In a dilemma with a 'new' head

[Steve]

Still working on my son's bike, '81 850. Got a new head from Paulyboy this weekend. In the process of cleaning it up, I noticed two broken exhaust bolts. Stuck in rather hard, I drilled them out and re-tapped them with no problem. (Funny how it's SO much easier when the head is off the bike.)

My problem now is that I used a spark plug thread chaser to clean the holes. In the last one, it got a little tight toward the end, so I quit and started to back it out. It won't back out. I have sprayed the area with penetrating oil (not PB Blaster, though), and let it sit overnight, but the thread chaser still will not move.

Would it help to break out the torch and heat that side of the head? Hopefully the head will expand quicker than the thread chaser and I might get it out.

.

[Matchless]

Steve,
I will be watching the reply to this thread as you have just brought up a brand new problem and your results will be my learning curve. I have to assume you were not using 'cutting oil" or any other lubricant while tidying up the threads?
I hope you get it out as IMHO heat will most likely be the only solution other than force.

[Steve]

No, I wasn't using 'cutting' oil, but I was giving it the occasional spray of silicone lube.

Force is out of the question. It just flat out does NOT want to move. :shock:

Will fire up the torch later.

.

[chef1366]

Turn the head over and see if there are any "metal hairs" coming out the other side of the spark plug threads. Did the thread chaser go in easy so cross threading is out of the picture? If no to either Q then a little heat should get that baby out. With force are you afraid of breaking the tap off?

[Nessism]

Not sure what to recommend at this point other than maybe getting some tapping fluid for aluminum. Not sure what they put in that stuff but it works. http://www.tapmagic.com/TMaluminum.htm

[Steve]

Can't see any "metal hairs" because the thread chaser is virtually flush with the inside of the combustion chamber. Yeah, it went in easy enough that the threads are not crossed. It did get a bit harder as I went, but I knew there was some carbon build-up in the lower threads, so I did not think much of it. I stopped every couple of turns to give another squirt of silicone lube, but probably should have backed the tool out, as well. With force, I'm not sure if I would break the thread chaser (it's a rather stout piece of metal) or just gall the threads, either one is a stiuation I want to avoid.



.

[salty_monk]

WD40 makes a decent cutting fluid for AL...... You could try some Kroil or something down there to free it off or freeze off.

Likely the torch will work though.

You should always go in a couple of turns & then back out a turn or so with a tap or thread chaser. Helps it clear the crud. Silicon is not a good choice of cutting fluid.

Dan

[TheCafeKid]

Steve, may just be the pic, or the light, but looks like that might be a "hair" there about 11 o'clock on the chaser..also, looks as if the wire wheel was taken to the head there, posible that some metal shavings from that got into the threads of the hole and more or less locked your tool up. Ive had that happen myself, and once i got the tool out, fearing that id cross threaded, investigated only to find nothing that explained the reason for the seize. However, i cleaned the holes well after, and then had absolutely no problem. Wasnt on a head, but the theory remains. Not saying you didnt clean it well either. Those metal bits are a PITA to get rid of sometimes. Just an opinion/idea

[Dogma]

It's probably hung on that Mitsubishi valve...What's that doing in there?

[TheCafeKid]

I think thats an "S" also on that valve. My guess is they are both produced to be used by either company.

[bwringer]

It's probably hung on that Mitsubishi valve...What's that doing in there?

I've also marveled at the Mitsubishi symbol on GS valves. Either Mitsu made valves for Suzuki, or they used the same supplier.

[Steve]

Update

After applying a bit of heat and a LOT of torque, the thread chaser is out.

Let's just say that it got carried away with its job description...it chased those threads right out of there. :shock:

Actually, there are shadows of threads left, but I dropped the head off today at a machine shop to have the threads repaired and get the head surfaced. Might be ready this afternoon or tomorrow at the latest, but installing it on the bike will have to wait for a week or so until after I get back from Kitty Hawk.

I posted a bit on the Meetingplace forum to see if there was anyone along the route that might be up for a meeting somewhere along the way, but so far, no takers.

.

[chef1366]

Bummer

[Steve]

OK, the head is back home. I need to talk to the owner of the machine shop tomorrow to discuss some extra charges on the bill, but the head is home. He told me on the phone, then again when he saw the head, that it shouldn't take more than 1/2 hour to do, so it would be $35. He normally charges $50 for a plug hole, but this one looked easier. The charge ended up at $75 :shock: so I DEFINITELY need to talk to him. Had the surface checked, and it looked slightly off, so I had it surfaced, too. They took off 0.006", which left just a couple of small areas untouched, and it looks good to me. Surfacing charge was $50, which seemed reasonable.

Gotta get other stuff ready to pack, then work on our GoldWing chapter newsletter so I can get it mailed out before we leave on Friday morning, so no time to work on the 850 for the rest of this week.

.

[robertob]

Mitsubishi is a HUGE company, they own everything from foundries to printing press makers.

Anyway, they're probably machined by Mitsubishi Heavy Industries. That's the industrial part of the company that makes turbochargers and other hard parts.

I've also marveled at the Mitsubishi symbol on GS valves. Either Mitsu made valves for Suzuki, or they used the same supplier.