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So in theory then, if a person cryo'd a wiseco piston....it should hold up a little longer right? Here's what's floating around in my head....if you cryogenic something, you are basically aligning its molecules closer together right? That's where the strength comes from? So if they are closer, wouldn't this change the size of the object as minuscule as it may be?
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So in theory then, if a person cryo'd a wiseco piston....it should hold up a little longer right? Here's what's floating around in my head....if you cryogenic something, you are basically aligning its molecules closer together right? That's where the strength comes from? So if they are closer, wouldn't this change the size of the object as minuscule as it may be?
Heat treating always alters the shape of the part being heat treated. Cryo is just another form of heat treating. Any form of heat treating will not WILL NOT FIX THE DESIGN PROBLEM associated with large bore forged pistons!
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The hardness and decreased ware of the plated bores is just a byproduct of these hard plating. I have not seen anyone talking about the main reason for plating cylinder bores. Iron transfers heat at approximately 1/2 the rate as aluminum.
The engine industry had to find a way to dissipate heat from problematic areas in some high performance engines about 40 years ago. Yamaha began using chrome plating in there road racing engines around 1966. Mahle developed the Nikasil process for Porsche around 1970. Kawasaki developed the electrofusion process in the early 1970s.
As the power levels of stock engines continued to go up, the engine manufactures had to abandon the iron cylinder sleeves. The addition of power valves in two-stroke cylinders created more heat dissipation issues in the vicinity of the exhaust ports making plated bores an absolute necessity.
Replacing an iron sleeve with a plated aluminum sleeve will provide improved heat dissipation over an iron sleeve but will not provide the heat dissipation of a cylinder without a plated aluminum sleeve.
The heat transfer is hindered anytime there is a discontinuity in the metal between the surface of the bore and the water jacket or cooling fins. Even though the junction between a sleeve and the cylinder is a tight press-fit the heat flow through this junction is dramatically hindered.
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Jerry, question on your statement:
The heat transfer is hindered anytime there is a discontinuity in the metal between the surface of the bore and the water jacket or cooling fins. Even though the junction between a sleeve and the cylinder is a tight press-fit the heat flow through this junction is dramatically hindered.
Would the aluminum (NICKELSIL PLATED) sleeve conduct heat better than a steel sleeve, what benefits would a LT500 piston get from this setup?
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#29 Reply
Posted by
Iceracer
on 11 Dec, 2013 11:01
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Mitch , look at the 4 the paragraph. He already answered it. Yes it will be better than Iron. But not as good as a cast cylinder with no liner. The liner wouldn't bear any significant benefit to the piston.
You could possibly run a tighter fit if the expansion rates were better matched. But in the end pipe choice engine load, lengths of runs all play more into the the piston life.
Really need a better piston, longer rod, taller cylinder etc to improve piston life.
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#30 Reply
Posted by
Dezsled
on 11 Dec, 2013 11:04
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Is it a good idea to run a tighter pis/cyl tolerance with the similar metals/expansion rates of the two parts?
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Really need a better piston, longer rod, taller cylinder etc to improve piston life.
Oh well thats all it needs...............
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Millennium Technologies quoted me less tan $200 for plating, they also aluminum sleeve cylinders, they only done my 4 poke cylinders so far, but i was looking when my LT500 cylinders hit 88.5mm having them plate over the steel to run 88mm pistons. The thought processes was at 88.5 mm the cylinder has enough meat in it to keep from going egg shapped, seen too many 89 - 89.5mm bored cylinders and are way too thin.
They claim on plated cylinders is that you should be able to run at least 2 pistons life as long the coating is in good shape. ( no flakes, cracks,)
http://www.mt-llc.com/
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#33 Reply
Posted by
GrkGuy
on 11 Dec, 2013 11:24
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so what you are saying is if you have a 88.5 bore, you should get this done to help make cylinder last longer.
and it will be ok. how often do you think you would need to get this done. like every 4 or 5 pistons.
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Don't know yet John, have not done a cylinder for a 2 stroke yet, end up finding 86mm 86.5mm cylinders
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#35 Reply
Posted by
Iceracer
on 11 Dec, 2013 11:30
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DEZ that's a loaded Question. How hard you want to run, how long a stretch at what HP? This will all effect minimum clearance.
I have one plated cylinder bet I have run 6 pistons in it so far. Hit the top above the ports with a dingle berry and your good.
I do just enough to get a quick ring seal. This is not really a new thing just not talked about much. I suggest it in some cases depends on the cylinder and porting. Also after its coated you don't want to be porting in there it exposes a open edge for oil to penetrate and the rings to catch.
AND IVE HAD A BAD EXPERIENCE WITH A COMPANY OTHER THAN MILLENIUM OR US CHROME doing these. My Q cylinder that was out in Glamis, was ruined by leaving in the Etch tank too long or too strong a solution used. They told me it was due to Suzuki's poor aluminum Quality. It looked like it had been packed in a pail of rock salt when I got it back and LITERALLY sprayed my legs with coolant once coming up to temperature. We tried everything to fix it.... I have @ 1500 into a paperweight, between original porting cost machine work plating shipping all over hell.
So just be forewarned Im 50/50 so far. The way most guys run, a properly sleeved NW cylinder will easily IF MAINTAINED Properly outlast your interest in these bikes. That said plating is half the cost to a hundred bucks less than a Sleeved cylinder if you can do it.
I will DO it again on a cylinder Im happy with and like.
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#36 Reply
Posted by
Dezsled
on 11 Dec, 2013 12:28
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So if I'm happy with my current porting and it's on 86.5mm I'd be ahead to get three Wiseco 87mm sized pistons and nikasil the cyl at 87 mm ?
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If the bore is not damaged or egged out, they will slightly overbore it and Nkikisil it back to 86.5 if you want. I belive the coating can be applied up to .3mm thick.
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#38 Reply
Posted by
Iceracer
on 11 Dec, 2013 13:10
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Ya pretty much. Sums it up.
The trend at Wiseco seems to be reducing stock on other older pistons. So sell out of every other os and not restock. Have to put in minimum custom orders. So far the 500 go through them fast enough we seem to be ok but our days are #ed.
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#39 Reply
Posted by
GrkGuy
on 11 Dec, 2013 13:33
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and how long does that last?
and when its time to get it coated again will it still be same bore.
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Are you saying in the future there will be a shortage of pistons for the 250?
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Sure seems like there will be a shortage in the future. There's a shortage already!
I'm telling ya guys, the combo of a coated piston on a nikasil bore wears alot longer than non.
my YZ125 was wide open almost every day for 2 years without any noticeable wear on the bore. The vertex piston was the only piston I ever put in it, and the rings were changed once just because I wanted to. I wish vertex made a piston for us.
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#42 Reply
Posted by
Q2W
on 24 Feb, 2014 07:18
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I wish vertex made a piston for us.
call them up
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Sure seems like there will be a shortage in the future. There's a shortage already!
I'm telling ya guys, the combo of a coated piston on a nikasil bore wears alot longer than non.
my YZ125 was wide open almost every day for 2 years without any noticeable wear on the bore. The vertex piston was the only piston I ever put in it, and the rings were changed once just because I wanted to. I wish vertex made a piston for us.
There is a big difference between a piston getting loose because of ware and a piston collapsing. Coating the skirts with friction/anti-ware agents WILL not prevent the piston skirts from collapsing. Large diameter forged pistons are more prone to rapid collapsing. The forged 125cc and smaller bores do not have as much of a problem as the 250 and 500 size forged pistons.
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#44 Reply
Posted by
ZillaFreak
on 24 Feb, 2014 12:37
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Or we are not going through them fast enough. If wiseco can make money off them, they will keep selling them. So people, blow you engines up more often, like once a month or replace the pistons more often.
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