Exhaust flapper

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Potato Wilson

Active member
We had a flapper cap on the exhaust of the Cub since we got it. It smoked a little like most old engines, mostly after coasting downhill with the compression.
I took the flapper off at the beginning of summer, specifically so the exhaust would rise straight up during a parade. Now it’s been off for a few months and it sure doesn’t seem to smoke as much. Seems like it just burns & breathes better. Anybody got any thoughts on this?
 
Hmmm... I don't see how the cap would alter how the tractor runs. I do know that I removed the cap from mine years ago because it sent the exhaust back into my face, not always but often enough I didn't like it. As you said, removing it allows the exhaust to go straight up in the air.
Maybe you just don't notice the exhaust smoke as much since it's not in your face...
 
Flapper isn’t going to make the engine run better or worse…..it just covers the hole so rain doesn’t run down the muffler. In my personal opinion NO CUB SHOULD BE LEFT OUT IN THE RAIN!!!! But that is just my personal opinion.

Seriously though taking the flapper off will not improve your engines health or performance.

NJ Farmer

If you want it to stop smoking add some Marvel Mystery Oil or Sea Foam into the fuel to help free up those stuck piston rings!
 
Potato Wilson said:
. . . Now it’s been off for a few months and it sure doesn’t seem to smoke as much. Seems like it just burns & breathes better. Anybody got any thoughts on this?
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For me it is best to not have any restriction/back pressure/ at the exhaust of the Cub. Especially, when the Cub is at idle, when the engine vacuum is the highest and the flow at the outlet of exhaust pipe (low) is not "breathing" at the "optimum" point.

Another point that is a similar concept. I've been burning wood (wood boiler) for 43 years now. You can think of my chimney as the "exhaust pipe". I was not having a problem with creosote build in my chimney. I decided I wanted to keep birds, rain, etc. from coming down the chimney. So, put a "chimney cap" at the top of my chimney. I went about 1/2 year in that configuration and quickly removed the cap. I couldn't believe the amount of creosote that formed in the chimney with the "back pressure" of the cap. It wasn't the "flakey" type. It was the dangerous liquid that cooled and glazed my chimney -- the very dangerous type that, if it ignites, it causes a chimney fire. I immediately removed the chimney cap and I never have had a problem since.

Something to think about. I know the pressures are totally different. InH2O of water VS. Lbs./In. But I believe there is a similar concept here.
 
My Cub has never had a cap since rebuild 23 years ago. Also, I never leave it out in the weather. I purposely installed a long straight pipe (with no muffler) to keep fumes out of my face. It does what I wanted it to do and is very tame until throttled up.
 
Thanks everyone for sharing your thoughts. I originally removed the flapper to help prevent the exhaust from permeating the crowd around during a parade, and to keep it out of my face. It definitely helps with that.
I didn’t mean to imply that I was leaving the exhaust un-covered while parked, or that I was neglectfully leaving the Cub out in the rain.
I do run a little sea-foam in the fuel, it’s great stuff. Maybe that’s the main reason why, but I can’t help but think that soot/carbon/oil are clearing out better now, just as Mihevic theorizes. While the blue smoke used to be obvious and annoying, it is virtually gone now. Again, it could be from better seated rings from regular use and good additives, but I’m convinced removing the flapper helped too.
Cheers!IMG_2896.jpeg
 
Potato Wilson said:
Thanks everyone for sharing your thoughts. I originally removed the flapper to help prevent the exhaust from permeating the crowd around during a parade, and to keep it out of my face. It definitely helps with that.
I didn’t mean to imply that I was leaving the exhaust un-covered while parked, or that I was neglectfully leaving the Cub out in the rain.
I do run a little sea-foam in the fuel, it’s great stuff. Maybe that’s the main reason why, but I can’t help but think that soot/carbon/oil are clearing out better now, just as Mihevic theorizes. While the blue smoke used to be obvious and annoying, it is virtually gone now. Again, it could be from better seated rings from regular use and good additives, but I’m convinced removing the flapper helped too.
Cheers!View attachment 68853
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Nice looking Cub!! I also like the scabbard! Very cool. There's been many a time while putting around the farm I'd wished I had a rifle handy for varmint control. In Michigan, any gun carried on a motor vehicle has to be encased to be legal. I wonder if the scabbard would qualify as a case...🤔
 
ricky racer said:
Nice looking Cub!! I also like the scabbard! Very cool. There's been many a time while putting around the farm I'd wished I had a rifle handy for varmint control. In Michigan, any gun carried on a motor vehicle has to be encased to be legal. I wonder if the scabbard would qualify as a case...🤔
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Not even close. I loaned a friend my shotgun and had it siezed by a deputy because the case was not zipped across the butt of the gun. It was later returned. Vern
 
Good morning, I only carry the long-gun like that when I'm on my own property, out of view of others. Deer season opened the other day, so I like to keep it handy. I wouldn't shoot one of the local bears or lions unless it was absolutely necessary.
Cheers!
 
v w said:
Not even close. I loaned a friend my shotgun and had it siezed by a deputy because the case was not zipped across the butt of the gun. It was later returned. Vern
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Before we changed regulation pertaining to hunting from a standing vehicle permits in Michigan , guns also had to be encased.
Which made little sense to those disabled desiring a bird hunt for example.
And what did encased mean? Oh yes an Ex had the D.N.R. harass her warming up in the truck when a case in the bad wasn't latched. What a wiener head.
Wrapped in a blanket is encased is it not? But a latch not fastened on a gun in a truck bed not under way? Typical possum cop mentality.

We worked on it. My friend more than I.
Permit to hunt from a standing vehicle now means we can be underway/moving with a gun uncased. But do need the chamber empty.

Picking on the honest users is a poor excuse to claim someone is upholding the law. As in accusing your friend of being some kind of shotgun quickdraw artist poacher. Never mind he wasn't doing so. There are multiple ways to justify ones job without stooping so low.
 
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