Which bottom end is what year

[kustomfab2003]

I have 2, 250r motors. Both have a 72.45 piston, one CT cylinder, one ESR cylinder. One has a spacer plate at the bottom and the other does not. I threw a rod bearing in the one without and need to order a new setup but dont recall the years of which motors I have.

Please help.

Thanks

[matt250r21]

Since both of your motors are built, I would think they are useing the 86 style piston. If thats the case then your motor without the spacer plate should be an 86 short rod crank.

[deathman53]

Should but isn't always. All of my motors excpet the crate 85 is with a 88/89 rod. You need to look at the rod to tell what crank you have.

Long rod

1-85 250r
2-86 250r
2-88 250r

Short rod

crate 85 250r

[kustomfab2003]

What are the lengths of the 2 cranks? I can measure the one I have apart but it wouldn't tell me much unless someone here knows the difference in length.

I would try my local shop... but it seems that lack of knowledge prevails at all shops around here when it comes to 2 strokes.

Josh

[matt250r21]

Short rod 85-86 125.3 mm center to center.

Long rod 87-89 130.3 mm center to center.

[SET THE STAGE]

if it's any help (not sure if it would be to you)

the 85-87(i think 87?) has a 72mm stroke. the 88-89 has a 77mm stroke.

[deathman53]

no stroke is the same, its just the rod is longer. 85/86 had a lower pin point on the piston as where on the 87-89 is was 5mm higher. Honda did this as they say it dregreases the angles and reduces wear on the piston and clylinder. Most people w/ 87-89 rods use a 5mm spacer plate and use a 86 piston as higher crank case volume, they say it eases the hit and its more ridable. As where the short rod is very snappy.