Bad Vibrations

[raistian77]

Ok, checked piston travel is equall in 1 and 4. Ran a compression check, hot.
1-135
2-130
3-130
4-100

Seems I am loosing some compression through the head. Did a valve clearance check again and found the clearance barley acceptable. When I first got the bike the clearances were way to tight. Wondering if the PO ran the bike without adjusting the valves for to long. Gonna need to pull the head and grind the valves.

Installed the Dyna-S today, like the stability of the timing better.

 

[tkent02]

Gonna need to pull the head and grind the valves.

NO, you don't. Run it a while with the valves adjusted correctly, go 1,000 miles or so. Check that cylinder's valve clearances again after 100 or so. The compression will come up. The compression is not the reason for the vibration anyway, some engines with terrible compression run very smoothly at cruising RPM. There is another problem.

But if you like pulling heads and spending money, go for it, just don't be surprised afterward when it still vibrates.

 

[bwringer]

Let's back up a bit -- exactly how bad is this vibration, and how does it compare to similar 4-cylinder bikes you've ridden?

It's an inline-four -- it's gonna buzz.

For example, my bike is wearing Manic Salamander bar-end weights, the bars are filled with lead shot, and it's probably one of the smoothest GS850s on the planet. But I still have to be careful to change hand position often so I don't go numb.

So are we talking a somewhat normal amount of vibration, or are we talking "load of cement in the washer"? What are you comparing it to?

 

[raistian77]

NO, you don't. Run it a while with the valves adjusted correctly, go 1,000 miles or so. Check that cylinder's valve clearances again after 100 or so. The compression will come up. The compression is not the reason for the vibration anyway, some engines with terrible compression run very smoothly at cruising RPM. There is another problem.

But if you like pulling heads and spending money, go for it, just don't be surprised afterward when it still vibrates.

Before I started it for the first time I checked valves (way to tight)
made the adjustment
checked again 2,000 miles later, to tight again so I reajusted again
now its 2,000 miles later and the valves are back to being on the borderline of being to tight, a .0015 shim will barely slide.

Is it possible the valves are reseating after being way out?

 

[raistian77]

Let's back up a bit -- exactly how bad is this vibration, and how does it compare to similar 4-cylinder bikes you've ridden?

It's an inline-four -- it's gonna buzz.

For example, my bike is wearing Manic Salamander bar-end weights, the bars are filled with lead shot, and it's probably one of the smoothest GS850s on the planet. But I still have to be careful to change hand position often so I don't go numb.

So are we talking a somewhat normal amount of vibration, or are we talking "load of cement in the washer"? What are you comparing it to?

This is the first bike I have been on since 1996.
Never been on a 4 cylinder bike before this one.

at 4,000 rpm the handlebars and highway pegs buzz and tend to put hands and feet to sleep.

at 5,500 rpm the whole bike begins to buzz kinda hard.

guess I need to look into bar end weights.

 

[tkent02]

That sounds like way too much vibration. Try this, let someone with GS experience ride it, or ride someone else's GS to compare. It may be something obvious to a GS nut.
My GSes of all sizes are all just about smooth as glass when they are working right. No bar end weights, no fancy grips, no nothing. 850s usually are the smoothest of the bunch. You can maybe feel a little buzz at high RPM if you are looking for it, but it's not really noticeable. If I ride it all day my ass hurts, but not the hands.

Yes it is possible and it is likely the valves will need a few adjustments after being too tight like that. That's how the compression improves with a few miles.

 

[JEEPRUSTY]

This is the first bike I have been on since 1996.
Never been on a 4 cylinder bike before this one.

at 4,000 rpm the handlebars and highway pegs buzz and tend to put hands and feet to sleep.

at 5,500 rpm the whole bike begins to buzz kinda hard.

guess I need to look into bar end weights.

you dont have bar end weights?
I thought all bikes had em stock.

 

[raistian77]

Dang, I should have asked Steve to test run it when he was here

 

[JEEPRUSTY]

Before I started it for the first time I checked valves (way to tight)
made the adjustment
checked again 2,000 miles later, to tight again so I reajusted again
now its 2,000 miles later and the valves are back to being on the borderline of being to tight, a .0015 shim will barely slide.

Is it possible the valves are reseating after being way out?

Shim and bucket gurus isnt that an extreme amount of clearance loss in 2000 miles?

Is it possible that your timing chain jupmed not sure if this is possible without breaking the engine.

Also maybe you are not checking your clearance properly.
There is a video of a gs 500 being done on youtube but I dont know if the process is the same.

 

[tkent02]

you dont have bar end weights?
I thought all bikes had em stock.

Just thumpers, V twins and other designs with poor primary and secondary balance. Some of them even have balance shafts and still need bar end weights. Inline fours generally don't need them. Should be about as smooth as a car engine.

 

[JEEPRUSTY]

Just thumpers, V twins and other designs with poor primary and secondary balance. Some of them even have balance shafts and still need bar end weights. Inline fours generally don't need them. Should be about as smooth as a car engine.

I took mine out and they are pretty darned heavy never ran the engine without them I Imagine they do a lot.

 

[raistian77]

I have put 4,186 miles on it since june 11

 

[raistian77]

Shim and bucket gurus isnt that an extreme amount of clearance loss in 2000 miles?

Is it possible that your timing chain jupmed not sure if this is possible without breaking the engine.

Also maybe you are not checking your clearance properly.
There is a video of a gs 500 being done on youtube but I dont know if the process is the same.

The service manual states to check with cam lobe straight up, prefered or intake straight back and exhaust straight forward. I did mine all straight up.
clearences are 0.001-.003 inch
1 I-.001
1 E-.0015
2-I-.0025
2-E-.005
3-I-.001
3-E-.00125
4-I-.009
4-E-.003

I have a metric set of feeler guages but they jump between ranges to much
my SAE guages are machinist guages they advance in .00025 measurements starting at .001

As you can see 1 and 3 are on the cusp of being to tight
2 exhaust is to loose as is 4 intake
4 exhaust is fine

 

[tkent02]

Use the Suzuki service manual method of lining up the cams, you get much more accurate readings. Looser is better than tighter, especially after having been too tight.

 

[raistian77]

Use the Suzuki service manual method of lining up the cams, you get much more accurate readings. Looser is better than tighter, especially after having been too tight.

That is the Suzuki method in the service manual

Straight up or to the rear for intake
Straight up or to the front for the exhaust

 

[tkent02]

Not quite, one of the pair up, the other forward. Measure them both at this position. So for instance, measure #3 and #4 exhaust at the same time, one lobe up, the other forward....
Maybe that's what you meant?

 

[raistian77]

Not quite, one of the pair up, the other forward. Measure them both at this position. So for instance, measure #3 and #4 exhaust at the same time, one lobe up, the other forward....
Maybe that's what you meant?

I usally check twice, once lobes up than pointed staight. But, in reality it should make no difference, when I ran a auto shop we had many cams ground to spec for us for blueprinted engines. Once you are off of the lift part of the lobe, the distance between the lobe and cam should be equall all the way around till you ramp up for the lift again.

 

[tkent02]

I usally check twice, once lobes up than pointed staight. But, in reality it should make no difference, when I ran a auto shop we had many cams ground to spec for us for blueprinted engines. Once you are off of the lift part of the lobe, the distance between the lobe and cam should be equall all the way around till you ramp up for the lift again.

The thing is the cam gets pushed out of line when one of the pair is pushing a valve down. Remember, unlike a car there are only two bearings on each cam. But it really doesn't matter, a slight error either way is not the source of your vibration problem.

 

[raistian77]

The thing is the cam gets pushed out of line when one of the pair is pushing a valve down. Remember, unlike a car there are only two bearings on each cam. But it really doesn't matter, a slight error either way is not the source of your vibration problem.

Good point, this is kinda fun learing the diffrences between auto work and bike work. But you are right that would not cause the vibration. However what do you think is causing the fast clearance changes?

 

[tkent02]

However what do you think is causing the fast clearance changes?

The fact that it was too tight. If you look through the spark plug hole while the valve is open, a good valve will have a silver circle where the valve contacts the seat. If you look at one that has been run too tight, there is no silver ring, it hasn't really been contacting the seat. You adjust the clearance, now it can close. But the sealing surface is a little messed up, not sealing as nice as it should. Maybe it's even burnt just a tiny bit. After the valve closes a few million times, that seal starts to get better, forms the silver ring again, the valve sinks into the seat a tiny bit further, the compression gets better. As it does, the clearance gets tight again. Not sure if my reasoning is correct, but they usually do improve, and they usually need a few valve adjustments along the way. I have seen this happen on four GSes this summer, probably will see the improvement on a few more once I get them on the road. Valves were too tight, adjusted them, the compression came up. They almost always get better with miles, and need a few adjustments along the way. Had a guy here today, shop told him it needed a rebuild, due to bad compression. Adjusted the valves, got 115, 115, 116, 115.
(Low numbers due to the elevation here, at sea level they would all be in the 130s)


Of course, if the valve has been burnt too much, it will never improve, but if that was that bad it wouldn't have come up to 100 psi right after the first adjustment.