Topic: Hard time getting exhaust spigot screws out

[killersoundz]

Looking grim over here. Got 4 screws out with a impact driver. Stripped 3 out and busted one off. I'll probably have to drill out bigger and tap. Weak!

[chewbacca5000]

Wow that sucks!  Same thing happened to me except the machine put in a heli coil.  If I had to do it again I would drill and tap.  Make sure you are using a quality impact screwdriver like a craftsman the Harbor Freight ones are junk.  You may be able to stay the same size bolt by progressively increasing the drill bit size.  I have done this and saved thread before.  Lots of patience here.  You could then use a tap or chaser to clean things up.

[bender01]

Propane torch and heat it up. Try the Impact again. wedge the the head somewhere so it doesnt move around when you hit it. Good luck.

[bollingball]

I think this is why Honda used studs later on. If I were you I would change over now.

Ken

[Jerry Rxman Griffin aka MuthaF'er]

What kind of penetrant did you use? How long did you let it work?

[killersoundz]

Tried a propane torch.

Although I usually use PB blaster I did not have any on hand when I got into this so I did not use it. I am not convinced it would have helped these screws anyways.

I ended up drilling and tapping out 5 of them to 3/8-16 thread and leaving the other ones intact. I'm putting a aftermarket 4 into 1 on here so I'll probably just use bolts. Whatever holds the exhaust on I don't care!



Two of my drilled and tapped holes came out pretty bad I did not keep them centered very well but it will probably hold fine, I just won't let anyone look at it up close. 

BTW - Anyone know what size the threads are on the stock screws here? this is a 74 cb750. I'll probably be able to figure it out in the hardware store but it wouldn't hurt to be prepared

[72500john]

kroil oil and some heat. or mix up some engine unseizer, acetone and atf, think its pretty much the same as kroil.

[bollingball]

I still thank studs would be a better option. You don't want to keep taking a chance screwing up the threads in the head. Just a stud nut and lock washer. From then on you can use a socket

Ken

[killersoundz]

I still thank studs would be a better option. You don't want to keep taking a chance screwing up the threads in the head. Just a stud nut and lock washer. From then on you can use a socket

Ken

Yeah sounds good. Do you think I can just use some all thread and cut it to length for the holes I tapped out?

[Jerry Rxman Griffin aka MuthaF'er]

I just installed a new set of stainless studs from a kit I got. They are threaded to different lengths on each end. The ends of the threads bottom out when going on so that depth may be an issue to deal with.