Welding exhaust to cylinder head??

[tnahvu]

So one of the bolts that mount the exhaust header onto the cylinder head snapped off and when trying to extract it out with an EZ out, I broke off the damn extractor in the broken bolt. nice and flushed.

So far, I have managed to drill some of it out, but still has a crap load left and it's starting to look messy. :/

I'm not sure if i can even re-tap this thing to a 7 or 8mm...so my question: is it possible to just weld the exhaust head to the cylinder head? If that's a bad idea, is there any other solution?

It's getting warm and I'm really itching to ride it.

Thanks

 

[Tim]

Bad idea and likely impossible given the materials involved.

Before you destroy your head consider taking it to a machine shop to have them remove the stud.

 

[tnahvu]

Bad idea and likely impossible given the materials involved.

Before you destroy your head consider taking it to a machine shop to have them remove the stud.

I figured.

Thanks

 

[Tim]

I mean there's a million other reasons like the vibrations that would have the header cracked off in a second etc. Focus on fixing the problem and it will get sorted.

What bike is this? Got a pic of the problem?

 

[Ahamay056]

Focus on fixing the problem and it will get sorted.

A machine shop can do wonders on these sort of problems and Tim is right on here, even if it comes to getting another head casting and putting your top end parts in it.

 

[rhavindog]

the proper technique is not to drill out the whole stud and thus destroy the threads, try a small bit, drill out the center of the stud. a tiny hole right down its length. dont go to deep, measure on the other studs. this will relieve the stud and allow it to turn easier. lubricate it then try to turn it out. Ive cross cut em before and used a flat head screwdriver to get them out. on a side not, this is also the way you get a stuck bullet out of your carry guns barrel.....I think maybe i should up the powder charge a bit. lol

 

[teazer]

Breaking off E-Z outs is one of my special "talents". Solutions depend on the part.
Sometimes the EZ out can be ground out with a carbide bit in a dremmel.

Sometimes the surrounding part is damaged and it's easier to dig it all out and weld it up and drill and tap a new thread.

Other people have success with spark erosion aka EDM IIRC.

Try a dremmel and carbide bit and then tap it for a helicoil insert. If the damage is too great, go up a size and it it's really bad you could open it up and fit an insert made from a larger bolt drilled and tapped in the center - like a grub screw with a thread inside.

 

[tnahvu]

Right now i'm leaning towards snatching a used cylinder head off of ebay for $100 since the current head has already been to the shop once before for tappet cap troubles and the shop i took it to has put a seal on that repair which makes valve clearance adjustments near impossible unless i break off the tappet caps. So best get a new cylinder head, me thinks. This recent incident was just a nail in the coffin.

The bike is a 1975 honda cb200.

Thanks for all the inputs. I'll definitely keep them in mind and put to good use next time this happens. Thanks for keeping this forum so fantastic!

Patience + dotheton = more DIY and less money spent at the shop.

 

[crazypj]

You obviously need a better shop
Damage to rocker caps is pretty normal after they have either been overtightened or left sitting for 20~30 yrs.
A machine shop could probably fix all the issues for way less than $100.00.
Find a smaller shop that does automotive work, You probably have something local you don't yet know about
You'll have to take hea there and explain exactly what you want done, never try and do it over the phone, they will just say no
Easy-outs suck, if the original screw/std was 6mm and snapped, why would a 3mm~4mm piece of metal work any better? (plus the wedging action of taper forces material tighter into top of thread)
I hate the damn things, had to remove way too many broken ones for people.
Soilid carbide burr in Dremel is way better but much slower
Check eBay for 1/8" shank burrs

 

[teazer]

Please post a picture of the damaged thread and the other damage so we can make a better assessment as to whether it's worth repairing.

 

[DrJ]

Get a shop to weld a steel rod to the stud then use it to back it out.

 

[tnahvu]

Please post a picture of the damaged thread and the other damage so we can make a better assessment as to whether it's worth repairing.

So here are a few photos of the damage.

The left side was where the bolt broke off, then drilled with a titanium 1/64 bit, then a 1/32. However, with the ez out still in there, i wasn't able to keep it straight and then ended up going through a little bit of the side where the heat fins are. Total screw up, i know.

I think a big contributing factor that catalyzed most of these problems is the stress placed on these bolts when my craigslist mechanic (before i found dotheton mounted both exhausts on the bike without further support/attachements to the frame; having the exhausts head bolts as the only support.

The original bolt was a 6mm.

The right side doesn't have any threads on it at all. I've used helicoil on it once already, but it didn't last long.

Here she sits waiting to be patched up.

But yes, please give me your feebacks as to whether it's worth saving. I'm starting the preps for taking the engine off the frame since i have to take the cylinder head out regardless of replacement or repair.

Thanks

 

[Titan performance]

A 6mm bolt is pretty small, and they often get stuck when screwed into aluminium. As a previous poster has already stated, a decent engineer will fix all that stuff easy. it's very difficult to drill out a broken bolt, or easyout, as the drill naturally wants to wander off the harder material into the soft aluminium. The shop will set it up under a pillar drill and drill it true. It can then be welded up and a new thread cut.
When we pull engines down on the Suzuki 500, we replace the exhaust bolts with studs, and a nice stainless dome nut on top. It looks better, and you never have this problem again.

 

[teazer]

Those are clearly rooted as they say in "Or stray lee are". Pop the head off and take it to your local welder who should be able to cut the damaged part out and weld it up for 20 - 40 bucks. Get the head home and dress the weld down and then position a pipe and mounting ring and carefully mark it and drill and tap it for a stud. We have had to get a few done like that and they were a PIA but not complicated or too expensive to fix.

What was the other damage that you mentioned - something about tappet caps IIRC?

 

[tnahvu]

What was the other damage that you mentioned - something about tappet caps IIRC?

Thanks for the advice!

The tappet cap damage was came from when I tried to open the cap when the engine was still hot (a bad mistake) and the threads grinded against each other and it basically became stuck. I don't know how the shop managed to take the damaged cap out but they did and put a new one on with a type of seal that is basically harden and i will have to break off to get the tappet cap off -- so they say. I haven't tried to open the cap but I will have to to get the cylinder head off, obviously.

 

[teazer]

Hmm. That doesn't sound too good. If they used something like JB weld to "stick" the cap on, it will never be very good. Wheil you are dropping the motor and stripping the top end out, keep your eyes open fr a replacement. I'm out of touch with teh real world. We bought one complete motor for 25 bucks IIRC.

I find that if I need something there's none around and they want top dollar. I try to buy things I will eventually need when they are available cheaply. That way, if I get them great and if not, there's always aother one just around the corner.

 

[hillsy]

Probably easier / cheaper to get another head by the looks of those pics......

And put some studs on the new head for the exhaust so you don't have this problem again

 

[tnahvu]

Yep. Im taking the the head to Popp Machine shop and see if they can save it for a decent price; i always do prefer to reuse and repurpose things rather than buying new things. But if not, then a replacement is in place of course.

Thanks again for all the comments and suggestions!

 

[tnahvu]

OK. So i got this off of Ebay for $80 shipped. It was originally $100 but has a missing stud. Comes with head cover, springs, valves and cam tensioner (not in picture.). A good deal, me thinks.

 

[teazer]

Sounds like a good deal and probably more cost effective in teh long run. Don't forget to fit new seals on the guides after you clean up the valves and seats.