Hey everyone I bought a '94 YZ 125 and I haven't taken the cylinder jug to a machine shop yet but I wanted to know if there's any reason that I shouldn't re-sleeve the jug.

I already has a sleeve in it, which according to a shop that looked at it with a digital micrometer it's slightly out of round. It's hard for me to say for sure, but it looks like the piston may have seized up in there at one time or another. The piston moves somewhat freely in most spots of travel, but does come across some tighter spots.

I'm not sure if I should be okay with pressing out this current sleeve and pressing in a new one, or if I should spend $520 on a new cylinder jug from Yamaha. Is it common to have issues when usng sleeves?? I really don't want to spend over $500 for a new jug, as I've already invested nearly $1,500 in parts since I picked the bike up a couple weeks ago, and there's still several hundreds of dollars worth of other stuff I need to buy for it. If I'm really much better off just paying the $500+ for the new jug please let me know!

Thanks,
Andrew

Hopefully Mac or Jr will chime in and help you out. These guys always have good advice. :thumbup


Ride safe.

Its a toss up really IMO yes it may be cheaper to resleeve if its possible and you can save money it is personal preference .

I have know people who have put a steel sleeve a aluminum nik plated cylinder.
for what ever reason the life expectancy can be less from what I have seen. maybe because the cylinder was originally designed to be aluminum and the rate that they gather and expel heat causes problems probably has more to do with mating the piston to the cylinder.I don't know. the good news with the steel sleeve is if you scar it up a bit it can be bored out a few times.

the answer is yes its cheaper but it is more work and maybe less dependable

Hey thanks for the replies guys! Yeah after spending all day driving around up the road and talking to a few people we came to the conclusion that it was better for me to just bore out the sleeve for the time being. The shop that I ended up dropping the jug off with masured the bore of the sleeve to currently be 55.06mm in diameter at it's widest point. He said it looks as if this was last a 55.0mm bore, but has some wear to it.

I already have a 54mm (stock bore) piston on the way, and the company that I ordered it from let me know that Wiseco only makes a 54.0, 54.5, 55.0, and 56.0mm piston, so the only thing left to really do was bored the sleeve to 56.0mm and order a 56mm piston. There's not a lot of material left to the sleeve toward the bottom, but just enough for a 56mm bore.

What I'll end up doing is when it comes time to do the next top-end rebuild I'll buy the new Yamaha jug and go back to the 54.0mm piston, just to start from scratch. The last thing I need is for Yamaha to later discontinue the jug after I possibly end up having problems later down the road with this one. According to some of Eric Gorr's literature/pictures, the piston that came out shows signs of composite flaking. Hope the fresh bore, hone and cleanup of this jug fixes that.

Also, I've been told a few different things for honing this sleeve. One person has told me to NOT use the ball-honer tool, but that I need to use the stone style tool. After that, someone else told me that I do NOT want to use the stone style, that I need a special one for two-strokes. I then read somewhere that the ball-honer one is what is needed. Haha. What is it??????? I'm not sure if the machine shop that I dropped the jug off to have bored has the right honing tool for this, as I forgot to ask when I dropped it off yesterday. I assume they do, but if it's something specially needed for 2-strokes then they may not have it because they mainly do car engines from what I noticed.

Thanks again!

http://www.lasleeve.com/master.html

What kind of hone one uses is a matter of personal preference. I've used both and they've had the same kind of results when done properly.