Above we see an example of poor vulcanization after only 50 hours. The rubber was not
properly vulcanized to the metal, and this allows corrosion in.  A very hot humid
environment seems to make this worse. These photos were sent to
JBM Industries by
various new customers as the reason they want to buy
JBM flange sockets
  • A good pre-fight inspection should have caught these before they got this bad.
    Inspect by trying to pull rubber away from metal and bending rubber to look for
    cracks. Age cracks and tears usually are visible by only bending slightly and putting
    some strain on the rubber. Without bending, tears can remain invisible.
Problems with carburetor flange socket failure.
There have been various attempts to make the rubber sockets stronger and solve cutting
and tearing problems. To prevent cutting of the rubber by the clamp, Rotax now supplies a
"limiter" on every clamp to prevent "over tightening" of the clamps. The problem with this is
that: sometimes the clamps are not tight enough, and the carburetor spigot can move and
"work" inside the socket. This causes the locking rib and inside of the socket to get chewed
up and torn. Sometimes the carburetor can "pop" off, usually on start-up.
JBM recommends
that limiters be removed when using the
JBM sockets to be sure the carb is tight and cannot
move in the sockets.  
WARNING:  Never over-tighten sockets.

At the left we see another solution to improper mounting of the carbs and air filters. This is a
bracket that is made to go under the clamp and attach's to the bolt heads. This is an attempt
at a solution to prevent tearing of the rubber socket that is too soft and weak for all the
weight of the intake tubes, air filters, etc. You will also notice springs that have been used to
help support the carburetor's weight.
HKS engines shake a lot and have all sorts of installations with very poor brackets to support
all the weight on these carbs. Some things can help, such as plates to interconnect the
carburetors or springs to help support weight. Another solution we have seen on Rotax 912
engines is "coil springs" to hold the carbs on. They have also tried to add an aluminum ring
internally to prevent rubber damage inside. Do
NOT use ring with JBM parts.

These various attempts to solve a problem are only working on the symptoms, and not curing
real problem. Be sure you have good motor mounts to prevent engine shaking, and take
the time to add the supports and brackets to take the weight of air boxes, tubes, air filters, etc.
Click here to go to JBM Rotax Page
with other parts we manufacture.
Click here to go to Rotax 912 socket
page with more photos of these flanges.


"Good day JBM Rubbers

About 1 year ago I was totally distraught with the life of the original HKS 700e carb rubbers and at about 100 hrs they were finished, now after almost 150hrs and installing your product they are
still going strong with no signs of perforations...so yes I am a happy camper !! Good products and I congratulate you on the development."

Many Thanks,
Paul Lintott
Owner:   Air Magic South Africa

Thank you for a great product. Fast shipping. Buyer:
johanngestur ( 56) Sep-08-09 03:26
ROTAX 912 & HKS Carburetor Socket Boot Bing & Mikuni H4 (#230359062145)

Great Seller,Great description,communication,packaging,shipping charges. Buyer:
jamesc9930 ( 25) Dec-13-09 09:14
ROTAX 912 & HKS Carburetor Socket Boot Bing 64 Carb JBM (#230396218810)
Acceptance Mark
Page updated 09/16/18
JBM Carburetor Flange Socket Boot of the "flange mounting type" to fit Rotax 912 or HKS engines.

  • This boot is made from a special long lasting rubber that will not age crack. This is made to replace the new type Rotax socket and has a metal flange embedded in the rubber. Our metal
    flange is steel and has a rubber sealing rib as well.  JBM Industries does NOT claim these are indestructible.

  • If you have had trouble with rapid age cracking or rubber pulling from the metal, or just want a less expensive Rubber Flange Socket made from exclusive TSR compound, JBM has your
    answer. The Rubber Flanges are made in the USA by JBM Industries and are NOT made by Rotax and not available from Rotax.  TSR is not stronger rubber, but better rubber.

  • These parts cannot be purchased from "Rotax only" dealers.

  • Rotax wants $112 each for this part. #267-787    JBM Price:  $76 each..........

  • This is not the short lived Chinese made part sold by others.

  • This socket is stiffer than the 70 durometer used on the HKS engine, as JBM uses 80 durometer .  ( Same hardness as Rotax )

  • This Flange Socket measures 75 mm hole centers, 29 mm high, and a 38 mm minimum diameter throat ( Smallest point ). Stud holes measure .350" diameter, but can easily be drilled out to
    .380" if needed.  Fits a Carburetor mounting spigot 1.675" diameter.

  • This socket fits Bing Model 64 CV type carburetors as used on Rotax 912 and HKS engines.

  • This socket is also a perfect fit for Mikuni H4 Carburetors.
This is the way the JBM part
looks as it comes out of the mold.
A finished JBM Rubber Flange Socket
replaces Rotax part # 267-787
Only $76 each
Email to ORDER: sales@jbmindustries.com
  • Some of the problems seen with sockets made by Rotax & others.
Please keep in mind some owners make horrible installations on their flange sockets and
carburetors. Engines sometimes shake
way too much, and can rip a perfectly good
rubber flange in two. Here we see various examples of rubber torn from the metal plate.
Failures of rubber flange carburetor sockets.
Click here to go to
NOTE:  JBM rubber flanges are made
only in
limited production. We are
often "sold out".
Click here to see Stainless Clamps
with inner liner.
Click here to see Stainless Clamps
$76 each
Order from: sales@jbmindustries.com