80G Pilot Jet buggered, air screw plugs

[Bonz]

He gents,

My "Interesting 79F" thread has run it's course, now that it is simply an 80G with a 160 MPH speedo.

Pilot jet:

As a preface, the carbs on this 80G have the rubber plugs covering the pilot jet hole, with the passage between the main jet and the pilot jet, if that helps any with the stuff I'm asking below.

-One pilot jet had the screw slot broken/buggered by a previous owner. What is the safest and surest wasy to extract the jet, if there is such a thing as safe and sure existing in the same operation.

Air screw plugs:

-three of the four (#1,#3,#4, I believe) air screw towers on the 80G carbs have a brass something in them flush with the top of the tower, but not the typical plug I'm familiar with that my 80SG had.

These are like donuts, where you can see down into the hole where the air screw is located, not the typical brass cap with the tiny hole in the middle. Is this simply another type of anti-tamper device that I would remove like the plugs I'm used to seeing, or is it something different?

-#2 tower has a brass screw head flush with the top of the tower, and it will turn but not in or out, just spins. Would this be an airscrew that may have already been uncovered, and has vibrated loose to this position, or something different that these particular carbs may have that I am just not familiar with? Just want to be cautious, if you will, and ask.

For what it's worth, this 80G was manufactured in May of 1979, possibly making it an 80 model in the grand scheme thus having different carb plumbing, per se? My 80 SG was manufactured in December of 1979 and has what I consider the "normal" 1980 carbs.

I've searched around a ton on the forum, but can't quite find info to piece together what I'm describing with respect to removing a buggered pilot jet or the type of cap on the air screw.

Thanks much!

[DGXSER]

I have worked on those early early model 80 carbs before. The only difference from the factory is that connecting passageway, and the plug. Otherwise, they are identical to your SG carbs.

As to getting out the buggered pilot jet, I have good luck using PB Blaster or similar and letting it soak overnight or even a day or so, then using a very small screw extractor. Now, the extractor is brittle, so easy on the twisting with it. You do not want to snap it off inside there.

For the mix screws, it sounds like perhaps someone had drilled out the caps of those carbs and not removed them. On the one that has a screw head and turns, can you turn the carbs upside down and pat them a bit and make it fall out, or turn it while upside down and get it to fall out?

[Bonz]

Thanks DG. I had a friend suggest to drill it out carefully if needed to make a small machine screw fit in there, and use red loctite on the screw. Let it sit overnight, then back it out. Any thoughts on that?

As well, I have a new 42.5 pilot jet from a GeorgeFix kit I used to rebuild the carbs on my SG. I have heard some replacement pilot jets aren't as precise as the originals. Should I replace all 4 originals with 4 new ones to keep them consistent, as I didn't use them in my SG carb rebuild. My thought is I'd be OK to replace just the broken one, but wanted to ask anyway.

Here's a pic of the #1 & #2 airscrew towers, does that change anything in terms of what we've already talked about for getting at the air screws? The screw would not readily "shake" out, but took the pic quick on the way out the door this morning, so need to try some gentle persauasion tonight.



Thanks much!

[crazy steve]

I've had good luck drilling those jets out, then re-tapping the hole. These do use a 'standard' metric thread (the size escapes me right now), so if you drill with the right size tapping drill, you can easily retap the hole. You do need to be careful not to drill/tap too deep or you can damage the 'seat' the jet bottoms on.

As to your idle mixture screws, what you're seeing is the 'anti-tamper' plugs that somebody has partially drilled out. You'll need to get those out to remove the idle screws. Try turning the idle screws in as far as they'll go (lightly seating them), then use a proper-size bottom tap to cut some threads into the plugs. Screw in a matching bolt, then pull the plugs....

[Bonz]

Thanks cs.

Looking at the pic, and up close at the carbs in person, the hole is centered and the inside edges are smooth, like they were made that way, and there was no drilling that took place, unless there was a plug within a plug, and only the center part was removed, leaving a concentric and smooth hole surface.

Is that what you are seeing/saying?

What about #2 that has the slotted head brass screw? Looks like someone might have been successful at getting a full plug out and the airscrew has been backed out too far or vibrated out to that point? Like I said earlier, the screw will spin either way when turned, but does not go in or out.

[Aches n Pains]

Agree with SG and Steve. Use a screw extractor (have to be careful drilling the hole to receive the extractor). Take it out slowly using lots of PB Blaster. Rethread with a metric tap. Again, go slow and be careful. I've done several and have never torn one up.

[Bonz]

Thanks, will do.

[crazy steve]

I don't like the screw extractors as they break rather easily; I've got several carb bodies floating around with broken ez-outs in them. Once you have that, the body is junk. Just drill it and retap....

[motoman]

I don't like the screw extractors as they break rather easily; I've got several carb bodies floating around with broken ez-outs in them. Once you have that, the body is junk. Just drill it and retap....

Howard, someone stuck a couple Mikuni main jets in there to plug off the top of that aluminum casting. Keep it simple, just screw a sheet metal screw in those jets that were used for plugs and jerk 'em out of that tower. Air compressor, and blow out that recess and a shot of WD-40 or similar before removing the idle mix screws, otherwise they may bound up and you'll split of half of the brass slot, then you'll have to get in there and cut a new slot with a dremal and tiny plunge router,(BTDT).

[tarzan]

I don't like the screw extractors as they break rather easily; I've got several carb bodies floating around with broken ez-outs in them. Once you have that, the body is junk. Just drill it and retap....

You can actually drill an extractor out with carbide. And yes I know that some extractors are made from carbide. I have machined quite a few carbide bits out with carbide. Some extractors are made of HSS, chrome Molly, or Cobalt.

Anyway, I would not throw out a carb body without first at least trying to remove those ez-outs.

[fredintoon]

- - - One pilot jet had the screw slot broken/buggered by a previous owner. What is the safest and surest way to extract the jet, if there is such a thing as safe and sure existing in the same operation. - - -

Hi Howard,
here's what I have succeeded with:-
Chuck up a hex-drive screwdriver bit in your bench drill.
Securely block the carb body on the bench drill platform.
Use the drill feed arm to force the screwdriver bit into the remains of the jet screwdriver slot.
Back up the drill chuck by hand while keeping pressure on with the feed arm to stop the bit riding up and out of the damaged slot.

[Bonz]

Thank you for all the ideas for the pilot jet!

[Bonz]

Brake piston

On another subject, one front brake piston is scored in the direction of piston travel in the area of the caliper seal ring. I've smoothed the surface, however the scores remain. My feeling is when the piston passes the seal, the scores will transport minute amounts of brake fluid past the seal over time.

Is my best bet to get a new piston? Is this something I am making more out of than needed?

[crazy steve]

Yep, replace the piston. That scoring will cause leaks and likely damage the seal to boot...

[Bonz]

Gotcha, thanks.