How do I fix my automatic transmission that keeps redlining and wont go passed 50 ?

'Passing gear' is a term that means the transmission is down-shifted to a lower gear (e.g., from 5th gear to 4th gear) for improved acceleration to pass another vehicle. There is no physical component called a passing gear in the transmission.
To engage the 'passing gear' with an automatic transmission should require nothing more than pressing the accelerator pedal down firmly. The transmission should downshift automatically to the next lower gear (sometimes it will downshift two gear ratios, depending on your speed and how far you depress the accelerator pedal).

It is very likely that a complete rebuild is needed along with a flush out of debris and a new torque converter.

the govenor is set too high

If it will go into all other gears but not second, the transmission may have damage like a bent shift fork, damaged gears and/or shift drum. If the bike has been raced or accelerated hard and gear shifts have been missed, it most likely has transmission damage and the engine will have to come out and be torn down in order to repair. If the bike was hopping in and out of second gear before it stopped going into second, the transmission is most likely damaged.
One more thing to try is to take the shift lever and push momentarily down or up on the lever and see if it smoothly returns to its original center position. If it does return to the center position the lever is not sticking and ir it does not return to center position then the shift lever is sticking and that will keep the trans from up or down shifting.

The vacume hose on the vacume modulater on the trans mission is nt hooked to full engine vacume or the engine isn't making vacume.The governer will make the trans shift to second anyway at redline but it's preety hard on an old car to redline it just to find out/ It's possible that youv'e got the shift detent cable that hooks to the carb set too tight or it's stuck as if it's floored. with the cable disconnected it should shift out al the way real early as long as thirs vacume on the modulater. Gas mileage freaks that drive around slowly unhook th shift cale so the trans shifts into high gear real early. Not much for passing and acceleration but they get a little bit better gas mileage.

Are you speaking of 10K+ in top gear? If so you usually don't find bikes able to pull to the redline in top gear. Try 5th gear.
If the bike won't pull in other gears try these fixes first. Put new plugs in (correct gap), check and or replace air cleaner element, replace fuel with at least 93 rated. If you find the gas has ethanol in it, then this could be a problem..it takes 25% more ethanol to provide the same amount of energy as gasoline.
Usually plugs and restricted airflow are the prime reasons higher RPM cannot be reached. Let me know if this helps.

JP

If the car is not getting into passing gear at all, check the kickdown cable from the throttle body to the transmission, to see if it's broken or binding. Also check the throttle body itself for smooth operation.

If those are okay, then check the throttle position sensor for proper output voltage. That should have thrown error code 24 if it failed.

As you pointed out, your engine has a rev limiter to prevent engine overspeed. As you approach redline rpm's, it will cut the fuel supply. If this is happening at lower rpm's than it should, then the limiter itself could be in trouble.

I hope this helps.

smell the fluid, does it smell like burnt rubber, if it does you may have burnt the clutches. also if is 4wd make sure is not in 4wd.

Have a look at the connectors fitted to the transmission.

There is a transmission speed sensor that may have come free or damaged.

Any connector you locate, you should pull free and clean thoroughly both the jack and plug with contact cleaner to help the signals pass efficiently.

Have you pulled the codes yet? You may see a code that'll give you some direction.