Yet another exhaust question

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Bikes: 1954 FL Panhead
1976 Sporty
1983 FXRT Shovelhead
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Yet another exhaust question


Post by LittleAl » Tue Mar 31, 2009 4:52 pm

I know this has been discussed to death and I've read through what I can find in the KB but i still have a question or 2 on the exhaust.

I have a '54 motor in a '51 frame. bought the 4 pipes from NOS Parts and a fishtail muffler from Bill's.

I mocked up the install last night and it all actually fit pretty good. The only mod I had to make to get it all to fit nicely and line up well all the way back was on the rear header pipe. It didn't fit deep enough into the "Y" pipe to allow the "Y" to fit into the squish deep enough or straight enough to let the muffler hang right. I marked it and cut it on an angle so it fits all the way in. at the front end of the pipe I cut about 1/2 to 5/8 of an inch off tapering back to nothing at the rear. my spigots are in great shape and the headers fit snug. all assembled and with just the muffler hanger the whole thing is pretty solid.

My questions are:

1) what is the current thinking on using a hi temp silicone when putting it all together? headers and all others?

2) where should I put clamps? I know at the muffler to "Y" and the muffler hanger at the rear axle. Rear header to "Y"? Front header to squish? Squish to "Y"?

3) i've read a few things in KB threads about using 2 "P" clamps on the front header for support, but where? something was mentioned about on the right downtube.

here's a few pictures of the mock-up

the lines & arrows on the "Y" and rear header helped me when cutting & fitting the header into the "Y"
IMG_2244.jpg (95.83 KiB) Viewed 1802 times
love the look of a Fishtail, lol. it hangs straight and level and parallel
IMG_2246.jpg (102.83 KiB) Viewed 1802 times
from the down low angle
IMG_2247.jpg (96.98 KiB) Viewed 1802 times


Re: Yet another exhaust question


Post by VT » Tue Mar 31, 2009 6:23 pm

Here's some stuff.
exhfinal002jp8.jpg (18.25 KiB) Viewed 1802 times
Wear Safety Goggles - Holds the clamp so you can run a nut up to tighten it, pre-squeezing it, then install the lock washer later.
Keep the top rim of the clamp 1/16" away from the cylinder head. The clamp bolt/nut will just about fully tighten on new spigots. Shake the header gently, and stop tightening when the header freezes.
exhfinal004zx8.jpg (81.75 KiB) Viewed 1802 times
If the muffler makes contact with the frame tube.
exhfinal007no0.jpg (49.79 KiB) Viewed 1802 times
Wedge some air gap.
exhfinal006vu8.jpg (77.24 KiB) Viewed 1802 times
exhfinal003ua5.jpg (51.96 KiB) Viewed 1802 times
With the exhaust completely installed and headers clamps tightened, these two tabs (frame and flat-pipe) should be making contact. Tighten this (anchor) bolt and nut first. (Leave the rear muffler clamp barely snug. Leave the front muffler clamp finger-tight.)
Check the swing clearance for the brake lever. You might have to grind a little off the backside if it hits the flat-pipes hub. Use black marking pen as dy-kem. Swing the lever back and forth. Grind where black was removed.
exhfinal005km0.jpg (68.55 KiB) Viewed 1802 times
exhfinal001ua2.jpg (20.81 KiB) Viewed 1802 times
The front muffler (adjustment) clamp is slotted to assist in aligning the rear section of the exhaust system. With the wood wedge in place, tighten the adjustment clamp and then check for muffler-to-frame clearance.
Muffler is a -58 (22") from the true-dual assembly. Rear V-Twin fender fit the V-Twin frame with no problems. Holes lined up okay. I used a pointed locator awl to align the two bottom tanks support holes, but left the two support-to-tank (1/4") bolts loose until I drew-up the fender to the support bracket. Great fun. Well worth the effort.

Some more stuff on the front clamp to the muffler:" onclick=";return false;

And some more Dope on the front header clamps:
exhst001tw1.jpg (85.28 KiB) Viewed 1802 times
Before I installed my front head, I assembled the exhaust (in case things had "moved" during the assembly and dis-assembly). Install the front header frame clamps first :!:
exhst003bk8.jpg (49.81 KiB) Viewed 1802 times
I used a long bolt to make the spread-reach and tightened the clamps (make sure your head is fastened down before squeezing the clamps inward). When you install the shorter bolt, don't tighten the clamp bolt too tight. I keep mine tightened only as much as it takes to keep the front header from moving back and fourth (with the header clamps not installed).
exhst003ht8.jpg (97.35 KiB) Viewed 1802 times
Then install the shorter bolt. My clamps aren't really squeezed yet. Now that the head is torqued to 65 ft. lbs., the clamps can be fully tightened. I applied a couple wraps of electrical tape to keep the clamp from busting the paint.

Leave a piece of blue tape on the last part you installed so when you go back to work on it, you know where you left off. Making a slice cut on the end of the rear header is a dicey move, since the next part you install (i.e; the front muffler clamp-to-frame) may throw everything off, but at least you can buy a rear new header if need be. But yea, having the rear header fit completely into the hub is what I'd demand too as a repair plumber.
About RTV sealant, in my plumbing opinion, I think it's cheating (seals are made by butt-joints or ground joints, clamp joints or gaskets only), but if you hide the RTV (heat-proof sealant) I suppose only you would know. :|

I think all of these exhaust are going to fit differently on each machine.
Then Don from Northland Industries (Frame Factory) told me 2 weeks ago, that he installed the stock 4-piece exhaust that V-Twin® carries "...and it fit right up...perfectly" :!: [Which, imo, is his way of saying "That frame you bought in 1997 was bum....but now we have it wired with the '55-57 frame, and building rigid Pans is a kick :!: ] I couldn't agree more. These days it's the only thing that makes sense.

Note: The front header clamps appear to be close to the case, but aren't anywhere near the case. Having the clamps in this position hides the bolts from view and it looks, from the street, that it's just two bands of metal looped together. The extra long bolt was to get the two loops squeezed together. A shorter bolt takes it's place. 8)
Last edited by VT on Wed Apr 01, 2009 2:35 am, edited 4 times in total.

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Re: Yet another exhaust question


Post by LittleAl » Tue Mar 31, 2009 6:44 pm

good stuff!


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Re: Yet another exhaust question


Post by john HD » Wed Apr 01, 2009 12:19 am


my ideas on exhaust.

silicone is good. it seals the system so you do not get those little pops and farts from the exhaust when you coast. it keeps the air out.

on my bike i have the front pipe frame clamp as vt has shown but pointed down to prevent it from rubbing on the motor case.

install the rear pipe and see if rotating it some helps get it deeper into the s pipe.


Posts: 263
Joined: Fri Jan 02, 2009 8:52 pm
Bikes: 1954 FL Panhead
1976 Sporty
1983 FXRT Shovelhead
2000 FLHT TC
2008 Anniversary Ultra
Location: New York City

Re: Yet another exhaust question


Post by LittleAl » Wed Apr 01, 2009 5:06 pm

good suggestions and pictures. Thanks guys.

Hopefully I'll be buttoning up the cam chest this weekend and and doing the actual exhaust install. Exhaust and me never really got along so I had some concerns. the installation of the drag pipes on my Shovel has been an ongoing 5 year struggle, lol

after some of the nightmare threads I've read about fitting AM exhausts I figured I especially would have some problems but I guess the OEM frame I have combined with decent repo 4 piece exhaust from NOS Parts turned the tide for me

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Re: Yet another exhaust question


Post by kevsett » Wed Apr 01, 2009 9:02 pm

I had significant problems with my replacement 2 into 1 stock style exhaust back in 95/96 and finally had them better tweaked by a bike shop in Leavenworth, KS. When all was said and done they did a great job using many of the above tricks and spacers, etc. What a mess from supposed bolt on stock style aftermarket pipes. I wanted to smack the designer and builder at the time. Actually I still want to all these years later.


Re: Yet another exhaust question


Post by VT » Wed Apr 01, 2009 10:08 pm

Yep, the '36-57 4-piece exhaust is a tough fit, but, we've worked on about 3 rigid Pans on this site and everybody can read the material over and over and probably find some foothold to get them through the steps.

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