I live in SF and I've worked on both a 97/98 Adventure 620 EGS-E (the first one with the dual low-mounted pipes),
as well as, the blue and orange 99/2000 Adventure R my friend use to own.
Just from your description and knowing the engine...it sound to me like you might have the bearings from the main shaft bearing dancing around in there.
This bearing is known to lose it outer race that hold the bearing in and when it does go the bearing themselves are free to reek havoc!
Don't ride it or run it very long.
Just check that bearing first by pulling the clutch plate and stator...etc
I only lost the race on my 620 LC4, but I kept going and the block actually cracked, destroying the engine!
Originally Posted by Disco97
I've been lurking for several months now studying and doing my homework. Lots of good info here. So, I'm finally checking in!
Just picked up a 2000 640 Adventure R a couple of months ago. It was supposed to be an easy fix (according to the previous owner) that ended up costing me a fortune and I'm still not done! It has been an adventure just owning this beast and I still haven't ridden the thing yet!
I am hoping there is someone in the SF Bay area (Peninsula or South Bay, Sunnyvale?) that has one of these monsters (any LC4?) I can come see and hear. I have heard that they sound like threshing machines to begin with, but mine seems to sound like a threshing machine full of ball bearings, marbles, wrenches, rocks etc. Please help! I'm in deep. I will post some pics once I get it back together. Thanks and I hope to get out there and ride one of these days and meet a few of you guys.