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Main Area => General GS500 Discussion => Topic started by: Dom on January 25, 2005, 07:50:52 PM

Title: Drilling out pilots, any advice?
Post by: Dom on January 25, 2005, 07:50:52 PM
I thought I might give this a shot, even though my bike starts fine in the cold with stock pilots...just to see if it can get any better.  Anyway, I bought a set of micro bits and was wondering what size bit to use to turn #37.5 pilots into #40 pilots.

I was also wondering if there were any words of advice...I remember something about putting the drill bit in an exacto knife... :dunno:

The smallest bit my kit came with is a #60(.040)  Is that small enough?

Thanks

:cheers:
Title: Re: Drilling out pilots, any advice?
Post by: se7enty7 on January 25, 2005, 07:55:42 PM
Quote from: DomI thought I might give this a shot, even though my bike starts fine in the cold with stock pilots...just to see if it can get any better.  Anyway, I bought a set of micro bits and was wondering what size bit to use to turn #37.5 pilots into #40 pilots.

I was also wondering if there were any words of advice...I remember something about putting the drill bit in an exacto knife... :dunno:

The smallest bit my kit came with is a #60(.040)  Is that small enough?

Thanks

:cheers:


I pulled the 37.5 pilots out of my DJ carbs and you would have to have a TINY drill bit... I mean... like a  piece of wire is too thick....
Title: Drilling out pilots, any advice?
Post by: Dom on January 25, 2005, 08:18:50 PM
Yeah, I remember dgyver or werase talking about needing a special bit you can get at a hobby shop.  I just tried to floss my smallest bit thru a hole on one of those other pilots with the 8 little holes and it was apparent that the bit I am going to need is much much smaller. :cheers:
Title: What
Post by: The Buddha on January 25, 2005, 10:48:25 PM
Dom didn't you try bleed type 37.5 pilots ... what did they do ...
Cool.
Srinath.
Title: Drilling out pilots, any advice?
Post by: Dom on January 25, 2005, 11:41:47 PM
Yeah, I bought the 40 bleeds by ignorance, havn't bought the 37.5 yet...proly this weekend.  

I need to pick up another bar end mirror.  I bought one, a CRG billet aluminium puppy off Ebay for $80 and I thought the auction was for two.   :roll:   I know...alot to spend for two mirrors but I had already bought two other sets of crappy mirrors and didn't want to make another mistake...well, I did just that.  doh.

At least I'll never have to buy another set of mirrors EVER...or at least until my girlfriend drops the bike again.   :lol:
Title: Drilling out pilots, any advice?
Post by: dgyver on January 26, 2005, 06:49:15 AM
Drilling jets will probably ruin them. Drill bits will leave a swirl in the jet which will affect fuel flow. Jets do not cost that much.
Title: You know
Post by: The Buddha on January 26, 2005, 11:40:58 AM
They had to drill them at the factory ... so why would us drilling it be any different ... of course they have a huge ass plate to which the jets are screwed in and they are clamped down on a table etc, but once you figure out how to hold it in place its game over for the Jet ... BTW I would try to drill it right in the carb.
Cool.
Srinath.
Title: Drilling out pilots, any advice?
Post by: aplitz on January 26, 2005, 05:43:21 PM
Advice:  Order correct jets online.  Not worth the effort to try and cheap it out.  The phrase stepping over a dollar to pick up a penny comes to mind for some reason.
Title: Drilling out pilots, any advice?
Post by: sprint_9 on January 26, 2005, 05:52:51 PM
Dom, what was the bike like with the 40 bleeders?  I did the same thing and got the wrong ones.
Title: Drilling out pilots, any advice?
Post by: Rema1000 on January 26, 2005, 05:56:59 PM
That .040 inch drill bit is way too big.  You need .040 mm.  Some bits around that size are 1/64" (.397 mm) or #78 (.406 mm).  These bits are about as thick as a mechanical pencil lead.

I'm the one that used an exacto handle and drill bits.  My reasoning was that the Mikuni distributor was 30 miles away, but the bits were sold just down the street.  Yes, it was cheap ($1 drill bit vs. two jets @$2.50), but cost was not really the reason.  I needed to keep enlarging the jets until I found the right size, since I was burning some unusual fuel, and the bits made testing a bunch of different sizes convenient.  My plan had always been to replace the drilled-out jets with new jets once I found the right sizes (but I never got around to it).  On the bright side, when I go to clean the jets, I'll have a good tool to ream them out with :) .

In your case, you mention that the bike seems to run fine.  There you have it... I'd leave it stock.
Title: Drilling out pilots, any advice?
Post by: Dom on January 26, 2005, 07:15:25 PM
Quote from: sprint_9Dom, what was the bike like with the 40 bleeders?  I did the same thing and got the wrong ones.

When I bought the 40 bleeders I knew they were weird(I thought it was "I" before "E" except after "C", except for the word "weird"...weird, huh?) because they had the 8 little holes, but the guys at the shop said they were the ones, so...I asked Srinath and he tipped me off that they were the wrong ones before I got around to installing them.  Thanks again Srinath  :thumb:

You have to hand it to Mikuni or whomever makes the pilots, though, because they actually are trying to do a favor for you by making the stock size pilot better than the original.   :dunno:  I guess they figure than when people rebuild their carbs they just ask for the stock pilot size and get better than what they ask for.  We just spun our wheels a bit I guess...but maybe we didn't...they didn't have to get all tricky on us and switch up the size scale either... Orrrr, it could be that they just make one pilot size for the entire world and don't give a crap about U.S. E.P.A. policies and standards....I know I dont...  S.N.A.F.U.  :mrgreen:
Title: Dom
Post by: The Buddha on January 26, 2005, 09:05:17 PM
well Dom I think you have it backwards a bit ... the bleed style is newer than non bleed's ... at one time (97-98) non bleed's weren't even available from mikuni as a replacement off the shelf item. The basic idea of non bleed is IMHO an ill formed one at best ... if it were up to me I'd have designed the carbs around bleed type jets.
Cool.
Srinath.
Title: Drilling out pilots, any advice?
Post by: Dom on January 26, 2005, 09:10:40 PM
I figured that the bleed style was newer because I have been to 4 different shops and none of them have the non-bleed type pilots.
Title: Drilling out pilots, any advice?
Post by: sprint_9 on January 26, 2005, 09:32:22 PM
Hmmm, I wonder what it would be like with the 40 bleeders cause I really dont want to order new ones.
Title: Drilling out pilots, any advice?
Post by: Dom on January 26, 2005, 09:45:36 PM
Well, I've since misplaced mine but, really, how long does it take to switch out the pilots... :lol:  :lol:  :lol:

TOO LONG!!!

But seriously, if you use a temp tank you won't have to put the tank back on, and I remember Srinath saying that pilots only effect rpms to about 3000.  You would think you could just turn down the idle to compensate for the higher volume of gas, but what do I know?  It might just make it idle higher, or lug... :dunno:
Title: Take off
Post by: The Buddha on January 26, 2005, 11:53:08 PM
Pilots really work right at the point where you're begining to move from a stop ... too rich there and it will fall on its face and want to die as you're leaving a stop, too lean and it will be low on power and actually its not that bad. You dont want to be rich at that low rpm range ...
Cool.
Srinath.