Threaded hole on exhaust header - plug it?

[boofer]

Put the NOS pipes on a frame up restoration 11F and after starting, noted exhaust coming out of the little threaded holes in the #2, #3 exhaust header pipes (down by the connection to muffler). I'm thinking that those need to have bolts in them but forgot to note it on the tear down.

Do those threaded holes need to be plugged ?

What the heck are they used for anyhow ???

Also, are there any other little exhaust tricks ??

Thanks much, she started right up nicely (after 2 years !!) and firing on all cylinders but needs some tweaking, syncing and testing. Initial observation is that the engine vibration seems a little rough when giving throttle....kind of like it is missing firing on one cylinder but they are all definitely firing and it idles fairly okay..........I'll see how it feels once dialed in with the carb balancing.......

Thanks much,

Craig

[Rasputin]

If they are quite small holes behind the down pipes but ahead of the mufflers they are likely the drain holes for condensation that are factory.

[IanDMacDonald]

Ras- I wonder if he is referring to the factory tuning ports?

[CaptonZap]

It sounds like the #2 and #3 headers were replaced at some point, and are not the original pipes. My 80G has the bungs in all 4 pipes, and I know they are original.
I asked the same question years ago, and got various guesses as to the purpose of the bungs. The most reasonable answer is that the factory used them for emission tuning. Some attention seekers might use them to inject smoke oil of various hues, and cause some consternation to the Harley rider that you just smoked, pardon the expression, off the line.
Get some metric bolts at Ace Hardware or equivalent, and plug them. I don't know the thread size, but try some bolts off of other locations on the bike until you find one that fits, and then you can match it at the store.

CZ

[Rasputin]

Ras- I wonder if he is referring to the factory tuning ports?

Thinking he is referring to the drain holes designed into the exhaust myself as an 11F would not have had the pollution control adds that the later yrs had

[MaximPhil]

Hey boofer, Yet another application for Pictures.....or a 1000 word essay.

If it is what has been suggested a Set Screw ( Grub Screw) with a touch of loctite.
https://www.boltdepot.com/Metric_set_screws.aspx

I would use stainless. Lowes or Ace hardware probably have them in Metric once you know the size.
Phil

[crazy steve]

This what you have?....



These were added in '80 to all XS11 exhausts, and also to all 'service replacement' exhausts bought for all years. Plug 'em with a 6mm (10mm head) x short bolt...

[boofer]

I think you all nailed it and I finally took a pic !!



I used stainless bolts and plugged them. I am also thinking that these pipes may be for an Australian version of the XS. The mufflers have some "warning" plates riveted on them and I never saw that on US version of the bikes. Plus, I did get the pipes from down under



I have bigger problems now though (sheeesh...) ...... I was simply warming up the bike for the carb sync yesterday when a "knock ping" started on the top end of #1 cylinder. It almost sounds like bad spark knock or even like a little ball bearing being tossed around in the valve cover (just trying to be descriptive). It seemed to happen after warming up and did not happen the initial days of firing up ........ wondering if oil somehow got blocked to the top end ?? Too early to tell but it sure is a big coincidence that the noise started happening right after I plugged up those tuning port holes !!!

Not going to panic as it is just how things go when letting an engine sit for 3 years during a restore Noises can be deceptive on these little beasts......

Thanks for all your input

Craig

[dpotter58]

I have a set of those on a 79 f and I was told the plates were put there as part of emission regulations.
The knock sucks. never a good thing

[crazy steve]

Those data plates were added to 'service replacement' exhausts to prove they complied with the noise regs that came in '82. The irony is the bikes were already out of production and the regs didn't apply in any case...

[motoman]

I think you all nailed it and I finally took a pic !!



I used stainless bolts and plugged them. I am also thinking that these pipes may be for an Australian version of the XS. The mufflers have some "warning" plates riveted on them and I never saw that on US version of the bikes. Plus, I did get the pipes from down under



I have bigger problems now though (sheeesh...) ...... I was simply warming up the bike for the carb sync yesterday when a "knock ping" started on the top end of #1 cylinder. It almost sounds like bad spark knock or even like a little ball bearing being tossed around in the valve cover (just trying to be descriptive). It seemed to happen after warming up and did not happen the initial days of firing up ........ wondering if oil somehow got blocked to the top end ?? Too early to tell but it sure is a big coincidence that the noise started happening right after I plugged up those tuning port holes !!!

Not going to panic as it is just how things go when letting an engine sit for 3 years during a restore Noises can be deceptive on these little beasts......

Thanks for all your input

Craig

Check that vacuum advance hose is plugged on #2 carb, and not intake boot. May wanna pull left-side ignition cover as vacuum cans can go array and cause same type of rattle.

[MaximPhil]

Hi Boofer,
More pictures please. Those close ups look like a museum piece of work. Please share the rest of it with us.
Phil

[boofer]

Sorry , was offline for a bit while on a ride on the FJR.

I will post some more pics Phil and thanks for the compliment, I have been working on it for over 4 years and it is %100 stock parts (yes, coils too) and probably museum quality. My brother taught me quite a bit on restoration and I am having fun rebuilding my memory

I swear that the vacuum advance is where the "rattle noise" is coming from and the bike seems like it is running on 3 cylinders......funny thing is that for a short 10 minute period after getting warm the bike started to run perfectly......enough for me to actually balance the carbs........then when I started it cold......whammo......I get the "ping knock" and like a cylinder is misfiring. I need to do all the coil checks and such before I dive into the vacuum advance, but that is where my gut is telling me the problem is.

Couple of pics that I have handy;



Rear Right



Engine ICU !!



Me at Deals Gap on FJR while you all were having fun last month !!

[boofer]

Not sure if this will work but here is one video that has the ping.....and one with it running great......

FYI, vacuum advance is plugged into carb 2 properly.......not on the intake, on the carb. All intakes are plugged in these videos.

Ping video

View My Video

No Ping video.....have not been able to get it smooth again (yet )

View My Video

[MaximPhil]

Hi Boofer,
Thanks for sharing.
Phil