Daves carb mods


21 replies to this topic
  • dstark

Posted April 05, 2006 - 10:30 AM

#1

Anyone have any pictures of a drilled slide on an '06 XR650L? Where to drill and how big? A little nervous taking a drill bit to my carburetor.

  • Muddin

Posted April 05, 2006 - 11:19 AM

#2

Pretty sure you use a 5/32 drill bit, very carefully, drill press if possible. Do a search for pictures there are lots out there, also a good video by :thumbsup: Dave :thumbsup: (doesnt show the drilling part).

  • XR650L_Dave

Posted April 05, 2006 - 04:14 PM

#3

All the pics are over in the hoinda tech section at 4strokes . com.
But, its the 2 holes not in the center of the slide.
Dave

  • Phuzzy McPhuzzface

Posted April 06, 2006 - 07:27 AM

#4

All the pics are over in the hoinda tech section at 4strokes . com.
But, its the 2 holes not in the center of the slide.
Dave


What Dave said.

Plus, as mentioned, use a drill press, if at all possible. Make a couple of dry runs at the first hole to endure you are lined up properly. Whne sure, then slowly bring the press down to ream the first hole. Repeat for the second hole.

Ensure there are no burrs on the edges of the holes. Blow the slide off with compressed air.

You're done. (with this part of the mod).

EZPZ.

  • jbird710

Posted April 22, 2006 - 01:18 PM

#5

Also, the holes are deeper than what I expected so a drill press really is the only way to go to ensure a straight, smooth bore operation. I did it to mine and can only tell a marginal difference. I've also re-jetted both jets (used the kit from Baja Designs that includes the needle and spring as well as the main jet). Replacing the main jet, needle, and spring made the most difference. Replacing the slow jet and drilling the holes cleaned up the remaining minor problems. As one of the others mentioned, there are several postings explaining all of this on this site as well as others. Main thing is to take your time and do it right.

Still think I'd like to get away from the vacuum slide and go with a cable operated model carb. Any recommendations? I'm searching this site for this. :thumbsup:

  • Dual_Dog

Posted April 22, 2006 - 02:40 PM

#6

A little nervous taking a drill bit to my carburetor.

Doesn't matter if it's new or old, beat or in good condition. These tweaks are the cure for this fickle & leaned out CV carb. Best part about it though is that it makes a big improvment over the stock set up :thumbsup:

These mods have been around long before the XRL. Problem is that this bike really suffers from the ultra-lean factory settings so rejetting is also necessary. Better have a service manual as well if you're planning on reassembling everything properly. :thumbsup:

  • dukeryder

Posted April 22, 2006 - 08:52 PM

#7

I'm having a bit of a problem getting the idle right. That Pilot Needle Jet Screw or whatever it's called I set to 2 1/2 turns out (with the tab ground off); but I'm having a tough time getting it to idle well, If I used the thing that sets the butterfly stop, it seems to either idle too high or too low (and die at a stop). I also removed the "snorkle" as well; I've been running a K&N and Big Gun exhause all along.

I also noticed that sometimes at steady high RPM; sometimes it seems like the fuel is cutting out intermittently. I didn't have this problem before with the stock jetting (but did get rid of most of the backfiring). I'm running 165 MAIN Jet and 58 Pilot Jet, needle shimmed, slide drilled (6ft Below Sea Level).

So which way should I be adjusting that idle screw?

TIA.

  • jbird710

Posted April 22, 2006 - 11:08 PM

#8

dukeryder:
My neighbor and I have identical setups similar to yours. Only difference is we both have White Bros pipes and 55 pilot jets. We worked together and did the exact same things and same parts on both bikes. The two bikes ('06 XR650L's) run differently. Mine has problems problems similar to yours. Mike's doesn't. We had to play more with his needle adjustment than I did to get his to idle right. We started at the 2.5 turns and tried working in with 1/2 turn increments. We then went back to 2.5 after going in 2 turns with no improvement. Working out in 1/2 turn increments, I believe he settled on 3. His bike still has an occasional pop on deceleration but doesn't have that "running out fuel" sensation. We live in Galveston County and are about 16 - 17 ft. above sea level. :thumbsup:

  • goblin127

Posted April 23, 2006 - 06:25 AM

#9

You don't need a drill press to do the mod.

  • bdoornbos

Posted June 11, 2011 - 09:02 AM

#10

Guys, I'm knee deep into Dave's mods and am very concerned that the previous owner was into this before. No other Dave's mod evidence but the needle looks much different than the pic on 4 strokes. I don't know how to post, but my needle has no top. There is a spring clip or "C" clip a few notches down and there was already a washer. It appears that based on where the spring clip and washer were installed, it was shimmed way beyond the .020 - .030".
Not sure if i should be spring clip on top and use the new #4 washer from Radio Shack.
Please help, this project was way above my pay scale and now i'm concerned.

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  • XR650L_Dave

Posted June 11, 2011 - 09:12 AM

#11

Sounds like they used the DJ jet kit.

Did they give you any parts with the bike?

You could contact them and see if they have the stock needle.

Dave

  • bdoornbos

Posted June 11, 2011 - 09:23 AM

#12

No shot at getting any past parts. The mixture screw had not been modified, the slide had not been drilled out to 5/32, but the jets are 58/155. I was going to put in 55/160
Not sure what to do with the needle.

  • bdoornbos

Posted June 11, 2011 - 10:13 AM

#13

Well, the bike ran too rich, now i guess we know why, it has a non-stock needle that was shimmed way up. I raised the spring clip 2 notches and have 55/160. I'm going to put it back together and see what i end up with.

  • XR650L_Dave

Posted June 11, 2011 - 01:22 PM

#14

If it won't jet quite right, a stock needle usually turns up here and there.

Dave

  • BravoFox27

Posted May 22, 2012 - 11:01 PM

#15

Posting in old thread I guess is better then starting another one. :cry:

I am living in a country where they have chucked the queens measuring system and are using the easier metric one. :cry: :ride:

I see the slide should be drilled to 5/32 inch which is equal to 3.96875mm

Do you think that it should be a problem to drill it to 4mm? Doubt that I would find a 5/32" bit anywhere here...

  • Page Mohler

Posted May 23, 2012 - 07:13 AM

#16

You don't need a drill press to do the mod.


+1

  • XR650L_Dave

Posted May 23, 2012 - 08:34 AM

#17

I can't imagine making the holes 0.03125 inches larger would make any diff...

  • wentz912

Posted June 17, 2012 - 03:15 PM

#18

I can't imagine making the holes 0.03125 inches larger would make any diff...


might be careful about that, .03125 happens to be exactly 1/32 larger...so an additonal 20%, might make more of a difference than you'd think.

  • motoman399

Posted June 17, 2012 - 03:38 PM

#19

Do you think that it should be a problem to drill it to 4mm? Doubt that I would find a 5/32" bit anywhere here...


Hey I'm curious if you would want to do a trade? I would love a set of metric drill bits.. would you be interested in a trade for a set of SAE bits?

  • wigner3j

Posted June 17, 2012 - 09:11 PM

#20

I can't imagine making the holes 0.03125 inches larger would make any diff...

might be careful about that, .03125 happens to be exactly 1/32 larger...so an additonal 20%, might make more of a difference than you'd think.


The hole is not 0.03125 inches larger, its in mm. This is only about 1.6% larger in terms of area. I doubt Dave determined the proper hole size to that level of precision. For what its worth, before I moved to an FCR carb I did Dave's mod on my CV carb with a 4 mm drill, it seemed to work fine.





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