access hole underneath silencer on 250r

[Macs]

i have just noticed something on my 83R. there is a square hole with a bolt hole on each side in the bottom of the silencer. i put a piece of duct tape over it and it seemed to run great untilo the tape came off. what is this. i just never noticed it. should there be something there. it also makes it alot quiter when covered.

[Wickedfinger]

Its the blow out hole for cabon build up. Your supposed to un-plug it and do a couple of WOT's to clean it out.

[ATCnut]

There is supposed to be a metal plate held on by two bolts that covers the hole.