In the riders seat
What would be the minimum thickness cylinder liner you would want to run
Alloy Barrel with a cast in sleeve and looking to do a major overbore on it which at the moment would only leave 2mm wall thickness
Keeping in mind the engine will be absolutely thrashed everytime it goes out
"If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough power."
Originally Posted by scracha
Royal Enfield user
Size of bike ?
Old school rule of thumb was .190" minimum wall
thickness to prevent cylinder flexing and loss of compression control.
but I have it written down somewhere I ll try to find it unless someone else beats me to it
Stephen
"Look, Madame, where we live, look how we live ... look at the life we have...The Republic has forgotten us."
In the riders seat
around 150-157cc single cylinder, around 66-66.5mm bore, stroke around 44-45mm
So going with your figures I'd need a total OD around 76mm?
"If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough power."
Hardcore Biker
I reciently finished my bigbore 92 cbr900 (1060cc) the liners were steel/plated and 2mm wall thickness.
Forum whore
Well 0.190" is just under 5mm. So ~71mm OD.
Didn't realise you could do them that thin. Half a mind to spend some extra money to have my XT350 sleeve cut down so I need to take less meat out of the CB250RS cylinder to fit it in. It's a stock sleeve so is relatively thick, maybe a 10mm or more.
Highway Biker
Used to work on 100 thou but have run thinner. Thats on 80mm+ bore. High rod ratio as well. From memory Phil Irving reckoned 100-125 thou for liners in alloy barrels. Different engines in those days. But with a 66mm shortstroke Id give 2mm a go. I presume majority of the load bearing area would be supported by the barrel. Overbored a trident once, 60 thou liner worked ok used to rev the snot out of it
Hardcore Biker
should be more than amble
my panhead has been resleeved in the past and rebored several times since, the sleeve is now only about 1.5 - 2 mm thick and it runs fine
In the riders seat
66mm bore with a 71mm OD would be a 2.5mm wall thickness
If I can get away with that the existing one might be close enough
"If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough power."
Forum whore
Royal Enfield user
all boils down to peak pressure and ring sealing, if the bore is flexing and thethe rings are flopping around you are going to get blowby , which causes a heap more problems ...2.5 mm on a 70mm bore sounds thin,,, but then I havent done the maths and my experience is with larger bores ( in fact i am ibn the middle of the calculation now for an 86 mm enfield bore )
Stephen
"Look, Madame, where we live, look how we live ... look at the life we have...The Republic has forgotten us."
Bucket Racer/Crasher
You need to get the best material possible and that will allow you to run the sleeve thickness down a bit. I've ended up using LA sleeve co. sleeves at about 2.5mm thickness on a 72mm bore. If you are machining them yourself keep an eye on the top flange where the sealing loads are relative to the support where it drops into the barrel. Also make sure you follow best practice when it comes to chamfers and radii on that top lip, especially if you use o-rings and copper gaskets. The o-ring grooves must be over the supported part of the lip. I had a problem where the sleeves would crack round underside of the lip. The right fit in the barrel is essential as well, too tight and the block cracks and too loose you get heat transfer problems. I actually ended up dropping bore size and divided the extra meat between the sleeve and barrel. I still get slight banding up/down the sleeve from the fins but at least it's not blue and straw bands like before.
Royal Enfield user
Honda CRF are 3mm and while it possible to run 2.5 on engines that are run for short times its pushing it a bit
One assumes that these will be used for buckets , ie short time and that there is no signs of blow by , ring trapping and detonation , then go go go !
bigger is better ,,,
Stephen
"Look, Madame, where we live, look how we live ... look at the life we have...The Republic has forgotten us."
In the riders seat
Our longest race is 55 minutes + 1 lap where it'll spend most of it's time at 11,000rpm+
Looking at the barrel I doubt I can go much bigger than 2.5-3 mm without the allloy casting getting to thin down the cam chain tunnel
"If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough power."
In the riders seat
After speaking to a engine reconditioner and explaining the usage he reckons I could do it with a 2mm wall thickness without problem
Although now I am currently investigating an alloy sleeve with nikasil plating
"If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough power."
Royal Enfield user
[IMG]file:///tmp/moz-screenshot.jpg[/IMG]blue is about 280 deg , Straw is about 230 deg c on the outside of a liner , add a few deg because of wall thickness and your running hot in there I would be using a good oil, That was with a 2.5mm liner, A 2mm liner if it is supported well,
but if the combustion pressures are up there , ie u intend to use high comp , then longitudinal and hoop fatigue stresses could be an issue as has been mentioned by the use of careful radii
Imay have some work lying around you can copy if you want
Stephen
"Look, Madame, where we live, look how we live ... look at the life we have...The Republic has forgotten us."
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