Machining from scratch and Nikasil plating motorcycle cylinder
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  1. #1
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    Default Machining from scratch and Nikasil plating motorcycle cylinder

    Hey guys,

    I have been casually reading the forum for a few years and finally have a project that I am considering.
    I restore vintage motorcycles and finally got my hands on a set of BSA B50 race bikes that I have been lusting over for years. These are early 70’s Big single cylinder bikes that are pretty rare. As I started to go through the parts I had, I noticed that the cylinders included were pretty ratty, scored inside and missing fins. The only replacement parts are used, and very expensive, with the best option to buy a good used cylinder and then press in a new Cast iron sleeve and bore and hone to size.
    I had recently done some work with some engines that use aluminum bores with nikasil linings and have heard nothing but praise for this modern practice: tighter clearances, incredibly long bore life and better cooling and weight. I noticed a few companies that manufacture cylinders for vintage air cooled Porsche's out of 6061 Aluminum and then send them out to be matched to pistons and nikasil plated by Millennium Technologies. I have been thinking about the feasibility of doing this myself. I have one good cylinder. I could have it dimensioned and drawn up in solidworks by a drafting expert and then offered out for machining complete from 6061. Millennium technologies says that they would finish the final bore and match it to the piston and plate. I believe that there would be a demand for this product, albeit small, a couple runs of ten or so, but it is an interesting thing to ponder. Currently there are several people who will re-sleeve with aluminum and then get the unit plated for a door to door price of close to $500. I am curious if there are any experts who might have an opinion on this concept and any advice.

    John
    Velocity Industries LLC New jersey

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    I'm no expert... but some thoughts.

    Are you intending to sleeve or make the entire cylinder out of AL? If sleeve, how would you deal with the differential expansion of the AL and Iron bore? Wouldn't it be better to line with a cast iron sleeve then plate (if you really wanted to)? If machining the entire cylinder, yep,it would look pretty but is what what a restorer wants? Are your stock gaskets/bolts going to work with the longitudinal expansion/contraction?

    Nikersil and chrome bores (both are used) are nice. Pro chainsaws have been doing this for decades... and they really do last. After a seize, I've scraped/dissolved Al piston residue off the bores, re-honed lightly (mostly to get a very light cross hatch back)and they last another 2000 hours.

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    Other option thats big in the model aircraft world is ABC, aluminium fins, brass liner and chromed bore, all three get along nicely.

    Fins on old cylinders are easy enough to make up and braze back on then reshape, its a common problem in the trade.

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    This may work or could be an expensive disaster. A big problem many British manufactures had back in the day when using aluminum for the cylinder was it going out of round when the bike got hot. An iron sleeve helped somewhat in preventing this. This is why the majority of bikes back then, besides a cast iron cylinder being cheaper, steered away from aluminum. Now on modern bike all these problems have been solved.

    Now I am not saying the nikasil cylinder won't work on your B50. If you have the time and funds to do it, I would say go for it.

    Back in the 1970's I had a factory race B50. Frame was different, all titanium hardware, head flowed, bigger valves and had been bored out to 584cc. It was the fastest B50 I had ever ridden. And yes I wish I had not sold it. But back then it was considered old worthless junk once the Japanese and Europeans were making much faster two strokes.

    I too restore old Brit bikes as a hobby. Currently working on a 1929 AJS.

    Bruce

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    I intend to go with a fully aluminum cylinder and nikasil bore-no cast iron. The benefits of the bore being the same composition as the piston include much tighter clearances for higher compression and longer bore and piston life. My real question is on the feasability and process that would be used in making these cylinders. Unfortunately they are not symettrical as in a Porche cylinder because of a tunnel for the pushrods. This company clearly turns their cylinders on a lathe Nickies / LN Engineering - Knowledge Base LN Engineering I will try to attach a good photograph. Here is a link: https://drive.google.com/file/d/0Bw2...ew?usp=sharing

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    Bruce,

    Both of these bikes belonged to Ted Hubbard at one time, he was pretty famous for making them fast. I imagine that if the cylinders were turned out of forged or extruded blanks they would hold their shape better as compared with the older castings-but your point is noted, thanks!

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    FWIW,
    when i was making alum cylinders for water cooled banshees, we would go .013" oversize on the final bore size prior to Nik. Then a vendor would plate and hone to final spec.

    as mentioned above, air cooled might be a 'hole' other ball of wax where any asymmetry of outside fins and whatnot may pull the bore out of round.
    really only one way to find out...
    or hone it hot.

    i could machine those from solid on my mill turn for around the re sleeve price, plus an NRE.

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    I would contact CCM in the UK. The purchased all the B50 parts from the BSA competition department once BSA went under. They made every modification possible to these bikes. It's likely they tried a nikasil cylinder as the process was developed in the 1960's. I believe Alan Clewes the owner is still alive.

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    CCM offers to replace you worn bore with an aluminum sleeve and Nikasil plate it. About $500 including shipping. I restore bikes and was thinking that it would be interesting to make a few of my own parts. I could make a new cyl/piston set and race it in AHRMA for a season and if it was successful, make a bunch and offer them for sale. MKD, I'll keep you in mind!

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    I've had a lifelong interest in old Brit bikes and worked on them in early years.
    As with most of us, many I wish I kept or connived to snag from the less than fully interested owners at the time. (In the US, waiting until they could fund a new rice rocket).


    So it would be disappointing if the power-that-be's makes this disappear or get the lock because you are not following rules including you locality.

    I imagine that if the cylinders were turned out of forged or extruded blanks they would hold their shape better as compared with the older castings-but your point is noted, thanks!
    What do you mean by forged? Like (some)old aircraft cylinders?
    That would be some interesting tooling and process for a few MC cylinders.

    I have some experience making patterns and having parts cast in Al & CI. My guess is that (stress relieved) cast would be better than say turning from barstock.

    smt

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    Stephen,
    LN engineering advertises 911 cylinders turned from what appears to be extruded barstock. There is a hole in the middle.How are Nickies cylinders made? / LN Engineering - Knowledge Base LN Engineering
    I assume that cast material is forced through a die, working the material for more strength and rigidity.

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    Aluminum cylinders work well sometimes, but not always. Aluminum expands much more than iron and not always in an even manner. Success is normally achieved when the cylinder is symmetrical in mass, on all sides and the cylinder is water cooled to limit high temperatures and greater expansion. Remember also the cylinder will grow taller in height with temperature and this must be compensated with waisted studs that will stretch accordingly without increasing the clamping force and yet not exceed the yield limit of the stud material. Since you already have 2 strikes against success with the mass symmetry and being air cooled, I think it is a very bad idea. You know iron sleeves from LA sleeve works all the time in your case, why take the chance? Further, in my experience aluminum cylinders do not make as much power as iron in the same way that aluminum heads also lose power over their iron equivalents. This is caused because aluminum wicks away heat with its greater heat conductivity and heat is power. Aluminum is used to reduce vehicle weight, not make more power. In your case, saving 2 pounds is not worth either the gamble of failure or the loss of power. I have a lot of motorcycle engine experience and this is just my 2 cents.

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    Steve-that is really interesting, thanks.

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    Quote Originally Posted by allflatblack View Post
    Steve-that is really interesting, thanks.
    Yes, it is. I am currently hot rodding a Rotax twin and it is equipped with all aluminum, water cooled cylinders with Nicosil bores. The cylinders also are of the modern open deck design. They are supported at the bottom of the bores and on the chain case side. I am experiencing an unstable bore where the bore is not staying round under load and moving at the top more than 1mm when at temperature. This is a really bad design. I would very much like to close up the deck and revert to iron sleeves for exactly the reasons I stated.

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    It's just a BSA B 50

    I'd just put in another CI liner, and call it good, Nikasilling a bore isn't going to turn it in to a world beater over night, Allan Clews and many others spent a lifetime and several bankfull's of money trying to achieve that.

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    Consider the total cost of what you intend to do, and weigh this against the potential use you think you will get out of the bike. I believe that the sense of accomplishment and the development aspects of the project are meaningful to you. If this is so, I think that it is good to carry on the aluminum cylinder project. If you do not use it much, you will be carrying out the work for future owners.

    Jim

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    I cannot imagine that 6061 is appropriate for engine jugs. You would need to stress relieve it at least. Cast aluminum has much stability built in and its higher silicon is more appropriate to the coating.

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    This brings back fond memories of a sponsored ride on a B50. What a mud bike! Start in 2nd, shift to 3rd and pretty much ride the whole slippery mess without shifting again. But it didn't take too long before I went back to my Husky 400 which was much lighter, better handling and a good bit faster on most courses.

    I think the comments pointing out CCM and Clews are pretty much spot on. They figured out how to wring all the juice out of that motor a good while ago. I'd look at where they went with it. I seem to remember they had a B50 based 600 or larger cc bike that was an absolute terror.

    Be prepared to struggle with the kick starter, or should I say be prepared to bump start the bike. I could never keep the kick starter shaft keys from shearing and leaving me with no choice. Finally gave a up and bumped it as standard procedure.

    I'd love to see what you do with the bikes.
    Pics if you got 'em!
    Last edited by henrya; 11-06-2015 at 08:45 AM.

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    Thank you for the advice guys-I will continue to look into the project to weigh out the possibilities, at least cost wise, but certainly see the issues raised here as useful and constructive. I will try to post some pictures once I get the projects rolling-I am surprised that there has been so much interest in this old bike on this board!

    John

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    Are Beezas really that rare now ? (Might have thought twice about machining the fins off the cylinders and head of my brother's project!)
    Attached Thumbnails Attached Thumbnails barrel-machining.jpg   beeza.jpg  


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