What rpm does a stock trx 90 run with stock gearing run? 4 th gear
What rpms does a modified run 5000 to 6500 rpms ?

 

A modded one will go 9k or so rpm.
It also takes thousands of dollars to do it.

 

So I read your message and still cannot find any information on a engine schematic for my honda 90 trx please help or direct me

 

No idea what you are on about and why post in a 10 year dead thread about rev limiters? The pre 2001 workshop manual is available free on line if you google it, I seem to remember getting one from Honda Australia. Very sparse, but would be what dealers used at the time. If you just need a parts drawing, any of the on-line sellers like partzilla or https://www.hondapartsnation.com/oem...trx90-ac-parts show exploded views.