i just bought a 86 250r with the long rod that i really like.i just want to get some opinions on both.i've heard good and bad about both,also wasn't the 86 the only year with the shorter stroke?does the long rod create anymore torque or top end speed?

 

A longer stroked engine is more "torquey" at lower RPM's. A shorter stroked motor will rev faster.

 

the short rod has a better r/s ratio, but i dont think its worth arguing about. seems like all the fast R's go long rod (at least drag).

 

You need to understand something.

All TRX250Rs in stock form have the same bore and stroke. All are 246cc.

The 86 had a shorter connecting rod than the other years, not a shorter stroke.

When they installed the longer rod in 87, they moved the wrist pin up higher in the piston to compensate.

 

Can you do a conversion To other connecting rods?

 

the connecting rod itself is longer so id say no, its no a good idea to try and make a 86 rod as long as a 89.

 

trapperB is exactly right again[img]i/expressions/face-icon-small-smile.gif[/img][img]i/expressions/face-icon-small-wink.gif[/img]

strokedbanshee- as trapperB said the 86 was the short rod model, but still had the same bore and stroke, and you wont really notice a diffrence between the two.




Do you mean put the long rod in the 86 motor, and short rod in the 97-89 motors? if so then yes all you will need to do is to use the same styler piston. Overall the rods are 5mm diffrent. the 86(short rod) had a style piston were the wrist pin was 5mm LOWER then the 87-89 pistons which were all the same. The 87-89 pistons wrist pin was 5mm higher than the 86 piston, because of the rod.

 

i thought he was asking to make his 86 rod and extending it to the length of a 89. haha

 

The bore and stroke is the same, they just moved the wrist pin on the piston to compinsate. The reason they did is reliability. The short rod version wore the cylinder to much becuase it was pushing the piston to much. That is why the 86 bores are egg shaped really bad on a tear down.

You can do a long rod and 86 piston setup - this is what you could consider a LONG ROD or Stroked setup. It requires a base plate spacer and some porting. THey are pretty good racers, but not your daily racer.

 

thank's for the opinions guy's.most of the 86 models i've seen have the long rod conversion.it seems to work really good.