PAIR of new carburetor diaphragms for the MIKUNI BS38 CV* Carburetor used on Yamaha 650 vertical twins. These are CV* ( constant velocity ) carbs used from
1970 till 1980.  77 mm OD of diaphragm groove. Does NOT fit the carbs used from 1980 on. If in doubt, check your diaphragm groove diameter.

 Cracked worn or torn diaphragms can allow imbalance to carburetors causing one cylinder to work harder than the other.

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.

Limited production for these old bikes. We guarantee that those that buy them will like them, or your money back.

Q.Your diaphrams work great. Do you have the carb holders ready? 1979 Yamaha XS650.
Regards,  Waldo
A. Yes we do have the carburetor holders, inlcuding those straight ones for early '70 thru '73. See our other page or watch on Ebay.


Item worked great and quick delivery very pleased
Buyer:
gerald.423 ( 4 ) Sep-14-09 07:15
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 20:10
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 18:05


great product
Buyer:
sherrieakin ( 36) Jun-20-09 16:16
YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#230348064346)


nice parts-good service
Buyer:
senpga ( 69) Jun-08-09 14:37
YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#330333032461)


Quick and accurate
Buyer:
joara172 ( 29) Jun-08-09 04:52
YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#330333032461)


awesome great part
Buyer:
970_anchondo ( 18) Sep-03-09 14:52
YAMAHA XS, TX 650 Mikuni BS38 CV Carburetor Diaphragms (#230359062132)


* 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 Carburetor Diaphragms for Mikuni BS38 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.
 This pair of Yamaha TX or SX 650 carburetor
diaphragms fits Mikuni BS38 CV constant velocity
carbs. Easy and inexpensive fix & made from aircraft
quality rubber so they will last.
 The first step to install the new diaphragms is to cut the
plastic retaining washers from the original slides as shown.
 Install the new diaphragm by pushing it over the lip on
the old throttle slide as shown. Rubber 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 small hole in the
throttle slide is what allows the engine
vacuum to operate the slide. This
constant velocity carburetor prevents
stalling and gives smoother running
than other direct acting carburetors.
 Note: When cleaning carbs or blowing
out passages with carburetor cleaner,
remove the diaphragm and all rubber
parts first.
Only $39 a pair
To order:
Call 330-678-9537
email: jbmindustries@att.net

Visa/ MasterCard........Pay Pal
CALL:
JBM Industries
330-678-9537
To order:
Send check or MO to:
JBM Industries
3761 Morley Drive
Kent, Ohio  44240  USA

Or phone: 330-678-9537
Domestic Shipping only $5.80
by Prioity Mail FLAT RATE BOX
Be sure to visit our page for
Carburetor holder socket boots.