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Offline afkrejci90

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Big bore cylinder air passage
« on: July 14, 2015, 09:10:44 PM »
Getting my block installed with new sleeves for 72mm pistons, I got a call from APE about the possibility of breaking through the air passage.  Figuring I'm not the first to install a kit this big, has anyone had an issue with oil leaks?  Is there any remedy for this?
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Big bore cylinder air passage
« Reply #1 on: July 14, 2015, 10:28:34 PM »
Sure there have been oil leaks. Jay did mine at APE. 71mm kit. He filled the openings in the block with epoxy. I have not run it yet however. I'll keep my fingers crossed.
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Offline 754

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Re: Big bore cylinder air passage
« Reply #2 on: July 14, 2015, 10:46:03 PM »
Yeah they can be leaky..If the sleeves are showing..it's prone to leaks..
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Offline Big Jay

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Re: Big bore cylinder air passage
« Reply #3 on: July 14, 2015, 11:57:46 PM »
These are larger sleeves are larger than what we use. They will break thru into the air passages.
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Offline afkrejci90

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Re: Big bore cylinder air passage
« Reply #4 on: July 15, 2015, 09:42:33 AM »
Jay, will your sleeves be the better option to go with here?
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Offline Big Jay

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Re: Big bore cylinder air passage
« Reply #5 on: July 15, 2015, 02:25:38 PM »
Alex;
Your pistons are 71.2 mm, an odd size.  Our sleeves were designed for 71mm max. I did the math and would have a .065" wall thickness. I really don't line anything under .075, .070max.   We can do it if you want. I hope you got rings to go with the odd size piston.

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Offline afkrejci90

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Re: Big bore cylinder air passage
« Reply #6 on: July 15, 2015, 02:36:30 PM »
Yes these were custom from JE so I have everything needed.  I really have no other choice but having these put in and epoxied. 

Just to clarify because I'm not too familiar with this, where is the break through on the cylinders?

Would brazing be better than epoxy due to the thermal characteristics?  I would think epoxy would warm up slower than aluminum and eventually break the bond.
« Last Edit: July 15, 2015, 04:42:37 PM by afkrejci90 »
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Offline Don R

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Re: Big bore cylinder air passage
« Reply #7 on: July 15, 2015, 03:36:32 PM »
 Between the fins
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Offline cbr954

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Re: Big bore cylinder air passage
« Reply #8 on: July 15, 2015, 05:35:31 PM »
I had a small seep even with the APE sleeves, ended up having to silicone the gap shut, though it isnt a permanent fix but it is working right now.  Cycle X will weld the gaps shut then bore them out for the new sleeves if it looks like they will break through.
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Offline bear

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Re: Big bore cylinder air passage
« Reply #9 on: July 15, 2015, 05:57:16 PM »
We use 72mm+ pistons in our race motors.
I would suggest you have them welded before removing the original sleeves by someone who knows what their doing.
Jim F would be the man I would think.
We used to use epoxy but the results where a bit hit and miss.

Cheers,
Brian
« Last Edit: July 15, 2015, 06:16:38 PM by bear »
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Offline 754

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Re: Big bore cylinder air passage
« Reply #10 on: July 15, 2015, 08:02:42 PM »
 I think what they may do is bore it out 90per cent..weld up any holes,  then finish bore and hone....for the best results.. But it adds cost...
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My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

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Lost quite a few CB 750's along the way

Offline scottly

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Re: Big bore cylinder air passage
« Reply #11 on: July 15, 2015, 08:40:54 PM »
You may want to consider one of Mike's billet cylinder blocks:
http://forums.sohc4.net/index.php/topic,49438.625.html
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Offline bear

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Re: Big bore cylinder air passage
« Reply #12 on: July 15, 2015, 09:13:44 PM »
Quote from: scottly on July 15, 2015, 08:40:54 PM
You may want to consider one of Mike's billet cylinder blocks:
http://forums.sohc4.net/index.php/topic,49438.625.html



No doubt the best option if the budget stretches.

Our solution is pictured below.

Mike's cylinders are a few steps further along the development path.

Cheers,
Brian



 


« Last Edit: July 15, 2015, 11:10:16 PM by bear »
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Offline Big Jay

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Re: Big bore cylinder air passage
« Reply #13 on: July 16, 2015, 10:47:25 AM »
Alex;

Have you seen the e-mail from Mike at APE?
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Offline afkrejci90

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Re: Big bore cylinder air passage
« Reply #14 on: July 16, 2015, 04:03:03 PM »
Quote from: Big Jay on July 16, 2015, 10:47:25 AM
Alex;

Have you seen the e-mail from Mike at APE?
Not yet, I pm'd you the correct email just in case.
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Offline afkrejci90

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Re: Big bore cylinder air passage
« Reply #15 on: July 16, 2015, 10:27:05 PM »
Quote from: scottly on July 15, 2015, 08:40:54 PM
You may want to consider one of Mike's billet cylinder blocks:
http://forums.sohc4.net/index.php/topic,49438.625.html

As much as I would like to get one of those blocks, I'm afraid it would just be a budget buster  :(
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'80 CB750C - Sold
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Offline Medyo Bastos

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Re: Big bore cylinder air passage
« Reply #16 on: July 17, 2015, 04:24:38 AM »
i have a freshly bored and honed RC BIG BLOCK 73mm


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