2 carb intake

I've seen them on CB750s. Anyone try this on an XJ? Is it possible or not?

 

I'm interested in the idea myself. If they can do it on a 750 Honda, I'm sure it's possible for the XJ750 or 650. Making the manifold would be the hardest part to fabricate I figure. Then figuring out what size carbs to use would be the next step. And there's the issue with the YICS ports, if they should be used or not, but that's not hard to block them off I guess.

 

i would also like to know this i was thinking four into one and puting the carb off of an older toyot and tuning it down some

 

It could most certainly be done, you'd have to design and build a manifold. Or two manifolds.

It will totally take the "edge" off your XJ's stellar performance. Guys frustrated beyond tears with the twin Amals on the Norton used to do a "Mikuni conversion" replacing them with a single Mikuni RS. Made the bike no fun anymore IMHO. Doing it to a 550 would be counterproductive.

YICS would be a concern. You'd have to pull the head and fill them with JB Weld or something, just blocking them would leave the rest of the passage into the port open still.

 

I'd have to disagree with the YICS ports having to be blocked off. Why? The pressure would be equal between them if you dialed in (synchronized) the carbs if you went with two carbs. And if you went as far as one carb, there would be no issues at all. All the ports would be running the same pressure anyways, so no need to block the ports.

 

umm im no carb expert but i figgured as long as there is the same fuel getting into the cylenders and the mixture is right why couldnt it be just as powerful as long as there is as much air and fuel as can be in the cylender the big bang should be the same like i said im not exspert by anymeans but im just looking at sym plicity one carb works 8 cyclenders on my mustang and its runin 12.9s

 

A couple of points that came to mind.

Some '60s and '70s muscle cars had ONE carburetor feeding EIGHT cylinders. One carb should be able to feed four smaller cylinders on a bike, yes?

On a similar note, General Motors had this neat thing called Throttle Body Injection. In other words, stick one big honking injector where the carburetor would normally sit.

Obviously I'm no mechanical engineer, which means I don't know diddly squat, but I'm just sayin'...

 

I looked in the plumbing section and found 1 1/4" PVC WYE. The runner length looks equal and smooth. I'm going to fit a couple of XS carbs and see how it works. The runner length might improve mixture velocity. As I understand it, the YICS evens out intake pressure.
If it works like crap I can always put on the stock carbs.

 

I think what'll happen is the droplets of gas will fall out of suspension and lay on the floor of the plastic intake manifold.
The V8 car intake is heated by exhaust under the carb, and heated by hot oil under the rest of it, also almost all V8 intakes are split in 2, not an open plenum.

Getting ALL of the jets right ( air bleeds, the size of the needle on the slider, the pilot system) would be a major challenge unless you copied the Honda 750 or Kawasaki 750 LTD.

 

i hyave a 90 model mustang converted to carb and mine runs fine when cold so there is nothing heating the intake the exhaust is wrapped so hardley anything heating there the only thing you should have to worry about would be the smoothness of the intake runner so i think pvc would be out of the question or you would have to rough it up somehow

 

I'll monkey with it until it works or I get bored with trying to make it work.
If you look at a WYE the 45 side is shorter but has a larger area so will intake more air/fuel. I could add baffles, rough up the bore. Experimenting is the fun of it.

 

thats the spirit
is PVC fuel-proof ?

 

Not sure for how long, but long enough to see how it works. They cost $2 each so if they work I'll make some out of copper.

 

I can hear ole Red Green saying....

'If you wife dont find you handsome, she should at least find you handy.'

or..'there aint nothing Duct tape cant fix.

 

I use Tuc tape now , way better and water proof.