1991 yz 250 parts interchange

[wayfastwilly]

:bang: Wrist pin clip came out yesterday and ruined my cyl. Will a cyl. from a 1987 yz 250 fit?

 

[MX851]

There is a good chance that it will because I don't think that there were any big changes from 1987 to 1991 but Im not 100% positive.

 

[MXP1MP]

why go older unless someone gave you a cylinder maybe I saw online once where a guy had an '89 yz and put the '96 top end parts on it.

 

[wayfastwilly]

****

I was searching **** and found an 87 and a 95. The 95 has a different left side power valve cover but the right side cover looks the same but it comes with the covers. Im lost on this one, the part is discontinued from the dealer. :bang:

 

[Speedfreek]

88 and 89 used a longer connecting rod. 88/89/90 had cast iron bore 91 had ceramic plated cylinder 90 to 98 used same length connecting rod and bore. 88 to 95 used the same base gasket if memory serves me correctly. 88 and 89 used longer powervalve linkage. I believe 88 to 94 used a "outtie" exhaust flange and 95 to 98 used an "innie" . 97 & 98 used differant reed cage .88 used differant reed cage as well. 89 to 96 uses same reed cage. The exhaust valve is pretty much specific to the year of the cylinder(each year uses differant ex valve) the cylinder heads from 88 to 98 will physically bolt on but be sure to check squish clearance and chamber design to make sure it works in your combination. I've spent a lot of time researching these years of cylinders so if you need any info I didn't mention feel free to e-mail me and possibly I can be of assistance.
Good luck

 

[wayfastwilly]

Thanks SPEEDFREAK

:cool: You could be my new best friend. The 95 cyl. i found has a fresh bore with new wisco piston and rings. But as you said I have to change pipes. I can buy the cyl. assembly and pipe for about 100 dollers less than having my cyl. repaired and plated with a new piston. What would you do? THANKS AGAIN> :aj:

 

[steve.emma]

mate i dont think you got what he was saying... the 87' barrell will NOT work on the 91' bottom end as the con rod lengths are different and so is the powervalve linkage length. also by the time you mucked around with a different exhaust and intake etc.. it would be cheaper to fix your old cylinder or get a second hand one of an online auction site... good luck.
steve.