Need help tuning a dual carbeurator

[brad sweet]

How would a homemade manometer be calibrated? Just curious. Its probably going to be something else..we havent herd and symptoms yet...

As far as carb sych, in the case of a small twin like that, I'd get a feeler gauge (about .020-.030 should be fine, I've heard of guys using a small diameter drill bit as well) and match each throttle blade to the size. Carb synch is mostly only relevant to about an 1/8th turn throttle opening.
You can make some adjustments after it's running if needed but it'll get you in the park and running a little quicker than making a tool that you may or may not know how to use.

Don't forget to turn your idle speed adjuster up or down a little. It'll be hard to start if too open and race when it does, or not start at all if idle is too low obviously.

Its probably sometime else..we haven't heard the symptoms yet..what is it doing and have you taken off the airbox?

 

[brad sweet]

http://www.iwt.com.au/mikunicarb.htm

this may help you out...but make sure all internals are cleaned first..and ignition/timing is good and set correctly..then apply this info

 

[brad sweet]

and if you have made any changes in the bike such as individual air pods no air box or exhaust up grades or baffle changes then the carbs will need to be tuned for those mods bigger jets needles and pilot jets...or bring it to me and i can get it real close

 

[logcabinman]

We used a manometer to tune SU carbs on my F Production TR3. However, you can use a piece of plastic tubing, lay it across the open air horn and adjust the carbs by sound. Go to you tube and enter "carb manometer".Lots of hits.

 

[galvatron]

First find a copy of the service manual. It will tell you how to set the linkage for base mechanical sync and which carb you use as the primary(yes, it does matter).
Then spend the coin on a sync tool, or bribe someone to use theirs.... See mine in pic below.
Then baseline your sync tool (overlooked far too often)
Connect tool
Then make your adjustments for sync
Simple.
Now you can beging tuning your carbs, swapping jets, etc., if need be.

 

[galvatron]

Start here for a manual if you dont have one. The CB200 one is pretty crappy ans sync isnt listed. May be in one of the basic manuals listed.

http://www.classiccycles.org/1852/1873.html

 

[Zombie Ninja]

Then baseline your sync tool (overlooked far too often)
THIS is the problem I see with the "homemade" synch tools. No air bleeds to calibrate the gauges. No one ever thinks about this. But admittedly, I never tried one.
Just use my motion pro like yours. Used to have a mercury sticks, but too many bumble f*cks don't know how to use them, and now I have blue sticks.
View attachment 798059

 

[logcabinman]

You can't use a mercury manometer for carbs, too heavy unless the column is very small. You use a float manometer, it is a small ball that floats on the vacuum caused by the venturi and air flow. Bit off subject but, SU carbs on a TR3 are not primary or secondary. You pick one and adjust the other to match. 3 X 2 Stromberg 97's are different(here is old age for you, who knows what a Stromberg 97 is?) Typically the center carb was primary and then adjusted all the others to it. Look at the Speedway web site-you order primary or secondary carbs. Choke went on primary. Yea, I'm almost as old as my Avatar!!

 

[tybo480]

Thanks for all the advice. Wow! Its a lot to take in. Im going to get some advice from a member on here tomorrow and see what i come up with. I have a few ideas now on how to proceed. Im going to be referencing this thread for a while!

 

[Zombie Ninja]

You can't use a mercury manometer for carbs, too heavy unless the column is very small. You use a float manometer, it is a small ball that floats on the vacuum caused by the venturi and air flow. Bit off subject but, SU carbs on a TR3 are not primary or secondary. You pick one and adjust the other to match. 3 X 2 Stromberg 97's are different(here is old age for you, who knows what a Stromberg 97 is?) Typically the center carb was primary and then adjusted all the others to it. Look at the Speedway web site-you order primary or secondary carbs. Choke went on primary. Yea, I'm almost as old as my Avatar!![/QUOTE
every bike shop, dealership, oem manufacturer and tech school I've ever been in use them. Used to at least, most I've seen lately have graduated to the digital versions.
I've used the needle gauge, the float style and Mercury sticks (now blue "manometer" fluid) and the sticks are my favorite. Float works well too. Old carbs are cool! Heard of those bergs but never touched one.
Most of the Japanese multi carb setups have a base carb as well.