Cylinder head broken exhaust port/spigot

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jack moghrabi
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Cylinder head broken exhaust port/spigot

#1

Post by jack moghrabi »

Good morning you all from S. Florida (Boca Raton)....

I highly appreciate the responses I got on the sprocket combinations for easier revs on my 63 FL while going down the highway.

However, a couple of days ago while looking over the bike I saw I had developed a crack in the rear cylinder exhaust port or spigot where the exhaust pipe clamps onto the cylinder head. I had this happen to the front cylinder about three years ago and I had it repaired by ACE Welding down in Davie. I got lucky because the welder had an old Harley and knew what to do (he even had a new insert to weld in).

Anyway, I've now got the rear cylinder head off and I'm getting ready to run down to Davie looking for the shop. I would appreciate any feedback/advice/thoughts anyone might have on the subject....especially as to why this may have happened and how to avoid this moving forward. Should I insert a section of flexible exhaust pipe to compensate for any difference in vibration between the motor and frame?

Thanks for any "comeback" and Rainjester, got your response on the richness issue yesterday. Thanks.
Rainjester
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Re: Cylinder head broken exhaust port/spigot

#2

Post by Rainjester »

Jack,

One of the things I learned in my adventures with mounting exhaust pipes is this:

The spigot does not reliably hold the pipes in place and the pipes will rattle off or create leaks if one thinks it does. The spigot designed to clamp the pipe onto it and seal the leaks. I've seen people put strips of aluminum or a strip of hose clamp around the spigot, then tightly clamping the pipe to it to try and keep it from slipping off. That's absurd.

I found that one of the issues that causes those spigots from becoming cracked is when a person is mounting the pipes to the spigot, the clamp used is way over tightened which could have lead to the type of problem you experienced.

I use 2 or 3 brackets (two on the top pipes and three on the bottom longer pipes which does not including the clamp to the spigot in that count) connected to the frame and pipes to actually hold them in place to keep them rattling. Only high temp silicone and the clamp mildly tightening the pipe to the spigot, it's the brackets at 2 or 3 different points that keeps it from coming undone.

This was my experience in this. Others might tell you otherwise. Once I did this, I never had a problem again with it.

Ya dig?

jester-
jack moghrabi
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Re: Cylinder head broken exhaust port/spigot

#3

Post by jack moghrabi »

Jester

I'm digging, loud and clear. Thank you. You nailed it true when you wrote "the clamp used is way over tightened....." That's exactly what I was doing, religiously torquing down on them with everything I had. After about five years of owning this 63 I should have know keeping the exhaust hooked up to the motor needed much more finesse and "body english."
Rainjester
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Re: Cylinder head broken exhaust port/spigot

#4

Post by Rainjester »

Glad to be of assistance. Wish I caught ya before it broke! Even if it doesn't break, I learned that over-tightening that spigot clamp squeezes all of the high-temp silicone out rendering it useless with leaks and the bike runs like crap.

I found that the most troublesome pipe is the first one that goes off the front head spigot before the squishy pipe. A fellow local panhead rider gave me a hint to put a bracket at the bottom curve of this front pipe and attach it to the frame. Never had an issue after that with it slipping loose or leaking and the damn clamp wasn't even muscled tight!

Before that, I did the same thing as you did, tightening it will all my might, and I swear, I was fk'n with it once a month before I got the hint with the brackets on the pipes. I haven't touched it since I hooked it all up that way.

jester-
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Re: Cylinder head broken exhaust port/spigot

#5

Post by PanPal »

Yes sir, you need those two frame to pipe clamps and watch for short header pipes. I had to weld an extension on the end that goes into the squish pipe. Same issues. I think Billy brought this up some time back. It helps!
jack moghrabi
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Re: Cylinder head broken exhaust port/spigot

#6

Post by jack moghrabi »

Allright Jester and Panpal, the wisdom is highly appreciated. I get my cylinder head back from Aim-Alloy Welding in Plantation, Fl next Tueday. If you're ever that way Aim-Alloy is a good place to go. The shop owner, Scott has an old Harley and knows exactly what to do at about the same cost as feeding a family at Kentucky Fried Chicken..... Good weekend and good riding.
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