83' GS550 Diaphragm needed

[Guest]

So I have another post in the carb forum, but this post is more specific. My mechanic buddy tells me I need new diaphragms for my carbs if we are to pull them apart and rebuild/clean them. I have an 83' GS 550, with the Mikuni Two-Barrel BS30 I think. The number on my carbs is 43440, and I have a pic here of what they look like (not my exact ones, just the closest photo on the web I could find). My question is where can I get a set of diaphragms, if its even possible. Thanks a ton!

[Steve]

There is a member here by the name of Nessism. Look in his signature and follow his advice. "To measure is to know".

Before you go off on a wild goose chase, ask yourself ... has your 'mechanic buddy' actually SEEN the diaphragms to KNOW that they need to be replaced?

Yes, it's possible, but rather unlikely, so do yourself and your wallet a BIG favor, open up the tops of your carbs, remove the diaphragms, INSPECT THEM YOURSELF, then decide whether you need diaphragms.

Why does your 'mechanic buddy' think you need diaphragms? I have been seeing a few posts from you, but I don't remember anything about you going out and riding the bike. Until you get it under load, you will have a hard time diagnosing a running problem that can be attributed to diaphragms.

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[Cipher]

Do yourself a huge favour and get clear of this buddy esp if its the same completely misinformed person who told you that you had the wrong carbs. Do not let him touch anything!
I've had these carbs apart a few times and in the sets I own I've only encountered on "bad" diaphragm and diagnosed it as such not on any performance problem but because it showed a tiny pinhole of light when held up to a very bright lamp.

[simmoto]

check your PM

[aabickett]

Cipher, Steve. Thanks for the help. Honestly I don't really know the guy, he was referred to me by a mutual friend. I am also ignorant about motorcycle mechanics. He told me that the likely hood of opening the carbs up would almost surely destroy the diaphragms because of the age.. Steve, I did get the bike running with the choke all the way to the left, spray some ether in the intake and the bike fired up. The bike doesn't like idling in the low end, it revs and runs fine seemingly with the throttle opened up though.

[Steve]

I did get the bike running with the choke all the way to the left, spray some ether in the intake and the bike fired up. The bike doesn't like idling in the low end, it revs and runs fine seemingly with the throttle opened up though.

Do your bike a favor, toss the ether in the trash can. It is SO easy to mis-use it, and mistakes can be VERY costly.

The fact that the bike does not idle just tends to prove that the jets and/or passages between the jets are clogged, not letting fuel through. A thorough cleaning is in order.

I can't tell you how many carbs I have opened up, most of them just a little bit older than yours. I have not yet seen a GS diaphragm that was in need of replacement. When I rebuilt the carbs on my son's Yamaha Venture, three of the four carbs had torn diaphragms. The fourth diaphragm was not torn, but it wasn't even connected to the slide.

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[cowboyup3371]

Steve's right, I have opened up the carbs on both of my 81 550s without ever doing anything to the diaphragms. I posted some part information in your other thread for a rebuild and as Cipher confirmed, you can get new O-rings from Robert Barr. I would tear them apart, clean them, and reassemble

[2BRacing]

Perhaps the OP should consider sending his carbs out to one of the members here offering carb rebuild services. It will mean he gets the job done correctly without having to purchase unnecessary parts.

[aabickett]

Thanks for all the input guys. I think I'm starting to get a better grasp of things, and I will try to at least clean the jets, replace all the o rings and the bowl gaskets and see what's what! I'll try and keep you posted to see how it goes! You guys rock