Lots of vibration, any ideas why?

[Don Lobacz]

I'm pretty sure that the GS650 has plain bearings.

Bad main or rod bearings seem very unlikely without noticeable nasty sounds. Also, there should be a metalic indication in the oil. There are some services that will analyze your oil and tell you with a high probability what is the problem. I would definitely do this before tearing down your motor.

[Anonymous]

There certainly is no visual indication of metal in the oil. I've changed the oil twice this summer and there's nothing on the plug and it looks used, but clean in the pan.

There has been no change in engine sound since I've had the bike.

I am convinced that the vibration is not normal, and has gotten worse this summer.

If the problem is not internal to the engine, then I am at a loss.

With the bike on the stand, I can start it(in neutral, of course) rev it too 3,500 rpm and feel the vibration immediately. This, to me, eliminates anything to do with the chassis, driveline or transmission.

The problem must be linked to the engine or possibly the exhaust.

I know this bike may never be vibration free, but I know it can be better than this.

I am going to get a hold of a timing light and check ignition timing, maybe check the valve clearances again and re-sync the carbs.

Thank you all again for helping to try and solve this dilemma and save me some time and money in the process.

[earlfor]

I believe you said that you had replaced the exhaust system with an aftermarket set. Considering all you have checked and the running test on the centerstand to find the vibration is not drivetrain, I agree that it is an engine problem. Also, as said, bad bearings etc., woul leave metal filings in the oil and you have none. My hunch is that the vibration is a result of the exhaust pulse resonance/phasing of the replacement muffler and header system. When the exhaust resonance wave from an engine is in alignment with the time,velocity and flow characteristics of a muffler system, it is said to be in "tune". I suspect that for whatever reason, your particular exhaust is close to 180 deg out of phase for the engine to breath correctly and that pressure wave is arriving back at the exhaust port just as the exhaust is trying to expel burnt gases. It would be something like two hammers meeting everytime the exhaust opens. If you still have the original exhaust (that apparently did not give this problem), I would reinstall it to see if the problem disappears. (just my theory and I'm sticking to it) :-)

Earl


[quote="Duke"]

There has been no change in engine sound since I've had the bike.

I am convinced that the vibration is not normal, and has gotten worse this summer.

If the problem is not internal to the engine, then I am at a loss.

With the bike on the stand, I can start it(in neutral, of course) rev it too 3,500 rpm and feel the vibration immediately. This, to me, eliminates anything to do with the chassis, driveline or transmission.

The problem must be linked to the engine or possibly the exhaust.

[AOD]

out of curiousity, are you talking about a buzzing vibration, or a very noticeable shaking?

my bike has a pretty constant buzz through out...probably due to the exhaust and some engine mount modifications. the carbs were sync'ed last weekend, and from what i can feel, it had no affect on the vibration.

i am trying new grips which i ordered this week.

what i suggest you try next is adding weight to the handlebars. people suggest using sand, bb's, or any other dense object that you can fit into the bar ends. you'll have to plug the ends afterwards.

sure hope you get it figured out soon.

~Adam

[Anonymous]

It is definitely a buzzing vibration I feel more in the seat and pegs than the bars. I did put a new set of foam grips on this summer which may have helped minimally.

I wish I had a stock exhaust system to try out. I threw away the original mufflers right after I got the bike. They had large holes rusted through both of them. I replaced them with Lu Hao Silencers Ltd. $60 slip-ons using the existing header pipes which are in excellent condition. I had to cut the mufflers off right behind the pegs.

Maybe if I could convince my local bike parts shop to loan me a new set of "better" slip-ons to try around the block, I would be able to tell right away if there was an improvement.

[AOD]

i believe GS550 exhaust will fit the 650...not sure about the years though. if you can swap mufflers easy, try that.

you're still running the stock exhaust headers though, right? have you verified they are tightened good to the head?

i've gotten used to the buzzing in mine...its not too bad. hopefully the grips will make it a lot more tolerable...i'm going to see what i can add into the bars weight wise when i swap grips.

you should try the same maybe. as for the buzzing in your seat...how do the bushing under your seat look? make sure your fuel tank is bolted tightely in...and it 'should' have a rubber bushing on its bolt as well...to help reduce vibration.

~Adam

[Anonymous]

I have the stock header pipes on the bike. I have checked the mounting bolts and they're snug.

There are rubber bushings on the 2 bolts for the gas tank. There are also 4 rubber spacers attached under the seat which appear to be in good condition.

The rubber bushings for the pegs are still there. They could possibly use replacing, but they're there.

[AOD]

i think you just might have the same buzz as me. you may want to look into adding some weight to the handlebars and see how it helps your hands.

~Adam

[Anonymous]

BZZZZzzzzz!!!!!!

Duke:
Heres one that has not been mentioned and I have heard of it happen to our style motors. As you know, our motors are a pressed fit built up type of crankshaft. More to the point , the crank is pressed together out of several pieces. I have heard of these motors 'twisting' the crank, the upshot being the cranks are no longer truly balanced with alot of vibration as a result. This is why the cranks were welded up on the 83 and up 1100s' & 1150s'. Just another tidbit of info, but it seems to be narrowing down to this.
Rick.......

[Anonymous]

being one who has twisted a crank GS1000 years ago it puts a vib through the whole bike. rear veiw mirrors became useless above 3000 rpm footpegs vibrating rear end going numb(rider that is) even had a few bolts come loose that don't normally. sounds familiar don't it.mine was caused by the fact i put a 1080 kit and a heap of mods in ,went dragging only did 3 runs before the vib arrived .have heard of a few stockers doing it.. good luck ozman

[Anonymous]

I took the mufflers off again last night. I sat on the bike and revved it up to 3,500 rpm several times. I don't know if I just missed it last time I did this, but the vibration is certainly still there.

I am confident now that exhaust has nothing to do with it.

I also checked the timing with a timing light, and it was bang on. I might re-check the valve clearances(fairly easy to do) and re-sync the carbs (again).

Something inside the engine is causing the vibration and that is what I'll have to concentrate on now. One of our mechanics at work has a stethoscope I'll try and borrow to see if I can locate any unusual noises.

It's looking more and more like a winter tear-down project unless something jumps out at me soon.

Believe me, if I ever find the problem, I'll let everyone know.

[Anonymous]

I checked the carb sync yesterday and they weren't far off at all. I didn't even need to make any adjustment. I also checked the valve clearances, also no adjustment required, all within spec.
I re-tourqued every nut or bolt I could get at with the valve cover off.

I have officially admitted defeat for now. I'll continue to monitor if anything changes, but I'll just ride it as is, the weather is too nice around here to take anything else apart.

A big thanks again for all the input from everyone.

[AOD]

Duke, here is something to try. Have you checked and made sure the exhaust collectors are not cracked anywhere? i think you said you have the original chrome ones still.

i just swapped the exhaust on my 550 this weekend, the old 4-1 was rusting and cracked. when i pulled it off, one of the pipes (which has been welding on in the past twice) had cracked yet again. not only did it make the bike louder, run worse, but it added a vibration. i rode an hour with the new exhaust on saturday...and it felt entirely smoother!

can't wait to get my new grips on

~Adam

[Anonymous]

Are you talking about the header pipes directly off the engine? If so they appear to be in good condition, but I guess they could use a closer look.

I do know that one of those goofy exhaust clamps has a crack in it on the No. 4, but in order to change it I would have to cut and weld the pipe, something I've been avoiding. Its been cracked since I've had the bike.

Maybe I'll take the complete exhaust off again and have a good look at it.

[AOD]

i'm talking about the area where the 2 pipes come together...then run into the mufflers. sometimes the pipes rust or crack there...and that was causing some vibration on my bike before i swapped exhaust.

if this crack you said you have is on the collector, it could be letting exhaust sound/noise into the frame and motor, instead of out the back of the bike.

~Adam