smaller jet? or needle?

coco /

Jan 25, 2009 09:47PM

21mm del. w7 needle,set at top ring leanest setting. jet it think 92 with the adjustment screw turn in max leanest setting.

80cc gila/malossi filter.

still low rpm bog just alittle then it kicks in and screams

plug chop a little dark but not bad.

so where do i go from here ? the previous needle was w9.@ top notch leanest setting and the low end was fouling out but great at the top.

if i tuned it lean for the bottom then it was way too lean at the top.

so do i need a smaller jet or fatter needle both?

thanks for reading all this.

pipe is dmp 16/40 gears

plug next hotter than ngkb7hs but its autolite

Re: smaller jet? or needle?

Novakarl /

novakarl

Jan 26, 2009 07:55AM

So at WOT, it bogs at low RPM, and rips at high RPM?

I'm running a 20mm PHBG on a Metra 65. I was running a pretty restrictive air filter, and 4-stroking with a mid 80's jet. With a higher flow filter, it takes a 94 main jet to get it to 4-stroke on the top end, but it runs better overall. Is the malossi filter restrictive?

As for the bog, going from a 55 pilot jet to a 50 pilot jet helped a little with the bog off the line, but I'm going to try smaller when the parts get here. I think the pilot jet feeds 2 circuits, and only one of these is controlled by the screw.

I guess one thing to beware of if you lean out the idle mix too much, is not getting enough lubrication if you're going down a hill with the throttle closed.

If you have the idle mix screw almost all the way in, a smaller pilot jet may be in order. What size pilot jet are you running?

Re: smaller jet? or needle?

coco /

cocoloco105 OP

Jan 26, 2009 05:02PM

not sure of pilot# but i still have lots of idle adjustment

Re: smaller jet? or needle?

coco /

cocoloco105 OP

Jan 27, 2009 02:03AM

im thinking w10 or w11 with the tip fatter it should lean it out at the bottom.

Re: smaller jet? or needle?

Eric Sabatino /

Go to branch

erics

Jan 27, 2009 05:24AM

You need to be looking at yr idle jet, i think.

Get around 35-40. That W9 should be working pretty well with the proper idle jet. the only difference with the W7 is very slightly shorter taper (leaner for slightly more time). Same beginning and end dimensions.

I've been switching W7's out for W9's on bikes at the shop here.

Re: smaller jet? or needle?

coco /

cocoloco105 OP

Jan 27, 2009 05:40AM

i had a w9 and it was good mid/top but it was very rich at the bottom at the leanest needle setting.

the W7 helped out alot but my lean settings are maxed out .

i will try a different idle jet.

now that i think of it the idle screw is screwed way out so that is leaned out too right?

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