Lots of vibration, any ideas why?

[Anonymous]

Just an update to everyone who offered suggstions in the past on this issue.

Well after contemplating doing the carb clean-up myself, I decided to take it into a bike mechanic so he could do it. The mechanic had very reasonable rates and was recommended by a couple of my friends with bikes and quads.

He said the carbs had some varnish but nothing seemed plugged or blocked. He gave them a thorough cleaning and sync. He also checked the cam chain tensioner and it was working fine.

Having said all that I was hoping that when I got on the bike and started to drive away that the first time I passed 3,000 rpm that the vibration would be gone, or at least notably less. It wasn't.

The buzzy type of vibration can still be felt in the seat and pegs and slightly less noticeable in the handlebars.

I guess it is time to start looking at other things now that I have eliminated the carbs being the problem. A few people have suggested the clutch as a possibility. What should I be looking for in particular other than the usual slop or wear?
If the problem is inside the engine I have no plans to dismantle it unless something blows up. I may have to live with it.

[AOD]

put the bike on the centerstand. sit on the bike. start the engine, warm it up, and put it in first gear. slowly give it throttle until you are above 3000 RPM.

vibrating bad still?

have someone 'look' at the rear tire as its spinning...is it wobbling if you look at it from the front, or rear? brake rotor is not wobbling?

if you are wobbling while in gear...put the bike back in neutral, leave it on the centerstand. rev the engine up to 3000 RPM, and hold it. vibrating still?

this will isolate engine from driveline vibration.

~Adam

[Anonymous]

I'll give that a try tomorrow, thanks.

[moto_dan]

Sorry I haven't replied in a while.

I am now certain that the vibration is either engine or exhaust related.

Does anyone with slip on exhaust have experience with vibration as opposed to stock exhaust?

We just installed an aftermarket slipon on my GS7/1100 and my son who is currently riding it complained on new vibration from the pegs. So it could be the exhaust as well in your case. We're going to isolate the rear exhaust hanger with rubber and see if that helps.

[AOD]

hmmn...if it wasn't such a bitch to get that exhaust bolt on the frame, i'd take it off and dampen mine with some rubber.

[Anonymous]

I slid some rubber in between the slip-on and the rear exhaust mount a while ago. It made no difference with the vibration.

I haven't ruled out the slip-ons as the source of the vibration as I think they're pretty low quality even though they're only a year old.

I put the bike on the centerstand and reved it to 3000 RPM in gear. The vibration was still there but the rear wheel and rotor ran perfectly true.

I am certain now that the vibration is caused by the engine or possibly the exhaust.

[Anonymous]

Grab some old kitchen oven mitts from the missus and do the centerstand trick again. This time have someone grab the exhaust pipes (wearing the mitts of course) to see if you notice a change in the amount of vibes.

[Anonymous]

I am slowly going insane!!
Its been several months now and I can't determine the cause of these vibrations. If they had always been there I would understand and claim that the bike simply vibrates, but this only started this summer some time.

I have checked everything I can easily get at. If the problem is internal, it will remain that way until the engine blows up and I am forced to rebuild.

I have now checked everything electrical to make sure each cylinder is running equally. (ie. spark, ignition, plugs, wires, boots, timing advancer, etc)

I have loosened and re-tourqued to spec. all engine mount, cylinder head and cylinder head cover bolts, as well as many others.

After the engine is hot, I've checked my spark plugs and they are a very light tan color, with cyl. no's 1 & 4 appearing to be slightly leaner than no's 2 & 3. This seems okay.

When I rev it to 3,500 rpm and feel around various points on the bike, the mufflers and rear pegs(where the mufflers attach) seem to vibrate the most. It is possible that the vibration may migrate back from another area to the mufflers, but I think my next step is to try and find a stock exhaust system to swap in.

I've tried inserting rubber spacers in a few mounting locations, but it does very little if anything to help.

Like I said before the carbs were cleaned and sync'd and the cam chain adjuster checked.

I guess I am looking for someone with the exact same experience who has found a solution. I NEED TO FIGURE THIS OUT!!

I'll go back to banging my head against the wall now.

[Jethro]

My bike vibrates so much my mirrors are useless! But I guess I would be going crazy with it if the bike wasn't always that bad. Anyway, I'm pretty certain that my bike is noisy and vibes alot due to worn cam chain guides. Not sure if this is my problem let alone yours, but it may be something to investigate?? Good luck.

[Anonymous]

Vibrations

My GS850 does this about 3-4K, my Kaw KZ900 does this about 3-4K, the Sportster I had did it about 600-4K! I'll take the buzz of Japanese over the constant vibes from a Sportster. It's the nature of the beast. But on the off-chance you find the culprit please let us know so my right hand will stop falling asleep Bob

[Dink]

Most Jap four cylinders were known to vibrate between 3-5000 rpm, however as I understand your bike has got worse since fitting aftermarket exhausts? have you tried finding a quiet bit of road and removing the mufflers (temporarily) to see if it has any effect? this should allow you to work out if it is exhaust related. I would not ride it any further than you have to without the mufflers as it will be running very lean.
Dink

[Don Lobacz]

There are universal joints on the shaft in your swingarm. If one of these "froze" it may produce vibration.

[Anonymous]

I did try removing the mufflers and went for a very short ride being too scared to run without them. It was very difficult to tell if the vibration was gone because of the very loud rumbling of the bike running with no mufflers.

I passed up on buying a complete exhaust system on ebay last night from another '81 650. I would love to get a hold of a completely stock exhaust for about an hour just to test it. Hard to come by though.

I might be barking up the wrong tree with the exhaust lead, but I would like to eliminate it.

Thanks again for everyone's input.

[Anonymous]

I was out riding the bike around the city yesterday and stopped at a aftermarket bike/sled shop that sells parts and work on sleds and bikes.

I began talking with the owner who works on all makes of bikes. I told him about the vibration problem at that 3,500 rpm range. He immediately suggested crank bearings, being that the problem seemed to be isolated to the engine. (I think someone on here suggested that) He also suggested connecting rod bearings, but the crank seems more plausible, either way it looks as though I'll have to make a decision this fall whether or not to tear down the engine.

If there is a bearing going, once it fails, the damage will be more costly than the replacement of the bearings so the decision is fairly easy.

I do have the factory and Clymer service manuals, so I think I'll try the work myself and take my time.

[argonsagas]

Before you get into opening the engine try a simple check on it.

If you have a mechanic's stethoscope, this is the time to use it. If not, get a broom handle or a piece of thick wood dowel. Do NOT use anything of a half inch or smaller diameter as it may damage your ear. Cut the length down to suit yourself. Put one end on the engine, and the other against your ear and listen.....works just like a stethoscope, but not as comfortable.

Check out the engine and try to identify the various noises it makes, placing the tip at various points on the engine and transmission cases. Once you have a good idea of the noises, run the revs up a bit.....just a bit...500 more than idle....and listen again. Then run it up to 3000 plus.

These engines have roller bearings, and I have not yet heard one of them going bad, so I cannot describe the sound. In plain-bearing engines, you would hear a distinctive thump from a bad main bearing, and the work "knock" is appropriate for connecting rod bearings.