Topic: 73 CB500 Boston Cafe

[calj737]

Machine shop. Will cost less if there still enough for them to grab hold of. If it shears at the surface, then either left hand bits or EDM is the only choice.

[MickB]

Lajos the trials of restoration, bad luck. You could try cutting a slot in the stud and try with an impact driver.

You also win some you lose some.

[SOHC4 Cafe Racer Fan]

A decent machine shop should be able to get those out for you.  Bummer.

[lajos]

I slept on it and decided that I'm not ready to throw in the towel just yet. Worst case scenario is I have to get a new case for probably less than the machine shop would charge me to get the bolt out.

I got a hotter torch that has oxygen and map gas. So I'll try to heat it to higher temp than I got it with map gas only.

The stud seems pretty soft so if heating/welding fails I'll drill it with with a left hand drill bit.

Unfortunately we have a tropical downpour in Boston so I need to wait to do this outside.

[iron_worker]

If you don't want to pay a shop to do it (I did ... and I can see why you'd want to avoid that bill  ) you could try something like this:

1) Cut the stud down as close to flush with the case as you dare get being *really* careful not to gouge the sealing surface. A few layers of tape around the base of the stud may offer at least some protection.
2) Center punch the stud making damn sure you're in the center (a transfer punch and/or drill guide might be handy for this)
3) Get a drill/tap guide (http://toolmonger.com/2008/12/24/drill-guide-might-make-a-wicked-hockey-puck/)
4) If possible, clamp or secure the drill guide to the flat surface.
5) Check this chart for the correct drill size ... I think it's M10 x 1 but maybe someone can confirm... (https://littlemachineshop.com/Reference/TapDrillSizes.pdf)
6) Drill out the stud. Use some sort of oil or WD40 etc. Start with a small pilot hole (maybe 1/8" ish). I usually jump straight to the size I want but some people go up in several steps. Either is fine so long as you can STAY ON CENTER. Use your drill guide to ensure you are going in straight.
7) One you've gotten to the tap drill size you should be basically left with a threaded hole but the thread still have the steel threads from the stud left in them. Either run a tap through the hole (with WD40 or oil). You will have to go in a bit, back out, clean the tap, go in a bit more, etc. OR try and pick out the remains of the steel threads with a pick. You will need much patience for this I imagine.

8 ) Optional: If the threads are too damaged you will probably have to purchase a helicoil kit in that size but if you've gotten to this point then that part should be easy as you have an existing hole.

Note: It is extremely important to stay on center and straight/true with the existing stud. If your drill bit wanders then you may be in for a TIG welding repair or new cases.

IW

[PGF550F]

Never Surrender!! I had one of the bolts in my brake caliper seized solid. I tried Oxy-Acetylene and welding on a nut until I broke it off so many times it was flush with the surface, drilled it out the same size of the shank of the bolt as Iron_Worker described and ran a tap in/out until I got the last of the steel threads out of the aluminum. Part of the challenge with these older bikes I guess...

Steel threaded into aluminum=

[Restoration Fan]

HOLD ON A SECOND!

You should be aware of something:  viewing this as giving up is one thing...but you need to know something.
When we broke off an engine case bolt in our build, I took it to a machine shop to get it out.  I described what I had done and how I had stopped when I thought I had better bring it to the machine shop.  It ended up only costing me $25 and that was because $25 was their minimum charge.  He told me, "Had you gone further, it would have very likely cost you between $100 and $200 to fix the same thing because you didn't get it down to an unmanageable state."

So just be forewarned that if you end up breaking it one more time, you can almost assuredly count on more $$ out of your pocket when/if you do end up going to the machine shop.

[lajos]

@iron_worker: Thanks for the great step by step! We have another day of rain coming in Boston, so the stud is now soaking until I can work on it outside. There's still material left for another couple rounds of nut welding and I got a oxy-map torch so I'll try to heat the area more before I get to drilling.

@restoration fan: Thanks for the warning! This is the first stuck bolt on this project, I got hundreds of screws out mostly with the impact screwdriver from HF (best $9 I spent on a tool). Obviously money doesn't grow on trees, but the reason I want to keep trying instead of going to a shop is not because this would put me over budget. This will happen again in the future and I want to know how to deal with it.

Thanks again for everyone's help and advice and sorry that this silly bolt hijacked the thread

[SOHC4 Cafe Racer Fan]

@iron_worker: Thanks for the great step by step! We have another day of rain coming in Boston, so the stud is now soaking until I can work on it outside. There's still material left for another couple rounds of nut welding and I got a oxy-map torch so I'll try to heat the area more before I get to drilling.

@restoration fan: Thanks for the warning! This is the first stuck bolt on this project, I got hundreds of screws out mostly with the impact screwdriver from HF (best $9 I spent on a tool). Obviously money doesn't grow on trees, but the reason I want to keep trying instead of going to a shop is not because this would put me over budget. This will happen again in the future and I want to know how to deal with it.

Thanks again for everyone's help and advice and sorry that this silly bolt hijacked the thread

Well, it was your bolt, so technically no hijack. 

I admire your perseverance.  I personally would pay $25 to have a machinist take out the stud, rather than risk having to pay more OR possibly have to buy new crankcases if things go south (with those possibly having multiple stuck studs).  You got heart!!

[iron_worker]

I had sent my cases in to a machinist that snapped a bit above flush. They also TIG welded and fixed one of my points cover bolt holes. Total bill: $500. 

IW

[calj737]

I had sent my cases in to a machinist that snapped a bit above flush. They also TIG welded and fixed one of my points cover bolt holes. Total bill: $500. 
IW

You obviously pissed somebody off...

[SOHC4 Cafe Racer Fan]

I had sent my cases in to a machinist that snapped a bit above flush. They also TIG welded and fixed one of my points cover bolt holes. Total bill: $500. 
IW

You obviously pissed somebody off...

Did they use any lube before reaming you?  That's nucking futs!

[iron_worker]

That's what happens around here when all the shops are used to getting work from a thriving mining industry.

IW

[SOHC4 Cafe Racer Fan]

That's what happens around here when all the shops are used to getting work from a thriving mining industry.

IW

Where's that?

[iron_worker]

Saskatoon, Sk, Canada

[Doctorlumen]

Hey lajos!
The Iron Worker method does work. You have super heated that stud, and mostly ended its structural life, so perhaps the welded nut (also super heating the stud) aint the way. Not to mention you have been whaling on that F***ker until now, so if it hasn't budged yet, you are probably not seeing the stud twist out on its own.

I have been where you are on a sad little Suzuki T350. The drill-and-tap method, if you are careful, is a sure fire way to success. But you have to be careful and slow. There should be no brute force involved...but tons of patience. Proper drilling and hand tapping holes is not something to shy away from when it comes to these old bikes. Its becoming a lost art of sorts, but still necessary to achieve professional results. Good luck with your project!   

[lajos]

!!!!!!!!!!!!!!!!!!! yay !!!!!!!!!!!!!!!!!!!

Got this sucker out! Thanks for everyone's help!

So looks like I just needed more heat. I've been soaking it for days, even mixed up some atf-acetone, didn't budge.

I welded another washer to the stud, then a nut to the washer. I got an oxy-mapp torch at home dippers and started heating the stud until it glowed red. I did this a couple times, still didn't go. I was getting ready to give up.

Then I used the oxy-mapp torch in one hand for the stud and my mapp torch in the other to heat the crank case. Whacked it with a hammer and the sucker just started turning with hardly any force!

I had to wiggle it back and forth a bit, soaked it with liquid wrench (that was the only thing that didn't instantly evaporate in the heat) and it slowly turned out in one piece.

Thanks again for all the help! Now on to more fun stuff. Or fun stuff after I clean up the mess I baked on there.

[calj737]

amazing the heat it takes sometimes... (Loud golf clap from the gallery!)

[SOHC4 Cafe Racer Fan]

Success! Now you're ready for anything!

[lajos]

While I'm waiting for the cylinders to be big bored and the valves/seats recut, I started cleaning up the carbs.

I have a set of carbs where two of them look very nice and clean with no oxidation, but the other two have lots of white stuff in the float area. This is what one of them looks like after ultrasonic cleaned in simple green hd pro.

Is it worth cleaning this up, or should I replace the two oxidized carb bodies? I've read some threads that suggest using steel wool and elbow grease to clean the oxidation out, is that the best way to go?

[calj737]

Clean it carefully. Too much force and you can damage the posts.

[lajos]

Thanks Cal, I'll be gentle with it.

I've read somewhere that soaking it in pine sol can take it off. I might give that a try before scrubbing.

[calj737]

Careful with Pine Sol. It can turn the alloy GREY due to pH differences. Tape up the outside of the body, pour some in the bowl chamber, and soak it that way. Check for results. I was going to recommend Oven Cleaner (with the same caveats) for removing the oxidation.

[lajos]

Thanks for the warning about pinesol, I've read about it changing the color of aluminum.

I have a perfect test case, a carb body that has a broken float tower that's buzzing away in the ultrasonic cleaner in pinesol now, we'll see what happens

[lajos]

Pinesol in the ultrasonic cleaner definitely ate all the white stuff off. It did darken the aluminum a bit, but if that's just aesthetic, I can live with it. Here's my test piece (with the broken float tower). The whole float area was covered with white oxidation.