New Vibration

'85 FXWG is having a bit of a problem. Started hearing an intermittent noise like something rubbing, appeared to be the drive belt. Backing off the throttle or pulling the clutch in made it stop. Also developed excessive vibration at about 60 mph in high gear. (It also does it at the same rpm in the lower gears too). I had spaced the rear pulley out to clear the 150 tire, so I put the stock spacer back in (have a 140 tire now). The noise went away, but the vibration is still there. No weird noises anymore, just the vibration. Drained the primary & looked around in there, but didn't see anything, no metal filings in the oil. The end play on the rear wheel bearings seems to be a bit too much, there's a slight amount of play there. (Just had rear wheel balanced due to a flat tire.) I'm thinking a loose clutch hub or main drive gear bearing, but I don't hear any of the usual bad bearing noise, and the clutch works fine.
Any ideas of what to look for?

Do you have the stock tank on? I just had an exact copy of your vibration problem. My bike would handle great, ride great, pick up speed the way it was supposed to, then all of a sudden I would be at 60 mph and my tank would just vibrate like crazy. I would let the throttle and the vibration would go away. As you, I would get the vibration at higher rpm in other gears.

I would start by checking your motor mounts making sure that they are not cracked and that everything is tight, I would also check ALL tank mounts. I checked only my front ones only to begin with, finally I pulled my tank and then discovered that my rear mounts were completely loose. I need to buy stock in locktite. I put them back on (with locktite) and my vibration has gone away. I do not have the stock tank, but just a place to start looking.

Good idea. I just put new gas tank grommets in not too long ago, so it might be a good idea to check the bolts again. I did check the motor mounts, & all the usual suspects. I'll have time to tinker on it this weekend. Thanks.

Nope, that wasn't it. Loose tank mounts wouldn't cause the drive belt to rub, but I thought I should re-check anyway. For some reason I feel like the vibration is in the drive train somewhere. It doesn't seem like an engine miss, maybe a new set of plugs??? I do have an M-6 primary chain tensioner, but the chain seems to be adjusted right.Has anybody had a problem like this with their M-6? I've heard horror stories about this unit, but mine seems to work OK. I guess I'll pull the primary cover & have a look-see.

Are your wires arching some place?

no problems here with the M6,

Found it. It was the top motor mount after all. The lock nuts that hold it onto the heads weren't torqued down all the way. I guess I got in a hurry & broke my own rule of Keep It Simple, Stupid. Check the basics first! Thanks for the input!

I will have to say that I am getting really good at checking things over and then rechecking them and then rechecking it again. We always seem to miss something don't we? Glad you got it. Now you can ride without being annoyed.