dynojet website (DT008) but I had to email them to see if they sell it seperately.

[stvemerz]

Well....I've read this over and over...I'm still having some problems...Stock 400ex 2007...Sparks 6 degree adv. Hmf Sport slipon with quiet core..Keihn 152 main and 42 pilot...Installed...Fuel screw was at 2.5 turns out...used a 2004 needle and put clip 3 down from top...Checked plug...sooty black...I then turned the fuel screw all the way in... of course this was after a full warm up...It died, but yet I could start it as long as I gave it some throttle...Once I let off..It died...So I figure my jet sizes are ok...plug is still a blackish color....I notice when I rev the throttle...looks like a fine puff of exhaust fumes come out...tells me fuel...still running rich...the fuel screw is now at 1 3/4 turn out...Any suggestions...quad worked great before the changes...and works great now...just a slight gurgle when I let off throttle...It runs good..do not get me wrong...but I do not have that nice brown color plug...that I'm looking for...HELP..

[AbnMP13]

U done any airbox mods?

[stvemerz]

No air box mods..I really do not plan on it at all...since were I ride is in dusty conditions..I also forgot to mention..I installed a uni air filter...anyone have any ideas...

[AbnMP13]

My opinion is to go to a smaller jet like maybe to a 148-150 and put the fuel screw back out where it was. If the bike backfires on decel BUT runs normally, then tweak the fuel screw. It seems easier to me that way as the bike is more likely to run when it's a little lean.

Also not to insult you but you are checking the porcelin portion of the plug by the electrode correct?

Hope this helps.

[stvemerz]

Yes..I'm checking the porcelain area..it is blackish...stock is 148...Maybe I will get a 150 and try it....Just baffling to me that the HMF slipon gives 152 and 42...I will try the 150 and put fuel screw out 20 like 2- maybe 2.5 turns out...Ive been cleaning the old plug..before i try the 150..should I run a new plug in it first..

[AbnMP13]

I would, it would definitely be easier to read with the new plug.

[stvemerz]

Well....I think I'm on the right track...pulled old plug and gapped and put in new one....at 1 and 3/4 turn out..running a a slight bit of tan on porcelain...and very dull white on elctrode but no backfire on letting off throttle....so I backed out the air screw to 2 turns and then checked same plug..little lighter white...went out 2.5 turns and now will go get a new plug and try it...Does it sound like on the right track...I think that I have some bad gas as well..mostiure in exhaust...water dropplets at the tip..not fuel dropleys...will try new plug and let you guys know...

[stvemerz]

Well...here we are....152 main 42 pilot, keihn...new plug and 2 3/4 turn out...no backfire..but on higher revs..fine exhaust fumes out the exhaust...also..plug is a super light tan....I mean super light not like a paper brown bag....Think I'm almost there...any advice or hints....and do I need change the plug after every run...thanks..NEW to this.

[AbnMP13]

Sounds like you're getting there, mine is light tan and I still backfire at times on decel, keep working it, change plugs when you make a major change, that way you'll know which way to go. I know I don't have to tell ya this but keep the plugs that don't foul, they're still good. I just changed mine on major jetting changes to get a true read.