Butterfly shaft seals

[GLoweVA]

Okay, I've diagnosed my idle problem due to bad shaft seals.
I ordered 8 from Partszilla. $4 each, plus shipping and handling. Ouch.
anyway, I got the bank separated, but I can't seem to get the shaft screws to budge. I've got a total of 3 banks, and on one I can get them loose, but the set I want to replace the seals on, no bueno.
I know they have been peened on the back side, but I figured I'd at least get one screw to move. Help. Should I get the drill out? I sprayed them with WD40 and I'm going to leave them overnight to soak. Maybe that'll do it.

Ps. After 40yrs, I think it's time these seals get replaced. I'm guilty of heavily spraying the carbs while cleaning, but I've never dunked them. But then again, my bikes have never really purred like some of you describe. So, maybe all 3 banks need new seals.

[DiverRay]

First off, I've NOT replaced shaft seals, yet! I have worked on carbs most my life, and I think if you take a little off the peened side of the screws they should come out. I would use a carbide drill and a drill press and just take about 1/10" off each screw. That should allow them to come out, as the peened section should be gone or so thin the screw will come out. Remember, they peen them so the screw does NOT fall out and into the intake!

[Radioguylogs]

The most important thing about removing those screws is to resist torqueing on them until you have a sharp #2 sized JIS screwdriver. It's like power steering.

Once the screwdriver slots are bugered, then you're in a for a lot more challenge.

I have removed them with an easy out, but it was tenuous.

[GLoweVA]

Thanks for those replies, I know they're bad cause it idles higher when I spray carb cleaner around the shafts. Sucks that stuff right in. I've always had some idling issues since I've owned these bikes, now I might have a culprit I can fix.Maybe I can get a little better/deeper vacuum when I sync too.

[Radioguylogs]

Another symptom of bad BBS is the idle with hang at at a higher RPM after the bike warms up. It's prevalent when you come to a stop sign.

[jetmechmarty]

Those screws come right out if you use a JIS screwdriver before you bugger them up. I've done several with no issue. The phillips is an improper fit and you're working against staked screws.

[bikerphil]

It may be the threads are seized/corroded, try some propane heat on them and then give it a go.

[GLoweVA]

Nobody in SE Virginia has a JIS in stock. I found a Phillips head that fit very snug and after the penetrate last night, today they broke free. Yippee.
Now for some pics.

[GLoweVA]

I took pictures of the shaft and components as they came off. It was nice to have another bank nearby to use as a reference.

[DaveT]

Those screws come right out if you use a JIS screwdriver before you bugger them up. I've done several with no issue. The phillips is an improper fit and you're working against staked screws.

This is a golden rule.

All cross point screws on Japanese motorcycles are JIS, similar to Phillips but different enough to cause easily gizzed up screw heads when using a Phillips screwdriver. A set of JIS screwdrivers will save you lots of grief, as well as time.

Anyone who works on Japanese bike should have them in his tool box. Good ones are available on Amazon.

I owned a Yamaha dealership and I fired a mechanic because he refused to use JIS screwdrivers, insisting the Phillips were as good. I got tired of explaining buggered screw heads to customers.