carb balancing

[cobra407]

is there a port on the side of our carbs to balance them?

[Bob_Roller]

There is a vacuum port on the bottom of the carbs .

I'm only familiar with the bikes that had emissions plumbing on them, a small diameter hose comes off of the brass fitting at the end of the carb closest to the head, it was used to operate valves in the airbox, to allow air into the exhaust to clean up the emissions .

[Julio A.]

There is a small tube on the bottom side sealed with a small screw. That's the vacuum tube where you plug the synchronizer.

Just be careful in pulling out those screws especially if you are removing them after quite some time. They do tend to stick and the heads strip easily.

The removal of mine for the first time was quite eventful. Putting it back, I just used a rubber grommet, similar to the one used in the newer 1150 oilheads' injectors to plug up the holes.

[mfrias2nd]

FYI I had purchased a carb sync gauge and it was a pain to read. It was easier when I had the throttle down but just to sync the idles was a pain (maybe I wasn't doing it right) regardless. Check out this video http://www.youtube.com/watch?v=nEE508WzNC8&list=LLUZG9PKXR4jBctddr9FmZXA&index=19&feature=plpp_video
I did this and it worked GREAT!

[Barry]

The vacuum take off port is shown here sealed with a screw slightly larger than the diameter of the stub.

Note this is a RH carb. On the LH carb the vacuum take off and idle mixture screw positions are reversed.

[cobra407]

very helpful! thanks

[montmil]

FYI I had purchased a carb sync gauge and it was a pain to read. It was easier when I had the throttle down but just to sync the idles was a pain (maybe I wasn't doing it right) regardless. Check out this video http://www.youtube.com/watch?v=nEE508WzNC8&list=LLUZG9PKXR4jBctddr9FmZXA&index=19&feature=plpp_video
I did this and it worked GREAT!

Eight bucks? That's outrageous. I have less than three dollars in mine after scrounging around the shop.

I have found it best to set up the manometer test area first. My balance stick hangs from a ceiling hook. There's a large fan positioned and running in front of the bike -blowing air over the running engine. All needed tools are ready.

After a ride long enough to get the engine hot, and this may be 15-20 miles in cold weather or shorter during our Texas summers, the bike is ridden into position, vacuum tubes attached and the carb balancing act begins.

After this photo, I added 12-inches of a smaller diameter tubing to each side of the gauge to serve as restrictors. This  mod has slowed down the oil movement and provides a bit more time to study each tweak.

[bruce_launceston]

Hi Monte, on my version I took the tubes all the way to the top of my metric yard stick. It gives a bit of breathing space before the oil threatens to go 'over the top' and get sucked into the carb.
The oil in mine was steady right from the start, I used red Stihl two stroke oil. It's starting to fade to a light brown now but still pretty good contrast.
I wonder if just having more oil in the tube helps with the damping effect?

[Barry]

I wonder if just having more oil in the tube helps with the damping effect?

That's a deeper question than I first thought. I believe it would due to increased frictional losses on the longer length of fluid.

[montmil]

... I used red Stihl two stroke oil. It's starting to fade to a light brown now but still pretty good contrast.

Ha! I initially used some BMW fork oil. Cool purple color that also faded away to a brownish-yeck color.

Wish I could find some real metric meter 'yard' sticks. Would be a fun practical joke to slip one into my bud's workshop in place of his 36-incher.

[beemer]

FYI I had purchased a carb sync gauge and it was a pain to read. It was easier when I had the throttle down but just to sync the idles was a pain (maybe I wasn't doing it right) regardless. Check out this video http://www.youtube.com/watch?v=nEE508WzNC8&list=LLUZG9PKXR4jBctddr9FmZXA&index=19&feature=plpp_video
I did this and it worked GREAT!

How many revs are you using Mont when you balance the carbs?
Eight bucks? That's outrageous. I have less than three dollars in mine after scrounging around the shop.

I have found it best to set up the manometer test area first. My balance stick hangs from a ceiling hook. There's a large fan positioned and running in front of the bike -blowing air over the running engine. All needed tools are ready.

After a ride long enough to get the engine hot, and this may be 15-20 miles in cold weather or shorter during our Texas summers, the bike is ridden into position, vacuum tubes attached and the carb balancing act begins.

After this photo, I added 12-inches of a smaller diameter tubing to each side of the gauge to serve as restrictors. This  mod has slowed down the oil movement and provides a bit more time to study each tweak.

[leswaller]

I would like to sync the carbs on my R60/5 which is fitted with the early slider carbs. As far as I can tell there are no vacuum points that I can use as a balancing point. (unless someone knows different)
So, how can I balance them using a Gunson type balancer? Is it possible to easily fit vacuum take off nipples and if so can some one point me towards suitable kit. Also where in the system should I fit them.
Les

[montmil]

UhOh, Beemer. I just caught your question buried in the quote block.

I first balance my Bings at the idle revs I'm looking for. Around 1000 rpm seems to suit. Tweaking the mixture screws and finishing up with the throttle stop screws. A little back n' forth sometimes needed. Watch the fluid rise n' fall, then finally stabilize. A fun exercise, it is.

The second balance is to confirm that my throttle cables are actually opening the butterfly flapper dealies the same amount. For this balance, I'll use the throttle friction screw -located under the right-hand switch assembly- to establish and hold revs anywhere from 3500-4000 rpm.

Big Note: Keep the large fan blowing across the engine and do not linger too long with this procedure.

At idle revs, confirm suggested slack in the throttle cables -approx 2mm- then dial up the higher revs. Turn the threaded cable adjusters located topside on the Bings. Remove slack and/or add slack to get the manometer juice in balance. While doing this balance, all slack will be out of the cables since the twist grip is, well, twisted. Snug down the lock nuts when all is in equilibrium.

I seem to do quite a bit of top gear cruising in the 4K rev area. With the cables equally tugging the butterflies open, the engine is quite smooth.

I have an nice article lifted from my Airhead Beemer Club website. DIY ghetto-style manometer and carb balance drill. My favorite. My way. I'll try to find it and see if I can pdf. it for posting.

[EGRG]

Ok, down here in Mexico I only use latest BMW diagnostics tools.
Concur with Monte.
Also ten minute drive is not enough to heat engine properly. Take your time riding it.
AND USE A BIG FAN TO COOL ENGINE WHILE ADJUSTING IDLE.

and Have Fun

[montmil]

UhOh... Careful now, Victor. You are using the BMW corporate logo on your DIY manometer. Even though you're in Los Estados Unidos Mexicanos, those rat bastid Beemer lawyers will track you down.

I'd suggest you apply a very large BMW logo above your garage door just to tweak their noses. [smiley=bmw_smiley.gif]
Lookie me! Another illegal logo usage. [smiley=whistling.gif]