Topic: Need a little clarification, please...

[Ricky_Racer]

Long ago, I bought a CB750 with many performance parts: CR750 tach, Dresda swingarm, etc. I kept the motor for a future build.

The motor has a Yoshimura Daytona cam and H-D springs along with an excellent port job. I wanted to check for performance rods and so I pulled the oil sump to check. Yep, aluminum rods! Now, to where I need an opion from you knowledgable brothers...

In the attached photo, look at the crank adjacent to the rod. I've never seen one like that. What do you think? Could it be a billet crank? The motor was a high-end build and I'd really like to know about the crank without pulling the case apart. Help!!!

RR

[newday777]

Hey there Ted!
From the picture it's a bit hard to tell. Maybe take more pics or video if you can as you crank the motor in different positions? Maybe the crank got lightened/balanced?

If you could get it up to Curt Jordan in Oceanside he could probably identify it. He was an engineer for Action Fours back in the 70s and 80s and has built a lot of race motors since then as well as he did some racing too. He is Very knowledgeable in this stuff.

[BenelliSEI]

That looks like a std. crank that has been seriously lightened to me. Interested to see what others think?

[MRieck]

Lightened and hit with a belt sander to smooth the counterweight....I had a similiar crank years ago done by Lindskoag Balancing in Massachusetts.  Bill Benton has the crank now.

[Ricky_Racer]

Thanks, Mike. That makes sense. I've just never seen one with the counterweights cut down instead of drilling lightening holes in the counterweights.

RR

[newday777]

Thanks, Mike. That makes sense. I've just never seen one with the counterweights cut down instead of drilling lightening holes in the counterweights.

RR

Cycle X lightens them in cutting the counterweights

[Jerry Rxman Griffin aka MuthaF'er]

And Big Jay cuts tapers into his