08WR450, I have a loud rattle that starts at about 9K RPM


16 replies to this topic
  • Demo_Slug

Posted June 30, 2008 - 01:00 PM

#1

On my 08WR450, I have a loud rattle that starts at about 9K RPM in second gear. its metal on metal sound. Sounds like a big washer resonating on a loose bolt. A resonating washer is a real good description of the sound. Kind of odd to be able to hear it over my exhaust.. And the sound is non-existent under 9K. I only noticed it after installing my leo vince slip on. And that might be because I rev the bike out more with the new exhaust. Or it could be internal to the pipe. But, I’m thinking it sounds like a loose motor mount bolt. Which, I messed with not to long ago to change my needle clip position in the carb.

The bike as 60 hours on it. last valve check was 20 hours ago(they were adjusted). Oil and air filter get changed often. I don’t have regular intervals but I don’t go over 4 rides without an oil change. But I’m averaging 6 hours per oil change(its had 10 oil changes in its life span).



My question:
Any known noisemakers?. Carburetor slide vibrating? Kick stand? Kick starter? Or just should I just start tightening everything.

Seams silly, but Piston hitting valves??? Is my engine going to explode or is something going to fall off the bike?

  • JSanfilippo

Posted June 30, 2008 - 05:18 PM

#2

Put the stock muffler back on and see if it does it. There really is no reason why it should be making funny noises at 9k rpm.

Damn you must be a riding savage. The only time my scoot is screaming that high is on hillclimbs when I need that juice.

  • Demo_Slug

Posted June 30, 2008 - 08:08 PM

#3

Put the stock muffler back on and see if it does it. There really is no reason why it should be making funny noises at 9k rpm.

Damn you must be a riding savage. The only time my scoot is screaming that high is on hillclimbs when I need that juice.


thaks for the input:thumbsup:

I'll check my valves too(its about time anyway) and tighten some bolts on the way in there. I think I've convinced myslef that its a motor mount bolt, I'm a chronic under thightener. some how even with a torq wrench I've already had 3 bolts fall off my bike :worthy: . but if that isn't it, then I'll slip the old exhuast back on. but the old exhuast is self limiting. I'll get board waiting for it to climb up over 9K. :p

In regards to "riding savage" I'm just playing with my new found over rev. I was a confirmed chain slaping, short shifter until I got the new pipe. I can only imagine what a full motocross system like a DRD would do. :thumbsup:

Trust me. I'm slower then 99% of the guys that post on this board. :p Timid is my middle name. for example... I actually put 37 hours on my bike before a put in the YZ throttle stop :cry:

  • WR_Dave

Posted July 01, 2008 - 06:07 AM

#4

I know this may be a little far fetched, but with the new exhaust, did you rejet, and do the grey wire mod. It may ( I repeat"MAY") be preignition at that speed in which case you will need to stop doing that ASAP. Preignition eats pistons. Try to go up a main jet or two and see if it still does it. Just an idea I had that I thought was worth sharing. WR Dave

  • beezer

Posted July 01, 2008 - 07:40 AM

#5

A bike with a skidplate on it bounces the mechanical noise back up to the rider.

The pipe changed how the bike sounds. I wouldn't worry about it.

  • Thumper_Bloke

Posted July 01, 2008 - 08:30 AM

#6

I agree with beezer, the skidplate bounces noice back to the rider.

As a check, put the quiet exhaust back on and ride it a bit. Then you'll know if its really mechanical or just a new audible.

  • brad the best

Posted July 01, 2008 - 09:27 AM

#7

I know this may be a little far fetched, but with the new exhaust, did you rejet, and do the grey wire mod. It may ( I repeat"MAY") be preignition at that speed in which case you will need to stop doing that ASAP. Preignition eats pistons. Try to go up a main jet or two and see if it still does it. Just an idea I had that I thought was worth sharing. WR Dave


i don't think thats to far fetched , i would personally be worrying about that more then anything else .

  • Demo_Slug

Posted July 01, 2008 - 11:31 AM

#8

i don't think thats to far fetched , i would personally be worrying about that more then anything else .


Kind of hard to believe that an 94db exhaust with the stock 38mm header would change jetting too much. But I’m game.

I'm game to jetting. my assumption is the detonation would exclusively exist only if the jetting was too lean. And if its rich then detonation is not an issue? Is that true or am I just dead wrong.??

My jetting is JD red needle forth clip from top, 168 main jet. Air temp was in the 90s. Altitude was 1200feet. During winter I had been running 5th clip, 170 for see level. seemed a bit fat but ran good. it did run crisper when I leaned it out to a 168MJ. the leo vince application notes from their dyno run was done with a 175 main jet(they are in itailian). but they do claim it works with stock jetting.

If we are looking at sources of detonation… then I guess maybe it could be bad gas??? Anyone recommend an octane booster??

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  • WR_Dave

Posted July 01, 2008 - 08:56 PM

#9

Detonation and pre-ignition are essentially the same thing. The fuel charge goes off before the spark is even fired in the cylinder. This usually happens under heavy load or high RPM's when a lean condition causes the combustion chamber to get extremely hot and light the incoming fuel charge before the spark plug sparks. Bad for the piston, rings piston pin and crank. A rich charge basically displaces more air so the combustion event is "cooler" in the cylinder. If the bike is basically stock in the cylinder then I don't believe that octane booster would help you any more than running premium fuel. I'd go back to the next jet size and give it a quick try to see if it changes anything. It could still be something mechanical. WR Dave.

  • ozwr

Posted July 02, 2008 - 02:00 AM

#10

I had a loud rattle when accelarating harshly in most gears and found that it was the swingarm chain guide slapping with the chain. I thought I had a dying engine, but after I used strong epoxy adhesive to stick the chain guide to the swingarm, it is nice and quiet. This could be an option?

  • Demo_Slug

Posted July 02, 2008 - 09:08 AM

#11

I had a loud rattle when accelarating harshly in most gears and found that it was the swingarm chain guide slapping with the chain. I thought I had a dying engine, but after I used strong epoxy adhesive to stick the chain guide to the swingarm, it is nice and quiet. This could be an option?


Yeah…. its not chain slap. I’ve already used silicon to isolate the chain slider, which helped with some of the chain slap noise.

  • JSanfilippo

Posted July 02, 2008 - 02:02 PM

#12

[quote name='Demo_Slug']Kind of hard to believe that an 94db exhaust with the stock 38mm header would change jetting too much. But I’m game.
[/quote]
You'd be surprised. The stock jetting leaned out considerably just by opening the airbox and fitting a PMB insert to the stock pipe.

[quote name=']My jetting is JD red needle forth clip from top' date=' 168 main jet. Air temp was in the 90s. Altitude was 1200feet. During winter I had been running 5th clip, 170 for see level. seemed a bit fat but ran good. it did run crisper when I leaned it out to a 168MJ. the leo vince application notes from their dyno run was done with a 175 main jet(they are in itailian). but they do claim it works with stock jetting.[/quote']
The 168 main is ballpark. Infact the 168 is what JD recommends running in a free modded uncorked bike with a pipe. I doubt the problem is the jetting. The 168 main/JD red 4th clip is what I'll be running when I put my full system on there. Right now the 165/JD red 4th is in there but it will be too lean once I put the free flowing muffler/bigger header on there.

[quote=]If we are looking at sources of detonation… then I guess maybe it could be bad gas??? Anyone recommend an octane booster??[/QUOTE]

I ran all summer last year with my current jetting and 91 octane pump gas and everything was good until I went to Clear Creek. The bike got a little warm on the singletrack in the morning and pulling a dozen runs in multiple open barren hillclimbs didn't help either. Well it at the end of the day there was a faint pinging sound coming from the engine past 1/2 throttle. My buddy and I speculated that the engine got hotter than normal which heated the gas and caused the pinging.

Since then I've been running Maxima high-test (1 bottle to 5 gallons) and CD2 lead substitute in my gas and I changed the coolant from stock to a mixture of 75% distilled water, 25% prestone, and water wetter. It hasn't pinged since.

  • Demo_Slug

Posted July 03, 2008 - 09:38 PM

#13

OK, I think I got it tonight.... my Hammerhead shifter. it has 2 washers that are spacers to let you re arange them to lift or lower the head. I guess they had assembly lube on them when new. but now they are dry and make a racket. I greased them and took it around the block. and all seems well.

  • Thumper_Bloke

Posted July 10, 2008 - 08:02 AM

#14

OK, I think I got it tonight.... my Hammerhead shifter. it has 2 washers that are spacers to let you re arange them to lift or lower the head. I guess they had assembly lube on them when new. but now they are dry and make a racket. I greased them and took it around the block. and all seems well.



Ahh, ok, that damn aftermarket stuff !!!

  • Demo_Slug

Posted July 10, 2008 - 09:30 AM

#15

Ahh, ok, that damn aftermarket stuff !!!


Agree! That’s how I figured it out. Previous experience has proven that any problem I’ve had with the bike is always associated with some after market part I’ve added… or maintenance that I’ve performed.

So I just took a long look at my bike and checked everything that I’d ever done to the bike.

The hammerhead shifter stayed on my bike, but that is only because my size 14 feet are not compatible with the OEM shifter.

  • swede426

Posted July 10, 2008 - 01:53 PM

#16

9K....., what are the rev limits on these engines (450,426,400)?

  • Demo_Slug

Posted July 10, 2008 - 03:21 PM

#17

9K....., what are the rev limits on these engines (450,426,400)?


I think it is 11K, that is where most of the dyno plots I've seen stop. personally I don't use above 9K much. I usually just get into the 9K range right before I shift. peak torq is usually around 8K.




 
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