Valve cover donut question for big fitz52

That was my point all along; the only way to really figure it out is with a test rig.

We need to be able to generate 0-11000 rpm, and know exactly what rpm we are producing.

I figure an electric motor, a rheostat and some sort of electronic rev counter for the rig would do the trick. I'm pretty sure 2400rpm=60mph, so speedos could be calibrated to that; tachs calibrated to be accurate at redline.

Or we could talk TIME into f*ing with his speedo and report back...

 

* = aff

 

I'm with the MiCarl idea that it only changes the pre-load at rest.
If I glued a second pointer to the speedo needle and didn't change anything else, it would point to 55 while the speedo needle points at 60.

But this won't fix my problem anyway. Installing another (stronger) spring would work, or putting a really big front tire on, (NOT!) or changing the axle sender unit from a smaller rim bike (Radian??)

Mr Fitz's Test rig:
One cheap, small box fan- - remove fan.
One ceiling fan rheostat
One used SunPro tach
One set of ignition components from a car to trigger the tach.
A speedo cable, bits of wood, screws, etc.
You probably have half this stuff anyway.

 

Wouldn't that be an idea for a motorcycle...

http://en.wikipedia.org/wiki/Penny-farthing

/Be Seeing You

 

I was thinking an electronic rev-counter of some sort from an electronics source, one that would be triggered by a magnet on a spinning component or the like.

Hadn't thought of the ceiling fan control, good idea.

And glueing a needle on at a different position would not change the spring preload at all, so in that case what Carl surmised is true.

 

Speedo ratio = 2460:60 for all XJ bikes

The manual tachometer ratio 1:4 will read 4 RPM for every turn of the cable. I think. I might have that backwards..........

Electric tachs take their signal from the TCI, which actually sends a signal twice as often as is necessary (wasted spark system), so the tach actually registers only 1/2 of the # of signals received.

 

It's twice as often as the spark plug needs, but it is a signal every revolution, so the tach displays the exact number of signals received.