Managing Exhaust Line Vibration at the Head Connection?

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jeremy
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Managing Exhaust Line Vibration at the Head Connection?

Post by jeremy » Sat Nov 08, 2008 4:20 pm

OK--there's a lot of talk now about flexible mounts for the engine, to control failure (of both engine castings and rider!). So who has elegantly addressed the resultant issues of stress on the exhaust line, which hangs upon a small attachment-area on the head and acts as a long lever, fastened to the frame somewhere farther back? Who if any has experienced failure?

This would be an issue with fixed mounts as well, considering the hellacious vibes these small industrial engines can generate at certain RPM's. On large equipment, a flex section must be incorporated made of double- or triple-wall stainless accordion tubing to prevent fatigue and cracking somewhere between head and muffler.

There is also a raft of questions regarding exhaust line size and how diesels like old-style factory silencers.

I'm mounting a Hatz 1B30--Any thoughts/elegant applications?
"It's amazing how long things take when you're not working on them..." (unknown)
--Building small, lightweight Clubman-style bike, based on 1972 Husquvarna/Hatz 1B30/Comet 500CVT--

oilburner
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Post by oilburner » Sat Nov 08, 2008 10:31 pm

I'd try a ball and socket type connection of the type used on snowmobiles. I've seen a variation on Ducatis. The ball would be welded to a flange and bolted to the cylinder head.
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jeremy
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Post by jeremy » Sun Nov 09, 2008 2:40 pm

Thanks for your response--I have suspected this to be one of the natural options; two-cycle dirtbikes use it too. It appears though that most guys just hard-fabricate their pipes straight through on these diesel conversions. That has led me to wonder if there is failure occurring in these cases. Must put a mighty strain on that muffler attachment area which was only designed for a small "pot"-muffler on a stationary engine application, not to mention pipes/welds etc.
"It's amazing how long things take when you're not working on them..." (unknown)
--Building small, lightweight Clubman-style bike, based on 1972 Husquvarna/Hatz 1B30/Comet 500CVT--

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taildraggin
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Post by taildraggin » Sun Nov 09, 2008 6:07 pm

Yah, I'm thinking old 2 stroke exhaust type springs.

The RE I'm working on just wedges the header in - no springs, only the downtube bracket a foot down the pipe. eeesh.

This answer for the yanmar might be to make a flange like the original yanmar, but to the OD of the pipe. Add a couple of hooks and springs and 'butt' the pipe in, free.

Not that 'finished street bike look' though. You can hide the ball & socket better.

jeremy
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Post by jeremy » Wed Nov 26, 2008 7:12 am

Yeah, Taildraggin, but where to source the ball'n'sccket joint? Most likely an orient-origin factory assembly part, though I haven't tried the web...could it possibly be procured in 1 3/8" dia. without an expansion chamber attached? I took a look at my old part from the Husky, too big surprisingly, being it was only a 250cc.
"It's amazing how long things take when you're not working on them..." (unknown)
--Building small, lightweight Clubman-style bike, based on 1972 Husquvarna/Hatz 1B30/Comet 500CVT--

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taildraggin
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Post by taildraggin » Wed Nov 26, 2008 7:53 am

I'd give Bassani in Anaheim a try: http://www.bassani.com

- Charlie

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LocomotiveBreath
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Exhaust solution

Post by LocomotiveBreath » Sat Nov 29, 2008 9:17 pm

I thought I might offer a couple of suggestions. Spiral wound flex pipe works good on diesels as the exhaust from a diesel is not as corrosive or the heat produced would work well.
http://www.jcwhitney.com/FLEXIBLE-EXHAU ... _10101.jcw

Also the graphite gasket/socket solution as I found from a discarded muffler. I like freebees and I do scrounge the muffler shops for bends and such.

After I removed my turbo, I needed a quick solution just to get my bike up and running till I figure my next exhaust system, so I thought I'd share. This would work great and removal of the joint can be done easily

Mind you, this was just a quick cut and hack, but I can ride my bike.

Dave



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Last edited by LocomotiveBreath on Sun Nov 30, 2008 2:15 am, edited 1 time in total.
“Face piles and piles of trials with smiles. It riles them to believe that you perceive the web they weave, and keep on thinking free. "Moody Blues"

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taildraggin
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Post by taildraggin » Sat Nov 29, 2008 9:46 pm

Flex pipe is a great idea. Found some lengths in 1 3/4" at the local NAPA autoparts. It's also good for covering up ugly header pipe. If the exhaust comes out kludgey looking, it's going over (like '50s harleys).

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