Vintage Motorcycle Eccentrics

if the alignment is the problem and I suspect that it is, you could try what I have seen done on exacting mill machinery such as veneer lathes- each bolt holds an individual tab and when they are all secured then they are welded together-voila! perfect alignment

Interesting thought Doug!
That kind of 'out of the box' thinking is what successful teams apply to their engines. I don't know if I can use it in this situation, but it does start the gears turning again!!! Thanks for throwing it out there.
By building an engine stand, and indicating on one fastener at a time on the vertical mill, while leaving the three fasteners installed and tight, and locking it down solid, I hopefully maintained concentricity.... hopefully!
Taking several pieces welded together, with known alignment for each fastener and machining flat and true is still a positive way to insure concentricity.

On a side note:
If any of you guys out there have any engine parts for a '93 YZ125 please let me know as I'm searching for a top end!

George

Or use the welded tab idea to make the perfect template or jig

Hi Guys,
I've been in touch with Roger, a Manufacturing Engineer at Holo-Krome whom manufactures the flat head fasteners that failed last month while I was competing on the Salt Flats.
Since returning home, I've been doing a lot of research of fastener failure. The number one cause of fastener failure is Fatigue!
I've also learned that fatigue failure can be almost eliminated with proper preloading during installation. Often the bolts are more than adequate in tensile strength for the application, they just haven't been installed correctly.
Preloading or torqueing fasteners provides clamping force like a spring. So when the fastened parts are subjected to a separation force (blown fuel combustion pressure @ 11,500 times a minute, typically my two-stroke) this fastener(s) has to have a greater force to keep the parts clamped together (picture a micro-gap developing between the clamped parts). BTW, I've always torqued these specific fasteners to the factory recommendations, 20.4 Ft-lbs.
Now, if these fasteners aren't torqued, preloaded sufficiently this allows them to wiggle and form tiny stress cracks beneath the heads.
Several other articles I've read agree with this as the major cause of fastener failure and proclaim that generally, bolts will take much greater load 'without failure' if they are properly torqued from the beginning.

After providing Roger all the details of my application, he has increased the safe torque for my application to 23Ft-lbs. He said that this small increase in torque will provide 1920 lbs. additional clamp force and should greatly reduce fatigue failure.
Will it be enough......

George

A couple of photos of George's bike at Bonneville this year. Photos by Afflick - Afflick & Afflick - AAA Land Speed Racing Team

Jay,
Thanks for posting the Salt Photo's from Speed Week 2017.
Jo Fysh is responsible for shooting them, she is a member of the AAA racing team and deserves the credit.

Sorry I didn't make it to last night's meeting as I worked late to get a job done and delivered....

I have a Nice T-shirt to give you from JP and AAA racing and was planning on bringing it in with me.

I'll be giving you a call to set up a convenient drop-off while I'm in Sequim or P.A.

George

Here's a shot of George's push starter. Now he is building a battery powered starter.
http://www.landracing.com/gallery/displ ... play_media

This is what it takes to be the fastest in the world. And at 11000 ft. altitude.
http://www.motorcyclenews.com/news/2017 ... ed-record/