1991 yz250 suggestions

[Vance98]

hey all I'm new to this site and everything but I've recently purchased a 1991 Yamaha yz250 2 smoke and I have a couple of questions to ask about it.

My first one being: Has anyone else out there owned one? I can't find any info on the bike or people talking about them I would like to know what they were like when they were showroom material

Second being: What are or were the main problems with these bikes? I've noticed that the piston is starting to slap in the cylinder and I'm getting it bored and getting a brand new piston for the bike. I want to also add that this bike was never rebuilt suprisingly everything is still stock other than gaskets everything is stock. If anyone out there has one or knows a good amount or even a little amount of info on this bike I would highly appreciate it.

 

[Mihylo33]

hey all I'm new to this site and everything but I've recently purchased a 1991 Yamaha yz250 2 smoke and I have a couple of questions to ask about it.

My first one being: Has anyone else out there owned one? I can't find any info on the bike or people talking about them I would like to know what they were like when they were showroom material

Second being: What are or were the main problems with these bikes? I've noticed that the piston is starting to slap in the cylinder and I'm getting it bored and getting a brand new piston for the bike. I want to also add that this bike was never rebuilt suprisingly everything is still stock other than gaskets everything is stock. If anyone out there has one or knows a good amount or even a little amount of info on this bike I would highly appreciate it.

Welcome!
If it has never been rebuilt then I suggest just replacing the piston rather than bore and sleeve. Nikasil cylinder so it may still be in good shape. Post some pics of this bad mambajamba.

 

[ossagp]

It was pretty good in it's day, and can accept the later model forks. that makes them work really well.

 

[Vance98]

Welcome!
If it has never been rebuilt then I suggest just replacing the piston rather than bore and sleeve. Nikasil cylinder so it may still be in good shape. Post some pics of this bad mambajamba.

I'll get some pics up later the website isn't letting me upload them! But I'll get something posted for sure! Have you owned one of these?

 

[Vance98]

It was pretty good in it's day, and can accept the later model forks. that makes them work really well.

Yeah my forks are going on it they will compress but won't be rebound back up, what year or style of forks will it take? Or where can I get some newer and better ones?

 

[ossagp]

the stem has same bearings as the current ones. probably the first and best move moneywise is to get some of the 46mm forks off of a 96 or newer. with that you need the front wheel and axle, and a brake caliper. sounds daunting, but with patience you can do that on ebay for about 200-250. way better than trying anything with the old ones.

 

[PALMER84ONE]

Oldie but goody, anything YZ is going to be fun. As sudgested above, get a new piston in next size up after a good inspection of the jug. If it's virgin, then it should be Nicasile and therefor you do not bore. If all is good then just measure bore and get a new piston to match.
Welcome to DBA.

 

[Vance98]

the stem has same bearings as the current ones. probably the first and best move moneywise is to get some of the 46mm forks off of a 96 or newer. with that you need the front wheel and axle, and a brake caliper. sounds daunting, but with patience you can do that on ebay for about 200-250. way better than trying anything with the old ones.

So I would need to basically get a whole front wheel assembly and everything with the forks? There's no problem in that. Now this might be an odd question but my bike has a red frame and has white plastics... With blue graphics on the white, I can't find any pictures of this bike?

 

[Vance98]

Oldie but goody, anything YZ is going to be fun. As sudgested above, get a new piston in next size up after a good inspection of the jug. If it's virgin, then it should be Nicasile and therefor you do not bore. If all is good then just measure bore and get a new piston to match.
Welcome to DBA.

Could you get it honed out? Just incase the sleeve itself is pitted or scratched, I've never take the head off and I don't really wanna take it off right now but I'm planning on getting it back on its feet and making it look correct

 

[ossagp]

quit talking about sleeves right now lol. that one came with a PLATED CYLINDER. those can be honed if need be. you can use 800 grit sand paper or a scotch brite pad if there are no big gouges or the plating isn't peeled or chipped. that usually happens around the ports if it is going to happen

 

[ossagp]

So I would need to basically get a whole front wheel assembly and everything with the forks? There's no problem in that. Now this might be an odd question but my bike has a red frame and has white plastics... With blue graphics on the white, I can't find any pictures of this bike?

Gary (palmerone) has pics or a memory of them all. yes on the front end, but i sold one off a 95 recently which is pretty much like yours and complete it got 145. so you are halfway there ebaying that.

 

[Vance98]

quit talking about sleeves right now lol. that one came with a PLATED CYLINDER. those can be honed if need be. you can use 800 grit sand paper or a scotch brite pad if there are no big gouges or the plating isn't peeled or chipped. that usually happens around the ports if it is going to happen

Yeah my dad rode the bike the one day and he said you can hear the piston slapping inside of the cylinder and I will note sometimes it acts like it doesn't want to run to its full power

 

[Vance98]

Yeah my dad rode the bike the one day and he said you can hear the piston slapping inside of the cylinder and I will note sometimes it acts like it doesn't want to run to its full power

But your advice is duly noted I'm more worried about the forks for now

 

[Vance98]

Oldie but goody, anything YZ is going to be fun. As sudgested above, get a new piston in next size up after a good inspection of the jug. If it's virgin, then it should be Nicasile and therefor you do not bore. If all is good then just measure bore and get a new piston to match.
Welcome to DBA.

Hey do you have any pictures of the yz from that year? I look up pictures for it and the frame itself is red and plastics are white and the guy basically peeled most of the graphics off but they are blue? I can't find anything I wanna do a vin check to see what I can find out through that but another person down below said you have some in not too good on this site at finding anything

 

[ossagp]

well there are lots of things that a bike will do with age, when it isn't kept in tune. cleaning the carburetor and setting the float is a good idea, but i think i would save riding until i had it apart and put in a piston. the skirts can break off and that gets spendy as far as what you may have to replace then.