i'ev been thinking about changing my 85 250r to a 87 style crank and rod setup and i would have to get the spacer plate to cuz the 87 rod is 5mm longer. but i hear it loses some of the rev on top end? i'm lookin to make my motor run a little faster with a little more power without spendin too much. any imput

 

Long rod = more torque
Shot rod = revs faster

 

Wrong. The longer rod has advantages everywhere over a shorter rod, asuming the same stroke and engine configuration. The longer rod applies less cylinder side load, resulting in less wear and slightly more power due to less friction. Also, the longer rod increases piston dwell time at top dead center....resulting again in slightly more power. The longer rod should treoretically outperform an identical set up with a shorter rod everywhere in the rpm range....just don't expect big differences in ultimate power output.
Gary

 

Nevermind..............I had a brain fart!!! [img]i/expressions/face-icon-small-happy.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img] my fault!

 

Looks like a battle at the Quad Patrol. Quick hide all the donuts. They'll both be hungry after this bout.

 

The only reason you would need a spacer plate is if you used the long rod WITH the 86 style piston. If you use the long rod with an 87-89 piston no spacer is needed. The only real advantage of a long rod is that the cylinder side walls wont wear quite as fast. Some people say the long rod will make you have more torque, however I have both short and long rod motors and have expierenced with both... Is there that much of a diffrence in power??? nope. When people switch to a long rod and keep the 86 style piston is where the power band will be altered due to the larger crank case volume. ( IMO more crank case volume will smooth out the powerband, but will not add power) This is mainly used as a trail riding set ups. Another reason why people think the long rod motor has more power is because of cylinder port mapping and eletrical componets were changed drastically over the 85/86 style cylinder/head, resulting in more power.... Overall, do I think its worth switching to a long rod from a short rod and keeping the 86 (or 85) style cylinder?? NOPE.

 

Stick with the short rod. Less base gaskets no spacer plate. More clearance when messing with spark plug. I have the long rod and will be switching back to short rod.

 

After finally re-reading my post I may have came off a little harsh. That was definately not my intention towards my good buddy Thrashandcrash....or anyone else for that matter. Pass the donuts [img]i/expressions/face-icon-small-smile.gif[/img].

 

gary all you had to say was ask any woman the longrod has advantages everywhere [img]i/expressions/face-icon-small-wink.gif[/img]

 

Any guy can tell you a short rod and a long stroke is a recipe for disaster. [img]i/expressions/face-icon-small-tongue.gif[/img]