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Discussion Starter · #1 ·
:icon_cry:

I have two diffrent kind of engine noise or at least i think it comes from the engine. The sound appears when i am acclerating but onley when i am in 3,4 and 5 gear and only when i am at low rpm as soon as i reach higher rmp the sound disappears. It sounds like when you shake an spray can or something. Like something is loose and flying around in the engine or ratteling. You can't hear the sound when you stand still. Then the engine runs perfectly. The second sound comes when i deacclerate and comes when i am closeing in to lower rpm in the higer gears. But it sounds diffrent than the other one more like if you have a loose steelplate thats vibrate.

These two sounds are making me crazy because i can't figure out were they come from. Or whats causeing it.??

Any help or ide is appriected.
 

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do you have an aluminum belly skid plate? Check and make sure it is tight because they rattle against the frame and it can sound terrible. Easy fix though! Hope its not the engine. Check everything outside the engine first
 

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Discussion Starter · #3 ·
do you have an aluminum belly skid plate? Check and make sure it is tight because they rattle against the frame and it can sound terrible. Easy fix though! Hope its not the engine. Check everything outside the engine first[/b]

Yes i do have an skid plate. I will check it and se if that might be whats causeing the sound. I know that i have placed rubber at most of the places where the frame is against the skidplate but i will checkit.

Thanks fore the ide :icon_biggrin:
 

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Discussion Starter · #4 ·
Yes i do have an skid plate. I will check it and se if that might be whats causeing the sound. I know that i have placed rubber at most of the places where the frame is against the skidplate but i will checkit.

Thanks fore the ide :icon_biggrin:[/b]

Checked the skid plate and the sound is still their... :icon_frown:

Its hard to tell where it comes from because you have to ride it to get then noise.

Any ide's???
 

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I have noticed on my YFZ that if you're "lugging" the machine the engine noise increases but once I get it wound up it seems to be in it's element.

Not sure if this is where your noise is coming from and it will be hard for us to tell what the noise is...we're only guessing.
 

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My '05 also has an alumiunum skid plate and makes tons of racket at low speeds. I think it's a combination of the plate directing the sound back towards the rider's ears, the chain, and the fcat that these types of motors are just noisy. The motor in my CRF450R was the same way, I wouldv't swore that thing was on it's last legs from al the racket it made, but that's just the way it is with killer motors, in my opinion. Use earplugs and be happy!
 

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Discussion Starter · #7 ·
My '05 also has an alumiunum skid plate and makes tons of racket at low speeds. I think it's a combination of the plate directing the sound back towards the rider's ears, the chain, and the fcat that these types of motors are just noisy. The motor in my CRF450R was the same way, I wouldv't swore that thing was on it's last legs from al the racket it made, but that's just the way it is with killer motors, in my opinion. Use earplugs and be happy![/b]

I think i have two options split the engine wide open or keep runing it and hope for the best.

I am planing on changing piston, head, cam chain and cams. Is there any way to tell if the crank is giving up? Because thinking about changing it allso.

The ratteling sound wasen't their when i bought it and i whant to get rid of it.
 

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Well, if it wasn't making the noise when you first got it, something is wrong. If it increases with engine RPM, regardless of what gear you're in, it's motor related. If it increases with vehicle speed, it's trans/drivetrain related. If it were my engine, I'd check the spark plug first. A wet, oily plug indicates oil burning, either through a worn piston or cylinder or valve guides. As long as you have the plug out, do a compression test. If it's low, squirt a bit of motor oil in the plug hole and do it again. Oil will seal up rings for a compression test, but not burnt valves. If all these areas check out, and the quad starts easily, doesn't use much oil, and has decent power, it's likely trans related. If the trans shifts into all gears, and doesn't pop out of gear, I'd suspect a clutch basket. If you drag race your YFZ a lot, or use the clutch like a two stroke to bring up engine RPM out of corners, you may have grooved your clutch basket, and they also make nasty noises. Before you split the cases, take a good look at the condition of your chain. Before I replaced the chain on my CRF450, it made more racket than the motor! Worn-out chains make bad noises as they pop around hooked spocket teeth (bad chains and bad sprockets go hand-in-hand) and they also move a great deal sideways, beating on the motor and frame. If you're going to sell the quad anyway, you don't want to dump a bunch of money into it, especially if you don't need to! Look at the simple stuff first, and if you can't find it, and the quad still runs well, why not drop the price rather than spend money? Lots of people would rather get a quad they can afford now, and spend the money as they can afford it later. Above all, be honest about the condition. NEVER tell a buyer that "they all make that noise" when you know full well something's wrong. Karma can be a bad thing, and it's never at the right time...
 

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Discussion Starter · #9 ·
Well, if it wasn't making the noise when you first got it, something is wrong. If it increases with engine RPM, regardless of what gear you're in, it's motor related. If it increases with vehicle speed, it's trans/drivetrain related. If it were my engine, I'd check the spark plug first. A wet, oily plug indicates oil burning, either through a worn piston or cylinder or valve guides. As long as you have the plug out, do a compression test. If it's low, squirt a bit of motor oil in the plug hole and do it again. Oil will seal up rings for a compression test, but not burnt valves. If all these areas check out, and the quad starts easily, doesn't use much oil, and has decent power, it's likely trans related. If the trans shifts into all gears, and doesn't pop out of gear, I'd suspect a clutch basket. If you drag race your YFZ a lot, or use the clutch like a two stroke to bring up engine RPM out of corners, you may have grooved your clutch basket, and they also make nasty noises. Before you split the cases, take a good look at the condition of your chain. Before I replaced the chain on my CRF450, it made more racket than the motor! Worn-out chains make bad noises as they pop around hooked spocket teeth (bad chains and bad sprockets go hand-in-hand) and they also move a great deal sideways, beating on the motor and frame. If you're going to sell the quad anyway, you don't want to dump a bunch of money into it, especially if you don't need to! Look at the simple stuff first, and if you can't find it, and the quad still runs well, why not drop the price rather than spend money? Lots of people would rather get a quad they can afford now, and spend the money as they can afford it later. Above all, be honest about the condition. NEVER tell a buyer that "they all make that noise" when you know full well something's wrong. Karma can be a bad thing, and it's never at the right time...[/b]

Thanks for the info :icon_biggrin:

I'am not going to sell it so i will start try to find whats causing the noise. :disgust:

The strange thing is that i doesn't increases when it reaches higer rpm it disappears. It does not take any oil or have any start problems and the plug looks fine. So i think it's on the transmisson side. It gears perfectly and the clutch is god so i don't realy know where to start. The chain and sproket is allso fine.

The sound appears and is noticeble when i am in 3,4 and 5 gear and drop of to idling and then increases the throttel and then it dissapers when I reach mid rpm. It sounds like a metal ball ratteling around. Could it be the cam chain?

I am greatfull for any ide's
 

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im going with skidplate as my guess . i had this issue with proarmor skid plate. about mid throttle it would rattle like hell. and then go away at top rpms. i just used some duct tape wrapped around where the skid sits on the frame (so its not metal to metal) and made sure bolte were tightened with loctite, it got rid of my problem.
 
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