Removing a broken pilot jet

[anytwowilldo]

I recently pulled the jets in a new to me KTM 525 for documentation. When I reinstalled the after market pilot jet half the top snapped off at the screwdriver slot, WTF!, Far left Pic. I was not ham fisting it. The jet snapped like brittle brass. I put it back together as the broken jet would not affect the running of the bike, I just could not change it easily if I wanted to. As time passed, I could not stop thinking about it. I hate broken, stripped, mismatched stuff. I also needed to balance the fact that the running of the bike was unaffected, but If I botched the removal of the jet, I could ruin a very expensive carburetor and take the bike out of service. I thought about different ways too remove it. Use a small easy out. Try to use a left handed drill bit to catch it and have it unthread itself. Both of the previous methods involved the possibility of breaking off more or drilling into the jet, getting closer to the very fragile threaded portion of the carb body. I decided to use a Dremel tool and do a little dentistry. :laughing I disassembled as much of the carb as I could to get closer to the jet. I then carefully removed the remaining high portion of the jet making then top flat again, middle pic, and then cut a screwdriver slot in it. What is not obvious in the pictures is that the jet is about 15MM down the body of the carb. I'm happy to say that even with a late afternoon coffee on board, my hands we still enough that I didn't damage the carburetor body and was able to successfully remove the broke jet.

If this happens to you take your time and think it through. With a little patients and luck you can remove a broken jet too.

 

[motomania2007]

good work! Probably better than I would have done.

I would have tried a small easy out especially since there isn't much torque involved in seating the jet.

 

[OaklandF4i]

That never would have happened on a XR. :teeth Is it too soon for the Kant Take Mexico jokes yet?

 

[anytwowilldo]

That never would have happened on a XR. :teeth Is it too soon for the Kant Take Mexico jokes yet?

If this thing fails on me, I know I will never hear the end of it. :rofl

 

[Eric B]

Good job Tom. :thumbup

 

[Cabrito]

Nice work Tom, when I was doing my carb on my XR I found aftermarket jets and it was suggested that I replace with OEM so I did. Not sure if it matters, but I wonder if OEM is better in your case.

 

[anytwowilldo]

Nice work Tom, when I was doing my carb on my XR I found aftermarket jets and it was suggested that I replace with OEM so I did. Not sure if it matters, but I wonder if OEM is better in your case.

The aftermarket jet that snapped was very brittle. I replaced it with a Pro X because I had a brand new one in my collection. My bet is that OEM jets are better than aftermarket. My guess is that the one that broke came from a bad batch, as it was installed earlier this year by a reputable KTM dealer.

 

[Busy Little Shop]

If this happens to you take your time and think it through. With a little patients and luck you can remove a broken jet too.

Good advice... also it helps to submerge the carb in hot water which will expand the clearances and loosen any dried fuel...

 

[ST Guy]

A preventive measure you can take is to use a fine artist's paint brush and brush the threads of the jet with moly paste.

 

[nakedape]

A preventive measure you can take is to use a fine artist's paint brush and brush the threads of the jet with moly paste.

I like how moly is your answer to many things moto. Notes have been taken...

 

[ST Guy]

I brush moly, mix moly, eat moly, drink moly. I worship moly. Moly is all knowing and all powerful.

I know it almost sounds like snake oil, but it's not. I'm also sure that many here have had the experience of trying to remove the jets from a carburetor and having to apply a LOT of torque to get them out and when they break free, there's almost a pop or noise as they break free. Moly will prevent them from getting so stuck to the aluminum casting so that down the road when you disassemble the carbs again, a reasonable amount of torque is all that's required to remove them.

Helpful hint: You can't have too many screwdrivers. For a screwdriver to work properly, it must fit the fastener properly. I keep a wide selection of not only Phillips drivers, but also flat blade drivers. If I can't find a blade that fits the slot in the fastener properly, I'll grind an existing screwdriver to it fits properly. This means a nice squared of end, fat enough so that it only just goes down into the slot, and wide enough to engage the entire slot without having outside the OD of the screw head.

 

[motomania2007]

I brush moly, mix moly, eat moly, drink moly. I worship moly. Moly is all knowing and all powerful.

I know it almost sounds like snake oil, but it's not. I'm also sure that many here have had the experience of trying to remove the jets from a carburetor and having to apply a LOT of torque to get them out and when they break free, there's almost a pop or noise as they break free. Moly will prevent them from getting so stuck to the aluminum casting so that down the road when you disassemble the carbs again, a reasonable amount of torque is all that's required to remove them.

Helpful hint: You can't have too many screwdrivers. For a screwdriver to work properly, it must fit the fastener properly. I keep a wide selection of not only Phillips drivers, but also flat blade drivers. If I can't find a blade that fits the slot in the fastener properly, I'll grind an existing screwdriver to it fits properly. This means a nice squared of end, fat enough so that it only just goes down into the slot, and wide enough to engage the entire slot without having outside the OD of the screw head.

Moly is really good for a lot of stuff!

And I thought I was the only one that cuts down and otherwise reshapes screwdrivers to do various specialized tasks... I have at least 1/2 a dozen in my tool box.

I have one screwdriver the is narrowed just to reach into the "well" of the primary jet on some carbs.

I had a very carefully rounded off 1/8" blade common screwdriver that was perfect for getting at hard to get o-rings and things like that. I lost it and it took me 3-4 tries before I got another screwdriver to work as well...

 

[ST Guy]

You must be a young whipper snapper. :afm199

Just for the heck of it, I counted the readily available flat bladed screwdrivers in my tool chest and on my work bench and counted 66. Though I will admit that some of those were double ended offset screw drivers. One driver I have is a double ended, double sided offset.

Oops....I forgot about my grandfather's woodworking screwdriver, the kind you push and it turns one way or the other. That has at least two heads. Call it 68.

 

[motomania2007]

Dude, I was only counting the screwdrivers I had customized for specific uses. I don't know how many screwdrivers in total I have...

 

[ST Guy]

I’d say about half of mine have been “adjusted” at one time or another.

 

[bobl]

OP, could you post a picture of the Dremel tool bit that you used? I don't see how you cut the slot when the jet was in the recess. I have some stripped pilot screw heads that are in a similar recess. Thanks in advance, I would really appreciate it. Also a description of the process would be nice.

Thankyou.

 

[Alan_Hepburn]

Helpful hint: You can't have too many screwdrivers. For a screwdriver to work properly, it must fit the fastener properly. I keep a wide selection of not only Phillips drivers, but also flat blade drivers.

If you're working on Japanese stuff it might be a good idea to invest in a set of Japanese Industrial Screwdrivers as well - they look almost identical to Phillips drivers, but they work a lot better on the screws that the Japanese manufacturers use...

 

[Biga]

Good job getting it out!
I've learned early on in life that if you walk in your friends garage and see the extractor tool set out on the counter, back way slowly... very slowly, like you have never enter the garage... :teeth

 

[anytwowilldo]

OP, could you post a picture of the Dremel tool bit that you used? I don't see how you cut the slot when the jet was in the recess. I have some stripped pilot screw heads that are in a similar recess. Thanks in advance, I would really appreciate it. Also a description of the process would be nice.

Thankyou.

I don't have the bits I used near me but I found this image on the net. I used one like the one on the far right to remove the top of the broken jet making it flat. I then use one slightly narrower than the one in the middle to cut the screwdriver slot. It was like playing Operation where you didn't want to touch the sides of the carb body. There has been other good info in this thread too, soaking the carb body in hot water before attempting to remove it/them. I also have a tiny torch and thought about warming the carb body at the threaded area to get it to expand. Good luck!

 

[bobl]

I don't have the bits I used near me but I found this image on the net. I used one like the one on the far right to remove the top of the broken jet making it flat. I then use one slightly narrower than the one in the middle to cut the screwdriver slot. It was like playing Operation where you didn't want to touch the sides of the carb body. There has been other good info in this thread too, soaking the carb body in hot water before attempting to remove it/them. I also have a tiny torch and thought about warming the carb body at the threaded area to get it to expand. Good luck!

Thank you sir. I think I have the idea now. Great job you did!