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. A quick mail to say that the M-77 fit BS36's on an '83 Suzuki GR650 Tempter. Your diaphragms work great. I have about 2K on these so far and so far so good. XS400 Regards, Waldo Rubber was nice. Almost to easy to install. Fit the grooves on slide and Carb body perfect. M-73 Hi Don, I just wanted to provide you some feedback on your products…they work great! I installed them on my ‘81 Yamaha XS400 with BS34CV carbs. They went on easy, and the bike ran like new. The bike went from almost non-running to tearing up the neighborhood in less than an hour. Thanks for the great product and fast delivery, Pete 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 What a great product. 15 mins to install, bike running like a dream again. A++++ Buyer: izibead2012 ( 28) Feb-16-13 YAMAHA Diaphragm SR250 XS650 XJ400 XJ1100 XJ900 Venture XS400 XV535 Mikuni BS34 ......Mikuni BS34 Hello! These M-73 diaphragms is just a awesome!!!Fit perfect to my Suzuki gsx 400e 1983. Regards, Tom, Finland. t.bergstrom@luukku.com 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 I have just installed M-70 diaphragms on my Mikuni BS 33 carburetors from a 1985 Yamaha Maxim X XJ700XN. The parts fit perfectly, installed easily and operate flawlessly. This diaphragm will also work on models XJ700XNC from 85' as well as the 86' models XJ700XS and XJ700XSC , (the only two years these models were made as far as I know) so please add these to your list of bikes these diaphragms will fit as it may help some poor soul trying to locate these rare and hard to find parts... or paying $180 per slide and diaphragm assembly (which there are four on these bikes). Thank you for an excellent part at a fair and honest price and prompt delivery (2 days). I hope this helps someone find a part that they are looking for....Thanks again! Randall Edwards 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. Hi Don, RE: XJ900F BS36CV That was fast - I got the parts this morning & installed them already. Work fine. Thanks for the fast service. Rgds, Chris. Hello, the replacement Carburetor Diaphragm came it today.The quality of these parts is perfect and better than the original in my opinion. I am working on Motorcycles since 1979 and was happy to get these high quality spareparts. Thank you very much for your kindful help and assistance and the fast delivery Berlin/Germany WOLF...... Hi Don, Thank you for your speedy reply. Payment sent via PayPal. PS. I just returned from a 1,000 mile round trip after installing the new BS34 set I borrowed from a good friend and they performed excellently I was very pleased. Ben Bennink I need 4 BS34 diaphrams. These will fit the 1980 Yamaha XS1100 SG (Special) that I'm rebuilding. Thank you for your time. -- Also the set I bought for my 1979 Yamaha XS1100 SF (special) work perfectly. Thank you for a great product. Peter Albers mindwebs99@yahoo.com I now have used several of your Diaphragms for the CB360, CB350 and KZ440 I have found them easy to install and they work VERY WELL . THANK YOU Gary G'day Donald, I received the diaphragms not this week, but last. I was waiting for my dad to pick them up and have a look as they are for his TX750. He is very happy with them. Your service has been excellent and would not hesitate in dealing with you again. Regards and best wishes, Tony Oxenbridge. * 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! |
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 77mm diameter Part M-77 |
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 "Super Glue" will work. Do not use other adhesives. |
Use fine sandpaper or Scotch-bright pad to clean the mechanical lock 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. |
Only $19.50 each To order: Go to HOW TO ORDER PAGE email: sales@jbmindustries.com |
Domestic Shipping only $8.00 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. |
A finished Mikuni BS38 CV carburetor |
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 EARLY & BS34 Fit later models. KAWASAKI KZ-750 Twins Note: There are 2 types of BS36CV carbs, and could be fitted with 77 or 73mm diameter. |
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 side. |
The "Hard Rubber Tire" is what holds the diaphragm to the slide. |
MEASURE diameter before you order as not all BS34CV carburetors use the same diaphragm !! Most common mistake when ordering |
BS38CV 77 mm OD of Diaphragm BS36CV 73 or 77 mm OD of Diaphragm BS34CV 73 mm OD of Diaphragm BS34SS & BS32 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. SEE NOTE: 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 Part M-70 |
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 if loose, 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. If metal insert tube is not loose, just cut the rings off plastic slide with side cutters as shown. |
SEE NOTES on Yamaha Venture installation shown down page. |
CLICK HERE for our "How to Order" Page. |
Click Here for the "How to measure" page and a listing of rough dimensions of our manufactured parts. CLICK HERE. |
M-73 Diaphragm |
M-73 Diaphragm |
Have a question about diaphragms? CLICK HERE |
Hi, Just to say thanks! The diaphragms arrived on Friday here! That's quicker than parts I ordered from the UK and still haven't arrived! Very pleased with the quality too. The bike runs great with them...Thanks again, Paul, England M-73 |
Hello Don, So the 4x diaphragms arrived last Thursday the 4th. My Bike is a Yam FJ 1200 “3CX” with Mikuni BS36 . The job to do is to cut and disassemble the 2 plastic rings on each sliders then your part “Mikuni M-73 “ fits perfectly. Then taking care about the orientation of the sliders before closing. My bike runs well now , Thanks a lot! David Batellier 72800 COULONGE FRANCE |
Gidday Don I have already restored a 1980 XS650SG and a 1981 XV1000RH, and fitted your replacement Vacuum Slide diaphragms to both Makuni and Hitachi carbs. They work great with total reliability. I am now restoring a 1979 Yamaha XS750F which is an Australian production bike. The bike is all original and fitted with Mikuni BS34-11 carbs. I would like to purchase 3 replacement diaphragms to suit the BS34 CV carbs. |
The fitment of the Mikuni 70 mm diaphragm of the BS 34 SS CV works on the Mikuni BS 32 that is on my 1982 Kawasaki 650 H2 CSR also. Awesome fit and one of the easiest replacement parts I have ever dealt with. Just as you said it would on your website. james.hopkins1225@gmail.com |
NOTE: JBM also makes a 68 mm Diaphragm that fits many smaller Mikuni & Hitachi carburetors. Please measure M-H-68-S |
If you think you have BS34SS carburetors: be sure to measure to groove OD. Do not trust manuals, spec sheets, or other owners. MEASURE ! |
Testimonial: We got your diaphragms for a buddy’s Yamaha 500 last year and they put the OEMs to shame. I had them on the slides in 10 minutes. Thanks for a great product! From: J. Jay Wilkinson BREJAY@Centurytel.net |
Went to your website on Friday, 13 December, and just finished installing your 73 mm Diaphragm on my Mikuni BS34. The installation was a breeze and I couldn't be more impressed! What an excellent product, and I believe you have done a real service for those of us with old bikes. I'm sure this will make my Yamaha SR250 "Café Racer" happy. Thanks again, and, Sincerely, Charles |
The 70 MM diaphragm I ordered works great in my Mikuni Carb, although it wasn’t designed for this model! (2000 Arctic Cat 4X4 ATV 300cc) Your product is far less expensive than OEM at $139. Please let me know if you decide not to carry or produce the 70mm diaphragm as I will need to order a few spares. Thanks again for a great product and fast shipping. ....Ben Stacy |
I am very pleased your fast delivery. diaphagms were very easy to fit mine cv36 Mikunis. And i tested them and finally my bike goes to rich, another time without new diags it goes lean and causing engine to overheat. my bike is fj 1200 yamaha. By the way ordered diags 01.08.2014 and got them to my home 08.08.2014 to Finnland, so VERY VERY FAST |
After you measure: Click here for HOW TO ORDER. |
YAMAHA XV535 Thanks Guys: My lil get around town cruiser was dead in the water. The dealer parts are to expensive and I was gonna part her out. Your diaphragm M73 fixed my issue and was a breeze to install. Although, I admit I read as much as I could on your website first. Thanks A Million, Mark Billings, Happy as hell in Sacramento |