Ironhead super b overflow

[Ferrous Head]

I have run an open velocity stack on my sidecar for years and never had a problem. I think if you look at Leo Payne's Turnip Eater you'll see he ran one too. And Rayborn went 246 MPH with an open bell mouth.
I do know that still air boxes do improve JP. Used to use them on my Kawasaki Superbike.
And S&S did move the air bleed from left to right side between the GAL and the MGAL but I'm not sure that was related to venturi effect problems with the bleed.

I asked about the gasket change and jet changes as something appears to be pressurizing the inside of the carb to force fuel out the sir bleed. I think this is why a few people are thing it's reversion.
But if it's reversion it would be possible to see this with the bike sitting still. Att whatever revs the reversion happens it will happen in any gear r even in neutral.

I do not believe that if your under4000 in top gear your going fast enough to have any effect on the carburetors functional ability.
In the lower gears you may be going through the rev range where yjr msain jet kicks in too quickly to notice that it's happening ?

The pickup tube was damaged and had to be replaced.

That makes me wonder.

At around 3000-3500 both the intermediate and main jets are working. This often causes a too rich area in the A/F ratio. But can't see how exactly that would relate to the problem.

i had bought an aftermarket rebuild kit that need some massaging to properly function.

So the discharge tube was replaced as well ?

I would pull the discharge tube and examine it carefully. The air bleed feeds into the chamber surrounding the atomizer section of the discharge tube. Fuel should be getting drawn up the tube into the throat of the carburetor, not forcing itself out through the air bleed passage.
It;s as if the signal is strong enough to pull the fuel up correctly but the passage is restricted and not allowing all the fuel to pass through.

I can't see where you mention jet sizes. But I did note that you have "no flat spots" with unequal length straight trough pipes.
So I am wondering if you do have way too big an intermediate jet in there.

Don't know if the engine is basically stock or not but should probably be running something like 68 and 270.

I'm guessing the drag pipes are purely for looks but you will be losing around 10-12 hp in the mid range with that set up. And that's not 10-12 hp at max HP that's off whatever the engine makes in the mid range.

[rickmodee]

I just want to give a final update on my woes with this conundrum.


So I figured this out about a month ago probably more but this personal triumph brought mixed feelings in the interim. At first I was ecstatic, relieved, then.... feeling somewhat sheepish after I cracked the code. I went out to Lancaster PA about 150 miles out from my home, just pissing gas through the overflow the whole ride there. (the ride home was cheaper gas wise) side note: I also swapped my front sprocket to a 23t, I know I'm getting off track. Anyway.. because of that swap I decided to hop on the interstate and cover some ground quick as opposed to my leisure county road rip out. About 15 miles in I was getting uncomfortable and moving my ass around on the seat. (rigid rear) and then it happens

The god damn bowl isn't leaking, 4th gear 3k rpm so I start moving around making sure my eyes are deceiving me. Turning my hands into a brim to make sure its not some dumb reflection thats throwing me off. As I'm doing that it starts leaking again. Then it hits me. Is it my xxxxing knee? Holy shit, its my xxxxing knee, my knee is making my fuel bowl leak.

My regular riding position has my knee positioned right behind the stack and it cause some sort of a blockage of air or vacuum causing my bowl to leak. As I move it away free and clear no leak.

I must've taken that carb off about 20 times just checking things and scratching my head.

[brucstoudt]

thanks for the update.twice it was mentioned to try running with an air cleaner.i assume that wasn't tried?

[rickmodee]

Originally Posted by brucstoudt

thanks for the update.twice it was mentioned to try running with an air cleaner.i assume that wasn't tried?

You are correct. It was something i planned to try but didn't have access to a stock air cleaner without purchasing one. But also wanted to figure out the issue with the current setup and not just give up on it. Even though the stock s air cleaner is definitely a better choice for a street application

[RicThompson]

Just curious why you run an open velocity stack? On the drag strip I can see it. On anything else though?

[Ferrous Head]

I run an open bell mouth on my sidecar. And I found out early on that when I hang off ib the rights my right knee very neatly covers it.
But my engine coughs badly whenever I do that. And I get a huge amount of fuel coming out.