Mikuni                 BS38CV                 77mm dia.                     25mm dia.                      4mm                         20mm         Fits Yamaha 650 & 750 twins, early XS500                                    
M-77                                                                                                                                                                                            Kawasaki KZ750 twin
                                                                                                                                                                                         Suzuki GN400 '82, GT750 triple

Mikuni                 BS34CV & 36         73mm dia.                     25mm dia                       4mm                         19mm         Fits Yamaha 650 twins '80 on, FJ1200, BS36, XJR1200-1300
M-73                                                                                                                                                                             XS250, SR250, XS400, Venture, XJ900F, XS750 & XS850 triples
                                                                                                                                                            Virago XV535, XV500 XS1100, & Mikuni BDS34-Downdraft carburetor.
                                                                                                                                                             Kawasaki GPZ750 '82-'83, KZ1100,
                                                                                                                                                             Suzuki GS450E, GSX1100, GS1150, VZ400 Desperado/Marauder

Mikuni                 BS34SSCV            70mm dia.                     25mm dia                        4mm                         18mm        Fits Kawa KZ750 & some twins, 700, 1000, Spectre1100, MI CSR
M-70                                                                                                                                                                                       Intruder
                                                                                                                                                                                         Yamaha XJ700
                                                                                                                                                                                 Suzuki '83 GS1000ES & Katana, '81 Suzuki GS650L, 1100 & 750
                                                                                                                               

Hitachi                HSC40                   78mm dia                      28mm dia                        3mm                         20mm        Fits Yamaha Virago 700,750,920,1000,1100
H-78
Hitachi                HSC32 & 33           68mm dia                      25mm dia                        4mm                         18mm        Fits Yamaha 650 Maxim/Seca '80-'84 ( NON-TURBO ),
H-68                                                                                                                                                                                     '81XJ750, XS850G
                                                                                                                                                                       Honda VT600, VLX600,  

Keihin                                              78mm dia.                      23mm dia                        4mm                         15mm        Fits Honda CB360, CJ360
K-78

Keihin                VG series              72mm dia.                       33mm dia                        4mm                         19mm        Fits Honda Hurricane CBR-1000F & VT-700 & 800                      
 K-72

Keihin                CV-32                    71mm dia                       26mm dia                        5mm                         20mm        Fits (Keyed groove) Kawasaki KZ250, KZ440, KZ400, KZ750/4,
K-71                                                                                                                                                                                                                   CSR305

Keihin                CVK36                   67mm dia                       17mm dia                        5mm                         19mm        Fits Kawasaki Vulcan 1500, ZZR600, Ninja(GPZ)900
                                                                                                                                                                                       Arctic Cat 650,
K-67                                                                                                                                                                                      Triumph Legend tt900

Keihin                722A                      73mm dia                       20mm dia                        3mm                         16mm        Fits CB350 & CL350
K-73
Teikei               YDLS                      63mm dia                       19mm dia                        5mm                          13mm        Fits Yamaha XT350,  SRX 250( 2 barrel carb ) ( TK carburetor )
T-63

Sheng Wey       VE                          60mm dia                        19mm dia                      4mm                            13mm       Fits  Johnny Pag 250 twin & other Chinese scooters & cycles.
SW-60
Make             Model Number     Groove Diameter        Hole Diameter      Slide Groove Width          Dish                                         NOTES
To order: We need the make of carburetor and outer groove diameter.
Example: Keihin 71mm   State how many you need.  ($19.50 each)
Please tell us what country you are in.
We will send you a Pay Pal Invoice for you to pay if you approve.
EMAIL:  jbmindustries@att.net
JBM INDUSTRIES manufactures diaphragms to fit constant velocity "CV"
carburetors used on certain older vintage motorcycles.
JBM is a part manufacturer and makes only the parts. We cannot give advise
on carburetors, jets, or engine problems.
JBM does not know which diaphragms can be used on your vintage motorcycle
or how many carburetors it has. The buyer must measure his carburetor body
as shown. Years and countries vary.
Never try to measure the old rubber as it may be swollen or have shrunk out
of the original dimensions. Measure the carb body only!

The best way to get the correct size is to measure your carburetor as changes
were made for different years and in different countries. The listing above has
notes on what buyer's have reported they fit. These diaphragm dimensions may
fit many other models not listed.
The JBM diaphragms all work on the same principle; in that a thick rubber tire
that has a minimum amount of stretch is used to replace the plastic or metal
rings that originally clamped the diaphragm. These rings are removed with small
side cutters after clipping in several places. The JBM diaphragm is held in place
by tension of the tire in the groove on the slide. The hole in the tire is usually a
millimeter or two smaller than the groove diameter, and this creates the tension.
Do not over-stretch the tire!    Do not bend the tire!
Some diaphragms might need to be held with adhesive such as Super Glue Gel
  for plastic slides, and regular Super Glue for metal slides. Use only a
minimum amount as solvents can attack the rubber. Keep any adhesive off of
the sides of the carburetor slide.

This method of diaphragm replacement relies on the installer to get the slide
back in place with the original alignment, and no "key" is used. Once correctly
positioned, a dot of paint aligned with the "key" slot can make removal and
replacement of the slides fool proof if you need to change the needle.
JBM "users tell us" diaphragm size chart for CV carburetors we manufacture diaphragms for.
Updated 05/17/12
Click here to go to JBM Home Page
It is helpful if you find a diaphragm that will fit your bike to email us with the year, model, and carburetor so that we can add it to the list above.
These diaphragms may fit other years and models of vintage motorcycles, but we do NOT know which ones. Click on links above for instructions.
This list means only that these diaphragms fit "some models" of the motorcycles shown. Different years and countries change usage. YOU MUST KNOW WHAT CARB YOUR BIKE IS FITTED WITH.
The same model motorcycle might be listed in several places due to different carburetors in different countries.
Remember that to be SURE of the
correct part you MUST measure goove
diameter. Shop and owners manuals
can be wrong! Different carbs may be
fitted in different countries on different
years & models.  MEASURE !!!
Questions and answers about JBM Industries replacement diaphragms for vintage motorcycle CV carburetors.
Q: What type of adhesive do I use to keep the rubber on the slide? I am afraid the slide might rotate.
A: Use regular Super Glue sometimes called "Crazy Glue" sold at Dollars Stores, Auto Parts Stores, and Discount Stores to glue rubber to metal slides. To glue to plastic slides,
use Super Glue GEL TYPE. Use only a small drop as it can run off very quickly as it is thin like water. Take great care not to get any on the side of the slide, as it must move
freely. Dry fit first to be sure everything is correct before you glue, as positioning time is very limited. Use glue sparingly, as solvents are not good for the rubber. Never use
Silicone sealant or glue. Do not try to "repair" holes in the diaphragm.

Q: What does the dimension "Dish" mean?
A:  It represents about 1/2 of the travel that you can get with that diaphragm.  Slides usually do not close the carburetor bore completely.  The slides move from about 1/4 throttle
on up. "MODEL" means the original carburetor the part was designed to fit, but it might fit many other types as well. Outer groove depth, width, and design can be different, so
you need to watch those dimensions. The hole in the middle should be about 2mm smaller than the root diameter of the groove in the slide so that there is some tension on the
tire.  As an example, the 68mm Hitachi diaphragm seems to fit a Keihin carburetor used on a Honda.

Q:  What can I do wrong installing these?
A:  Failure to position "air hole" in the slide correctly when you place it back into the carb body. ( Do them one carb at a time. ) Failure to remove sharp or rusty edges that could
cut the rubber.   Over-stretching the "tire", as the rubber is designed to not have much stretch and contains no fabric. Be sure slide groove is clean and free from oil or
grease.
JBM does not think glue is needed, but many users want to do this. *  If you are using Super Glue, don't get glue on the sides of the slide, and use only a very small amount.
       Most enthusiasts have no trouble. Look at all the photographic instructions for all carburetor models to get an idea of how they work.  While JBM diaphragms are easy to
install, some enthusiasts are very poor mechanics and should know their limitations. Take the carburetor to an expert.    * MEK Tolulene, Acetone, etc. are solvents that destroy
rubber.

Q: How long will these last? How will they affect my performance?
A:  We really don't know an exact answer to this question as we have only been making these types for vintage motorcycles for about 3 years. We have been making diaphragms
for other uses since 1978 that work in a similar manner. We think it fair to say you should get at least 5 years out of them, but a lot depends on installation. We have sold more
than 2000 of these diaphragms. They will probably outlast your originals. These diaphragms should make your engine run like new, but will not cure all carburetor and fuel
delivery problems. Manifold vacuum operates the slide and is very powerful, just like power brakes on a car. Diaphragms have nothing to do with your idle. We have many
testimonials at the bottom of installation instruction pages. Please check them out.

Q: I don't see my bike listed. Do you have a diaphragm that fits?
A: The chart at the top of this page serves only to inform that we might have what you need, or that someone has used some JBM diaphragms on a bike and it worked. In most
cases you should measure to be sure, and look to see what make of carburetor is fitted to your bike. If you don't see your machine listed above, there is a small possibility that
one of the above diaphragms will fit, but you better do a lot of measuring before you order. JBM does not make all sizes for all bikes, and we try to manufacture for vintage or
collectible motorcycles as much as possible. You can return undamaged diaphragms that don't fit, but JBM does not refund shipping and handling costs.

Q: My slide has a metal top ring. I need to slide the diaphragm up the slide as it is the only way I can get it on. Is this OK?
A:  No. You MUST cut off the metal ring.   Sliding it up the length of the slide will ruin the diaphragm.   JBM diaphragms are made from a rubber that has very limited stretch. JBM
diaphragms MUST be installed from the top. Please look at all pages of instructions on this site. Metal rings must be removed from the slide by cutting in several places with side
cutters. ( Twist the cutters back and forth. )  If you are unable, or unwilling, to install by removing the rings, please return the diaphragms for a full refund. Only plastic slides have
a molded lower ring that cannot be removed, but the JBM diaphragm is designed to fit these, and a small amount of Super Glue Gel type adhesive must be used to install them
on plastic slides.

Q: You list a diaphragm that fits a Mikuni BS34 carburetor. I have a BS36 carburetor and wonder if it will work?
A:  Yes. It will work. Many carburetors use the same housing and slide, but the bore in the throat is different. JBM stamps the diaphragm for the carburetor model number that it
was originally designed for, but it might fit several different models of carburetor. Measure the groove OD, as that is the best way to judge a carburetor series, as the slides are
usually the same. In some cases a diaphragm from a different brand of carburetor will fit another brand.  Measure the outside diameter of the groove!

Q: I have a bike model that is not listed and live in a foreign country. Can you tell me what diaphragm to order and do you sell needle jets?
A: No. JBM Industries cannot tell you what model carburetor your bike has. We have no motorcycle parts, and are not motorcycle enthusiasts. We know nothing about your bike,
and only you can decide what diaphragm to order. We do NOT have all sizes for all bikes. We will ship to foreign countries with no problem.

Q: I just bought my used bike and need to clean the carburetors. How do I get the slides out?
A: Remove the screws that holds the cover, and the rubber diaphragm should lift out. If your carburetor is full of varnish from evaporated fuel, the slide might be very stuck. You
must remove the carburetor, and place it under a lamp to heat the body. When hot, the slide should pull right out, unless someone has butchered it by using force.
NEVER use compressed air to blow through jet holes unless you remove the float bowl first, as air pressure will collapse and crush metal floats. Do not soak or spray carburetor
cleaner on rubber parts.  .... Slide removal and broken slide repair can be seen if you CLICK HERE.

Q: My old slide diaphragm had holes in it, and I tried to fix it with glue. My diaphragm seems too big to fit in the groove now. Do I need a new diaphragm?
A: Yes.  Your old rubber can be swollen by the solvents in the glue or ethanol in the fuel. Carburetor cleaner can also cause rubber to swell. The rubber swells because it absorbs
the contaminant, and this will also soften and weaken the rubber so it tears more easily.  -- You can also have rubber get harder from getting the plasticizers  ( Softening oils )
washed or leached out of the rubber.  All rubbers get softer when heated, and most motorcycles have carburetors mounted where they will get hot. Heat can cause rubber to
rapidly age.  JBM uses very high quality and temperature resistant rubber stock that works well with 10% ethanol auto fuel.

Q:  Will new diaphragms improve the performance of my motorcycle?
A:  That depends on how bad your old diaphragms are. Diaphragms control performance at speeds above 1/4 throttle. They don't affect your idle mixture. Some things to check
before you order new diaphragms are:
  • Condition of old diaphragm. Hold it up to a light while stretching slightly. Look for very small pin holes or tears. Diaphragm must fit in groove and not be shrunken or
    swollen from the ethanol or carburetor cleaners in the fuel.
  • Check fuel delivery by pulling fuel line from carburetor to be sure you get at least one pint in one minute fuel flow. You might need to suck a vacuum on a vacuum operated
    fuel tap to make it open.
  • Check to be sure floats do not leak and be sure plastic floats have not swollen from the ethanol, and not rubbing on anything such as the float bowl. Float needle must
    open fully.
  • Check for a clear varnish covering the holes in the main jet if a bike has been sitting for a long time. Varnish can be very difficult to see.
  • In no way does JBM Industries claim that your bike will run better or faster than when it was new by installing JBM diaphragms.  People that report this just never knew how
    it was supposed to run when new.  JBM Industries does NOT provide diaphragms for you to "try" to see if it will help. Only unused or defective diaphragms can be
    returned for refund or exchange.
Click here to go to "How to order page.
JBM Diaphragms do not have a "KEY" in most cases. The installer MUST position the slide when fitted. A mark of paint can serve to align the
diaphragm and slide assembly for future use. NOTE: These diaphragms require some mechanical ability and knowledge to install.
For balance: Be sure to replace all diaphragms at the same time.  ( If you have mechanical ability you would know that. )
REMEMBER: The listings below are meant as a guide. You should still MEASURE, as this information only means that it
worked for "someone", and you might not have stock carburetors. Our thanks to those that have sent us this information.
Click her to see how to remove and restore a
damaged carburetor slide.
  • Others now copy our diaphragms, but they
    cannot copy our material. Don't be fooled.
    Use genuine JBM diaphragms !
See the ABOUT US PAGE HERE.
Note:  Please be sure you have spent at least 30 min reading
the information on this web site before you order. Be sure to
click on links to see instructions and special notes about
your installation.  See Q & A below.
Shipping and handling for ANY number of diaphragms is only $4 for both foreign and domestic. These items are very light & sent by mail.