I read that exhaust can suck in from one cylinder to the other on bike with 2 into 1 pipes?

Has anyone ever heard of this?

The reason I ask is I drilled the cat out of my Fat Bob stock exhaust and supposedly the cat material (leftover dust) can get into the engine that way.

I would think that would take perfect conditions for that to happen what do you guys think?

 

yes it does suck in. if you did it with the pipe on the bike pull it off and blow it out with an air hose.

 

I seriously doubt air or exhaust would come from the pipe into the heads. The air and fuel come in to the heads from the intake port, not the exhaust port , meaning while a cyl is taking in the a/f mix there is a closed valve keeping foreign material out. Plainly speaking one cannot suck and blow! Dust and debris would take the path of least resistance and blow out the back before ever being able to actually climb up your pipes defying both gravity and blistering quick exhaust fumes. JMO
i'm going to assume that you fired it up long since this thread so whatever was going to happen already has. Put it behind you.

 

Yes I did fire it a few times and rode it since then but thats what I was thinking its kind of a long way up from there and that would take alot of suction.

When I fired it the first time I did it with the muflers off didnt look like anything was left in there when I looked after that.

It seems to run and sound good.

 

Your good to go bro! keep the rubbery side down!

 

it would take quite a bit to get in there but i never take chances. better safe than sorry. im sure itll be fine though.

 

Thanks for the input guys.

 

If you have rode since then, I doubt you have anything to worry about. The amount of suction back through the exhaust valves is very minimal, and the outgoing pressure once you give it some throttle is much greater so if you rode, I'm sure anything in there was blown out the tailpipe rather than sucked in the exhaust valve.

 

to everyone saying that the exhuast sucks in... please explain! an engine is a big pump that only works in one direction... the exhaust does not "suck in".

EDIT:
I understand the theory that with a 2-1 exhaust the pressure from the exhaust in one cylinder going "back" up the pipe of the other cylinder. But in reality- given the exhaust path/direction of the merge for the 2-1 (the exhaust would have to essential turn around), and the fact that even at idle each cylinder will have about 5 exhaust strokes per second this will never happen.

Also, whenever the exhaust port is open it is expelling gas, how can something possible go against the exhaust gas?

 

<FONT size=3><FONT face=Calibri>O2dynaHH asks HOW can exhausts “suck.” It is called reversion. All engines have a particular RPM range where reversion is