Make your own pilot fuel jets

[Night Vision]

reference: http://ridersofvision.net/forum/zindex.php?topic=1914.msg17495#msg17495

I need to get some wire size drill bits to make my pilot fuel jets larger... # 60 is as big as they come.
in that thread, there is a link to Grainger and they list wire size drill bits...

I'd like to know how big the #60 fuel pilot jet is.... I don't know if it's a #60 wire size.....  the lower the number on wire, the bigger it gets... our jets; the higher the number the bigger they get

and Dave T is talking about #41-#50 wire size bits for an XT610? (huh?) but does not mention the size of the pilot

any one know the size of the orifice on a #60 pilot fuel jet  ???

[fiat-doctor]

Six tenths of a MM.  A 125 main jet is 1.25mm.
Steve

[Night Vision]

gracias! I'll still get a range of sizes..... jsut needed something close to start with

[Night Vision]

ok, that was way too easy.... something going that right doesn't happen to me often :o
I changed the name of this thread because it's so easy, even you could do it....

I took the pilot fuel jet size in mm (thanks again Steve)

converted to inches

related those to wire gauge size drill bits

ordered an assortment of them on line Monday morning at 7:30am

received them today (Tuesday) at around 2:00pm (they were delivered by UPS before I got the order confirmation and tracking #)

stopped by Lowe's and bought an assortment of collets for the dremel (which I didn't use)

put a #60 pilot fuel jet upside down into the air pilot jet hole of a spare carb top and clamped into a vise

slapped the smallest bit I ordered into a Stanley hand drill

couple of cranks and.........

presto! #62.5 fuel pilot jet

[joevacc]

NV, the suspense is killing me!  Tell us how it works in The Red Skunk!!!!!!!!

[Blake]

Im definitely going to have to try this.. as the pilot jet is the one thing i was having trouble with, with my k&n's and exhaust.  It needed more and there simply werent any bigger sizes.  hmm.. i wonder if any local places would have the wire size drill bits.

just found this:
http://bobmay.astronomy.net/misc/drillchart.htm

hopefully that helps you

[Night Vision]

Joe; 62.5 is pretty damn close... might try to tune a slight lean stumble out with the air pilot screws... or go 65

Blake; if you have a free flowing exhaust and k&n pods.... most likely you're lean and need bigger fuel pilots, air pilots, and mains

I have a predator race can and UNI filter (probably comparable flow wise to systems you have) and went:
135's air pilots front/back
130 f/ 127.5/r mains
and 62.5 fuel pilots front and rear (for now)

I have the bits to make 62.5, 65.0, 70, and 72.5    but unless you have a bunch of 60's lying around to send to me, you can get bits and make your own..... start off small and keep drilling them bigger as needed.

I went to Gainger.com and got part numbers for Chicago-Latrobe Jobber drill bits and then went to:

www.drillspot.com to order them

62.5= #72 wire gauge
65=#71 wg
67.5~70=#70 wg
72.5=#69 wg


I got 8 bits, two of each size in case I broke one, for under $20 with shiping.... they come shipped from Grainger, but unless you have a Grainger account, this was they only way I could get them

[Blake]

Ah Glad to see you're dabbling with the k&n's too.

I have the jetting the same for both carbs-and it works.  I took off the plastic plate that blocks the radiator from the carbs and have only had good results. i think with that off, and no airbox it makes a nice air flow underneath the tank, so no worries about jetting differences.


I just ran out to the garage and this is what i have.

135 airs
60 pilots
155 Main

Note: i just switched in 150's in the mains for this time around

Now I've jetted my bike using a wide band afr meter and basically everything is pretty much right on.  Far from perfect to make power but its in the right neighborhood (generally around 14:1 to 13:1 all around)  The problem is WOT in the upper rpm's was dipping down to 10:1 to 11:1 - SLIGHTLY too rich (i want around 12:5 to 13:1 for max power).  But when i did this, the extra richness from the mains picked up the slack from the pilots and the stumble was a lot less.  so i just ran it this way and lived with it for the time.

Now it's been a while for me, but how does the predator exhaust look.  Its a full system correct?   I'm trying to see why there is such a big difference in jetting.   If its a full exhaust, would you mind measuring the pipe diameter- primary and secondary?  if the secondary is 1.5" i would up your mains to 145 or 150.  thats just a general guess going on what i have, and adding in richer pilot jets.  Basically im trying to see how similar our systems are.  Basically what im running is straight pipes with a glass pack at the end, using the stock rear cylinder Y pipe a merger for both the front and rear cylinders.

I have some visual data logs of runs i made with the o2 sensor hooked up recording on my laptop that i'll have to find and show you, but honestly i have no clue what the jetting was with those runs, although it should be somewhere around what i have now.  Also note i always did two runs, so that i could put the o2 in each pipe to make sure the jetting was correct on each.  after 10 or so runs of getting the same results i just put it one of the pipes to save me time.

[Night Vision]

no, I have a UNI filter... basically a foam version of the oem one

the predator is a full system and 1.25" id tubing

my low end was lean and the 62.5 smoothed a brisk acceleration stumble into a gurgle. I can slow roll past 5k rpm with no stumble...

my top end circut is great

I tried larger mains and lost a lot on top

I guess they are two different animals

[Blake]

OHHh.. sorry.. i must have been thinking UNI pods on your bike.  haha sorry.  i was a little too excited.  definitely seems like you're getting it now.  makes me wonder what even the 62.5 would do for me.