Counter Balancer? 81-84 250r

[200x newby]

Is it possible to eliminate the counter balancer on the 81-84 250r motor and replace the crank with one out of the 78-80 cr250?

[SYKO]

I think you can, somewhere I heard that you can, part numbers interchange with the old cr air foolers

[200x newby]

I think you can, somewhere I heard that you can, part numbers interchange with the old cr air foolers

correct me if im wrong but doesnt the counter balancer just act as rotating mass to off set the crank since the crank is completely round and doesnt have its counter weight built in?

[TeamGeek6]

correct me if im wrong but doesnt the counter balancer just act as rotating mass to off set the crank since the crank is completely round and doesnt have its counter weight built in?

No, the C.B. is there to offset the "reciprocating mass" (crank is "rotational", piston and rod are "reciprocal") of the piston and rod. The crank wheels and crank are "round" and self balanced (or should be) but the piston and rod going up and down make the crank "out of round" and cause vibration. "Making your arms fall off" vibration.

LIMA OHIO? Id get out of there ASAP LOL I lived in St Marys and that was bad enough

[Billy Golightly]

I dont think the aircooled Rs had a round crank, from what I can remember. That was another improvement made on the 85+ ones be cause it also helped with the crankcase volume.

[3Razors]

Unless you are strictly drag racing, I would def. keep it in there. It makes for a MUCH smother ride.

[300rman]

the 84 r does not have a round crank. it is kinda triangled where the rod connects to the crank.

you CAN get a round, balanced crank for 84 R, i have one in my closet i am going to have checked and rebuilt for the next time i rebuild my motor.

it came out of my motor when i got the thing (no counterbalancer). I didnt feel like rebuilding it, so i got a stock one, and slapped a counterbalancer in there, and called it a day.

not sure what kind it is though.

[stealthduner]

Here is a picture of my crank out of my 83 250R for reference
http://i59.photobucket.com/albums/g307/stealthduner/ATC%20parts/crank.jpg

[TeamGeek6]

BGl makes a good point, a round set of wheels stuffs the cases much better.

Any particular reason you want to take it out?

[200x newby]

cut out rotating mass i was planning on using a cr250 crank form 78-80 since they did not use balancers

[TeamGeek6]

Why cut rotating mass when that costs torque to the rear wheels? That mass is there for a reason! IT takes that narrow little shot of power from the piston and stores it in the crank to feed it smoothly to the transmission.

[JethrowMan]

hey 300rman i need a crank where did you say you can get the fully round ones? or any body else out there that has a spare lying around let me know! and 200x newby can u really use a cr crank?