Updated  10/26/22
Yamaha Teikei YDLS XT350 & SRX 250 Carburetor Diaphragm installation instructions for JBM Industries replacement diaphragms.
Parts for these vintage TK motorcycle carburetors are hard to find, and if you need a new diaphragm, you have found a source right here. Great to have as spares as they
are light and easy to carry along with you. Easy to install, even on the road or trail.  Also fits Mikuni BS30 & 28 used on some YX600 & FZ600 & XJ550.  
63mm outer groove diameter.     Yamaha Duo Intake System  ( YDIS )     NOTE:  Some Tekei TK have a 68 mm OD diaphragm and can use our H-68
To install these diaphragms you must first cut off any plastic or metal retaining rings using
side cutters. Cut is several places and twist the cutters on metal rings.
Be sure there are no sharp edges and install as shown. Rubber has very little
stretch, and the central hole in diaphragm is slightly smaller than the slide.
POSITION on engine side of slide:
This Yamaha YDLS carburetor has two barrels,
one working mechanically , and the other opened
by vacuum. CV type carburetors allow the use of
very large carburetors, as they will only open as
much as the air drawn in will allow. As revolutions
increase, the slide will open to prevent stumble or
cutting-out. Yamaha single cylinder.
Click here for "How to measure" page.
Click here for "How to order" page.
Click here for "JBM Home Page"
Click here for "About us" page.
Teikei Carburetor YDLS

HISTORICAL DATA: Teikei Carburetor

May 1953 Established as TK Engineering Co.,Ltd. in Koromo City(today's Toyota City) with a capital of 5million yen.  
June 1956 The corporate name was changed to TK Carburettor Co.,Ltd.
April 1957 The capital was increased to 14.8million yen.
October 1957 The Main Office and Factory were relocated to the present address of 5-10,Kotobuki-cho,Toyota City.A new plant was completed for
integrated production from die casting to assembly.
April 1958 The capital was increased to 20million yen.
January 1960 A precision machine tool division was established,commencing the production and sales of precision automatic lathes and single-purpose
speed lathe.
November 1961 The Capital was increased to 40million yen.
April 1962 Developed a hydraulic automatic screwing machine,and commenced its production and sales.
May 1962 Commenced mass-production of“Duracon” cocks and other types of greaseless gas cocks.
June 1965 The corporate name was changed to Teikei Carburettor Co.,Ltd. for the Japanese market. For the foreign market,“TK Carburettor Co.,Ltd.”has
continued to be used.
February 1967 Completed the Asuke Plant intended exclusively for the assembly of fuel cocks and gas cocks.
February 1969 Completed the Asahi Plant intended exclusively for the assembly of fuel cocks.
July 1969 Completed the Second Main Factory.
June 1970 Developed a small-sized automotive diaphragm carburetor,there by succeeding in its domestic production.
June 1973 Commenced the mass-production of automotive PCV valves.
June 1974 Completed the Inabu Plant intended execlusively for the production of carburetors.
June 1975 Commenced the mass-production of automotive fuel pumps.
April 1977 Completed the expansion of the Main Factory.
September 1978 Integrated the Asuke Plant into the Head Office and the Asahi Plant into the Inabu Plant for rationalization of production.
September 1981 Won the PM Exellent Buisiness Sile Award.
November 1981 The capital was increased to 72 million yen.
August 1993 Commenced the production of resin PCV valves.
September 1994 Entered into a contract with Yamaha Motor Co.,LTD.regarding establishing a joint venture corporation for production and sales of two-
wheeled vehicle carburetors in China.
December 2001 Certificated ISO 9001  
October 2003 Certificated ISO 14001
August 2005 Established TK Carburettor(Ningbo)Co.,Ltd.in Ningbo,Zhejiang,China.
April 2010 The Capital of TK Carburettor(Ningbo)Co,Ltd. was increased to 210 million dollars.

Dear Mr. James,
at first i`ve to thank you so much for the quick delivery.
When i get them i started mounting immediately.
It was so easy i couldn't`t believe it.
After a year of only 75% power, my Yammy ist full reloaded again.
What do you mention for the lifetime of the diaphragm?
Is it reinforced with  seals like the original?
Wish you a good time, health and luck

A.Israel,    Germany

Hi Don,
I just put the new diaphragm in today and it works Great!  Smoothness and throttle response is greatly improved, and there is no longer an abrupt chop in power when rolling off
the throttle like there used to be. My only problem now is that my clutch has started slipping from all the extra torque!  Thank you very much for you're help - I'll try my best to get
the word out that these are available.
Kevin Haas

Hey, I just wanted to message you and let you know this diaphragm works perfect with my 1987 Yamaha SRX 250. Also has YDLS carb.

Thanks for quick delivery.
I have mounted the diaphragm`s on my bike and they work perfect.
Thanks very much!
Kjell Zanders

I just received the (Yamaha YDLS)diaphragms I ordered on 6-7-13.
All I can say is wow! What a great product!
It's a shame that only you and I will be the only ones to see it.
The fitment and quality is perfect.
Thanks for the quick shipping and excellent product!
Greg White
Schenectady NY

    I am using these on Mikuni BS30 carbs that are typically found on Yamaha YX600 1986-1990.  I installed all four (T-63)of the diaphragms I got from you this past weekend.
They do fit, though the "tire" is a millimeter or two thicker than what I would think would be ideal, though I don't see any issues. The I.D.is a bit snug, no glue needed. The original
nylon and metal rings were cut off as per your instructions. The O.D.is spot on.
    The Mikuni BS30 was apparently used on a few different models of varying displacements by multiple manufacturers. As far as the OE part number goes for my specific model,
it is listed by Yamaha as "obsolete" and was used on the 1986-1990 YX600 as well as the 1986-1989 FZ600.   Robert Himmelstoss:   rob.himmelstoss@gmail.com

    Hi Don,
Just a quick follow up, have a look at the link below... it seems that the T-63 fits perfectly to the Mikuni BS-28  for XJ550R.
Thanks    http://www.caferacer.net/forum/technical/23709-yamaha-xj550-diaphragm-replacement-tutorial-mikuni-bs-28-a.html
Raviv Cohen    ravivos.c@gmail.com      ISRAEL     
This TK-63 Diaphragm can be also used on a Mikuni BS-28  as shown by the following link:
Hi Don,
I received the H68 diaphragms and they fit the
Tekei 28mm carb on the Yamaha SRX400
Thanks for the help.
Regards, Mick