strong vibration and noise diagnose

[Peter Tez]

so I have a quite strong vibration, metallic sounding issue, and I would like some opinions about probable causes.. it is a 2005 gs500, 11k miles (I'm not very sure it are the real miles..), and here is my list of observations:

- it happens between 3500 and 4000 rpm
- worst when cold, still there when hot
- happens in all gears
- worst with pillion
- it's not there when I go to 2 & 3th gear with rear wheel lifted (no resistance)

is it correct to assume that it is the engine and not something loose on the bike by this observations?

Sometimes I do notice when I'm in that rpm range and I hit a bump in the road, it does something with the sound, which makes me this might be something loose on the bike.

I have checked this already, but will do it more thoroughly soon.. (bad weather and no garage)

I use the bike daily to commute to my job, and want to know what might be the cause and how safe it is to keep on riding it until I have more time and knowledge to figure it out...

I'll also try to record the sound, although that will not be easy as it only happens when riding..


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[The Buddha]

Sounds like it could be resonance like form an exhaust collar or something. Find where its coming from.
Cool.
Buddha.

[BockinBboy]

That's the rpm range that something is loose toward the front of the motor. Could very well be the front engine mount. Do you have sliders or an engine guard?

- Bboy



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[Peter Tez]

Sounds like it could be resonance like form an exhaust collar or something. Find where its coming from.
Cool.
Buddha.

YES! thank you Buddha!

the exhaust collars weren't loose, but I just got them off and on again and now the noise changed a lot. so it is defenitely the exhaust collars... I tried my best to put screw them evenly so the plate is straight and with the specified torque. now it's less loud and they seem to resonate at a lower rpm up to 3k. It's still there, but I know where it comes from which gives me a great peace of mind

I guess it is because of the aftermaket pipes that are not a perfect fit?

[Bluesmudge]

Maybe try installing new crush gaskets on the exhaust headers. Those collars should not be loose at all. Maybe you have aftermarket bolts that are slightly too long?

[The Buddha]

And those collars also look like sheite.
Cool.
Buddha.

[BockinBboy]

Lol the collars definitely don't seem to fit too well to start with. I'd second some new gaskets, and find some better collars. They look like something off my motorized bicycles.

- Bboy


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[ShowBizWolf]

+1 for the exhaust gaskets. I learned this way later than I should have lol not gonna lie!

At first (at least for me) it looks like there isn't even anything to remove... but once you remove the pipes and shine a bright light on the header holes on the engine... dig around carefully a bit with a small straight screwdriver, you should start to see that there are old gaskets. I bought two new OEM ones and used those after getting the old ones pried out and I cleaned up the surface of where they go (just with some brake cleaner sprayed on q-tips).

Also, I'm a fan of getting rid of the mounting bolts and switching to studs and nuts. I did that earlier this year and am very happy with it. (Info can be found here, about half way down the page, if interested: http://gstwins.com/gsboard/index.php?topic=70880.160 )

Good luck!!

[Peter Tez]

yes, the collars don't look to good indeed, but I didn't know that could be a problem. they do make the pipes fit firmly.. bolts are worn but not long enough.. anyway I just ordered a gasket repair set with gaskets, bolts and washers.

I just can't find any collars though.. any tips on where to find them?

[The Buddha]

Collars are put on the header before the end flange is rolled/welded.
You cant slap new collars onto it without hacking/grinding off the flange and then welding it back.
You can however run 2 exhaust crush gaskets and see if that helps.
In the old days we used to get these 1/2 and 1/2 style collars - I had a couple of kawis that had them. The headers were much smaller IIRC. Try a junkyard. They split apart and the bolts put them back into the collar shape.

You could find those and run 2 collars making for a more rigid fitting.
Cool.
Buddha.

[yamahonkawazuki]

indeed. do like buddha said. or as he also said can replace them but highly labor intensive . your choice there.  heres hoping for the best outcome .
Aaron

[BockinBboy]

Didn't think of the flanges on the pipes keeping them on.. doh! they literally look like the ones on my motorized bicycle, and those do come off and are replaceable. But that pipe is straight and disconnects from the can... definitely wouldn't work the same for an H pipe.

- Bboy


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[The Buddha]

The thing can cause noise but not much more vibration than original - its possible you have a bigger exhaust leak in 1 chamber than the other, that will cause it to vibrate more.
Cool.
Buddha.

[Peter Tez]

Also, I'm a fan of getting rid of the mounting bolts and switching to studs and nuts. I did that earlier this year and am very happy with it. (Info can be found here, about half way down the page, if interested: http://gstwins.com/gsboard/index.php?topic=70880.160 )

I guess this will be my next move as well...

so today I didn't want to wait for the gaskets I ordered on ebay, and went to a motorshop where I bought them for 5x the price on ebay... but at least I could move on. I use the bike daily to commute, so am confronted with this issue every day.

everything went well, but there was 1 bolt that was hard to get in all the way. it felt normal up until it almost seated the collar, from there on I had to use a higher torque get it in further. by eye it seemed that the bolt had a very slight angle, so I am guessing the previous owner screwed up the tread in the cilinder (the bolt looks fine).

with some (but not excessive) force I could get it to sit deep enough and tried to seat it evenly with the other bolt.
the result was it's back to how it was before I started messing with the exhaust. the sound and vibration is back to it's 3,5k - 4k rpm range.

so I guess the next step is to install studs, so I can connect the collar nice and evenly with the correct torque. or are there any other ideas?

having the exhaust off, I took some pics inside the cilinder... how does it look to you?

[Peter Tez]

Problem solved!!!

I feel so stupid.. when I searched for loose bolts in the beginning, I completely looked over the 2 most important ones.... twice!!!

today we finally had nice weather (no garage  ) and I had time to sit down with the bike and check all the bolts again. I experienced all kind of sensations discovering the lower fron mount bolt was loose! but like 'turn it with you pinky'-loose..

then I went on and discovered that the nut from the rear mounting bolt was.... MISSING!!!



I could have hit myself on the head and was so happy at the same time 

anyway thanks everybody for your input! sorry that is was absolute unnecessary...

now I'll write a mail to the previous owner (I just own the bike for a month or so), to tell him that he should bring his bikes to another shop, or to any shop if he was doing it himself. this is not the first assembly fail I encounter (so I should have known)

[ajensen]

Congratulations. As has been said, "It's the little things that can get you." Happy riding