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Author Topic: Would I get away with a new grind... or do I need a new head..  (Read 1847 times)

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Offline KirkBurner

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Would I get away with a new grind... or do I need a new head..
« on: July 21, 2016, 11:42:58 AM »
if you look at the attachment...

I had an issue with a broken valve...
Fixable?
or have I just made myself a new boat anchor?

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Offline 754

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #1 on: July 21, 2016, 11:49:59 AM »
Hard to say with valve in the way, did the guide break? 
If the seat looks good it will take a new guide and start grinding to see if it's good.
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Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

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73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline KirkBurner

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #2 on: July 21, 2016, 11:52:02 AM »
alright.. I will get a new picture tomorrow, without the valve...

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Offline 754

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #3 on: July 21, 2016, 01:01:54 PM »
Just run it by an engine shop.
Hard to photograph, but easier to see with naked eye..
Us giving you advise on this,  is a bit like us giving you medical advice... Better to just go to the doctor.
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Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline KirkBurner

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #4 on: July 21, 2016, 02:30:16 PM »
True true...

Spoke to my mechanic.... he said the engine just became my project for this winter ...

I have a spare head.. I will test the engine with.


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Offline rusty_tank

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #5 on: July 21, 2016, 03:45:55 PM »
Quote from: KirkBurner on July 21, 2016, 11:42:58 AM
if you look at the attachment...

I had an issue with a broken valve...
Fixable?
or have I just made myself a new boat anchor?

How did this happen? Or did you buy a used head with a busted valve?
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Offline seanbarney41

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #6 on: July 21, 2016, 06:02:04 PM »
That valve smashed into the seat?...What does the top of the piston look like?
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If it works good, it looks good...

Offline KirkBurner

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #7 on: July 22, 2016, 01:09:41 PM »
I made it smash...

Anyways.. I promissed more pictures...






Sent from my iPhone using Tapatalk
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Offline CBGhia

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #8 on: July 22, 2016, 01:34:15 PM »
I'm no expert, but I wouldn't use that head. 
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CB550 Cafe, GL1000, Buell Ulysses
Quote from: dave500 on February 14, 2014, 03:53:33 AM
if you dont trial spin the camshaft in the head and cover you are a novice,with no natural mechanical appitude,destined for destruction.
"The cleaner the dipstick, the closer to God." -Rev. Horton Heat
“Faster, Faster, until the thrill of speed overcomes the fear of death.”  - Hunter S. Thompson

Offline 754

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #9 on: July 22, 2016, 01:55:49 PM »
I think the marks by the sparkplug thread, is he dealbreaker...
 Seat could be replaced..
Pretty light damage. Considering it dropped a valve..
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Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline KirkBurner

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #10 on: July 22, 2016, 02:08:41 PM »
Thanks for the input..

I will get to a proper machineshop and have them look at it..

I think I´ll just tear out a top from another CB I have and run that top out this season...
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Offline BomberMann650

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #11 on: July 22, 2016, 04:22:37 PM »
Ouchie
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Offline PeWe

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #12 on: July 23, 2016, 12:08:44 AM »
Time for a ported head as compensation for the accident!
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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

Offline Bodi

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #13 on: July 23, 2016, 08:47:22 PM »
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Offline 754

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #14 on: July 23, 2016, 09:47:17 PM »
Now That is what it usually. Looks like if it happens at high rpms..
In the OP,s situation,  it just needs a new seat,not too expensive..
« Last Edit: July 24, 2016, 12:13:06 AM by 754 »
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Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline PeWe

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #15 on: July 24, 2016, 02:54:22 AM »
Where to find a new seat? I do not need any, but good to know....
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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

Offline Lostboy Steve

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #16 on: July 24, 2016, 06:42:38 AM »
Quote from: PeWe on July 24, 2016, 02:54:22 AM
Where to find a new seat? I do not need any, but good to know....
Yes +1
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Offline MRieck

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #17 on: July 24, 2016, 08:02:53 AM »
Quote from: PeWe on July 24, 2016, 02:54:22 AM
Where to find a new seat? I do not need any, but good to know....
Kibblewhite. I replaced all the intake seats on the last head I did for my CB. Stock intake seats are soft
 
« Last Edit: July 24, 2016, 12:23:18 PM by MRieck »
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Offline KirkBurner

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Re: Would I get away with a new grind... or do I need a new head..
« Reply #18 on: July 26, 2016, 12:57:01 AM »
Quote from: MRieck on July 24, 2016, 08:02:53 AM
Quote from: PeWe on July 24, 2016, 02:54:22 AM
Where to find a new seat? I do not need any, but good to know....
Kibblewhite. I replaced all the intake seats on the last head I did for my CB. Stock intake seats are soft
 

sweet, thanks then I know where I can get them... I need atleast one new valve, and they are from Kibblewhite so.. maybe the order increased.. thinking I might D-port the exhaust valves or make some torque cones
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