Author Topic: Should I be worried (cracks in head)?  (Read 6578 times)

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Offline SOHC4 Cafe Racer Fan

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Re: Should I be worried (cracks in head)?
« Reply #25 on: April 18, 2015, 07:26:53 AM »
I don't know if the machinist caused any damage but if not, he could have told you that head was a list cause and not worth using.
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Offline PeWe

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Re: Should I be worried (cracks in head)?
« Reply #26 on: April 18, 2015, 07:59:18 AM »
What happen if the washer on the cam at the cyl 1 end is not mounted?
Can the cam slide closer to cyl 3-4 or will it be held in place by the cam chain? The washer must have that purpose.
The valve cover has damage as this has happened. Or is it not thread locked cam sprocket bolts?
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Offline strynboen

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Re: Should I be worried (cracks in head)?
« Reply #27 on: April 18, 2015, 08:22:31 AM »
the maskinist must stop the vork vhen he fund this cracks..no matter the other damage parts
..he vork on the head..and must kontroll the material before start mashine on it

.pay for kleaning of the head.is all you can be taxed for.so he can kontroll for any damage..rest are fzuck up vaste.
..he must absulut stopp the vork ,vhen he find this cracks..and kontakt you..

..all vork are vasted..and the maskinist  to blame ,and eat all vork and matriall vasted on this job...
im self maskinist,,,and it are just a tele call or mail to you..to do it korrekt and soper..
« Last Edit: April 18, 2015, 08:25:22 AM by strynboen »
i kan not speak english/but trying!!
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Offline LesterPiglet

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Re: Should I be worried (cracks in head)?
« Reply #28 on: April 18, 2015, 06:26:18 PM »
If I had been tasked with this work I would have drawn attention to the damage straight away, otherwise I could be held respsonsible.
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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Offline LesterPiglet

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Re: Should I be worried (cracks in head)?
« Reply #29 on: April 18, 2015, 06:27:55 PM »
Ive also had a cam like this. The owner broke it peening the bolt.  :-\
It was me.  :-[
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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Offline MRieck

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Re: Should I be worried (cracks in head)?
« Reply #30 on: April 18, 2015, 07:48:39 PM »
I was going to say it looks to me as though the seats are the source. Widest crack begins on both seats, then travels to plug hole. Also upper seat looks chipped where it approaches the lower- Be interesting to hear from Mike R on his opinion to cause and recommendation.
I have seen hundreds of 750 heads and never seen cracks like that. Cracking between the seats isn't uncommon on GS1100 heads. After looking at all the pieces involved who knows what the hell happened.
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Offline hotdog

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Re: Should I be worried (cracks in head)?
« Reply #31 on: April 18, 2015, 08:03:38 PM »
Early xr250/350 heads used to do that a lot, caused by running plugs that were too hot.

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Offline calj737

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Re: Should I be worried (cracks in head)?
« Reply #32 on: April 19, 2015, 07:41:27 AM »
I was going to say it looks to me as though the seats are the source. Widest crack begins on both seats, then travels to plug hole. Also upper seat looks chipped where it approaches the lower- Be interesting to hear from Mike R on his opinion to cause and recommendation.
I have seen hundreds of 750 heads and never seen cracks like that. Cracking between the seats isn't uncommon on GS1100 heads. After looking at all the pieces involved who knows what the hell happened.
Well that wasnt worth the wait... :-* just messing with you, Mike!
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Offline Noddy78

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Re: Should I be worried (cracks in head)?
« Reply #33 on: April 19, 2015, 04:57:07 PM »
So, the rest of the head:

4.


3.


2.


1.


And 1 and 4 exhaust:



I'm off to have a chat with the "machinist" this afternoon...

Offline hotdog

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Re: Should I be worried (cracks in head)?
« Reply #34 on: April 19, 2015, 06:10:20 PM »
In the bin for that one....

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Offline Noddy78

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Re: Should I be worried (cracks in head)?
« Reply #35 on: April 19, 2015, 06:54:46 PM »
Yep, and the head as well...  >:(

Follow up question number 2: When they planed the cylinder head, should they have planed the mating surface on the cylinder block as well?

Re-asked follow up question number 1: Are the valve guides removable and reusable on a new head (they were brand new Cycle X valve guides)?

Thanks again for the advice guys.

Offline calj737

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Re: Should I be worried (cracks in head)?
« Reply #36 on: April 19, 2015, 07:22:02 PM »
I see no reason that the guides can't be pressed out? I'm not Mi,e Rieck, but they only need to be replaced when worn. These are new and unused, so press them out and install in a new head.

Milling the underside of the head is only necessary if there's warpage. The deck doesn't necessarily need to be milled unless it is showing signs of unevenness. If both are done, then you must also trim the dowels the corresponding combined measurement to allow the two surfaces to fit together and not be held apart by too long dowels.
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Offline Noddy78

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Re: Should I be worried (cracks in head)?
« Reply #37 on: April 19, 2015, 07:25:15 PM »
I see no reason that the guides can't be pressed out?

Yeah, that was my assumption also, just wasn't sure if in the installation and removal process they are likely to get deformed in some way.

Offline Noddy78

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Re: Should I be worried (cracks in head)?
« Reply #38 on: April 19, 2015, 10:42:25 PM »
Well, upshot is the bloke was trying to tell me "No, that's fine, its not a water-cooled head, I've done hundreds of bike heads, Z900s, twins, singles etc and heaps of them have looked like that and I've had no trouble with them at all. It'll be totally fine."

"You can't be serious, everyone I've showed it to said that head is toast. Can you guarantee me 100% that when I put this back together it's not going to implode on me at 110Km/h down the highway?"

"Yep, it won't be a problem. But if you're not happy I'll reco another head for you."

"And charge me how much?"

"Nah, I'll just redo another one if you're not happy, but it'll be totally fine like it is."

"Alright, look, I'll take it and get a second opinion, and if they say it's toast, then I'll get you to redo a good one."

So, off I trundle to my local bike workshop: "Would you put this engine back together?"... "Nope".
Off to the other machinist in town... "Would you put this engine back together?"... "I wouldn't touch it with a ten foot pole. A lot of guys will tell you they can chase the crack and re-weld and whatnot, but it'll never be the same. Just get a new head and be sure."

So, I rang him back and said, sorry mate, you're the only bloke telling me it'll be fine. I'll bring another head in and you can redo it for me.

So that's where we are... I really don't trust this guy now, but he did do my last engine and that was fine, and he does pretty much do all the motorbike work in town and came recommended, so I really have to give him a chance to fix his stuff up (even if he doesn't think it is). Otherwise it's just going to be a PITA trying to get the money back off him...

So, replacement head time!

Offline hotdog

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Re: Should I be worried (cracks in head)?
« Reply #39 on: April 20, 2015, 01:21:36 AM »
Where are you based noddy.?

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Offline Noddy78

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Re: Should I be worried (cracks in head)?
« Reply #40 on: April 20, 2015, 01:23:47 AM »
Little ol' Hobart!

Offline calj737

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Re: Should I be worried (cracks in head)?
« Reply #41 on: April 20, 2015, 04:03:58 AM »
Noddy - could I make a suggestion: yeah, I know shipping and duty is horrendous to NZ from elsewhere, but, I'd bet we can locate you a very good head, get your guides installed (guaranteed right) and get it shipped to you so it will be 100%. Peace of mind may be worth a bit extra spend in the long run-

If you're up for some help from abroad, PM me. I can get your head done right. Press out your guides and send them to me. I'll send you back a ready to bolt on head. I am too addicted to your build to see you go off the rails looking for and waiting on another head locally and slow your progress.
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Offline hotdog

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Re: Should I be worried (cracks in head)?
« Reply #42 on: April 20, 2015, 04:09:07 AM »
Little old Hobart eh, (that's in Australia calj) I'm there now on holiday, small world.

I'm in Queensland but I'll offer some help as well if you get stuck. Can you source one locally.??

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« Last Edit: April 20, 2015, 04:27:10 AM by hotdog »
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Offline calj737

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Re: Should I be worried (cracks in head)?
« Reply #43 on: April 20, 2015, 04:11:04 AM »
Yup, knew that. But last he (Noddy) said, he was living in NZ. Perhaps he's moved? If he's in Oz, may be much easier for him to sort out and source a head then. Plenty enough good and trustworthy folks there.
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Offline ekpent

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Re: Should I be worried (cracks in head)?
« Reply #44 on: April 20, 2015, 04:56:05 AM »
What year is the engine/head in case someone wants to donate one ?

Offline Noddy78

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Re: Should I be worried (cracks in head)?
« Reply #45 on: April 20, 2015, 04:50:46 PM »
Hey folks, thanks for the offers! It's a K2 engine, but I believe anything from that to a K5 will fit? More than happy to pay for it if someone's got a good'un laying about they can get to me. Definitely none I can find is Tassie, only one I've found so far in Oz (and now sold). Heaps in the US but freight is a bit pricey!

Little old Hobart eh, (that's in Australia calj) I'm there now on holiday, small world. I'm in Queensland but I'll offer some help as well if you get stuck.

Haha, welcome to the best place in Australia then mate ;) You're not an ex-dentist/lawyer riding around on a Beemer with your wife are you? I will drop you a line if my search ends up fruitless though, thanks heaps.

I'll send you back a ready to bolt on head. I am too addicted to your build to see you go off the rails looking for and waiting on another head locally and slow your progress.

Thanks for the offer mate, and kind words. I'll try and see what I can source closer to home first, bit if it comes to that I will definitely be in touch. But you must also have me confused with someone else on the NZ thing, I've been in Hobart for the last 34 years...

Offline hotdog

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Re: Should I be worried (cracks in head)?
« Reply #46 on: April 20, 2015, 05:00:23 PM »
No,  not on a BMW. I was following a very sick sounding f2 from up north 3 days ago - its shat itself on the motorway north of Hobart. It is a nice spot, been here checking out real estate.


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Offline Noddy78

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Re: Should I be worried (cracks in head)?
« Reply #47 on: April 20, 2015, 05:21:14 PM »
It is a nice spot, been here checking out real estate.

You and every other mainlander at the moment! We finally bought our place a couple of weeks ago after 2 years of looking - so if you need some Hobart Real Estate advice let me know!

Offline mick7504

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Re: Should I be worried (cracks in head)?
« Reply #48 on: April 20, 2015, 05:27:00 PM »
If you do get stuck Noddy, give big Hugh a call at Robinson Engineering in Kelso, NSW.
He likes his Honda 4's and he may be able to help to source another head.
His workmanship is A1 and that's coming from personal dealings with him.
http://www.rpengines.com.au/
If I was you
I'd be worried about me.

Offline PeWe

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Re: Should I be worried (cracks in head)?
« Reply #49 on: April 21, 2015, 03:43:20 AM »
If you do get stuck Noddy, give big Hugh a call at Robinson Engineering in Kelso, NSW.
He likes his Honda 4's and he may be able to help to source another head.
His workmanship is A1 and that's coming from personal dealings with him.
http://www.rpengines.com.au/

Their video is great! I guess it is very easy to get expensive ideas when watching videos like this! http://www.rpengines.com.au/big_bore.htm
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967