Carb upgrade?

[Luddite]

All,
First, thanks for the insight. This site (and the people on it) is fantastic.
Well I disconnected the enrichers and no change; but isn't that the essence of troubleshooting, i.e. "Find out what it ain't?" When I rebuilt the carbs, by the way, I did NOT replace the enrichers "O" ring...
I pulled the carbs and they look O.K, gonna re-clean and pay particular attention to the idle circuit...and I replaced all the fuel lines.....
Lastly, anyone done the throttle shaft o rings? Is it really that bad?
I'll keep you posted...

[mrclubike]

The shaft O ring aren't bad to change but you should use  new screws so you can peen them over.

[montmil]

I've gone through several Bing CV carbs and have never changed out the butterfly shaft O-rings. It's the danger during the peening of the screws that can become problematic. The carb must be secured in such a way as to provide some sort of anvil on the back side of the shaft prior to that correctly applied, single whack to lock each screw. The potential of even a minute bend in the shaft, or damage to those new O-rings, could lead to shaft/butterfly binding and serious emotional trauma.

In this situation, I'm a subscriber to the if'n it ain't broke, don't fix it school of thought. When I can't detect any metal-to-metal contact nor see a bit of shattered rubber O-ring dangling, I'm good to go.

Just my thoughts based on my limited experience.

[Mike V]

Luddite,

Re: Throttle Shaft o-ring Replacement ...

It's not a terribly difficult job.  Take your time. Make notes and sketches how things come apart or take detailed photos.  Do one carb at a time and organize all your parts.

Yes, new screws.  I'll share my procedure and photos with you keeping in mind others may have a different procedure.

To remove the screws I use a Dremel Tool to carefully grind the exposed threads down.  Careful to collect all chips and debris. But first select a correct sized and well conditioned screwdriver to loosen the existing screws on the shaft only an eighth of a turn or so to make sure they are not seized. Don't apply too much downward pressure on the shaft while trying to loosen the screws without a support.  Don't be ham-fisted on these parts.  Be SURE to make index marks on the butterfly and shaft before you remove them so you can reinstall them correctly.  The butterfly edges are precisely chamfered to fit the interior radius of the venturi while closed. (closely inspect everything during disassembly with an intuitive approach if this is your first time).  Remove the shaft and pay attention to which radial boss the o-ring goes on, there are two grooves. The outboard groove is a guide slot.

I like to clean the shaft with a little light oil and 000 steel wool.  Make sure everything is clean including your work area.

Install the new o-ring with a very slight and light smear of Silicone grease, you may need to tape the end of the shaft in a tapered manner to get the new o-ring installed in the proper place.

Here's the important part - before repositioning the butterfly and securing it with the new screws attach the mechanism at the end of the shaft on the carb.  This positions the shaft correctly laterally.  Then wiggle the butterfly around and fiddling with the shaft until it fits perfectly in the walls of the carb with NO daylight peeking through around the edges.  Now with just a touch of Locktite Blue install and secure the new screws constantly checking no daylight peeks through the perimeter of the butterfly.  Secure the screws - DON'T over tighten.

I've NEVER peened the shaft screws.  Personally I don't like using a hammer regardless of size, on soft precision parts.  I've always taken a pair of needle-nosed pliars and slightly marred the exposed threads of the new screws. The idea here is to keep the screws from working loose and being ingested into the combustion chamber.  Highly unlikely but an important precautionary procedure.  I'll attach a few links of one of my rebuilds for some pictures - hope they help.

If your shaft O-rings are damaged and pulling in air while not sealing ... you will notice a much improved situation in performance and responsiveness with the rebuild.

Good luck, it ain't brain surgery but easier than you may think.

http://s428.photobucket.com/user/gruntyman66/library/81%20R650%20Restoration/Bing%20Carb%20Left

http://s428.photobucket.com/user/gruntyman66/library/81%20R650%20Restoration/Bing%20Carb%20Right

Flat-Tops

http://s428.photobucket.com/user/gruntyman66/library/Bing%2064-32-223%20Lt%20Flat%20Top

http://s428.photobucket.com/user/gruntyman66/library/Bing%2064-32-224%20Rt%20Flat%20Top


-Mike V.

[Luddite]

I am all about avoiding serious emotional trauma! There is nothing ( no play around the shaft, no pieces of o ring
found, etc.) that indicates that this may be a problem, but the advice is great. I'm figuring out my options. I have lots of stuff to check (and recheck). I never seem to get things right the first time (ask my first  wife....) gonna get busy cleaning...

[Luddite]

Oh, and I tried re-engaging with my BMW guy who was dissin' flat top Bings. He's on vacation. Wait till I get my hands on him...

[wilcom]

Flat top performance:

One year it was my turn to map out the yearly ride. I marked every high pass in Colorado and connected the dots and that was our September ride. We left California at about 1000 feet elevation and made the ride. Most of the time in Colorado we were at above 6500 feet and the passes were up to 14,000 feet(as I remember).

The flat tops never missed a beat, never chugged , never coughed, never failed to fire up in the morning.

How do you improve on that?

[Mike V]

I am all about avoiding serious emotional trauma! There is nothing ( no play around the shaft, no pieces of o ringfound, etc.) that indicates that this may be a problem, but the advice is great. I'm figuring out my options. I have lots of stuff to check (and recheck). I never seem to get things right the first time (ask my firstwife....) gonna get busy cleaning...  

Luddite,
I had to chuckle at your reply Luddite.  This is not a traumatic operation.  Changing a diode board in 100° heat in the middle of Kansas on an RS while on the road ... that's what I consider traumatic.

Anyway - I appreciate your reluctance.  A quick test on a failing throttle shaft o-ring is to spray some Brake Cleaner at the shaft ends while the bike is idling.  If the idle speed changes while doing this you have defective O-rings.  

You won't notice any play in the shaft due to a defective o-ring. The o-ring does not act as a shim as the machined end of the shaft is a precision fit into the carb body. If you decide to go ahead with the shaft o-ring job, let us know.  We can walk you through it.  We're here to help and allow you support whichever direction you decide to go.

Joe W (Wilcom) - great response about the Flat Tops ... +1!

[Bob_Roller]

I've replaced the o-rings on all 6 of my R65 carbs .
Not difficult at all .
But, I did have two that refused to come out even after removing the peened end of the screw .
I stripped the threads on two throttle shafts, they cost about $15 US at the time .
To peen the new screws, I used an automatic center punch, it's a spring loaded center punch, just push down on it and it will peen the screw without risking bending the throttle shaft, took about 25-30 cycles to get the screw peened properly .

[Motu]

Here's my carb upgrade - 34mm Blue Magnums....well, ones a 34, the other is a 30 bored out.  I used them on a Yamaha XS1, and are supposed to go on another XS650, but thought I'd see how flat slides went on the R65.  They went well enough, but never got them fully sorted.  I'll need air filters, the ones I had on them have gone on the TLR200 and Stornello 160.

[wilcom]

I used an automatic center punch

To peen the new screws, I used an automatic center punch, it's a spring loaded center punch, just push down on it and it will peen the screw without risking bending the throttle shaft, took about 25-30 cycles to get the screw peened properly .

Great tool Bob............I am apprehensive when I draw back with a hammer and direct a "killing blow" at my lil carbie

[Luddite]

All: Been awhile, I've been busy spending you tax money but managed some bike stuff in between. I went BACK through the carbs, paying particular attention to the idle circuit and also went back to the stock main jets, more to baseline than anything else....
I  read elsewhere on the site (re idle adjustment) that a guy had gone out a turn and a quarter on the mixture screw, so I gave it a shot and it worked! The bogging down (especially when cold) is gone, pretty much. I still don't have 'em dialed in quite right. I will synch them up, etc. when I get a chance. Still seems like a lot of turns....
I read with interest about having to use the choke even when it's ( the ambient temp) is warm. I'm doing the full choke a start up, back to around 1300 RPM and then off after a few miles.....I guess this is pretty normal?
Thanks to all; you guys are awesome.

[Mike V]

Luddite,

Bing baseline settings.  Find your particular carb number.  The highlighted row is for my specific carbs.

[Barry]

Luddite,

Looking at Mike's list reminded me that your carb 64/32/203 will have the early version of the enricher disk. I'm assuming that's what 831 vs 861 means.  Anyway if you look at the disk and compare it to this pic you will probably find, if it's not already been done, that the smallest of the fuel holes has not been drilled.  If so I can recommend either replacing the disks with the later part or carrying out the mods on the attached service bulletin.  The need for this mods is perhaps one justifiable criticism of the early  flat tops.

If your enrichers work well then the mods may already have been done.