Carb sync

[Bill Conquest]

Hi everyone, Just had my carbs rebuilt on my '79 R65..can anyone explain the process of sync'ing them..I've never done it!
Thanks, Bill

[bruce_launceston]

This is not the guide I use but it might be what you need.
If I find the link to the one I have printed out in the garage I will post it as well.

http://rossmz.blogspot.com.au/2008/12/tuning-40mm-bing-cv-carburetors-for-bmw.html

[Lucky_Lou]

There is this in the Tech/FAQ section which is basicaly the same from our old friend Trolle
http://www.bmwr65.org/htdocs/yabbfiles/Attachments/Tuning_40mm_BING_CV_carburetors_for_BMW_motorcycles_by_ear.pdf
It is critical to have the engine fully warmed up so you may want to put a fan in front of the engine to give you more time.
The idle screws are usualy set about 3/4 turn open.
Lou

[bruce_launceston]

Okay Bill, it was easier to find my hard copy and scan it for you, I use these instructions with my home made manometer and they work fine.

[georgesgiralt]

Hello !
Here is what I've done after rebuilding my carbs :
First ensure valve clearance is set tip top.
Then set the carbs as per the manual (idle screw set just to contact the butterfly lever and screwed for the amount specified, mixture screw opened for the correct amount) this will ease start the bike.
Start the bike and synchronize idle and just above idle using the manometer you've got/made.
The engine should run quite well. It is safe to use on the road.
Go for a ride until the bike is hot.
Back at home, repeat the synch procedure and idle adjustments.
Go for a ride to pay yourself.

[Bill Conquest]

Thanks everyone for the great tips..this week-end I will have a go at it!

Bill

[Bill Conquest]

Just installed & sync"d my carbs after a rebuild and the bike runs nicely, has power  i'd forgotten about.. borrowed a friends vac manometer but does anyone know the home build way?

Thanks, Bill

[Barry]

Bill,

Here's a picture. It's just a length of tube secured to a vertical support and half filled with ATF. Mine is is a length a of slotted shelf mounting bracket. Many use a wooden yard stick which works well although graduations are unnecessary. None of the dimensions are critical as long as the tube is a good fit on the vacuum ports. You will need a good length of tube. I forget how long mine is something like 16ft - 20ft in total. Plenty of length helps to keep the tails away from the hot exhaust. If you made them long enough the manometer could be mounted on the garage wall and it wouldn't matter if one tail was longer than the other in order to reach the far side of the bike.  I have a red sleeve on one tube to remind me which side connects to the right carb.

[Bill Conquest]

Thanks, Barry..nice looking r65.. next question is where are the ports? My bike has 2 small holes with what looks like a plug in between in the front of the carb..
Thanks,Bill

[montmil]

... next question is where are the ports? My bike has 2 small holes with what looks like a plug in between in the front of the carb...

Look on the bottom of each carburetor. Spot the protruding stub/tube that is closed off by either a very small machine screw -don't misplace 'em- or a closed end rubber cap. Those are the vacuum take-off points.

[Barry]

Here's a pic top go with Monte's description. Vac port is the the small one nearest the outside. This is the RH carb.  on the LH carb the mixture screw and vac port locations are reversed.

If you are going to do a vac balance a good tip is to mark the basic 1/2 turn out setting with a dab of red paint.  This gives you a good reference to return to if you get lost. The Red mark is just about visible in the pic. My finished mixture setting is a little less than 1/2 a turn out and the red mark tells me by how much.

[Bill Conquest]

Thanks a lot, guys..I see 'em nowand will give it a go tomorrow. Good tip on marking the mix screw, Barry.
Bill

[wa1udg]

AS I recall, the "California" emissions bikes sold all throught the US with the pipe from air cleaner to a port above the exhause valve have a vac line from each carb which runs into the actuation system in the air cleaner assembly.  Many have removed the pipe and plugged the air cleaner and cylinder head connection but left the hose and valve assembly in the air cleaner.  There is a line to each carb, thus a good place to hook to.  

[Semper Gumby]

I know this is madness but I replaced my throttle cables two weeks ago. Mine is the round resevoir type of throttle brake assembly that has the two throttle cables up on the handle bar.  Since my bike was running nicely before I started I just put on the new cables and then I matched the amount of exposed cable at the top of the throttle cable between each of the two cables by twisting the adjuster down on each carb. After re-assembling the the throttle, I made sure I still had some free-play in the cables at the carbs.

It ran good enough that I didn't even throw the twinmax on it.  I guess I'm just getting lazy...