Hellcat vibration issue
 

Just got a Hellcat yesterday after riding around on an Icebear Lil Monster. I haven't had any major issues with the Icebear, apart from needing to replace the engine mount bolts, but it seems like the Hellcat has a few problems going on.

The major issue is both vibration and what I can best describe as a harsh clicking sound around 40mph (clunk clunk clunk type, not a tick like you would hear when listening to lifters. More like the wheel/chain is oblong). I took a look at the rear axle and had the dealer do some minor repairs to the seal over the bearing - but I'm still getting the issue. Deceleration you can hear it too, but it quickly fades (like I said, it seems to only occur around 40 mph)

As far as the vibration, seems like if I get anywhere above 6-7k, it starts to vibrate to kind of a 'whum whum whum whum' type of sound. I've seen suggestions about putting rubber grommets or washers from Home Depot between the plastics and the frame - but is there something more I should look at, like some sort of bushing on the main engine mount bolts?

I've done the normal upgrades to the Icebear and haven't had any of these issues at all, even when upwards of 55-60mph. In fact, I almost prefer it at that speed, since it travels pretty smoothly. I'd hate to get the mods done on the Hellcat if I run into this problem at that speed.

Also, any suggestions for axle/brake/caliper upgrades or replacements?

i have an issue with my x20's with that similar sound. i have to keep chain on the tight side(not too tight) to avoid chain hitting the front sprocket cover on the lower side of it where is leaves to the rear sprocket when enough tension has developed in the chain, especially if you have a larger sprocket on it. i have contemplated on grinding off an inch or two on lower part of cover where the chain makes contact making clink clunk noise...this maybe a tangent problem for me but yours sounds very similar to my noise....after i take the play out of the chain to the tight side sound goes away, and i usually adjust jtr h2 chain 3 times from new. would take a few min to remove front sprocket cover and test ride to see if that's it....

I could see how this could cause this problem -except- that I haven't yet changed the stock sprockets (waiting for them to be delivered), and the chain is pretty snug. Not too tight that it puts undue tension on the links, but maybe about an inch total give either push or pull.

Going to buy a swingarm lift from Harbor Freight on my way home from work and disassemble the rear axle, then maybe move on to the front to see if anything there may be misaligned. Hopefully I find something that the dealer just didn't quite put on right and fix the issue.

So I took apart the rear on the Hellcat and checked everything - took in the sprocket/hub into the dealer since there was some obvious damage on it that was caused by them. Luckily they're working with me - they've been a bit hard to deal with in the past.

Out of curiosity I disassembled the rear on the Icebear and put it on the Hellcat to see if I noticed any improvement (so glad that the parts on these anklebiters are more or less the same) - when I took a test drive, unfortunately I was still noticing the vibration. Definitely something to do with higher revs, I notice the issue when I downshift and when I'm nearing the top of the band.

I took the 17t sprocket from the Icebear as well, and since the revs stay lower with that on, it helps a lot too. The engine definitely needs the carburetor changed out and the airbox removed - it doesn't like to go above 45 all that quickly, it's simply not getting enough kick out of the stock carb and airbox to run a 17t front sprocket - but at least I have the vibrations mostly managed for now.

Ordered replacement pieces for the Icebear, have Grom axle bolts coming in, and will probably do the brake rotors since I'm noticing a bit of shaking when I come to a stop. Probably should bleed the rear and add some fluid too, idiot mechanic at the dealer didn't refill it when he replaced the caliper the first time around. Might also have to try some sort of 'bushing' for the engine mounts, too, just to see if I can get it to stop affecting the frame so much.

Any suggestions for improvements on this bike are always welcome. Might start a new thread with the whole experience and build, not to mention the Icebear, which has now been torn apart, reassembled, and even painted for my wife to ride.

UPDATE!

I've done almost a complete disassemble and reassemble of the major bolts, panel screws, and some of the rubber bushings that hold the various plastics together. On the swingarm bolt and the two engine mounts, I put rubber washers on the side of the bolt head in order to take out some of the vibration as well as lock washers on the side of the nut. I also took the suggestion of putting some rubber washers between the metal mounts of the frame and the panels (so they're hidden from view) - after reassembly, whatever was causing the clicking has vanished - and I'm pleased to report that the bike is smooth as butter now.

I believe the original issue lie within the engine mounts - I noticed that the nut on the engine mount that is behind the rear set was not as tight as it should have been, and was spinning a little when I revved the engine. I put a lock washer under the nut and re-tightened it, and now it doesn't do that anymore.

Learn from my example - tighten your nuts, people!

Pick up some loctite blue and some M8 class 10.9 bolts from Fastenal (or other places). Those bolts are pretty weak. Some guys in Vegas report they sheared. They said only the lower of the 2 engine mount bolts needs to be replaced... but may as well replace both. Costs about $9 for both bolts combined.

I'd have to agree with your post, though it appears that the bolts I had replaced them with from Ace seem to be holding up pretty well. I keep hearing about using Loctite - I was debating doing that the first time around but wanted to keep the option open to mess with the bolt without issues.

Since a ZS190 sounds like a very very appetizing replacement. *drool*

So I have the same problem on our Vader a high pitched buzzing vibrating . I took the sprokrt cover off and drove it and it it's vibration free. Closer inspection shows where the chain is rubbingthr bottom of the cover..I'm going to grind off a inch ,That should fix it. vader 125-15 thought you would like to know your not alone.:tup:
Good luck,
Wolf

I ride my HC "mad-max" style with no tank plastics.
My first rides, there was a bad buzz/vibration from somewhere sounding in front of me... like headlight/handle-bar area.
Turns out it was the gas cap. While it fit and latched into place... it buzzed like crazy. It needed the plastic surround that goes on the top of the tank to properly latch and be snug (buzz-free).


Probably not your issue... but a source of buzzing for folks not running the plastic.


Cheers!