Just pulled my front wheel so my wife could lower my front forks and when we put it back together my speedo didn't work, check the little gear drive and it seemed to be in place put back on tire and still didn't work need help fellas.

 

not sure if this applies to a 90 model but everything I find says it does...

Speedo Checks ('03 and earlier):
press the odometer switch in while turning the ignition on (with the run switch engaged)

d01 is the Speed sensor output shorted low,
d02 is Speed sensor power output shorted high or open,
d03 and d04 are not used,
d05 is Speed sensor return shorted high,
d06 is Speed sensor return shorted low,
d07 not used,
d08 is Speedometer power overvoltage,
d09 is Speed output shorted high and
d10 is Speed output shorted low or open.

 

The '90 EG was a mechanical gear with a cable..not electronic.
Make sure that the tit on the gear drive is fitted into the wheel slot.
Make sure your cable isn't broke.
My gear drive broke @ 80k miles..bought a new one and drilled a pinhole in the housing. Pumped grease into the gears and sealed the hole with silicon. Use a grease gun with a tip that's like the needle you fill a basketball. I did this once a year and never had another problem.

 

Water can get into the bottom of the cable and rusts the inner until it stops rotating and breaks. As well as following 2Sore's tips you can fit a tv aerial rubber boot over the cable join, to keep the wet out. Pic is of my 1990 front end and boot:

 

i used some heat shrink tubing, like you use to seal wires up. slip it over the cable end and hit it with some fire(cigarette lighter).

 

Good tips all. Also remember you need to get going well over 10 mph with a mechanical speedo for it to register on the dial. I thought my speedo was out one winter just running up and down my driveway after doing some other work. Put new speedo cable on and same thing so forgot about it 'till spring. Low and behold when I ran it up and down the road in the spring for fresh gas the speedo worked!!