[250R cranks] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

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250R cranks
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Posted by: xlr810

I was all pumped to try out the new Hotrods 4mm stroker crank, until I learned that a head modification is required. I think it would work with an 89 piston and a 2mm spacer plate without head mods, but I am over 68mm, so I can't use 89 pistons. 7mm spacer sounds like a little much...

Anyway-- here's a question for you.

Rebuilding a crank: Can either rod length be used on either style oem crank? For instance, could a short connecting rod be run on an originally long rod crank? Or is there a difference in them besides the rod itself?

Posted by: wilkin250r

That is a very good question, and I don't have a definitive answer for you. I doubt anybody on here will.

However, I suspect the rod length is the only difference, and if you were to rebuild a crank, you could use either length rod.

Posted by: Blown 331

quote:
Originally posted by wilkin250r
That is a very good question, and I don't have a definitive answer for you. I doubt anybody on here will.

However, I suspect the rod length is the only difference, and if you were to rebuild a crank, you could use either length rod.

I agree, they still have the same bore and stroke. The newer ones just have a longer rod so the pin is moved higher up in the piston.

Posted by: wilkin250r

There may be slight differences in the balance of the crank, but I can't imagine it's all that significant. I would think a simple overbore would have more dramatic results due to the increased wieght of the piston.

If you're planning on having your crank rebuilt, you're certainly not going to do it yourself, you're going to send it to a shop. Anybody qualified to rebuild your crank will obviously be able to give you much better answers then we can.

Posted by: ZRider400

http://*********.net/techinfo.htm

click "long rod vs short rod"

Posted by: xlr810

Thanks for the replys...

I was thinking along the same lines.

Posted by: machwon

The only difference between the long and short rod is the length of the rod. The difference in rod length is made up for by using a different piston or a spacer plate on the 250R's. A stroker crank is one in which the pin is moved.