Lefty1998 tutorial on using an aftermarket carb diaphragm on the VTX 1300

http://www.vtxoa.com/forums/7-vtx-1300-riders-board/346513-diaphragm-replacement-vtx-1300-s-

cheap.html#post3705097

Diaphragm Replacement VTX 1300 S cheap to $$$

I have had to replace the Diaphragm of the Carb on my Honda 2003 VTX 1300 S. This is a Keihin VE7BA carb.

The Diaphragm measures 72 mm on the outside, and the Metal Piston is 34 mm.

THREE Ways to fix.

1- Use some HONDABOND (Honda CAR Shops) that will stand up to Gas & Oil, that contains XYLENE (Do this

with the Garage door open) Spread a Thin Layer across the cracks/holes, and let dry over-night. (put some on

Both Sides) You May Not have to remove the diaphragm from the piston to do this. ( Permatex Grey Seal will

not stand up to gasoline. ) About $9.00

2. After Removing the Piston/Diaphragm from the carburator, and maybe removing the needle, pull the

diaphragm down to expose

the Black Plastic ring. Note where the 'tab' in the outer edge if the diaphragm is. Carefully with a Small Drill cut

a narrow slot in the black plastic ring, and then remove the Black ring and diaphragm

from the piston. Leave the RED ring in place. From JBM Industries get a replacement Diaphragm. The one for

this bike is a K-72. Costs $20.00 + s/h Place a Ring of Epoxy ABOVE the Red Plastic Ring, and then stretch the

new diaphragm around the piston into place. (remember the 'tab' on the outer edge & where it goes)

You can then turn the piston upside down and press the new diaphragm all the way on. Wipe off any excess

epoxy. Be Sure Not to bite/cut the diaphragm.

Let the epoxy set over-night and your done.

3. Buy a New Piston/Diaphragm. Honda Part 16111-MEA-671 $75 each from Bike Bandit.

This bike only needs one. See the pictures and decide for yourself.

$68 + s/h fromPartzilla.com #22 PISTON, VACUUM 16111-MEA-671 $89.11 $68.66 1/27/2016

$62+ s/h from hondapartshouse.com 6/15/2017

Thank You Lefty1998

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PDF by Hans 6/15/2018 186

Note: Slide valve is Moly coated, probably explains the cost

Notes from 6/7/2018 186,138 miles

https://www.vtxoa.com/forums/61-maintenance-accessory-log/291220-2005-vtx-1300c-2.html#post4532042

I installed the JBM Industries slide valve diaphragm based on "Lefty" method.

The K-72 was to fit the slide leaving the red ring in place.

I did not like it sitting on the groove with the rolled edge/flange/rim holding it in place with glue/epoxy.

I cut the red ring, the diaphragm hole is 4mm thick and fits the 4mm groove.

I built up the groove to give it a larger OD to center the diaphragm. It is working as expected.

Revision to doc 2/21/2020 195,423 miles (9,285 miles)

I ordered the K-72 diaphragm(tire) and noticed it would sit above the red ring, on top of the groove and on the thin ridge

above the groove. I really did not like that so I removed the Red ring and the tire fit in the groove except the tire ID

was the same as the slide valve OD. I epoxied a thin metal strip in the groove to make the groove diameter larger. This

allowed the tire to be in the groove and centered. I verified the slide valve “butterfly notch”, diaphragm vacuum port and

probably used the epoxy to fasten the parts together.

I went back and looked at the JBM products and the K-72S had the smaller ID that was made for the VTX slide valve.

In the future the K-72-S diaphragm will be ordered and installed, adhesive only and the o-ring.

I did add a 1/8" o-ring to replace the red ring in reference to the body length.

The red ring set the stop point from what I could see so the o-ring now has that job

Pictures of my slide valve

NOTE: Only plastic slide needs glue per JBM. I used glue because of a loose fit.

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New info from thread:

https://www.vtxoa.com/threads/hose-replacement-oem-vs-parts-store.467392/post-4628909

Earl Riviere mentioned>> If you want, you could replace just the rubber diaphragm only, with this, It says for Harley but

will fit your carb;Twin Power Keihin CV Carb Vacuum Piston Diaphram 27690 | eBay

https://www.ebay.com/itm/Twin-Power-Keihin-CV-Carb-Vacuum-Piston-Diaphram-27690/303429892165?_

I know the HD slide valve is different and I cannot see how thick the center of the diaphragm is.. It may work with the red

ring??? $10 - $20

Some of the links that showed up also had the slide valve diaphragm and accelerator pump diaphragm in a rebuild kit.

Just adding this, I have no knowledge if it works or not……………Hans

07Blackcherry found a video of Keihin carbs with similar slide valve being fitted with JBM Industries diaphragm.

https://youtu.be/6zK_69809dc