Vibration

[Dragon Tamer]

After about 42,000 mi. the trusty old Fire Dragon has developed a small but irritating vibration. It starts at about 2600 rpm and increases until about 4200 rpm and at that point it stops abruptly. At its best it is just barely apparent in the foot pegs and at its worst if actually vibrates the whole fairing. The most vexing part of it is that it does not do it all the time, I may ride for days or weeks without it happening and it may start up right in the middle of a ride (usually right after a stop sign or some other stop). It is an engine vibration because if you pull in the clutch and idle the engine and coast it stops until you rev her up again.
Does anyone else have this problem? It is starting to get on my last nerve.

[81xsproject]

Welcome aboard. Now we have a dragon tamer and a rider. My first suggestion is to do a vacuum sink on your carbs. If they are not in sink it can cause a lot of vibration.

[81xsproject]

Oh yeah, you can read all about it in the tips section under maintanance and even find how to build your own to save some $

[jeffe]

I'm not sure what kind of a fairing you have but I have a Vetter Windjammer IV on mine. It was doing almaost the same thing. Turned out that it was the knob that adjusts the headlight up or down. Turned it just a little and it hasn't happened again. Good luck.

[TopCatGr58]

Hey Dragon Tamer,

After 42K miles, could be many things. Loose exhaust header nuts, or loose nuts/bolts that secure the pipes to the frame. ALso, loose or worn engine mounts and bolts! Hope you find it!
T.C.

[skids]

Re: Vibration

Contact of the exhaust system on the frame can do that, or bad damper rubbers at it's mount.

[LoserShoes]

Or how about a intermittent missfire due to a bad plug cap?

Steve

[Dragon Tamer]

Thanks for all the help so far guys, here is where it stands, plugs and caps/wires are new. Also tried different plugs. There is NOTHING that I can find on the bike that is loose or out of whack. I am afraid that there will be if it keeps this up.
I was not aware that out of sync carbs could cause a vibration and so will check sync soon, hopefully yet this weekend.
It is a Vetter Windjammer fairing with lowers and does not seem to be the source of the vibration, I know that the fairing itself will vibrate at about 85 MPH but this is not the same vibration. I have also removed the fairing and taken a short test ride and the vibration is still there.
Exhaust system is a Jardine four into two with crossover, it has been on the bike for some years now. On a bad bump the rear axle will tap the right muffler just a little but other than that it does not touch anywhere. Other than a couple of minor blemishes the bike looks almost showroom yet, I would send a picture if I could figure out how.
As of yet this vibration is just an irritation, but it seems to be getting worse and that bothers me. Myself and the Fire Dragon are old friends and I would not like to think the old girl was getting sick.

[HobbyMan]

I had a little vibration in your ranges. I did 2 things. First, I replaced my old TCI plastic connections and cleaned the terminals. Then, in stead of recleaning the carbs, I ran the engine on carb and choke cleaner for a minute. After that I drained the float bowls. Now, as a cruise with no fairing, at any speed, it is like I am floating on air. Even at 75MPH

[Dragon Tamer]

Will take that into consideration although the carbs run a steady diet of high test gas and occasional cleaner, all wiring on the bike was replaced a year ago, by me, electrical engineer. Forty plus years on bikes and this one has me stumped so far. Know what you mean by floating on air, The Fire Dragon is like riding a LARGE electric motor for the most part, just humms at low r's and snarls at high r's and goes like greased sh*t. When I am in the mood I love just eating up the v-twins, they cannot stand it when a 27 year old bike just walks by them without sweat.

[Goin Commando]

and goes like greased sh*t.

hhmmm, so thats what that feels like huh? and i never thought i ever wanted to know.

[soccer4m]

Hi, this happens in autos and bikes, the problem could be the tire-rim balance and /or the tire is developing an out of round or weak area with small bubble. At low speed and high speed the dynamics of the tire will not vibrate until a certain rotation speed is attained then centrifugal force will overcome that at higher speed. It could be worth a check to inspect tire,rim and possibly rebalance tire's. Good luck, Mike in calif.

[HobbyMan]

Since is most definitely engine related, As you said the electrical aspect was OK and no other frame contact. I assume the coils are OK too. It is leading me down the path of engine mounts or carburation. Don't be fooled about high test gas and cleaner. In some locations, premuim has more addatives than regular. AKA: extra stuff to gum up your carbs. Other off the shelf addatives only go so far to clean the carbs. Nothing beats a good tear down. If it was me, I would clean them to make sure. It only takes 30-60 min, for me at least. If not, I have heard a few things about engine mounts. They may not be the problem, but if you are on you last nerve, it is worth a second look. When all else fails, re-check elecrical.

[mro]

originally posted by Dragon Tamer
most vexing part of it is that it does not do it all the time

Hate intermittent problems. Seems you've covered most likely suspects. Have seen bad bearings (ball bearings) that spun smooth at low and high RPM's and sometimes growl and then not.

May need to wait till problem becomes acute.

Wonder if a cylinder was dropping out (not firing) could it cause the bad vibes???

When wiring done, pick up coil wires too???


mro

[Dragon Tamer]

Thanks for the thoughts there mro, new pickup coil wires along with the new pickups, I have been waiting patiently for the problem to get bad enough to find it. Don't think that it is a cylinder dropping out because the frequency of the vibration is higher than that. The idea of the bearing thing is interesting because that is begining to feel more and more to be about right. I just don't want to have something just let loose at the wrong time before I figure out what the heck is going wrong.