Oops. I need help: Damaged Pilot screw

Ok, so I was working on the pilot screws of an XJ650j, and I managed to chew up the top of the screw. Can someone walk me through how to rectify this situation?

 

Here is how I fixed mine,
- used a tiny drill bit to create a centre hole,
- tried to extract using a tiny ezi-out but the brass mix screw just would not hold,
- drilled with a bigger drill until it was just a brass plated hole and used some picks and jewellers screwdrivers, as a chisel, to chip and peel the brass out.
- then bought a matching ultra-fine(you might have the coarse threads in comparison?) tap from chacal and put that through to clean it up. Also put the tap through all the other carbs too.
- stuck a new mixture screw in, also from chacal.

Carbs are back in and the whole process worked a charm but was EXTREMELY painful to do and I think if I ever came across a tight mix screw again I will be heating and oiling way before I put any pressure on it after that debacle.

I did try heating and cooling and a few other things at the ezi-out point but to no avail.

 

Thanks,

I have hit it with PB a couple of times and am hoping to get to drilling and ez out tomorrow. I also have a small hand-held propane torch I can use to heat it up. Fortunately it is the #4, so I don't have t break the rack apart.

I sure hope I don't have to go where you did ...

 

that was soldered while the screw was stuck in the carb, i think the amount of heat to make the solder flow is what broke it loose

 

Now that is cool!

 

Nice.

So, for those of us rather unexperienced with solder, what are the steps? And what is the piece you soldered in? Looks almost like a standoff from a computer (what you mount the motherboard to) ... except that those don't have a solid top with a screwdriver slot ...

It would seem you would:drill something of a bowl into the head of old screw, make certain of rough edges for it to grab on, fill with solder and while still melted, insert the add-on?

 

A left turning drill bit will also work. When it grabs into the soft brass it will turn the screw out. Left turn bits can be hard to find but a good auto parts or hardware store should have them. I'll start with the smallest and drill a pilot hole them go to a larger size.

 

I'm pretty sure harbor freight carries left hand bits.

 

if your not good at soldering, you'll have to be real lucky
if there's ant kind of slot left, try to file a matching ridge in the new part, i made that one on a lathe so it had a point to match the drill hole in the screw, kind of like >>
whatever you use needs to be "tinned" or pre-soldered, solder melted and flowed on it
strip the carb bare, drop a tiny chunk of solder in the hole with the screw, then the hard part, heat the carb till the solder melts and add some flux when it does, this takes a whole bunch of heat to do , i used 2 torches
when the solder in the hole melts put your new top in and try to center it and don't get burned, don't move it till the solder hardens(dab the carb body with a wet rag)
a few other things, don't use too much solder if it gets on the threads i think all is lost, if it fails you can still use a ez-out or left hand drill, accept that this might be the end of the line for that carb
i'am not sure i'd try it again, i think i got lucky

 

95-Hundred Members and we can't find this fellow a Pilot Screw.

Fine or Ultra Fine Thread?

 

'82 XJ650, Rick, ultra-fine. I already have the replacement, just need to get this old bugger out now.

 

Which Carb Body is the Pilot Seized in?

You might be better-off doing a "Body-Swap with a Carb Body from Parts.

A desperation maneuver:
Drill-out the Screw until there just a sleeve left.
Pick-out the Needle, Spring and Washer.
Drill-in, ... from the SIDE.
Remove aluminum until you see Brass
DREMEL the aluminum covering the Brass.
Remove enough to set a Small Drift on the Brass Sleeve.
Drive the Brass, folding it away from the edge.
Grab with Needle Nosed and muscle-out.

Clean-up.
Thread a Bolt with Matching Thread into the Pilot Hole.
Prep the Bolt.
Threads smeared with grease or antiseize
Two layers of Teflon Tape

JB Weld side hole
Cure
Remove prepped bolt after JB Cures
Re-Tap

Have a Swap Body standing by.

 

If needs be you can shoot the carb body to me and I'll get it out.

 

Is it really all that bad to seperate the bodies?

 

Not in my opinion. That applies only to the Hitachis, I don't know jack about the Mikunis.

 

The manual says don't do it to the mikunis but it's because you have to properly align them. Not really hard to do. Just lay them on a flat surface

 

The safest way to handle un-removable mixture screws is:

"the trick to removing them safely is to be able to drill into them straight, so you don't get into the carb bore threads (then it's game over!).

My best advice....and what we do......is take the rack to a local machine shop, and let them precisely jig it up onto their fancy CNC drill press, so they can get dead-nuts accuracy is drilling thru the center of the screw, and then easily EZ-out it or use a left-rotation drill bit to twirl it out.

It's a 5-minute job with the right tools, something that can be done during their smoke break. Take a $20 bill with you to grease the wheels of progress."

 

+1^^^ Our machinist is top notch and does incredible work!

 

Hmmm, I don't know any machinists,. but I will see if can track one down. I do know someone who is quite handy with solder ...

Tell me what you think of this: carefully apply JB weld to top of screw. Due to nature of chewed up top, has nice rough surface for adhesion. Then, attach an extension screw with a better top and allow to cure. Twist out. Basically the same idea as the solder method but using JB weld instead.

Rick, carb body is #4 so is on the outside and easilyt accessible without removing from bike.

 

No.
Separating the Bodies is only Labor Intensive.

When the Bodies are separated you have to reposition a great many Spring-loaded items to reassemble the rack.

Its TIME consuming.
Once the Rack is reassembled, with the fasteners tight enough for allowing the bodies to be repositioned, ... slightly ...

Place the four on the side of a New 4-foot Level.
Bump them with a light Rubber Mallet.
Once they are Leveled tighten the Fasteners.

The trick is getting them back together in the frames.
Once the farames are back-on, ... you arent too far "Out" that leveling them and bumping them level and plumb won't correct.

 

which one is it, i'll see what i got

 

I'm sorry but I recall offering assistance in an earlier post. Just in case you strike out where you are. If you end up replacing it (Polock, you ROCK it!) I'd love to get your old carb body to play with (i.e. finding out how hard it is to remove that screw on the mill at work with a reverse twist drill bit).
I wish you well on this effort however you land, best of luck!

 

Sorry Robert, didn't mean to disregard, I was trying to think local.

What do you think of the JB weld modification of Polock's solder job idea?

 

Either is a possible fix. I like the JB Weld idea but heaven help you if you get it in places it ought not to be. Polock's method is by far the most trick I've ever seen...right amazing.
Your boned either way if you get stuff in the wrong place so I guess I'd try the JB weld first, solder second. That is IF I didn't have a machine shop handy (my first choice by far).

 

Dealing with the same ting right now! Fused and stripped pilot. I wussed out and ordered another body used off ebay... we tapped and drilled and picked out brass just to find we screwed ( pun intended) the threads on the body.... the threads are crazy fine on mine (.5 pitch i think) I am ordering extra pilot screws from Chacal just incase it happens again...

 

i took one out the other day got the ezout at abuchon hardware # 1 size I let pilot screw soak in penetrating oil over night. used a centerpunch to set a spot to start the drill.
came out real easy i used pb blaster used the same method to remove the pilot jet but did not have to drill it

 

I know this is a very old thread, BUT, i just wanted to share how i`ve removed brass mixture screws where the screwdriver slot was destroyed and you couldnt get the mixture screw out.
The method i`ve used for many decades without fail, is to drill a small hole into the mixture screw, then tap a T8 torx bit into the drilled hole of the mixture screw, you`ll be able to walk that mixture screw right out.

This method has never failed me...ever.

 

Ahh, when you say 'tap' you don't mean tap a thread... I get it. Sounds good!

 

No, not as in tap used for threading... i just drilled a hole down into the top of the brass pilot screw, then i used a small hammer to hit a T8 torx bit into the hole that i drilled in the pilot screw.
Then i turned the T8 torx by hand and walked the pilot right up out of the carb body. This method is all i`ve ever used when removing pilot screws where the slot is either worn off or stripped.

 

Interesting.... I may have to experiment with doing it that way sometime

 

Actually, its the only method that has ever worked perfectly for me. I like using the torx bits because it actually grips better than the old easy-out bits, if done right.
I`ve never had good luck with easy-out`s... easy-outs always end up stripping the brass, then you`re screwed.

 

Whilst pulling apart a carb rack I bought this weekend I finally met a stripped and STUCK brass mixture screw that I couldn’t remove.

This is my fourth carb rack rebuild. Though I’m certainly not a pro I wouldn’t call myself a rookie.

Copious amounts of time with WD40 and heat did nothing. As I removed the other brass fittings from the carbs I found grit/ sand like material in the carb. Maybe it got swamped at some point in its life..

I ordered a set of Spiral Screw Extractors and even the smallest looks too big.

What’s the most current “bestest” way to remove a stripped and stuck brass mixture screw? If you use an extractor, which one?

Hopefully Hogfiddles chimes in

 

The way you’re doing it. But if the extractor breaks (been there) or the threads strip ( been there, tooo) then it’s time for a replacement body

 

Not a fan of the stud extractor (easy out), but had success with a suitable torx bit and suitable drill (find the right combination before doing it on the stuck screw). Also some heat from a fine flame helps more than WD40.
If you lose the thread you can machine out the remains, have an insert made and press it in, but it's specialised stuff and desperation if the body is rare, machine too deep or offcentre and the body is scrap...

 

Personally, I wouldn’t bother with trying to machine it, or get an insert..... you’ll spend as much or more than just getting a replacement body.
For the most part, these aren’t RARE,except for a few

what carb and bike are we talking about here?

 

Well, I would be doing it all myself, couple of hours work, and I did say it would be desperation measures for a rare item - I did one of my Vmax carbs a couple of years ago, every screw had been mullered. The mikunis on the vmax have the same screws as the XJ mikunis. Better to be slow and methodical trying to remove the screws in the first place. I also have some LH taps - M4, 5 and 6 which I find better than easy outs because the don't spread the screw as they dig in - this spreading is one of my main dislikes of easy out extractors.

 

Well yeah, for most of the screws, yes— but as I read it, the question was regarding a stripped and boogered MIXTURE screw. That is what my answer was regarding. I had long conversations with fine machinists..... they wouldn’t do it. Setup time, blocking, trials, risk of messing up anyway, two different thread possibilities make it do you can’t have just one procedure/tools, etc......

 

Yes, mixture screw. I did it on my little mill, you need a lathe as well and some skill, or rather accuracy. If someone were to ask me I would want some up front payment on the basis it could end up in the bin, but the chances of that happening would be slim, seeing as I managed it at the first attempt. You do have to buy the right taps for the screw type though, which you use to tap the insert before fitting it (yes you have to make the insert).
Like was said a few posts up, depends how rare Vs cost of replacement etc, but certainly doable.

 

I like that idea of drilling a hole slightly smaller than the points of a torx driver and driving it into the hole. I think tapering the leading edge of the torx bit would also help centering the bit into the hole.

 

I got the mixture screw out. I bought two different types of ez outs , tried a torx bit and various flat heads.

I ended up basically drilling and chipping the brass out.

tried a new mixture screw and it seems like it should work.

 

You are DARN lucky. Hope it works

 

I got the whole rack for $75 from someone local and I was prepared to throw this carb in the trash. It was also destined to be a spare, spare (spare x 2). It was a lot easier to break out the drill with this set of circumstances.

For others reading that have this issue:
Once I drilled past the threaded portion of the brass mixture screw I could feel a definite change when I reached the spring. The drill stopped forward progression and spun. I really couldn’t have drilled past this point if I wanted to.

I can’t remember what drill bit I ended up using (they got progressively larger) but it was something like a #8. It was just smaller than the threaded portion of the brass.

Once drilled to the spring I dug the brass threads out with an offset pick. To get remnants of the needle out I the blew air through the pilot jet port (with the pilot jet already removed).
Finally, I picked the undamaged factory rubber from the needle seat.

Offset pick:


The mixture screws all had their factory caps on when I got them, so I thought taking them out would be cake. But, as I said previously, I found these carbs had grit and green corrosion throughout. I bet they were submerged in water (maybe seawater) at some point.

To add context, this was a Mikuni BS30 carb.

 

That mixture screw remnant seems to be missing its tapered tip......make sure it's not stuck in the passage hole (in the carb throat).

 

Eagle eye! I never did find the tip of the mixture screw.

I was able to fully thread a new mixture screw into the carb and I reasoned that I would not have been able to do this if any portion of the screw were left.

I will double check though.

I’m going to put this carb in the ultrasonic cleaner, then blow carb cleaner through every passage. Hopefully this will get any stubborn remnants out.

 

Those tips often get broken off

 

I just double checked with a flashlight . All clear