Author Topic: Replace a cylinder sleeve / liner.  (Read 581 times)

Offline Erwin83

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Replace a cylinder sleeve / liner.
« on: February 01, 2020, 09:49:23 AM »
I decided to pick up my old engine and see if it is at all suitable to rebuild.
I found a little surprise in cylinder 4.
Now I have another old 350 cylinder block on the shelve, also with damaged cylinder due to a piston failure.

Is it possible to replace a liner?
If so, how?
CB350f with 400f engine

Offline Trigger

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Re: Replace a cylinder sleeve / liner.
« Reply #1 on: February 01, 2020, 10:43:08 AM »
That's is not too bad, ask a re borer to bore it to 0.50 and see if it will clean up  ;)

Offline Erwin83

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Re: Replace a cylinder sleeve / liner.
« Reply #2 on: February 01, 2020, 10:56:01 AM »
I don't think that will work. There are some deep pits (i brushed it off in the meantime).

Plus: that will mean 4 bores, 4 pistons, 4 sets of rings

Whereas if i replace the sleeve, i can fit 1 other standard size piston and just do the rings.

Matter of cost vs benefit...
CB350f with 400f engine

Offline Erwin83

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Re: Replace a cylinder sleeve / liner.
« Reply #3 on: February 01, 2020, 11:01:23 AM »
BTW. This was a good running engine, I just replaced it because of oil leaks, and over a decade ago, 400/4 engines were available for less than the price of a gasket kit....
CB350f with 400f engine

Offline the-chauffeur

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Re: Replace a cylinder sleeve / liner.
« Reply #4 on: February 01, 2020, 11:28:13 AM »
To get the liners out, stick the barrel assembly in the oven.  The aluminium block expands at a faster rate than the liners, so once the oven's hot enough, the liners will fall out.  If you stand the assembly right way up (like it would sit in the engine) gravity will help pull the outer block down; you'll hear a thump when it goes.  Can't remember what the "right" temp is, but it's not all that high - 200 deg C or something similar should get you started.

Usual caveats apply: make sure there's nothing rubber left in/on the assembly - like the rubber rings that hide around the liners under the block (or the fin spacer plugs on the '750s) - and if you're doing it in the house, clean the whole thing thoroughly before you start.  Even then, it's probably going to get a bit smokey . . .

Refitting is basically the same process in reverse, but when you do it, put the assembly upside down so the block falls onto the liners as they heat up.  And if you're swapping liners between blocks, don't forget to check they seat properly and the top faces are completely flush.  You may need to skim the deck depending on how closely matched the liners are.  I tend to use the sandpaper-on-glass/MDF technique for that.
« Last Edit: February 01, 2020, 11:30:23 AM by the-chauffeur »

Offline Erwin83

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Re: Replace a cylinder sleeve / liner.
« Reply #5 on: February 01, 2020, 11:38:45 AM »
Thanks. I'll give it go right away.
CB350f with 400f engine

Offline Erwin83

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Re: Replace a cylinder sleeve / liner.
« Reply #6 on: February 01, 2020, 12:07:11 PM »
Wow. That did not disappoint at all.
Baked at 225 degrees celcius for 15-20 minutes.
I put the sleeve i wanted to remove on a spanner, so at first sight when it came up, i removed the block from the oven and tapped it out. No force needed at all.

This is why I love forums :-)
CB350f with 400f engine

Offline Erwin83

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Re: Replace a cylinder sleeve / liner.
« Reply #7 on: February 01, 2020, 01:14:27 PM »
And, all done!

Allthough it does seem to need a refacing, as even with some massaging with a block of wood and a hammer, i can't get the cylinder to seat completely flush. Just a hair though.
« Last Edit: February 01, 2020, 01:16:43 PM by Erwin83 »
CB350f with 400f engine

Offline mickwinf

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Re: Replace a cylinder sleeve / liner.
« Reply #8 on: February 01, 2020, 03:15:36 PM »
Just be aware cylinders wear oval so piston may not fit, Trigger told me that!
Love the 500/4 and 550 own a 550 f2 at the moment

Offline Erwin83

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Re: Replace a cylinder sleeve / liner.
« Reply #9 on: February 01, 2020, 03:32:43 PM »
Just be aware cylinders wear oval so piston may not fit, Trigger told me that!

Do they wear, or do they warp?
In case of wear, i would assume pistons only fit easier (with oil consumption as a result). If the cylinders warp (i can’t see how), I can imagine the fitment is going to be problematic.
I didn’t check the direction of the liner when installing, but looking at the machining, I may have ended up with a 90 degrees turn, which is worst case for ovality...  ::)
CB350f with 400f engine

Offline Trigger

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Re: Replace a cylinder sleeve / liner.
« Reply #10 on: February 01, 2020, 03:41:20 PM »
This is not as easy as it seems. Never had a worn bore that is round in all my 28 years of doing this job. Pistons are not round at the skirt, this means a bore is not round with use.
You need to get the piston to bore clearance right or it will smoke and burn oil with low compression. 

Offline Erwin83

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Re: Replace a cylinder sleeve / liner.
« Reply #11 on: February 01, 2020, 06:46:05 PM »
Thanks! I’ll definitely check before putting everything back together.
CB350f with 400f engine

Offline Trigger

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Re: Replace a cylinder sleeve / liner.
« Reply #12 on: February 01, 2020, 10:35:26 PM »
The bores in your picture have rust were water has been sitting on the pistons. You will need a piston kit over size and a re bore. If you try to clean up those bores, they will not be within spec  ;)

Offline Erwin83

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Re: Replace a cylinder sleeve / liner.
« Reply #13 on: February 02, 2020, 09:56:18 AM »
The cylinder with rust is replaced now, so there is no more rust.
The piston seems to clean up well.

So, I need a clearance check, (all is standard size now), maybe a hone job and a ring kit.
I wouldn't know why I would bore 4 good cylinders to oversize..?
CB350f with 400f engine

Offline Nurse Julie

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Re: Replace a cylinder sleeve / liner.
« Reply #14 on: February 02, 2020, 10:15:16 AM »
The cylinder with rust is replaced now, so there is no more rust.
The piston seems to clean up well.

So, I need a clearance check, (all is standard size now), maybe a hone job and a ring kit.
I wouldn't know why I would bore 4 good cylinders to oversize..?
It doesn't matter how good or undamaged the cylinders are if they are very close to or beyond spec, they may still need a rebore.
Im a Nurse, trust me, this won't hurt.....much !!!

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