Piston ring and head rebuild

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Piston ring and head rebuild

nilsthenomad
Hey All,

Need to replace the piston rings on my '81 750K this week for the first time. Figure this is quite an undertaking for a newbie like myself, but have attempted to brush up on with every shop manual and instructional video I can find. If anyone has any great sources (beyond the shop manual) or videos they could  share, I'd love to see 'em with regards to removing the head etc.

Also, does anyone know if I can pop off the head and get at the pistons without removing the engine from the frame on the DOHC's? It looks as though the clearance would be pretty tight, but I imagine someone has attempted it and would have the answer for me.

I purchased new piston rings and a full new gasket set. If anyone has any major suggestions or anecdotes for techniques or common problems that could be helpful for a first timer I'd greatly appreciate them in this thread. Thanks in advance!
'81 CB750K, '70 C70. As long as the Honda's older than I am, I'm happy...
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Re: Piston ring and head rebuild

TOOLS1
Administrator
You can remove the head, and cylinder from the DOHC engines without removing them from the frame. I would however suggest you build a table 5ft long X 2ft wide X 2ft high to put the bike on if you are not removing the engine. This will make it so easy to work on, you won't believe it.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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Re: Piston ring and head rebuild

seestheday
If it has never been removed, or hasn't been removed in a really long time it can be a serious beast to get off.

Check out this thread: http://www.cb750c.com/modules.php?name=Forums&file=viewtopic&t=11804&highlight=cylinder+removal

I would just remove the engine from the frame.  It's not that hard to do and should make the job easier.
1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals

My wife's recipe website that I'm trying to help promote: Strawberries for supper. Yes, I am a lucky man.

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Re: Piston ring and head rebuild

FastCletus
I second the above thread.  once you understand how to remove the engine.  (in my instance remove the bottom bar on drivers right, not just unbolt one side, completed remove it) its a cakewalk.  You can do it solo with a floor jack, but 2 people make it easier

Take it from me I did my first engine rebuild about 6 months ago.  I was scarred shitless.  I took my time, understood what I was doing and raised my hand when i needed help.  For 3 months after the rebuild i kept thinking it was going to break cause I did something wrong, but she ran like a champ!  you can do it!!
@FastCletus552 aka Jimmy C, buildin' rides out of Napa CA
Current Build 1980 CB 750 F
Finished Build 1975 CB 500T Cafe Racer - SOLD
2002 Ducati 998 Biposto
2005 Rossi #46 Scooter
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Re: Piston ring and head rebuild

nilsthenomad
Well I'm underway. Really appreciate all the advice thus far and am relying heavily on that link you posted seestheday. Since I didn't have an easy spread to jack up the engine on I went with the leaving it on method, and am now regretting it. I got the head loose today quite easily even though this is the first time its been taken off. Slid it straight up and it wont clear the vertical bolts before being blocked by the frame. I know everyone said it should clear on the DOHCs, so is there something I may be doing wrong? Clearly the correct answer is to simply remove the engine now that I've tried to cheat with the easy route, but if anyone knows of any little tricks I might be able pull to make some room and pop the sucker off I'd love to hear em. Thanks!
'81 CB750K, '70 C70. As long as the Honda's older than I am, I'm happy...
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Re: Piston ring and head rebuild

seestheday
I still don't see how it can be done in the frame.

Sent from my BlackBerry device
From: nilsthenomad [via Honda CB750'S]
Sent: Saturday, June 8, 2013 3:53 PM
To: seestheday
Subject: Re: Piston ring and head rebuild

Well I'm underway. Really appreciate all the advice thus far and am relying heavily on that link you posted seestheday. Since I didn't have an easy spread to jack up the engine on I went with the leaving it on method, and am now regretting it. I got the head loose today quite easily even though this is the first time its been taken off. Slid it straight up and it wont clear the vertical bolts before being blocked by the frame. I know everyone said it should clear on the DOHCs, so is there something I may be doing wrong? Clearly the correct answer is to simply remove the engine now that I've tried to cheat with the easy route, but if anyone knows of any little tricks I might be able pull to make some room and pop the sucker off I'd love to hear em. Thanks!
'81 CB750K, '70 C70. As long as the Honda's older than I am, I'm happy...



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NAML

1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals

My wife's recipe website that I'm trying to help promote: Strawberries for supper. Yes, I am a lucky man.

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Re: Piston ring and head rebuild

TOOLS1
Administrator
In reply to this post by nilsthenomad
It should clear. Where is it hitting?
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)