Hi, everyone

I wish everyone here a fantastic new year!

Something weird is developing with my bike. I'm getting a regular rattling sound coming from somewhere in the engine, not sure whether it is up high, or down in the crankcase. The weird thing about this noise is that I can only get it while turning the throttle. It goes away while coasting, when the throttle is closed. I can detect it starting at about 4500 RPM's

Last spring I replaced the crankshaft, with rods, because I had spun a rod. My first suspicion is that another rod is about to give out, but the fact that I only hear the noise under acceleration has me doubting that the crankshaft is the problem. I mean, if it was, wouldn't it rattle even while coasting?

What do you guys think it could be? Where would you look?

Thanks

Mauricio

Usually hear rod bearings when backing off load but mains knock under load.  Not sure when balancer bearings start to knock, I've never had a bearing problem in all the miles I've put on my GSs.  Knock experience is with the old cars I used to have.    With over 100k miles on my 02 the jugs are really starting to rattle though.

Makes sense in my case (the mains rattling) because when I changed the crankshaft I didn't change the mains. I simply swapped the bad crankshaft with the replacement one. Didn't want to go through the checking and fitting of main bearing as described in the book.

Common sense tells me that I better open it up and check it, but it is such a major thing to do... Anyone with some info that would give me hope that I don't have to crack it open?

Thanks again

With it being only under throttle -- just under throttle, or under load? ex: is going uphill with it worse than on a flat?

Any change in sound when the bike is cold/warm/hot?

Within a specific range, or anywhere above 4500 revs?

Just under throttle. Haven't noticed difference under load, just under throttle. Will check the cold vs warm vs hot. Will check the range (I think it is simply above 4500, but haven't thought of pinpointing the range, thus I might have missed if it goes away at higher revs)

Good ideas for a better troubleshooting. Thanks. Not sure where the results will lead, but will check nevertheless.

Quote from: vasama on December 31, 2013, 11:39:47 AMDidn't want to go through the checking and fitting of main bearing as described in book.

Looks like you are going to have to now......and the big-ends 

um, if you had to replace the crank due to a spun bearing, you might wanna check the counter bal shaft bearings. it gets shitty oiling to begin with.