making my 1st attempt to re-jet my 250ex....any suggestions?

[ryanh250ex]

tomorrow (today really, it's half past midnight here) i'm going to try to re-jet my quad. while my quad has been re-jetted (twice) before, it was done by a shop and not me, and since my shop is filled with morons (if i ever need to go back to one, i'll be heading elsewhere) and they take forever, i have decided to take matters into my own hands and correct my jetting once and for all. the only thing on my carb i have ever messed with is the fuel screw, which i think i've made a bit too rich (38 pilot @ 3.5 turns out, i will try 3 and 3.25).

the main thing i want to accomplish after re-jetting is that i want to get rid of the deceleration backfire (note: it also did this when the fuel screw was at 2.75 turns out), or since the pipe flows so much air out, at least get it down to a minimum. also, when i nail the gas quick, it will die on me (wont completely shut off, but it just wont rev, it simply dies) , and i also want to get rid of that. i believe most of the mentioned symptoms will go away if i richen up the needle which is done so by raising the clip, yes? as far as i know, the needle is the stocker at the stock position.

since this is my first time opening up a carb like this, i want to make sure i dont screw up big time. i have a service manual from honda, but i find the carb section to be a little confusing for someone relatively new to doing their own work on quads.is there any tips or bits of advice one could give for working on a 250ex carb? what exactly will i need to take off or whatever to access the carb?

any help at all would be MUCH obliged.

thanks in advance,
Ryan

[NoWingNoPrayer]

Its all brass!!!! meaning its soft so dont force anything.
and unload a bottle of carb cleaner on those parts befor you put it all back together, just to get rid of non petroleum materials.

[ryanh250ex]

thanks. would a dealer have carb cleaner in stock?

[White_Knuckles]

The de-celleration backfire is normal. Your stock needle clip is on the lowest available position so no deal there. I've tried a 40 pilot and the T-4 will still pop. Best setting is 2.5-3 turns out on the fuel screw which helps backfire. Here's a little theory for ya:

When the throttle valve is in the idle position, fuel does not flow out of the main system (needle, needle jet, main jet). Fuel is only delivered to the engine by the pilot (idle) system.
The combined effect of the closed throttle and elevated engine rpm is to create a fairly strong vacuum in the intake manifold. This vacuum, in turn, causes a high airflow rate through the small gap formed by the throttle valve and carburetor throat.
Under these conditions the pilot (idle) system cannot deliver enough fuel to create a normal, combustible air/fuel ratio. The mixture becomes too lean to burn reliably in the combustion chamber. It gets sent into the exhaust system unburned and collects there.
When the odd firing of the lean mixture does occur, it is sent, still burning, into the exhaust system where it sometimes ignites the raw mixture that has collected ---- the exhaust then pops or backfires.
Completely stock Harleys do not do this until open-end mufflers, such as the popular Screamin' Eagle slip-ons, are installed. The exhaust must be both free-flowing and have an open exit for the popping to occur.