epic fail on the intake manifold

LS614

LS614

Well-Known Member
here is the sciemetiffic explanation for what happened. I was ridin' along on a curvy road, and ZOOOOOOOOOOOOOOOOOOOOOOOMREVVVVVVVVPUhhhhhhhhhhherrrrrrrrrrrrrpttt. Do you know what that is the sound of my fellow bikers? That is the sound of a 68.5cc two stroke engine with significant performance modifications revving beautifully and reaching the ideal resonant frequency of the surrounding aluminum intake tube. This means that the inferior metallurgy of the intake vibrated to just the right frequency where the molecules in the intake separated and broke. In simple terms, my intake shook itself to death today
Here is the result:

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P.S. the teflon coated clutch cable is a CUTE idea, but I give up with it, teflon makes the set screw slip, and mine slipped TWICE today and it was a major inconvenience. Back to the stock cable for me :)
 
The cast aluminum intake manifolds are a true source of trouble. Get yourself a steel one and your problems will go away. Check the weld bead where the bolts/nuts seat. Most of the welded steel manifolds need a little work with a Dremel to allow the fasteners to seat correctly (flush).
Good luck.
Tom
 
best engine kit I ever owned, before I tore it down ( :( ) was an SD stinger, took the steel manifold and installed that, and it's fine now. Nuts always sat flush, never an issue :) Thanks for the advice old man. Try to get some sleep and us young guys will try to keep it down :D
 
Bummer man!
Hmmmm... I have a teflon clutch cable. Right where the cable end attaches I scraped the teflon off of the cable by burning it with a Bic lighter and brushed it with a wire brush and my cable end has never slipped.
 
Mine broke too, only it was one of the ears on the flange. I'm ready to order a new one, but I have some HTS-2000 aluminum repair brazing rods I want to try first. I was going to try to make the repair, and after seeing that pic, maybe add a nice fillet all around if possible. But, as most of my hair-brained schemes go, it prob won't work and I'll end up just buying a new one. Mine is tapped for dual boost bottles (i know, i know) and I don't think they make a double-tapped steel intake for those unfortunately.
 
Here's the repair I did using aluminum repair "welding rod". I made a mold around the flange with a piece of soup can steel and "casted" a new ear. I then dremelled it to the finished shape and drilled the hole for the mounting stud. I also built up a fillet around where the tube and flange meet. Works great so far. I'm just waiting for the vibrations to shake it apart...
 

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That looks great! My simple fix though was to just switch to one of the steel manifolds I had lying around lol. Those alumalloy rods sure are cool :)
 
Yeah they are. I got them here while supplies last.

10 - 9" Aluminum Repair Rods HTS-2000 Brazing Low Temp - eBay (item 220756119784 end time Aug-14-11 12:21:49 PDT)

I bought them with the intent to make an aluminum, vintage looking drop stand, but haven't got to it yet. Apparently they'll work on a variety of different non-ferrous metals, so I might try it on the copper connections on my exhaust. I don't know how well it'll hold up, as the melting point of this stuff is 717-737 degrees. I've read that the exhaust gets over 750. It's definitely worht it to have a few rods handy though...
 
A very proper and professional repair.
As opposed to some here that would slather JB-Weld all over it and call it a day.

There's also alumiweld and alumaloy for aluminun.

Going to be trying some steelaloy soon (for brazing steel).
 
I'd like to try that too for my exhaust. I'm rebuilding it using a set of old 10 speed drop handle bars. It gives me the same bends that I need as my copper elbow slip-fit does only now with no leaks. I just need to join it to the flange and to the expansion chamber and if I don't have to take it to a welder, that would be a plus. I just wonder if it will hold up to the heat...
 
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