JBM Industries

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JBM Industries - Hitachi

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Diaphragms
H-78
H-68
H-32 Air Valve

$19.50 USD

Installation Steps

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Step 1

Tools:  Side Cutters, Razor Knife

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Step 2

Cut both rings, insuring not to damage slide.

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Step 3

Remove both rings.

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Step 4

Slide should be free of plastic rings and undamaged.

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Step 5

Install diaphragm from the top into the groove.  Do Not overstretch.

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Step 6

Insure diaphragm is seated in groove.

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Step 7

Note the holes in the slide.

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Step 8

Insure that the holes lign up on the engine side.

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Step 9

Roll the diaphragm prior to putting the cover on.

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Step 9

Support the slide through the intake side of the carb to maintain the roll in the diaphragm as you attach the cover and spring.

Finishing Notes:

To Prevent Rotation or Removal:
Some folks want to use Super Glue adhesive on the slide, and this will not harm anything, but be sure not to get adhesive on the sides of the slide. Use sparingly, as solvents are not good for the rubber.

These photos should help you identify your Hitachi Carburetor as there is no name or model numbers on it. This one is a Hitachi HSC32/4H7.00 from a 1980 Yamaha Maxim XJ650G. Hitachi carburetors were used on many other vintage motorcycles.  68 mm diameter groove shown here.

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Please note the different lengths on the cover screws

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Please note the different lengths on the cover screws

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YAMAHA VIRAGO XV700 XV750 XV920 XV1000

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Yamaha Virago 78 mm groove

Order Hitachi 78 mm for Hitachi HSC40 Carburetors used on Yamaha VIRAGO XV750,920,1000,1100.  Diaphragms fits fine to Yamaha XV100 TR1

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H-32 Air Valve Diaphragm is available as shown below if you need one. Fits HSC40 carburetor.

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What our Customers are Saying...
"I ride a 1984 Honda VF700 Magna. The H-68 diaphragms (with the addition of an o-ring on the air tab) fit as well as I could have ever imagined. I have no doubt when this bike is re-assembled that the carbs are going to work like a dream. Thank you for making such a great product. ..- Matt Davis, Shade, Ohio"
"Just send me an invoice as soon as you have more ready because I'll take them, I used them on one bike already and I'm a believer, they worked awsome! ..Thanks, Greg"
"(JBM), WOW!!! That's so much better than my old, tired, stiff diaphragms. Thank you so much. Hitachi H-68mm ....Dan Timmons"
"I purchased two H-78 for my 1982 Yamaha Virago 750 and they work perfect. Saved me lots of money. You are awesome. Thanks again . Dennis."
"Hi just wanted to leave some feedback on the H-68 slide diaphragms I purchased from you: they work great on my 1981 Seca 750 rh .. This has to be one of the best products I have ever bought. Saved me a lot of money and I look forward to doing business with you in the future. Thank you, Cory Silver"
"I have received the diaphragms today in good order. 6 days!! Must be a record for items sent to Australia. Your package actually arrived before a similar sized item I ordered from my home State of Queensland! Thank you again, I will be ordering K-78 diaphragms for my CB360 soon. Kind regards, Adam James"