2005 Monster 620 -Had a very slow but consistent leak that I traced to a bolt hole at the bottom of the alt side engine casing (right under the lower front sprocket cover bolt hole) . My first reaction was "why is there no bolt in there?!?" When I tried to screw a bolt in it wouldnt thread. Upon further inspection it appears that the previous bolt broke off somehow and the threaded portion is still in there but the rest of the bolt had fallen out. I inserted a small piece of paper towel and sure enough over night it was absorbing oil.
I've got two lines of thought here.
1. As the broken bolt is recessed in the engine is it even worth removing the alt side engine casing when I try and extract the broken bolt?
2. I should probably remove the alt side engine case cover so I dont damage it and have better access to the broken bolt.
Either way I've had mixed results removing broken or damaged bolts with extractor bits. This is going to suck.
Thoughts?
Pics below - The upper bolt hole with theads is for mounting the front sprocket cover. The bolt hole with the broken bolt is the lower one.
(https://farm5.staticflickr.com/4365/36569667786_4e65bf7bb7_k.jpg) (https://flic.kr/p/XHx7ay)Untitled (https://flic.kr/p/XHx7ay) by ricknieto (https://www.flickr.com/photos/65036619@N04/), on Flickr
(https://farm5.staticflickr.com/4405/36219428720_4b75614627_k.jpg) (https://flic.kr/p/XbA3hY)Untitled (https://flic.kr/p/XbA3hY) by ricknieto (https://www.flickr.com/photos/65036619@N04/), on Flickr
It's hard to tell from here, but it looks like you might be able to grab the broken bolt with pliers or something if you remove the cover.
Remove the cover, it is not that much work and it is in your way. If you can't get at it with pliers try tapping it out with a small ceter punch and hammer. No luck? Left hand drill bit. Still no luck? Easy out.