JasonsBanshee Posted December 4, 2013 Report Share Posted December 4, 2013 Hey guys, I’m in the midst of a 421 cub build. Although this is my third Banshee build, this is my first build that is not a stock cylinder so this is new territory for me. I have some rookie questions about Cub cylinders. From what I understand, these cylinders have to either be sleeved or Nikasiled? Most people go with Nikasil? So does this mean that the bore is always 68mm and unlike stock cylinders, you can’t bore/hone when damage happens to the cylinder wall? If I understand this correctly, Nikasil is very strong, but if you do damage the Nikasil, instead of boring/honing like you would on stock cylinders, you would have to have the Nikasil redone which would keep the bore size at 68mm? I’ve also heard that if you did sleeve a cub cylinder, it can be difficult to find any other size pistons than the standard 68mm? So if you went 30 over, it would actually be difficult to find a piston to match the bore. Can someone please help me clear this up? Thanks! Quote Link to comment Share on other sites More sharing options...
KaN Powersports Posted December 5, 2013 Report Share Posted December 5, 2013 Nikasil is a Silicone/Carbide blend cemented with nickel. It's hardness is second to diamond, and it is 'oillific' meaning that it chemically bonds with oil and retains it in it's pores. Meaning=harder than a sleeve, more slippery, and it's elasticity (thanks to the nickel) is similar to aluminum, so a tighter clearance can be utilized if desired. It's thickness averages .002-no more than .010 so there is not much maintenance available and it takes a diamond hone to perform correctly. In the event of a failure the cylinder needs to be stripped in a Nitric acid, welded and bore restored, then re-plated. A sleeve is 'serviceable' meaning it can be bored, honed, replaced at will etc. Newer sleeves are alloyed with a CrMo cast iron blend that helps reduce friction over their predecessors, and their rockwell testing yields better results than ever before. They need more initial clearance to a given piston due to different expansion rates of aluminum/steel at same temps. Their biggest crutch is that they retain more heat than nikasil, therefore, it runs hotter or needs a better cooling system for similar set-ups. 1 Quote Link to comment Share on other sites More sharing options...
dave5.0 Posted December 5, 2013 Report Share Posted December 5, 2013 Buy a cub cylinder, have your builder clean up the ports, slap it together, shit yourself. Just that easy. Key here is don't burn it down. Then you don't have to worry about all that crap. Dirt bikes have been that way for a LONG time. Proven tech. 1 Quote Link to comment Share on other sites More sharing options...
registered user Posted December 5, 2013 Report Share Posted December 5, 2013 steel sleeves r gay. nikisil is the way brotha. even if you fry the piston a few times it aint gonna hurt the bore 1 Quote Link to comment Share on other sites More sharing options...
Jereme6655 Posted December 5, 2013 Report Share Posted December 5, 2013 While sleeves have been around forever in the iron that KnN is talking about......nikasil has been around a long time too. Snowmobiles come with nikasil bores. Some dirtbikes I've seen are niked. It is much stronger and does wear WAY WAY WAY less than iron bore sleeves. It IS way more of a cost to have a nikasil bore replaced if you damage it. You can melt your pistons down and use a specific acid to wipe off the melted on aluminum piston. HOWEVER do not think that you cannot hurt nikasil.......it has happened....usually it takes something serious though, such as a connecting rod snapping and shoving into the bore. an example of how nikasil bores wear rates? My 97 Yamaha 500cc twin cylinder snowmobile has 8300 miles on it on the stock bore, stock pistons. It has NEVER been opened up and never played with. And I STILL see no time in the near future of having to open the motor up..... 1 Quote Link to comment Share on other sites More sharing options...
Finch Posted December 5, 2013 Report Share Posted December 5, 2013 Only took me 5 mins to ruin nik but good stuff stock cyls I would of had to thrown away. 1 Quote Link to comment Share on other sites More sharing options...
JasonsBanshee Posted December 5, 2013 Author Report Share Posted December 5, 2013 Awesome thanks guys! Quote Link to comment Share on other sites More sharing options...
camatv Posted December 5, 2013 Report Share Posted December 5, 2013 as with any motor bad build and/or horrible tunning will make it melt down.. nicko usually doesn't get damaged its the aluminum underneath that fails. coolant likes to eat it out when its very hot ( like when you blow an o-ring or head gasket) if you take care of the motor and it is built right they should and can last a very long time. most fail from trying to get more power out of them than is possible, or bad setup . it is not a good idear to sleeve a cub cylinder ( yea i know some have done it bla bla bla i wont) Quote Link to comment Share on other sites More sharing options...
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