Constant Carb Equalization

81XSChopper · Posted: November 11, 2007, 1:31 am Post subject: Constant Carb Equalization

I am going to throw this out because it's a solution that twice has made different Xs's run better & I don't recall hearing about it on any board.

On an old 80 XS with stock CV carbs, even after synchronizing them, they did not run perfect. Part of the reason was lower compression on one cylinder. But one day on a lark I ran some tubing to connect both barbs on each carb and found that it ran noticeably smoother. My theory at that time was that the tubing acted as a vacuum equalizer between both carbs.

My latest ride has the first Mikuni flatsides in a custom frame that didn't really allow me much room to reach the left carb equalization barb after install. So again I ran a piece of fuel line from the hard to reach area. Then I use a piece of plastic tube to join it to the carb synchronizer when synching carbs. After I'm done I simply attach that tube onto the other more accessible barb. I did this so I wouldn't have to take the carbs out of the holder every time I wanted to do a synch, but I've notice an added bonus that once again it has helped my bike run better.

Maybe this is an old time thing I've just not heard about, but it does seem to improve the balance & performance of the carbs. I'd be interested in any opinions. I'm providing some fuzzy photos in case my rhetoric is even more unclear...

greg

xsjohn · Posted: November 11, 2007, 12:05 pm Post subject: Re: Constant Carb Equalization

Greg......if I understand this correctly you are connecting the two vacume barbs together....this may be making it lean because the active side woud draw air form the inactive side.....then visa versa when the other cylinder is active.....maybe I didn't understand what you are doing....?

Could use the macro button on the camera for close ups so it wil focus.....

John

royfisk · Posted: November 11, 2007, 5:31 pm Post subject: Re: Constant Carb Equalization

This may be working good on engines that are not tunned correctly. These barbs are designed for putting on vaccume gauges and measureing the vaccume from each port so that the carburator can be correctly tunned for each cylinder. If one cylinder is low on compression slightly that carburator will need to be adjusted to compensate for the weak cylinder. If your running both vacume barbs together then both carbs will be running the exact sane and your not gwtting top performance available for what you have. What is happenning is the extra vaccume is richening the weaker cylinder and leaning the better cylinder. If the engine is excessively worn on one cylinder you may find a nice hole in the good cylinder at some point.

grizld1 · Posted: November 11, 2007, 8:29 pm Post subject: Re: Constant Carb Equalization

The 256-series engines (XS1-TX650) were set up with a balance tube between the intake ports, Greg. What John and Roy have pointed out may have had a lot to do with why Yamaha eliminated the tube on the 447 engines (TX650A to close of production).

81XSChopper · Posted: November 11, 2007, 8:59 pm Post subject: Re: Constant Carb Equalization

Hmm, I did notice that with a tube connecting the barb on both carbs that the bike may have lost a tad of zip, but I'll watch the plugs carfeully to see how running this way affects them. I may have babbled a bit too much in my original post. My old bike had a low compression on one cylinder. My new bike is fine & actually runs very well without the connected barbs. I simply noticed that it seems to run a bit smoother with them connected.

My apologies for the fuzzy photos. I have a great wide angle lens on my Nikon slr -- but it works like crap on closeups. have been too cheap to buy another lens.

Some interesting theories. I did not know why Yamy discontinued the equalizer tube on the old bikes. Thanks for the input.

greg

beatpoet · Full Member Joined: Jan 05, 2008 Posts: 33

I think my friend's '68 Triumph Bonnie was set up the same way..

The two carbs had an equalizer 'H' on both the fuel line and the intake boots.

xsleo · Posted: May 26, 2008, 12:02 am Post subject: Re: Constant Carb Equalization

as far as fuzzy pics go i am amazed at the quality of the pics from my $85 h-p digital camera from wally world. the close up feature works very well, and getting them in the computer is a snap. getting the from there into here is where i have trouble.

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