vacuum diaphragm

[boone]

I think I have found my fuel economy problem. I have found fuel in the vacuum supply line to the engine from the vacuum diaphragm. Would anyone have a good used one for sale or is this unit still available through the dealer?
Thanks
boone

[pggg]

Boone, if it's strippable it's fixable.

[TopCatGr58]

Hey Boone,

Let me translate: You've got an 80 MNS, using the Octopus, Pggg recommends just removing the Octy! I've heard that the K&L kits don't fit the diaphragm exactly? I've seen a similar looking square rubber diaphragm part with the "other" petcock repair kits for the E,F,G,H, models, but I'm pretty sure that it is for the vacuum controlled petcocks, NOT for any Octopus, since the Standards don't use one! The below picture from Old Bike Barn is listed for the Specials, and it sorta shows the needed diaphragm, but it's not that clear...sorry, it's the largest they have, it looks like something is over the square diaphragm? The description says something about a Plastic? piece not included?

Bike Bandit sells the complete diaphragm assembly!

39: DIAPHRAGM ASY 34275-001 $55.22

Old Bike Barn Petcock K&L repair kit:

Description:
K & L Fuel Petcock Repair Kit. Contains parts to rebuild 1 Motorcycle fuel petcock. Kit contains all necessary O-rings and diaphragms to rebuild one fuel petcock. Made in Japan. Note: Does not include plastic diaphragm spacer block.


$24.95
Applications: Yamaha XS1100 SF/SG/SH Midnight Special 79-81, XS1100 LG/LH Special 80-81, XJ1100 J Maxim 82

T.C.

[boone]

Thanks for the reply. I sure this will get my mpg back where it should be.
boone

[pggg]

Ah - I did mean repairable, rather than buying the whole unit. Of course the sledgehammer fix is always a fun option.

[prometheus578]

Plastic piece

The "something over the plastic piece" looks like the thin piece orf cardboard that protects the diaphram during packaging and shipping. (just rebuilt a customer's petcock yesterday) The plastic piece referred to is part of the petcock. There's actually two diaphrams on the assembly. You squeeze one side through the hole in the plastic piece, so that there's a diaphram on each side o' the plastic block.... to also act as sealing gaskets.
Also... before taking the petcock vacuum block apart, (petcock, plastic block. and end piece where the vacuum line hooks up), take some fingernail polish(impervious to gasoline), and mark a line across the assembly. Then when you put it back together, just re-line it up. Saves you the hassle of having to take it apart again after you've put it together and now have the vacuum nipple pointing in the wrong direction.

[Dragonrider]

Buy the complete unit guys! The rebuild kits DO contain the diaphram for the octopus, BUT it is not correctly designed and will not shut off the gas. The valve length is wrong and it will never completely close.

The complete unit is available and not all that expensive.

[don07tncav]

As I recall, I paid under $60 for the complete unit from a Yamaha dealer in Jackson, TN a few weeks ago. It took them a week to get it in.

[boone]

Well, I called Yamaha and was told that they will have to ship the diaphragm out of Japan with no ETA. None of the dealers in the country have one. Does anyone have a used one from a parts bike that they would like to unload? I’ll try the local Bent Bike here in the Puget Sound area to see if they have one.

boone

[Winterhawk]

I'm pretty sure Bob Jones's has them in stock. Not sure how much and all that but if you need something it is priceless.

[boone]

Bob Jones’s? I'm not sure whom you are referring to or how to contact. The link is broken. boone

[pggg]

Boone, there's nothing to these octopuses. Just 2 thin rubber diaphragms, a spring and a small rubber O-ring. That's it. Just strip it and clean it out. There's probably nothing wrong with the diaphragms. If there are pinholes, a light smear of silicon will soon fix that. If it's leaking , the screws are probably not tight enough.

[boone]

Thanks, I'll look at it this weekend....boone

[Winterhawk]

Bob Jones at Merriam Cycle

[boone]

Thanks for the post, I'll contact them and see what they can do for me.
boone