Topic: Exhaust Flange / Spigot Removal and Seized Bolts

[mrkaylor]

Since almost every aftermarket exhaust appears to be made for later model CB750K's.  It looks like I'll be removing my K2 engine again to tackle the removal of the flanges and replacement with studs.  I was able to get the farthest outside screws out by just running the engine for a few minutes and using my craftsman hand impact, but I broke the bit on the inside screw on the #1 port, which got me thinking.  I could cut the ears off the spigot pull the tub out and then I would have good leverage using whats left of the ear to wiggle the bolts to hopefully brake them free; or I could then cut the rest of the ear off and then the bolt head would be fully exposed allowing a vice grip for leverage.

Has anybody else done anything similar?

Another idea:
I found this which looks similar to something I had thought of earlier today:  Bolt Removal the "Right Way" by O'Reilly Fab

Either way I'll start stripping the bike again to get the engine out...
Michael

[nancy]

Seems like too much work - I bet the solution can be had much more simply. My K2 motor had studs to mount a 4 into 1 when I bought it 3 years ago. I removed these and refitted original spigots & star clamps for old set of 4-4. No need to remove the motor. I found the screws that hold the spigot to the head can be hard to get a grip on, and these screws mangle......but it does go into soft alloy in the head and the threads there are easily stripped. If u got access with your impact driver - why not put a drill into that screw and use an easy out to turn the stuck screw out? All fitting of the studs can be done easily with motor in bike.
I had to do this on my Triumph back brake caliper...frozen hard as the hobbs of hell....stripped the bolt really bad. Drilled it, turned in an easyout bit - and out it came.
Pic shows my end result of pulling the 4-1 exhaust with stud mounts off my bike. Studs shown.
regards
mark

[SOHC Digger]

I recently went from studs to spigots on my bike and the studs were very difficult coming out.  I had to use a propane torch and even then, two of the holes stripped, requiring heli-coil.

My suggestion would be apply heat and then try your hand impact again.  If you don't have a propane torch, get one.  They are inexpensive enough and very handy.  Breaking impact bits is never unusual.  These little things take a beating and need to be exchanged frequently, even the more expensive Snap-On ones.

[mrkaylor]

I had tried again heating with a map gas torch, which easily heats the aluminum head to 400° F+ but that inside bolt just won't move.  I've been dousing all the bolts with penetrant so hopefully by the time I have some replacement impact bits they come out easier.  I don't really so any other way to get a couple of the inside bolts (#2 and #3 ports) though without taking the engine out, I might be able to get by with just taking the front forks off but I'm not going to get my hopes up there.

Michael