A couple of the well know builders, including Fuel Moto, are finding the M8 crank runout to be very good. As in less than 3 thousandths in everyone they have checked. One builder stated than 1 or 2 was what he had found in every case. A DIY guy posted a picture of his measuring crank runout and he was getting 8 thousandths. But in the picture he clearly did not have the dial indicator aligned properly. I used a dial indicator in my job and there is a definite learning curve in how to properly use one. In the beginning I got readings all over the place. I am not saying it is complicated. But it does take some experience. So for the DIY guy. Before you freak out and think your crank needs to come out and be trued, see if you can find a friend who has experience using a dial indicator to check behind you. Not sure if this post is helpful but just a thought.

 

Wow, all the dial indicators ive used are pretty fool proof, what was the mileage on these bikes? even the twin cams were within tolerance & read pretty good "New" but as the mileage built & the cheaper bearing being used & seated - that's when the run out truly got ugly in some cases.

Maybe the MoCo learned (don't laugh) that they needed to build a better more precise bottom end - time will tell.

Not to be mean - but how were you mounting your dial indicator? once its set - its set (unless your moving it or its not mounted correctly/permanently), not sure how you got readings all over the place?

 

I image you are referring to me.
if I'm doing it wrong, I sure would like to know how to do it right.

https://youtu.be/n7Tcx17xdIs

 

 

Getting it setup and true is what I was referring to. See one of the other responses for verification that people who have never used one often don't get it set up correctly.

 

Wasn't you I was referring to. Most of the pros have a jig they have built to ensure the dial indicator is true.

 

Have to be careful with some jig's as well. Some have the bore for the Crankpin very close to pin size. This will act as a support to the end of the crankshaft pin and you do not want that when checking for runout.

 

so do you see an issue with my method? Do you agree with the amount of runout the indicator shows?

 

Watching your video it appears the dial indicator is not completely perpendicular to the crank shaft. Also, at one point, you can see some deflection in the dial indicator itself. Either of those will affect the accuracy of the measurement.

 

Yeah & I guess that's were im losing you, I have a couple different types - clamp & magnetic, my favorite is from Jegs which is mine - a buddy of mine has a digital one, he works on aircraft engines (a lot of turbo type rebuilds).

Either way once you set it up (zero out as we say) you should be good to go, good luck & hope all is good