Hey guys, I joined to help get some assistance on a vibration problem I have. I will describe the scenario in as much detail as possible in the order that they occurred to help you guys with troubleshooting. I have a 1998 Dyna FXDL, I had a slight vibration in the front handlebars when I got it and it was completely bone stock, I didn't think much of it because it wasn't bad. This vibration only occurred on deceleration around 2,000 rpms.

Winter came, time to customize a bit. I swapped out the 39mm front end for a 49mm front end with progressive lowering springs, everything was disassembled and powdercoated and reinstalled (gas tank and fenders included), 11.5" progressive shocks on the back, thunderheader exhaust, new T style bars, andrews 27 cam, and daymaker headlight. At this point my front fender was still not installed because it wasn't done being painted yet.

So all that work was done, got the bike back, everything was exactly as it was. I still had a slight shake in the bars on decel at 2000 to 2500rpms. It never bothered me much at first, and I put a couple thousand miles on it this way. Eventually I said **** it, I want it to be smoother, so I had a new front motor mount installed from JPCycles, it didn't seem to do anything. I still had a very minor vibration on decel at 2000 rpms. I then went for a ride with my girlfriend on the back, she's 120lbs, and the vibration got noticeably worse with her on the back. When she was off the bike, vibration lessened a bit.

So next, I bought a rear motor mount from JPCycles and had it installed at a local shop. While the mechanic installed the mount, he also installed stock length progressive springs in the front, and my front fender. When I got the bike back, vibration was 2x worse in the front, and now I could feel a little vibration up through the seat to my ***, and slightly on the footpegs as well. I complained, he took it for a test ride, and he noticed it too. he said I have a bad flywheel and it will be $2500 to $3000 to fix.

Here's my issue....the vibration was never THAT bad, it was honestly probably pretty typical for a dyna. I was just hoping to smooth it out a bit. The excessive vibration only started happening after the rear mount, progressive stock length springs in the front, and front fender was installed. And in my opinion it can't be the flywheel, because the vibration happens while in neutral and I'm not even moving. I can literally start the bike, rev it to 2000 rpms sitting on it, and the vibration is noticeably throughout. please helP! I recently just bought a predator front mount because I'm trying to do whatever I can for as cheap as possible, I don't want to have to replace the flywheel on a 1998 bike,e specially when I feel like it's not the problem.

Sorry for the long winded post.

 

 

what you are feeling is the timing is too advanced ...at that rpm ...
remove the nose cone cover ...and check out how the ignition pick-up is mounted ...loosen the two hold down screws and RETARD the timing one increment at a time ...and retest ..till the vibration is smoothed out ..
only retard as much as needed , cuz too much ...and you will lose some power too ...
good luck ...

 

Both motor mounts were replaced with aftermarket motor mounts from JPCycles, roughly $100 each. I know that they were just bolted in, there was no alignment or calibration of them at all, he just swapped them out

 

I am not mechanically inclined, is this something simple that anyone can do? lol

 

Join the club!! Mine vibrates so bad I don't even ride it. Have replaced everything except the flywheel/crank/primaries. Your mechanic is right. Harleys are notorious for flywheel slippage, which screws everything up. Not worth fixing. Throw some peanut butter in the oil and dump it on a wholesaler unless Grandma gives you a new engine for Christmas.

 

His is an evo and highly doubt the flywheels have shifted (runout bad).

 

Maybe time for some True Track stabilizers?

What makes me think this is how the bike behaves with your GF on the back. Shifts the weight rearward and unloads the front wheel a bit, and the extra torque needed makes the whole chassis wiggle with every power stroke.

True Tracks are expensive and the rear is a pain in the butt to install, but very effective. They ship fast too.

 

I also have a 98 fxdl and mine vibrated violently at 2000-2500 rpm, probably worse when decelerating from 2500-2000 rpm. After a lot of parts changing, I did both mounts and installed a true track, I discovered my compensator was shot. The spring pack in it was totally collapsed. I replace it with a drag specialties unit and it took out a lot of the vibration. I compared the two before installing the new one and could see the difference, the old on wasn't "compensating" at all. Now it just has "normal Harley vibration". Hope this helps

 

Definitely helpful information, anything that points me in the direction of not replacing the entire motor or flywheel is good info. The reason I feel like it's NOT the flywheel, is because this was a single owner bike, and she was a woman in her 50's that baby'd it. I've had it and only put on 2,000 easy miles, no burnouts, no racing, no hard down shifting / engine braking. Chances of the flywheel being out of wack on an evo to me is unlikely, but we'll see.