carb sink ?

[Reed]

what is the base number of vackum when sinking the carbs? mine is about 24 that seams low.using mercury sticks.

Are the tubes with the mercury in them supose to be steady or do they move up & down ?

[pegscraper]

I couldn't tell you what the absolute number is. My mercury sticks aren't marked with numbers.

 

The mercury may bounce a little, but it should be pretty steady. Are you sure the restrictors are in the lines? Or maybe you need to make some new restrictors with smaller orifices in them.

[Marcarl]

Numbers don't matter a whole lot, what's important is that they are all the same, and yes the sticks will wiggle a little, but if it's too much so you can't get a good read, you need to restrict the lines.

[Squeeze]

the Base Value is 200 mm Hg.

[KiteSquid]

The Yamaha factory service manual (which is free to download from this site) on page 2-9 states Intake vacuum 37 kPa (280 mmHg) at an Engine idle speed of 950 - 1,050 r/min

 

 

The procedure for synchronizing the carburetors starts on page 3-14 HOWEVER I understand that carburetor one and two are backwards in the writeup.

 

 

There is a note on page 3-15 that is important

 

The difference in vacuum pressure between two carburetors should not exceed 1.33 kPa

(10.0 mmHg, 0.4 inHg).

[Squeeze]

The Manual for the XVZ13DA© states 33.3 kpa(250mm Hg) at 950 to1050 RpM on Page 2-14.

 

 

But actually, i've never seeen such high Vacuum Amounts on the Bikes i worked on. Usual Value is around 260 kPa which equates to around 200mm Hg. The Value isn't inportant, as long it is in somewhere in that Ball Parl. Unison is the Key Word.

[T.J.]

I just did mine again last week. When the carbs are out of sink the sticks will be moving all over the place. You won't believe the difference when in tune. Very slight movement at a steady RPM.

 

Be patient and just move the screws a little at a time.