GS850 carbs.

[Guest]

Don James from JBM industries has asked me to measure the internal diameter of a Mikuni carburettor off a GS850 1981 model, to make sure I'm ordering the correct diaphargms, would GS Resources have an information page link showing the diaphargms dimensions or specifications.
Don doesn't specific OEM numbers, he matchs the item up with what he has in stock. I'm trying not to spend $180 per diaphargms for the carby rebuild.
Thanks in advance.

[Steve]

OK, here ya go.

The inner diameter is 60mm.


The outer edge of the diaphragm is 70mm.




EDIT: Where are you shopping that you find diaphragms for $180? They are $130.98 at Parts Outlaw.

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[Vmass]

Are you sure the diaphragms need to be replaced? I haven't done a ton of carb work, but the few I have done I reused the diaphragms without issue.

Are they prone to have issues that I am not aware of?

[sinkankan]

The carbs are getting a total rebuild, and thanks for the photo's guys.
Jets, o- rings, gaskets, diaphagrm springs, float pins, you name it it's getting done.
And I'm not taking any chances with the old rubbers, so new ones are going back in. The dollar prices vary from supplier to supplier and for a bit of rubber 70mm around the asking prices are totally outrageous. I've had Holley's on my cars before, on on the odd occasion I've had to do a carbie rebuild I could get the pumper diaphagrm for $25 US. So if I see a supplier (FBM Industires) doing them for a fraction of the price, and they are guaranteed, I'll jump at them.

[Steve]

While I can certainly appreciate your enthusiasm for a "total" rebuild, usually the only things necessary will be the o-rings and bowl gaskets.

Unless the diaphragms are torn or otherwise deformed, they will work just fine, there is no need to spend $500+ "just because I want to". By the same token, I have never seen the springs go bad, and there is no need to change the float pins, unless they are physically damaged.

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