Carb rubbers - Same old story...with a twist

[Athedra]

Spoke to a guy today who mentioned the following:

You take your old rubbers and grind them off just before the aluminum base. The way I understood is that the aluminum base has a piece of pipe attached to it going into the rubber. You then clean it of to almost against the pipe. Make a groove for an O-ring, then use normal Suzuki round Carb rubbers on there.

Everything sounds good, but here is my questions that you guys can maybe answer:

1) Does the distance from carb to head play a part in the gas atomization?
2) If it does play a part, would it improve atomization or decrease it?
3) How far does the Aluminum pipe attached to the base come out?
4) Anyone heard or tried something like this?

[Rasputin]

What you talking about Abbott?

[81xsproject]

I think pggg did something like this with radiator hose. The distance makes a difference in intake scavenging. Shorter intakes make for better top end and vice versa. IIRC

[The Lorax]

I read a thing about that in cycle world or something a couple years ago maybe. when Yamaha re designed the R1, they went back to a 16 valve head, gave it throttle by wire and had some kind of variable intake length contraption on there, it was all controlled by the ecm if I remember correctly, they spoke of it as though it was the greatest thing since sliced bread. I'm guessing that (on our machines anyway) unless everything on the bike is in absolute perfect tune all throughout the RPM range, changing the intake length will do little more than give you a psychological boost, if even that. anyone feel free to correct me if I am mistaken (it happens alot, so I won't be offended), but given the age and the advances in tech that have occurred since ours were new, that I don't think it will make much difference either way, have a nice day and ride safe

[Crazcnuk]

I would think that longer would be better for top end, much like the old highrise manifolds, and tunnel rams.

The longer intake runner allows more time from the carb to the cylinders. tunnel rams were used for 6000+ rpm engines.

Shorter may not give adequate atomization time, but I think the big thing would be too much engine heat moving the carbs close to the engine.

I doubt a 1/4" either way would make any noticeable difference.

[motoman]

Yeppers Lorax, new V-Max has variable venturis.

[81xsproject]

I have heard the old high-rise argument before. If that is true then Yamaha has it wrong on both the R1 and the new V-max. At a certain Top end RPM a solenoid, activated by the ECU, detaches an extent of the intake track, thereby shortening the intake for better top end.

A LONG time ago, I posted a link or something with a long read on variable intake and exhausts and relative performance gains. I'll see if I can dredge it up again.

[Athedra]

LMAO, not really the answers I was looking for, but gave me a fairly good idea as to an answer to my question.

I basically just wanted to know if it is possible, and how important the carb to head distance is.

But thank you for the answers.

[mxmikie]

so i should put a tunnel ram on my xs ????? and scrap this set up http://rides.webshots.com/album/5758...ey?vhost=rides

[CatatonicBug]

As I have never taken the rubbers off the engine on my bike, I'm a little confused... Is there any aluminum involved in any of this? I thought the rubbers were solid rubber rings with 2 layers for the "tube" area. The engine is just a flat area with 2 mounting holes for the bolts that hold the rubbers onto the engine case with a flat mating surface. I was not aware of any aluminum in the rubbers or as a protrusion out of the engine case. Am I wrong on this?

[Ivan]

Of course there is aluminum. Have you ever tried to torque a bolt down on soft rubber like that? If there wasn't aluminum, then the bolts that hold the boots to the head,would just pull through the holes.

As for the variable intake setup, I don't think it would matter much for our scoots, since they have a relatively "rounded out" tuning already. A very peaky engine will do well with a variable runner. I think these XS's would do better with something like the ExUP system that Yamaha had, that varied the exhaust tuning based on RPM. Seems that the XS is much more picky about exhaust than intake.

It would be cool to have a big tunnel ram setup with a couple Holleys on either side of the tank though.

[CatatonicBug]

Of course there is aluminum. Have you ever tried to torque a bolt down on soft rubber like that? If there wasn't aluminum, then the bolts that hold the boots to the head,would just pull through the holes.

Good point. I didn't think of that...