This diaphragm set does NOT include new throttle slides. This is a easily installed rubber part that goes on your old slide. The rubber is attached to the slide by pushing the thick section over the swagged lip that held the plastic washers. The thick section of rubber grips the slide and replaces the plastic washers. The pictures should explain how this works. Please print these instructions. We guarantee that those that buy them will like them, or your money back. Q.Your diaphragms work great. Do you have the carb holders ready? 1979 Yamaha XS650. Regards, Waldo A. Yes we do have the carburetor holders, including those straight ones for early '70 thru '73. Hi, Just wanted to say that I received the diaphragms and that they were absolutely great! Allthough the old diaphragms didn't have any holes in them, replacement improved performance dramatically. Best money I've spent in a long time, great value, thanks for making such a product available! Best regards, Oeyvind Elbert Hagaveien 15b 1387 Asker Norway I just received the new BS38 diaphragms, and am extremely happy. Very nice work, and I can't thank you enough for saving the carbs on my 79 XS. Thanks a million! Norm McRae Just to say diaphragms arrived on friday 21st, I fitted them today 22nd, they fitted perfectly and very straight forwardly. Ballanced carbs , one very happy FJ 1200. Regards Graham...... Northumberland, England. Great alternative to $300 NOS slides. Works as advertised. Buyer: wch69sooner2010 ( 3 ) Apr-09-10 YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#230435468325) As Usual...PERFECT!!!! Buyer: spydercycleworks ( 3184) Mar-31-10 YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#330413174303) Super quick, great product and seller! Thanks Don Buyer: bluebikerblan ( 57) Mar-24-10 Yamaha XS 650 Carburetor Holder Socket Boots USA made (#330411790711) Item worked great and quick delivery very pleased Buyer: gerald.423 ( 4 ) Sep-14-09 YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#330355707704) Thank you. Very cheap shipping A+ Good part at a super price wish I had got more Buyer: jeremyb977 ( 26) Jul-09-09 YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#230348064346) Worked like a charm. I wasn't sure if I'd ever be able to find this part again. Buyer: shadowstep07 ( 20) Jun-22-09 Great product Buyer: sherrieakin ( 36) Jun-20-09 YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#230348064346) Nice parts-good service Buyer: senpga ( 69) Jun-08-09 YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#330333032461) Quick and accurate Buyer: joara172 ( 29) Jun-08-09 YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#330333032461) Awesome great part Buyer: 970_anchondo ( 18) Sep-03-09 YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#230359062132) The parts fit and work perfectly Buyer: Member id klaus_the_great Nov-13-10 YAMAHA 650 Mikuni BS34 CV Carburetor Diaphragm, Suzuki (#230539666945) hallo Thanks for the very good service and perfectly parts. besten dank für den tollen service die schnelle lieferung . die membranen passen perfekt sehr gute einbauanleitung bin sehr zufrieden!!! vielen dank aus deutschland. sven spicker Just wanted to say thanks ............ The diaphragms arrived yesterday, were put in today and I couldn't be happier with the results !!! WOW !!! Thank You !!! John M. Wright 388 Painter Street Rio Dell, CA. 95562-1432 These diaphragms are easy to install and restore XS650 carbies BRILLIANTLY!!! Buyer: Member id laoshi50 ( Feedback Score Of 304) Apr-12-11 03:20 YAMAHA XS, TX 650 Mikuni BS38 Carburetor Diaphragm 77mm (#330543642298) Test drive was awesome! Great diaphragms, huge performance difference! Thanks Buyer: Member id 1105sunnylake ( Feedback Score Of 1 ) Apr-22-11 06:52 Diaphragm KZ700/750/1000/1100 VS-750 MIKUNI BS34SS 70mm (#230598414002) RE: XJ900F BS36CV ...-Thanks for the delivery. I installed the diaphragms and they work like a charm. My bike has full power again and is running great. Regards, Henry. Thanks for the BS34CV73mm diaphragms. I have fitted one to my Yamaha SR250SE 1981 and it works a treat, the old diaphragm had a total of 5 holes in it! Richard Warner. I purchased a pair of diaphragms for 35mm Mikuni s for my 1980 XS650 a while back, which have been fantastic, not a problem. I live in Newcastle, Australia Quick message to let you know BS38 diaphragms fit yamaha XS500 fitted with Mikuni BS38 CV carbs...fitted a treat. * Constant velocity carburetors actuate the throttle slide and needle at anything over a fast idle. The atmospheric depression or vacuum caused by the venturi of the cut-away is used to raise the slide by means of the vacuum on the top of the diaphragm. ( There is a communication hole to the venturi in the throttle slide.) Made in USA on limited basis with high quality rubber. Reasonable shipping worldwide! Email us and let us send you a Pay Pal Invoice: jbmindustries@att.net |
Yamaha SX, TX 650, Venture, & Kawasaki KZ-750, XS500 Carburetor Diaphragms for
Mikuni BS38, BS36, BS34, & BS34SS CV constant velocity carburetors. This easy to
install part can cure engine stuttering, unwanted acceleration, uneven and
unbalanced carburetors caused by leaking or worn diaphragms. Until now
replacement meant you had to buy an expensive new throttle slide.
Please state carburetors you have or measure diameter of groove when ordering:
Mikuni BS38, BS36, BS34, & BS34SS CV constant velocity carburetors. This easy to
install part can cure engine stuttering, unwanted acceleration, uneven and
unbalanced carburetors caused by leaking or worn diaphragms. Until now
replacement meant you had to buy an expensive new throttle slide.
Please state carburetors you have or measure diameter of groove when ordering:
| This pair of Yamaha 650 or KZ 750 carburetor diaphragms fits Mikuni BS38 CV constant velocity carbs. Easy and inexpensive fix & made from aircraft quality rubber so they will last. JBM "TSR" Compound |
| The first step to install the new diaphragms is to cut both the plastic retaining washers from the original slides as shown. ( Remove stuck slides by placing carburetor body under a 100 watt lamp to warm it and soften varnish. ) |
| Install the new diaphragm by pushing it over the lip on the old throttle slide as shown. Hard rubber tire fits tightly to slide. We are asked about adhesive on this part, and while "Super Glue" will work, you really don't need it. |
| Use fine sandpaper or Scotch-bright pad to clean the groove and remove any sharp corners that might cut the diaphragm. |
| Install your needle and clip as shown here. |
| Position the throttle slide and diaphragm as shown with the cut-away facing the open mouth of the carburetor. Roll the diaphragm a bit to push it into the groove. |
| Place a dot of paint at the "key" tab location for easy future removal and positioning. |
| Place the slide return spring and check that the diaphragm rolls properly. |
- Install the top cover and check for smooth
operation. - A smoothly moving slide is needed as only a
very light return spring returns the slide. - A small hole in the throttle slide is what allows
the venturi vacuum to operate the slide. This
constant velocity carburetor prevents stalling
and gives smoother running than other direct
acting carburetors. - 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. (This prevents rotation or removal.)
with carburetor cleaner, remove the diaphragm and all
rubber parts first. ( Diaphragms are sometimes called
membranes. )
- BS38 carbs use 77mm diaphragms
- BS34 carbs use 73mm diaphragms
- BS34SS carbs use 70 mm diaphragms
| Only $19.50 each To order: Go to HOW TO ORDER PAGE email: jbmindustries@att.net Visa/ MasterCard.. |
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| To order: Send check or MO to: JBM Industries 3761 Morley Drive Kent, Ohio 44240 USA Request a Pay Pal Invoice: jbmindustries@att.net Or phone: 330-678-9537 |
| Domestic & Foreign Shipping only $3.00 per order for any number of diaphragms by FIRST CLASS Mail |
| Be sure to visit our page for Carburetor holder socket boots for Yamaha 650 twins. See Carb Holder Button above. |
ORDER: MIKUNI BS38-CV Diaphragms if
you have a Yamaha 650 twin made from
1970 thru end of 1979, or XS1100 '78 - '80
( Sold each )
ORDER MIKUNI BS34-CV Diaphragms if
you have a Yamaha 650 twin made in 1980
until end of production.
you have a Yamaha 650 twin made from
1970 thru end of 1979, or XS1100 '78 - '80
( Sold each )
ORDER MIKUNI BS34-CV Diaphragms if
you have a Yamaha 650 twin made in 1980
until end of production.
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| A finished Mikuni BS38 CV carburetor |
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Last updated 10/27/11
| This is a photo of a pair of diaphragms or bellows that you will need to restore your carburetors. |
| BS38CV fits these models that we know of: Yamaha XS-650 1970-thru 79 XS 650 A,B,C,D,E,F,SE,SF TX-650 XS-1, XS-2, XS500 XS1100 '78 - '80 KAWASAKI KZ-750 Twins |
| Special note when installing BS34CV & BS34SS Diaphragms and slides: While your BS34 slide may not have a cut-away as shown on the BS38 above, it is important that the vacuum hole is positioned towards the engine. |
| The "Hard Rubber Tire" is what holds the diaphragm to the slide. |
| BS38CV 77 mm OD of Diaphragm BS36CV 73 & 77 mm OD of Diaphragm BS34CV 73 mm OD of Diaphragm BS34SS 70 mm OD of Diaphragm |
| Mikuni SIZES we have at this time: |
| Note: BS36 CV carbs were used on certain FJ1200, 86-93 XJR 1200-1300 XJ900 F Please measure OD of Diaphragm to be sure. 73mm fits Yamaha Venture |
| To see if you need new diaphragms, just hold your old diaphragms up to a strong light. If you see any light passing through, you need replacements. |
| BS34SS CV Carburetor Diaphragm is shown above and below. The outer diameter of this diaphragm is 70 mm |
JBM is a manufacturer of parts.
We cannot give any technical advise.
We cannot give any technical advise.
| BS34SS CV Carb has a 70 mm diaphragm |
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| Click here for HOW TO MEASURE |
| Yamaha Venture Notes: The 73 mm Mikuni Diaphragm fits the Venture models even with plastic slides. Remove the short metal tube from the plastic slide and remove the rings. Place the JBM Industries diaphragm on the metal tube, and then push tube into the plastic slide. Use Super Glue on metal tube. |
| Notes on Yamaha Venture installation shown down page. |
| CLICK HERE for our "How to Order" Page. |
| CLICK HERE for our "How to Order" Page. |
| CLICK HERE for our "How to Order" Page. |
| How to measure page. |