Removing air/fuel mixture/pilot screws

[Anonymous]

When cleaning my carbs, I had trouble removing the air/fuel mixture/pilot screw (I think those are the most used terms). I could not get it to back out all the way, and therefore could not remove it. I could get it to screw in until it seated, and then back it out about seven turns, but it seemed to come to a point where it wouldn't go further, as if the threads didn't match anymore, or had some type of blockage. Needless to say, I just left them in and opted not to dunk the carb bodies.

Has anyone else experienced this? I'm wondering if they were designed to be hard to remove to discourage owners from monkeying with them and therefore mess up the factories settings. Or it could just be me and my bike. If not, any suggestions will be much appreciated.

Much thanks.

[lhanscom]

Just screw the screws in, and hit the threads with some penetrating oil, like PB Blaster. Let it sit a bit and try to remove it again. The treads get junk in them, and they don't like to come out.

[Anonymous]

There's no tamper-resistant thread, if that's what you mean.

I wonder if you could get in there with a brass rifle cleaning brush (for a .22, for example) and spin it a bit, with a little carb cleaner, and then blow out the cavity with compressed air, to clean up the threads.

A number of people have had problems getting these out, but I don't think it's that common. It's the troublesome ones we hear about, though, so it probably seems more common than it is. Not that that helps your situation.

Perhaps some previous owner used too large a screwdriver to mess with the screws, and gouged the threads doing so. Can you get a good look at the threads?

[Anonymous]

Thanks for the replies. I've been out of town and haven't been online for awhile.

The .22 brush idea sounds good, in addition to the penetrating oil. I've also considered running a tap (or die, whichever) through the top part of the threads.

Now that I've finished with the brakes on my truck, I can turn attention back to the bike. I'll post updates.

Thanks again

[Pete's GS]

There's no rhyme or reason to these things. You can get a set of CV carbs with one, two, three, all four, or none of the pilot screws frozen. According to motorcyclecarbs.com Mikuni froze them with Superglue or Loctite. I had three of them frozen (2, 3, and 4) and I used Gunk Superpenetrant, PB Blaster, heat from a hair dryer, water (for Loctite), nail polish remover (for Superglue) and got nowhere. I assume the pilot screws were frozen for the then-current emissions regs but why some and not all or none of the carbs were finished this way defies reason. Apparently it depended upon the whim of the assembler that day. At any rate, Robert at motorcyclecarbs.com will remove them for you with an Easyout and/or heat and replace the screws and o-rings and set up your carbs just right. You'll love them but it costs about $50/carb.

[Anonymous]

I had frozen screws, and used a rotary tool (Dremel) to deepen the slots in the screws. You have to also cut through the top part of the screw housing, but not to the point where it affects anything. I turned out the screws as far as they would go, lined up the slots with an angle convenient to the Dremel, and cut through the housing into the screw slot, making about a 1-1.5mm deepening.. After turning the screws back in and soaking the threads in PB for a couple of days, I backed the screws out again as far as they would go, heated the screw housing with a lighter, and then backed the screws all the way out using a flathead bit in a high-speed drill (2500 rpm). I have cleaned out the threads and reinstalled the same screws, and the carbs seem to work fine. Just remember to continually blow out all of the shavings with compressed air, and reinstall the screws into the same housings that they were removed from. Good luck.

Austin

[Pete's GS]

All I would say is that motorcyclecarbs.com used an Easyout on my No. 3 carb and it broke ! There were a couple of ways we could've gone but the best was to use a used carb body. I have the old carb with the broken-off Easyout still in it. You're welcome to try this any way you want but, personally, I wouldn't f_ck with it. The floats were also adjusted, the carbs sight-synched, the pilot screws set at 1.5 turns out from seated, and it runs great. I don't even need to use the choke.