Need help on a yfz linkage

[protraxrptr17]

Having trouble with my buddies YFZ. We put in my old 525sx engine and I moved the shock mount to set up the bottom out height to 1.5" to stop the frame dragging the ground. Now he says it rides rough. I think it is because of the Elka long travel linkage having too much progression higher up in the travel because the shock is now further up to get the ride height where it needs to be. Should we go back to the stock linkage, or can some of you show me how to design a custom linkage that would be softer at that specific height. number52, you got any ideas? I know you said you could do this with a Honda. This is another reason I like the no-link. You can change ride height without this happening. This bike has never really worked right anyway, and I think most of it has to do with this linkage. We don't have a stock linkage layin around to try. I don't want to buy one if it's not gonna help. Also, the weight is substantially less than it was before the engine swap. We didn't weigh it before, but now it only weighs 355 with fuel, water, oil, etc.

[protraxrptr17]

Where is everybody? :)

[dustin_j]

I think number52 was pointing out how much easier honda linkages are to machine and design. Something to consider here.

You could either guess and check, or take measurements and I could try to graph up your current progression curve and suggest some changes (showing their corresponding curves). It might take me a little while to generate the first graph, but after that I'd be able to show graphs for whatever linkage idea you'd have.

To guess and check, you could remove the shock and jack up the frame to the height at extended shock length (rear tires just touching). Lift the rear wheels (axle) about an inch at a time, measuring what the shock length would be at each point. Plot shock length vs wheel travel to see your progression. You could then machine simple test linkages, the only thing that would matter would be center to center relationship of pivot points. You could then repeat the first test to plot the new progression curve and compare the two.

Maybe someone else has better ideas? Should be interesting either way.

[dustin_j]

Any progress?

[protraxrptr17]

Nah, we had a big ride planned saturday, but it all fell apart. I was the only one that went.