Topic: Need help now - exhaust screw stripped. Results....

[sparty]

Trying to put on my new exhaust and the PO stripped one of the exhaust flange screws.  It is a total loss.  I tried to cut a slot in it so that I could use a straight bit, but there isn’t anything to grab.  How can I remedy this situation?  I need help fast.  All of the other screws came out smooth.  Also, how do you dig out the old exhaust copper gaskets?

Thanks,
Sparty

[StevieMac]

Thy copper gaskets come pry out pretty easy with a sharp flathead screw driver or knife. 

Are you talking about the studs coming out of the head that the exhaust bolts too? I hope not, those a a b!tch.  Or is your motor the earlier style?

[sparty]

Thy copper gaskets come pry out pretty easy with a sharp flathead screw driver or knife. 

Are you talking about the studs coming out of the head that the exhaust bolts too? I hope not, those a a b!tch.  Or is your motor the earlier style?

I am talking about the exhaust bolts (screws in my case) and they are a #$%*.  I am thinking I may have to drill it out and retap the SOB.

[StevieMac]

Gotcha.   I had to use an impact driver to get mine out.  Drill and tap as an absolute last resort. 

Oh how I wish I had that advise before I drilled........

[tmht]

Gotcha.   I had to use an impact driver to get mine out.  Drill and tap as an absolute last resort. 

Oh how I wish I had that advise before I drilled........

I concure... $20 hand impact driver has saved me from getting out the drill over a dozen times on my bike.

[sparty]

That is the problem, I already tried my impact driver, the screw was already dished too much.  I'll post a pic of the screw in a few minutes.  You will see how fubar it is.

Sparty

[tmht]

heat, pb blaster over and over again... That is the only other thing I can think of before getting out the drill.

[sparty]

Here is the best pic I was able to take.

[StevieMac]

I'd try an extractor before I drilled it out completely at least.  Lots of PB blaster and heat as mentioned (well not TOO much heat...).

[cmorgan47]

liquid wrench, heat, and easy out?
good luck.

[Rushoid]

liquid wrench, heat, and easy out?
good luck.

Ditto

[DME]

Do you have access to a MIG-welder?

If so, take a nut that´s approximatly the same size as the head of the screw.

Weld it onto the head of the screw through the hole in the nut.

The heat from the weld will help break down the bond between the cylinderhead and the bolt.

Then use the nut to unscrew the bolt...

That´s what I would do 


Cheers and good luck!
Daniel

[colb]

http://www.boa-uk.com/boa_grabit.html#

These are available in the UK, not used them but maybe worth a try.

I always used drill and screw in extractor in the past, these Boa things look easier to use.


Colin

[sparty]

Wish I did have a MIG welder, but no, I don't have access.  Great idea however.

I just tried the heat/PB Blaster.  No dice!  I gave myself a nice blister trying to turn that sucker.

I am finished for today, my back is killing me.

Sparty

[johnny-from-bel]

Do you have access to a MIG-welder?

If so, take a nut that´s approximatly the same size as the head of the screw.

Weld it onto the head of the screw through the hole in the nut.

The heat from the weld will help break down the bond between the cylinderhead and the bolt.

Then use the nut to unscrew the bolt...

That´s what I would do 


Cheers and good luck!
Daniel

I have done this many times.I have a rod welder I use 1.6 mm rods. It allways works. After you welded on the bold. Use heat, WD40 and plenty of patience. I also have a pneumatic impact wrench. That gets it out every time without ripping the bolt of.

[pelicanwheel]

This is simple..but has worked for me a time or two:

Based on your photo...get a cheap (harbor freight) 1/4 wide chisel.  It's important that the tip is very sharp.  A screw driver's tip is too blunt.  Position the chisel on the screw so that the flat part is facing to the right and the beveled part is facing left...we're trying to dig into the screw.  If the screw was a clock face, the chisel would be on a line that starts at the clock center (the center of the dish in your case) on up to the "12 o clock" position.  (if this was a regular screw and not phillips and we were using a screwdriver instead of chisel, the position I'm trying to describe would be as if the srewdriver is not center in the slot, but in fact half in and half out).  Tilt the chisel to the right to a 45 degree angle.  Take a hammer and start tapping the chiesel so that the sharp tip digs into the outter circumference of the screw edge.  The combination of the chisel digging in to the screw + you tapping the chiesel in the direction to unsrew the srew + impact of the hammer usually will break free the screw and after tapping a few times (you'll have to reposition the chisel to the new 12 o clock position each time the screw turns.

I've tried to describe this as detailed as I can.  I have never failed to get a screw/bolt out from this technique.

Hope this helps

Pelican

[sparty]

I just found that I can rent a MIG welder for $39.00 if I must.  I tried the chisel, there isn't enough screw left to bite into.  This is pissing me off!

Thansk for all of your help so far.

Sparty

[DME]

I just found that I can rent a MIG welder for $39.00 if I must.  I tried the chisel, there isn't enough screw left to bite into.  This is pissing me off!

Thansk for all of your help so far.

Sparty

Take the bike to your nearest workshop. They should have a welder and be able to weld that nut on for you, its a five minute job

Cheers
Daniel

[750goes]

the tip by pelicanwheel is good,

give it a try before you blister your fingers some more, an old screwdriver with a sharpened end like a chisel works the same also, just be patient with the tapping technique and get a good angle on the screw head,

I had a similar problem on mine two days ago installing the headers...got to the last screw and it only went in two turns then stopped....

after cleaning out the thread, trying another screw, more wd40 and lots of swearing, I had to retap the existing thread...
what a pain, but I did not need to helicoil or anything like that..

[sparty]

I worked on it for another hour this evening.  I sharpened a cold chisel and tried that method.  No luck.  At this point the screw head is really a mess.  I bought a bolt extractor - I have to drill a pilot hole in the screw and then reverse thread the bit into the screw.  I am praying that this will work.  I will again use some PB Blaster and heat.  My garage smells like I was making crystal meth from the Mapp torch.

later,
Sparty

[nteek754]

Hey  been there done that  if you can drill in the  very middle then try easy out if that dont do it drill a bit bigger take the spigot off and use vise grips as long as you  have enough  screw sticking out good luck it worked for me  Craig in Maine  seven fifty four ever

[750goes]

If you use a bolt extractor - weld something to it, then try and turn it out...

must be really stuck in there - is this the first time you have taken these off -???

[sparty]

If you use a bolt extractor - weld something to it, then try and turn it out...

must be really stuck in there - is this the first time you have taken these off -???

Yes first time they are off.  The PO really messed the bugger up.

Sparty

[750goes]

The PO may have used some loctite on the threads...because if it is not turning with all that you have done so far, then I don't envy you in trying to get this out.

keep trying it will happen

[sparty]

Well, it seems that this bugger isn't coming out.  I am now thinking of cutting off the exhaust flange to see if I can get a better bite on the remaining screw head.  So far, every indication of this stuck bolt/screw is lending itself to drill and tap.  What size would/should I tap it if I must?  Do you recommend the use of a Helicoil?

Thanks.

A very frustrated,
Sparty

[oldbiker]

You may not want to hear this, but I recommend that if you cannot get the remains of the stud out, you take the head to a decent machine shop and get them to remove it. Over the years I have made several attempts to drill and clear a broken stud and have found it almost impossible to keep the drilling central. This results in a damaged off centre hole which then has to be repaired with either a helicoil or timesert insert. A good shop will clamp the item down and use machinery to stay dead central so they either clear the tapped hole or put in an insert. Easy out are hardened and have a habit of breaking off leaving a hard center that you CANNOT drill through.

[johnny-from-bel]

Well, it seems that this bugger isn't coming out.  I am now thinking of cutting off the exhaust flange to see if I can get a better bite on the remaining screw head.  So far, every indication of this stuck bolt/screw is lending itself to drill and tap.  What size would/should I tap it if I must?  Do you recommend the use of a Helicoil?

Thanks.

A very frustrated,
Sparty

I think you are not giving it enough time. I have spent up to three weeks heating, WD20, tapping, etc...

Now if you are determined to drill it out.
Helicoil is very good. I have used it before.

I believe these bolts are M8, please correct me if I am wrong.

Start drilling out the hole using a 4mm drill. Make shure you drill straight and not to deep.After you drilled the hole put a 4mm rod in the hole and check that you have 90 degees in every direction. Now Increase drill size with 1mm until you are at 6mm. You may now be able to pry out what is left of the bolt. If not drill a 6.8 mm hole (7mm if you do not have 6.8mm). Now you can try to recut the M8 thread. Pry out as much as you can at the top to get a good starting point.
If that fails drill the hole with the drill that came with the helicoil, cut thread, insert helicoil and done.

Patience is the key to success

[spitfire]

I recently had a similar experience with my 76 750F, though the exhaust attachment is different the principle is the same. when I removed the exhaust system one stud broke leaving about 1/2" protruding. Following advise from people on this forum I spent 2 - 3 alternatively soaking the stud with WD40, spraying it with a freezing penetrating spray, heating it with a torch and giving it a sharp whack with a hammer to try and jar the threads loose. I then used a roller type extracter which broke the stud revealing that nothing at all had penetrated.
I had been toying with the idea of checking the pistons and rings on the bike as it had not been fired up in 12 years, the broken stud made up my mind so out came the engine and off came the head and cylinder barrels. Rather than butcher the head myself I took it to a car engine shop for a small amount of money they drilled the head and fitted an insert, while it was there they soaked it in a bath for two days to clean it. If I had not wanted to check the pistons and rings I could have taken the whole bike for the work.

[spitfire]

Whoops, should have read 2-3 weeks

[sparty]

Two hours of tapping, spraying, heating, tapping, tapping, tapping, and repeating.  A broken back, stiff neck, scuffed knuckles, and one extracted screw!  What a wonderful day to be alive!  I got the SOB of a screw out about 20 minutes ago.  Here is a picture of what I had to deal with.  Guess which screw wouldn’t come out?

Now I can install the new exhaust.  This part of Nightmare CB750 is over.


Sparty

[johnny-from-bel]

Congratulations !!

[750goes]

Be gentle with the new screw, and clean the existing thread hole out with a wash of wd40 or some lubricating fluid, and make sure you can screw it all the way in easily before putting on the exhaust.

As i mentioned mine came out ok, but screwing it in I had to clean out the old thread- and that took a while to do as well.

did you put new exhaust gaskets on the head

[sparty]

Be gentle with the new screw, and clean the existing thread hole out with a wash of wd40 or some lubricating fluid, and make sure you can screw it all the way in easily before putting on the exhaust.

As i mentioned mine came out ok, but screwing it in I had to clean out the old thread- and that took a while to do as well.

did you put new exhaust gaskets on the head

I will no longer be using screws for the exhaust.  I am going with stainless bolts and anti-seize on the threads.  I will be cleaning out all of the bolt holes first, that is for sure.  And YES, I will be installing new copper exhaust gaskets.  I never take shortcuts with my mechanical repairs/modifications.  If something is wrong, I usually over-fix it.  I have also been updating the bike to make it safer (ex. new sportbike MC with braded lines, rebuilt front fork, and new rear shocks).

Sparty

[oldbiker]

Well done Sparty. I admire your perseverance.

[sparty]

Well done Sparty. I admire your perseverance.

Not really perseverance, but rather desperation - I want to ride the damn thing...

I learned or re-learned a very valuable lesson in patience.  I have never had to spend eight hours extracting a screw/bolt before.  However, my celebratory beers afterward never tasted so good.

Sparty

[spitfire]

Great news, glad it worked out for you.

Cheers

Dennis