[14wntr]

I am working on a friends bike and here is the issue. I took it out to help diagnose the issue with his 05 LT. As soon as it started to warm up it began making a noise like a sewing machine while under light throttle beginning at 2800 and getting louder until 4200 then it starts to go away. I tested this many times and it is always noisy under a light load but not under heavy accel or decel. Seems like it may be missing occasionally.No noise in neutral but I think I hear 1 clunk when I rev it. I took all of the covers off to do other maintenance including the valves. I ran it up 1st in the shop with some rear brake and could reproduce the noise. I am quite certain that the noise is coming from the front of the engine like possibly a chain slapping. When I took the valve cover off, nothing seems obviously amiss but I need advice from someone who has dug deeper than a valve check.
How much slack should the chain have if the tensioner is working properly? Should I be able to lift it easily or should it be fairly tight? I can lift it up with a screwdriver and it seems kinda loose. It is not so loose that it will jump gears but it is loose none the less.
Is there a way to test the tensioner without taking the front cover off?

Oil is 20-50
19000 miles

 

[14wntr]

Does the chain tensioner work with oil pressure or with a spring? I am wondering why the top part of the chain is slack. Someone please chime in!

 

[Wolfgang]

A cracked exhaust manifold will sound a lot like your description. Mine did that and I heard the noise on and off for several month until it got louder and I found the source. I had mine re-welded. Worked out great.

 

[14wntr]

Where did it break? I am looking at it now and dont see anything around where the headers attach.

 

[14wntr]

Would an intake valve that is too tight be the cause of this? I have one that is measuring .005 instead of .006 or greater.

 

[Razmataz]

Where did it break? I am looking at it now and dont see anything around where the headers attach.

Look down underneath where the four into one is welded.

 

[JPSpen]

Tap the header with a rubber hammer.. It will rattle if that's the issue..

Also.. The place where the lower and upper tupperware meet at the front will rattle as well..

Also.. There is a spring somewhere under the exhaust that will rattle..

While you had the valve cover off, Did you check the valve clearance ?

The LT definitely builds a buzz that abruptly goes away above 4500RPM..

John

 

[14wntr]

I am very familiar with the normal buzz and rattles. This one is VERY pronounced at 2800-4200 RPM's. It sounds like the chain is slapping but I am not conviced. I found 1 intake bucket is .001 tight. I have inspectd the exhaust very carefully and cannot find any cracks or damage.

 

[gary45]

How much slack should the chain have if the tensioner is working properly? Should I be able to lift it easily or should it be fairly tight? I can lift it up with a screwdriver and it seems kinda loose. It is not so loose that it will jump gears but it is loose none the less.
Is there a way to test the tensioner without taking the front cover off?

Oil is 20-50
19000 miles

no slack in the chain on mine when I checked the valves this spring, you can check if you remove valve cover

 

[14wntr]

The valve cover is off.

 

[jzeiler]

The tensioner is oil fed and I have never heard of one getting loose in the last eight years. A tight exhaust valve will also not make the noise but it should be fixed as you don't want a burned valve. .005 is out of spec period. These are very noisy engines when we run them without our helmets on. Suit up and ride it naked (the bike not you!!!) just to see if you still hear it.

 

[bobst2]

are you sure the noise is not tipical k wine rpm sounds about right. the first few times i herd it i was concerned. but read some threads about it & concluded what i herd was normal

 

[14wntr]

I am certain this is far above any normal noise. I am going to get it running again either today or tomorrow and see if its still doing it. If it is I may record the noise and put it out there for eval.

 

[fpmlt]

Can you arrange to ride with other LTs? You can listen to them, they can listen to yours. Another trick my be to get a mechanics stethoscope. You can go probing around until you isolate the exact area of the noise.

 

[14wntr]

I will do a ride today to see if it is still haunting this bike. I still need to do a few maintainece items today before I take it out but I will report back as soon as I do.

 

[14wntr]

Noise is still there. I have recorded it here if you can help.
http://youtu.be/z_sZZ6KlJnE