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xs650 > > High Performance Modifications > > Top End Work > > Constant Carb Equalization |
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Constant Carb Equalization
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81XSChopper 650Rider Supporter
Joined: Sep 01, 2007 Posts: 48 Location: Houston, TX
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Posted: November 11, 2007, 1:31 am Post subject: Constant Carb Equalization |
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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.
y 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.
aybe 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
_________________ Bike History: Vespa 150, 200; Honda CL175; Honda CB350; Yamaha XS650 stock (4) XS650 Bobber; Honda Magna; Kaw GPZ550; 59 panhead; XL chopped. Current Rides: Yamaha 81XS650H Cchopper; 75 Honda CB750 bobber; 78 CB 750F Stock |
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xsjohn Full Member
Joined: Jul 30, 2006 Posts: 5857 Location: North Carolina USSA
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Posted: November 11, 2007, 12:05 pm Post subject: Re: Constant Carb Equalization |
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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
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royfisk Full Member
Joined: May 24, 2006 Posts: 1597 Location: winchester, new hampshire usa
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Posted: November 11, 2007, 5:31 pm Post subject: Re: Constant Carb Equalization |
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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.
_________________ build them , ride them, tear them down, rebuild them, ride them, etc. etc. etc.. They only get better and better |
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grizld1 Full Member
Joined: Jun 20, 2005 Posts: 594 Location: Carbondale, IL
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Posted: November 11, 2007, 8:29 pm Post subject: Re: Constant Carb Equalization |
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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).
_________________ It ain't whatcha got, it's whatcha can get to the ground! |
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81XSChopper 650Rider Supporter
Joined: Sep 01, 2007 Posts: 48 Location: Houston, TX
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Posted: November 11, 2007, 8:59 pm Post subject: Re: Constant Carb Equalization |
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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.
y 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
_________________ Bike History: Vespa 150, 200; Honda CL175; Honda CB350; Yamaha XS650 stock (4) XS650 Bobber; Honda Magna; Kaw GPZ550; 59 panhead; XL chopped. Current Rides: Yamaha 81XS650H Cchopper; 75 Honda CB750 bobber; 78 CB 750F Stock |
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beatpoet Full Member
Joined: Jan 05, 2008 Posts: 33
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Posted: May 25, 2008, 3:44 pm Post subject: Re: Constant Carb Equalization |
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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.
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xsleo Full Member
Joined: Oct 28, 2007 Posts: 1528 Location: Earlville NY
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Posted: May 26, 2008, 12:02 am Post subject: Re: Constant Carb Equalization |
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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.
_________________ "You live more in five minutes on a bike than most people do in there whole life"
'75 XS650B with a 79 dual disc front end, rear disk brake, Chrysler reg, Radio Shack rect, LED tail/ brake and turn signals. |
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