Steel sleeve or nickasil

[darwin88]

I have purchased a 99 yz125 that had the cylinder replated and am looking at buying a second yz that has had the cylinder sleeved. I understand that plating is superior but was wondering the effects of having a steel sleeve on engine life and performance, or any other differences there may be...thanks

 

[a454elk]

I know that you can only run one type of piston in a sleeved one, and I know that I can't remember which one! Sorry, I know that plating is better because it gives you the option of different styles of pistons unlike the sleeved ones.

 

[enduroman]

Another issue I encountered with sleeving, is clearance with the power valve. On subsequent top end rebuilds, (which requires an overbore with a sleeve to get everything straight and true), you may break some rings if you do not get the power valve clearance adjusted for the overbore. Having done the sleeve option a couple of times, I would spring for the extra bucks for plating in the future. Too many problems like I listed above, plus sometimes jetting issues make it not worth the savings to me. Also, several shops I contacted with problems I was having would not even consider working on the motor after they learned it had been sleeved.

 

[KaTooMer]

Not sure why the second YZ you're looking at has a steel sleeve, but the one time I did that years ago (before I became edumacated) was because I melted a piston and a steel sleeve was the cheapest fix (that bike never ran the same with a steel sleeve). Think about that when you consider the second YZ...who knows what else might have been fixed using the cheapest method. Aluminum sleeves, used in most higher-performance bikes, transfer heat better than steel, meaning a steel sleeve may have greater chances of overheating during extreme use. And plated sleeves are generally more durable than steel - the plating is an extremely hard coating. I'd say take a pass on the steel-sleeved YZ unless they're practically giving it away; if that's the case, have it re-sleeved and re-plated.

 

[Matdog]

The biggest problem with a steel sleeve that I have come across is that a steel sleeve holds the heat in the cylinder and causes detination from the high compression head designs used to day to get good mid range and good throttle response. This is why you can not get a sleeved engine to jet clean and run as well as with a coated cylinder. You get what you pay for. A coated cylinder gives the best performance, lasts much longer, Pistons lasts longer, jetting is consistant, lots of different pistons available, and the bike runs much cooler. If you buy the bike plan on buying a new cylinder to get it to run correctly.

 

[darwin88]

Thanks guys, that is very helpful. What can I expect to spend on a different cylinder? Is this one no good then or can it be repaired by eric gorr or someone. (eric did my engine rebuild last year and I have been very satisfied with it) This one I am looking at happens to be an 01, are the 99 and 01 cylinders interchangeable? Thanks again

 

[kcsteck]

replate is best.advantage to steel sleeve you can go oversize =more power. disadvantage you really need to be careful when you start bike that you warm up real good before reving it. We steel sleeved cylnder and was real cold morning like 34 degrees and aluminum cylnder melted away from steel sleeve ruining cylnder.