Carb Rebuild - Jets are "Frozen"

I got one carb cleaned and rebuild with all new parts. The second carb is giving me problems. Neither jet will come out. And I stripped the main jet pretty good. There still might be a little grip left on it, but that brass(?) fell apart like butter when I tried to unscrew it.

I think the pilot jet is still in pretty good shape. It's been soaking in PB Blaster for almost 2 hours, and I'll likely let it soak longer. Maybe even overnight.

Anyway, what is the best way to back them out? I assume a screw extractor might just drill a hole through it? I don't know. It's such soft metal that I don't want to try anything more until I hear from someone with more experience.

Thanks!

Try acetone and transmission fluid mixed in equal parts. Only mix up what you will use
and do not store any extra in a closed container. It will build up pressure. If they can not
removed by normal means, a small rotary tool like a Dremel can be used to whittle away
material along with a dental type prick to pry things out.


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Do the mains come out with a socket? then use pliers & wrench to get jet out

The 750 twin jets need a special screwdriver with correct blade thickness and width. Usually, somebody uses a thin blade screwdriver and tears up the jet slot then you are hosed.

hill wrote: Do the mains come out with a socket? then use pliers & wrench to get jet out

The mains are under the drain screw in the bottom of the bowl. Uses a slot screwdriver to remove.

hill wrote: Do the mains come out with a socket? then use pliers & wrench to get jet out

Please clarify what you mean by "mains". (sorry. I don't have the vocabulary yet).

The jets are buried. They are each a good 1/4" underneath the surface. So I can't get anything wider than about 1/8" in there. It's going to have to be some kind of driver... or driver-shaped tool.

I can do a drillbit, pick tool, screwdrivers, etc.

PaulyWally wrote:
Anyway, what is the best way to back them out?

Get all your flat blade screwdrivers. Find the one whose blade thickness exactly matches the notch on the top of the jet. Grind the screwdriver width to match the width of the jet, then you have the tool you need to remove jets.

I thought the main jets were like the kz900.Im not familiar with the 750 twin.
Sounds like bounty hunter has the right idea.

bountyhunter wrote: Grind the screwdriver width to match the width of the jet, then you have the tool you need to remove jets.

Good idea! Thanks!

Yeah, someone chewed them up a little bit before I got to them. I got both out of the 1st carb with a little PB Blaster. The pilot came out of the 2nd with a little PB Blaster, but the main is still in there. And it's pretty chewed up. I put it in a Gunk Carb Dip. Hopefully that'll help loosen it too.

And I did use a screwdriver that is darn close to the size of the jet. I looked all over for one that fit really good, so it's not like I just went in there with any old driver.

hill wrote: I thought the main jets were like the kz900.Im not familiar with the 750 twin.
Sounds like bounty hunter has the right idea.

Sorry... I got backwards when you said "mainS". Yeah, the main jet is under the drain screw. The pilot is in the inside of the float bowl - screwed in under the surface. Both are flathead screwdriver (style) only.

They are a really odd size for American tools (like everything on these old Japanese bikes). But I used to be an automotive electronics tech... so I just happened to have a flathead bit that is the right length, and just a tad under thickness. I doubt I could grind one down to be a better fit. But I'm not going to force it, either.

BountyHunter has the right idea, unfortunately you've already stripped out the jet so there's not much for the right size screw driver to grab on to.

There are two options I can think of for removing such a small stripped jet...

Option #1: Safest option.
Drill out the jet with successively larger drill bits. This takes patience, several small bits and lots of light to see what you're doing. Calculate the I.D. of the threads in the carb and use the nearest undersized bit for your final drill. If you're bit is too big you'll drill out the threads in the carb bowl. When you're done drilling, all that will be left of the jet is some flaky brass in the threads that usually drops out with some aggressive picking and wire brushing.

Option #2: Risky option
Soak jet with penetrating fluid, heat and cool with small torch, repeat several times. Clean assembly so no gunk or penetrating fluid remain. Get a small flat head screw driver. place carb bowl gasket side down on a flat piece of wood. Place screw driver against jet and give it several gentle whacks with a hammer so the screw driver tip wedges itself into the brass. while applying pressure try to back out the jet. This method has worked for me several times. The thread are often distorted and need to be chased with a metric tap so my new jets will screw in smoothly. I have forced in new jets with out chasing the threads but that's pushing your luck.

There are also "Easy Out" bits but I've never sourced a set for such small applications. Might be worth researching.