'04 crank in '01 cases?

[seajay]

I went with Darkhorse.https://darkhorsecrankworks.com/

[aswracing]

We developed the machining operations and special spacer needed to install the XR/XB crank into 1991-2003 cases, that's true. We did about 100 of these conversions until the crank became unobtanium. We still do them, if the customer can source the crank.

But despite that crank being interchangeable with a 2004+ crank in 2004+ cases, the same process and spacer does not apply to a standard 2004+ crank. The whole reason this process is feasible with the XR/XB crank is because of it's larger sprocket shaft, as shown in the image below:



The stock 2004+ crank is the same only in the area of that inner bearing race, the sleeve you see that's all the way up next to the flywheel. From there, the stock 2004+ crank necks down.

Because the XR/XB crank has such a huge sprocket shaft all the way out, it let's us machine out the 1999-2003 left case half, and then run timken bearings from a Big Twin.



That's what's happening here, we're hogging out the 1991-2003 left case half for Big Twin sprocket shaft bearings.

The tricky part about all this was placing the crank laterally in just the right place. Ultimately it's lateral position is a function of where you place the groove that that the internal c-clip lives in, the one that sits in between the two inner bearing races (the races get pressed into to the case half and butt up next to that c-clip). It has to be placed just right, so that that the front primary sprocket is aligned with the clutch basket, and enough of the sprocket shaft is left exposed to accept the front sprocket and a spacer that acts as the seal surface for the crank seal.

It took a fair bit of trial and error to figure all that out. Fortunately, over the years Dan and I had trashed a fair number of cases via our racing endeavors, and we had some scrap ones sitting around.

I have never really studied what it would take to put a stock 2004+ crank into a set of 1991-2003 cases. I can't say it's impossible, but it's certainly not the same process. Maybe this is something we should work on, though. We occasionally get contacted by people who have lost the big end in their 2000-2003 crank (pressed), and if the 2004+ could be made to work, that would give them another option for repairing it. But don't assume it's simple, it's almost certainly not.

[Curbside]

Originally Posted by aswracing

I have never really studied what it would take to put a stock 2004+ crank into a set of 1991-2003 cases. I can't say it's impossible, but it's certainly not the same process. Maybe this is something we should work on, though. We occasionally get contacted by people who have lost the big end in their 2000-2003 crank (pressed), and if the 2004+ could be made to work, that would give them another option for repairing it. But don't assume it's simple, it's almost certainly not.

I would certainly be interested in knowing, but it's looking like my original plan to run off the tach signal is probably going to be a much more economical and simple solution.

Given that Harley has ceased production of the Evo Sporty, I could see it potentially being a viable option as the supply of usable rigid-motor cranks will eventually dry up.

[t120r]

Originally Posted by Curbside

I would certainly be interested in knowing, but it's looking like my original plan to run off the tach signal is probably going to be a much more economical and simple solution.

Given that Harley has ceased production of the Evo Sporty, I could see it potentially being a viable option as the supply of usable rigid-motor cranks will eventually dry up.

Just make a 16-2 timing cup. Will work fine with the megasquirt that you were planning. Go optical and you can run more teeth. I just tested a 20-2 timing cup and it worked fine. In theory it can read 200 teeth, but the megasquirt won't read that many. I'm going to try out a 60-2 wheel in the next month or so. If you want I can send you the details.