Author Topic: Bored cylinder question  (Read 2449 times)

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Offline cheapride

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Bored cylinder question
« on: December 22, 2011, 06:50:14 PM »
I just got my cylinders bored and I noticed something on a cylinder.  It looks like the cylinder moved when it was bored.  How much of a problem is this?  It looks like the o-rings would suffer.  How is this solved?

1978 cb750f Supersport

Offline Ernest T

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Re: Bored cylinder question
« Reply #1 on: December 22, 2011, 07:34:18 PM »
Take it back to the shop and have them realign it.  They shouldn't give it back to you like that.

Offline Old Scrambler

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Re: Bored cylinder question
« Reply #2 on: December 22, 2011, 07:46:56 PM »
WoW!  and who cleaned the deck with a #12 wire brush?  Did the machine shop match the new pistons specific bores? 
Dennis in Wisconsin
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Offline grcamna2

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Re: Bored cylinder question
« Reply #3 on: December 22, 2011, 07:57:32 PM »
It looks like they "decked" it with a surface grinder.
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Offline mrrch

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Re: Bored cylinder question
« Reply #4 on: December 22, 2011, 08:21:15 PM »
Cameras sometimes pick up too much light and make things look worse than they are. Lets hope this is the case.
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Offline 754

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Re: Bored cylinder question
« Reply #5 on: December 22, 2011, 09:26:30 PM »
 Warm it up and twist it back...
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Offline cheapride

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Re: Bored cylinder question
« Reply #6 on: December 23, 2011, 05:16:46 AM »
WoW!  and who cleaned the deck with a #12 wire brush?  Did the machine shop match the new pistons specific bores? 
My local doesn't do motorcycle jugs so I sent these to a well known company.  That company knows what pistons were being installed.  I really don't like the idea of shipping this across the country to have this fixed.  I would rather have it fixed local, but don't think it should cost me extra money either. The deck is pretty smooth I think my camera flash made them deeper than they are.
1978 cb750f Supersport

Offline Doctor_D

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Re: Bored cylinder question
« Reply #7 on: December 23, 2011, 06:40:38 AM »
Warm it up and twist it back...

+1

Put the cylinders in a 350deg oven.  The liners will release and you'll be able to rotate it back into position.

It'll be hot, so don't burn yourself.  ;)
Take care,
David
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Offline cheapride

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Re: Bored cylinder question
« Reply #8 on: December 23, 2011, 06:45:26 AM »
How long in the oven?  A hour or so?  Any risk of damage?

Thanks
1978 cb750f Supersport

Offline knowsnothing

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Re: Bored cylinder question
« Reply #9 on: December 23, 2011, 07:02:36 AM »
If it is a reputable company,  you could probably give them a call and have them pay for shipping both ways.  Its their screw up and if they want to keep customers happy they should fix it no cost to you.
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Offline Grabcon

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Re: Bored cylinder question
« Reply #10 on: December 23, 2011, 07:02:57 AM »
Personally I would call that well known company up and ask them what they are going to do to rectify the issue. If they are worth their salt they should pick up all costs and fix it for free.

This is a quality control issue and should have never left the shop.
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Offline ekpent

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Re: Bored cylinder question
« Reply #11 on: December 23, 2011, 07:18:18 AM »
What pistons are you going with by the way.? Was the box damaged at all where that could of happened in shipping,no dings or damage in the lower part of sleeve hopefully.

Offline cheapride

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Re: Bored cylinder question
« Reply #12 on: December 23, 2011, 07:25:25 AM »
I will give them a call in a couple of hours.  I know things happen but with this build it is starting to happen too frequently.  I am going with the wiesco 836 f2 kit.  No damage to the box or part.  Was packed with "unique" style but arrived ok. 
1978 cb750f Supersport

Offline Doctor_D

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Re: Bored cylinder question
« Reply #13 on: December 23, 2011, 07:28:41 AM »
How long in the oven?  A hour or so?  Any risk of damage?

Thanks

Just enough time to get it up to temperature.  20 minutes should be fine. And, no, there's no risk of damage.

FWIW, I agree with others that it shouldn't have happened, and that whoever did the work should take responsibility -- but if my choices were a half-hour fix or days/weeks in transit...
Take care,
David
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Offline jessezm

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Re: Bored cylinder question
« Reply #14 on: December 23, 2011, 08:30:42 AM »
My only concern with heating it and turning it back yourself would be the possibility that as the cylinders and sleeves cool off at different rates, the sleeves may want to pop up and stand a tiny bit proud of the deck.  Honestly I have no idea if this could happen, but when I looked into replacing my sleeves that was one of the things I was warned about.  So no direct experience, and take it for what that's worth.  If you have a way to clamp them into place as it cools, maybe that would be a good way to go.

Offline cheapride

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Re: Bored cylinder question
« Reply #15 on: December 23, 2011, 08:46:10 AM »
I was told that this was not an issue.  I am using the new MLS gasket and you don't use the dowels or orings since the gasket hugs the hd cylinder studs.  Sounds right I just looked that the gasket and those holes are much smaller than the factory gasket that uses dowels and orings.  It just looked funny so I was alarmed.  I really don't want to risk messing up the deck surface by placing them in the oven.  I guess I will leave it alone.   ???

Thanks for the info guys :)
1978 cb750f Supersport

Offline 754

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Re: Bored cylinder question
« Reply #16 on: December 23, 2011, 08:48:17 AM »
 You have to mount it on blocks, nail up a frame outa 2x4s, and hold the sleeves down after you turn it..till it cools. Thedy are not in there very hard..light interference..
 My guess is it turned slightly while boring. To illustrate the light press fit; got a panicked call oned from a buddy, was cooking the paint on his barrels, carried it across the room from the oven.. sleeves were pointing down slightly and started to creep out.
 They are not in there that hard, but expand after startup.
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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 MCRider

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Re: Bored cylinder question
« Reply #17 on: December 23, 2011, 09:00:28 AM »
I was told that this was not an issue.  I am using the new MLS gasket and you don't use the dowels or orings since the gasket hugs the hd cylinder studs.  Sounds right I just looked that the gasket and those holes are much smaller than the factory gasket that uses dowels and orings.  It just looked funny so I was alarmed.  I really don't want to risk messing up the deck surface by placing them in the oven.  I guess I will leave it alone.   ???

Thanks for the info guys :)
I was just getting ready to post that you might be told it was not issue. But then i chickened out.

Remembering that the earlier model bikes did not have ORings there, I was going to speculate that you could probably leave them out altogether and nothing bad would happen. Guess my guess was right.

There is no oil pressure there, the oil is simply returning to the sump by gravity. The purpose of the ORings was to try and further eliminate a chance of the head cheese seeping oil.
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Offline crazypj

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Re: Bored cylinder question
« Reply #18 on: December 23, 2011, 09:37:44 AM »
I've found it to be a problem with several Honda blocks.
 The liners are too loose and you can't take more than 0.010" cuts
 It's usually better to take around 0.006" but it then takes a long time to remove a few mm
It looks like they were trying to save time and took a deeper cut which causes liner to rotate
I've measured around 0.0007" ~0.0015" interference fit, at 'low end', liner can move when honing as block heats up.
 I don't like boring stock Honda blocks for big bore kits, prefer to fit new liners first to have at least 3.25mm wall thickness when finished (0.003" interference, liners shrunk in)
 LA Sleeve recommends 0.004" but I find that too tight and liners can crack when you overbore them (XS650, 800cc conversion)
 Correct thing to do would be remove all the liners, have the outside copper plated then shrink them back into block.
They need clamping into position, plus, cool top of block (otherwise they tend to 'grow' as block cools evenly.)
I've made various fixtures and have a baking tray I bolt to top of block (with various adapters to hold liners down) fill it with ice cubes to chill top of block.
I found out the hard way about this stuff, combustion leak into oil-way was not a good thing at 80mph (liner 'dropped' about 0.010"  :()
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