Rebuilding Bing Carbs

[Crossrodes]

I've been away for awhile and just got back to installing new floats, gaskets and O rings and cleaning my '79 Bing Flat Top Carbs.  So far everything is going well.

I just want to point out that the O rings on these carbs are in pitiful shape and if anyone out there has an R65 and they don't know the history re the Carbs and when they were rebuilt last I would highly recommend rebuilding them.  I hadn't had any problems with the carbs but I'm guessing that it would not have been long before they would have been giving me problems.

Just an FYI.

[Bob_Roller]

I'm on my third set of o-rings, gaskets and diaphragms on my '81 R65, this incessant desert heat really degrades the rubber in the seals and diaphragms .

Did you replace the o-rings on the throttle shaft ?

Those never get changed, a lot of owners are too scared to replace them .

[Crossrodes]

So far I have replaced the O Rings on one throttle shaft.  I have replaced all the O rings on the other carb except for that one.  It's not a big deal except for getting the screws on the butterfly loosened up.  Right now I've got the screws soaking in Liquid Wrench.  Hopefully I'll be able to remove them tomorrow and then remove the shaft to clean it up and replace the O Ring.

[Bob_Roller]

The screws are peened on the back side, usually you need to file off the bit of screw that protrudes through the throttle shaft to get them out .

[Crossrodes]

Goo tip Bob.  I'll try that tomorrow.

[stockman]

If you have a drill press you can take a screw driver bit slotted or Cross recessed (Philips) and put it in the chuck- adjust the table up high enough so you are only moving the chuck down a few inches- they apply downward pressure using the quill in your right hand ,and with your left hand rotate the chuck counter clockwise to keep the screw tip seated in the screw and you can usually back the screws out without damage.
This is of course given you can access the screws clearly. I used to work in electronics and the largest screw used was an 8-32. Most of the screws were 2-56 or 0-80's all slotted  flat head S.S. (MS-35249 for you mil spec folks) so they were always tough to get out especially after they were coated with epoxy paint. Try it works great.

[Crossrodes]

I'll try that too.  Thanks Stockman.

[caci]

There are 2 issues with replacing those shaft o-rings:

1)  You can easily strip the threads in the butterfly shaft, if the "burr" on the end of the screw is not sufficiently removed before backing it out.

2) It really is somewhat difficult to reinstall the butterfly and obtain proper, centered alignment with its bore.

The risk may outweigh the reward.

Been there, done that, have the t-shirt!

[Crossrodes]

Today I used my Ryobi circular cutting tool to grind away the burrs on the backs of the screws.  I then was able to get the screws out...no problem.  I've cleaned everything up, replaced the O-ring and re-installed everything.  Now another question:

I was wondering if it might be advisable to use blue loctite on these screws to prevent them from working loose?

[Rob Valdez 79 R65]

New screws, support the shaft, and peen them, again.

If a screw gets sucked into the combustion chamber, you will be "screwed".

[Bob_Roller]

I've used an 'automatic center-punch', it's spring loaded, when you press down on it, it clicks .

With the soft steel/iron that the screws are made from, they deform quite easily, without any risk of bending the throttle shaft .

[Crossrodes]

I have one of those automatic punches.  I'll use it tomorrow.