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My KLX250s engine sound. Help!

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So i have a 2007 klx and it has around 5k on it. I get a sort of diesel clack up to 4k rpm. Im not sure what it is, but i feel like the valves need to be adjusted. Any other opinions would be great

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I have a KLX300 in the shop now and it also makes some noise.

I measured the valve clearance but they are all within factory recommended tolerances. (IN 0.10-1.19, OUT 0.15-0.24)

The ACR mechanism is sloppy though and when I move it with my fingers it makes a metallic noise. So I suspect that it's making the noise. I will remove it now and see if it helps, this bike has no kick start, so there won't be any issue with the idle gear as is mentioned in this thread about the 250: http://www.thumpertalk.com/topic/488365-can-the-kacr-be-removed-on-the-klx250s/

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Theanks. Im not sure its necessarily a metallic sound. Its more like a misfire or preignition. I mean, if you watch videos online, you can here it from some other bikes.

. It sounds somewhat similar to this. And as the engine goes up in rpm, the clack is less prevalent. Im using 93 octane. Shouldnt be detonating early due to compression. This is weirdd.

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I had the same problem on my KLX300. sounded just like preignition engine knock. Turned out to be the automatic chain tensioner had lost its ability to keep th timing chain tight enough. Replaced it with a Krieger manual tensioner and the sound went away. 

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I had the same problem on my KLX300. sounded just like preignition engine knock. Turned out to be the automatic chain tensioner had lost its ability to keep th timing chain tight enough. Replaced it with a Krieger manual tensioner and the sound went away.

Thanks a lot. Yea i wasnt sure what to do. But thatnks for the help, ill be sure to get on that. And i only thought it was the drz's that needed manual cam chain tensioners lol.

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Hold on, i didnt give the cam chain tensioner a thought. I dont believe valve timing has much to do with engine knock. Unless it were on the exhaust stroke and the valves were closed. But i believe it is on the power stroke and if the valves were open, closed or off, the "ping" would not occur. Idk. Im just not sure about the acct. knocking occurs with pre ignition and compression. I may be wrong. I just can put two and two together.

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The chain tension as far as I know just keeps the proper amount of tension on the chain to keep it from slapping around in there. Unless the chain itself is stretched there should be no effect on valve timing. I must admit your sound video does not lead you that direction but I would check it anyway to eliminate it from the discussion one way or another. It is pretty easy to get off.

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Jeez, that sounds a lot indeed!

So open the valve cover and check the valve clearance  (IN 0.10-1.19, OUT 0.15-0.24) and if valve clearance is ok check the ACR mechanism.
I just removed the ACR from a KLX300 here:

 

543900_500082683411278_1793684695_n.jpg

 

1240128_500082853411261_1629702356_n.jpg

 

Hope you get your noise sorted!

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Yea. Well thanks for your help everybody. Time put this baby away while i go to school.

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Most definitely not this

 

Can you say "Cam chain tensioner"?   I thought you could.  I'm pretty much positive that noise is the cam drive.  When you got close to the cam chain area with the camera the noise definitely became louder.  If the noise comes from that area it is the tensioner.  You can use a long handle screwdriver or a mechanic's stethoscope to trace noises.  Put the tip in and around the area of the compression release, the cam cover and the tensioner, wherever the noise is loudest is where the problem is.  On a KLX650 it doesn't even take that much.  The cam drive will make the loudest noise on the left, loose valves higher and in the center front, the KACR will be on the right side and will usually definitely make a clacking at idle with a rough idle then get quiet with revs.  When a KACR loses it's spring it will clack up to around 1200 rpm on the 650.

 

When it comes to the cam chain tensioner, the term "tensioner" is a bit of a misnomer.  The chain should run with as little tension as possible, kind of like a drive chain.  If it is too tight it will pull on the cams that are running in a plain bearing head (can you say "big dollars"?).  On the other hand if the chain is loose it will be slapping around in the cylinder, possibly damaging the sliders, wearing out the chain with all the snatching, and possibly allow the cam timing to jump.  That could damage the valves, head, and piston if they decide to occupy the same space at the same time.

 

If you pull out the OEM tensioner you may see some polishing on some teeth and three or four teeth with a wear pattern - that is where the rack is being snapped back skipping across and rounding the teeth of the rack and the pawl edge, then sliding back forward.   Look at the back side and you will likely see wear and polishing showing it is sliding in and out.  It's like when a worn set of shifter dogs allow a bike to pop out of gear.  The tensioner is junk.

 

The spring in the tensioner is there only to put some relatively light pressure against the rack to allow it to index in (move a specific amount) and engage the next tooth.  The pawl locking in the rack is what holds adjustment, not the spring.  Problem is when the chain only seats in or wears enough to start to let the pawl snap into the next rack tooth - it doesn't seat and when under decel the momentum of the cam drive will push the rack back, hard, chipping and wearing teeth and pawl.  That is happening over and over and over before you even realize it is starting. 

 

Doing the short cut methods to force seating can put excess pressure on the cam drive - remember that expensive head where the cams run in a plain bearing machined surface?  Break that oil film and they may get to share metal.

 

A manual tensioner is actually a manual adjuster.  You turn in to take up the play, not to put tension on the cam drive.  The object is to have as close to zero chain play as possible without having any tension when using a manual adjuster.  It is easy to do.  Finger tightening the adjuster will not overtighten the adjustment.  Actually very simple.  The other method is by sound with a fully warmed engine.  The adjustment is done very slowly while carefully listening to the cam drive ticking.  When the ticking just stops that is perfect adjustment.  The engine should never drop rpm in this adjustment process.  If it does the drive is too tight, back off immediately.   I've actually found that the cold adjustment will be within a few thousandths of perfect and the play is so little it doesn't matter.

 

This is all basic reasoning and method for proper use of a chain drive in anything.  Chains are not meant to run tight.  Go flip a bicycle over, tighten a bicycle drive chain too tight then pedal it by hand - think of your cam drive and that very expensive head and cams.  That is the best analogy to realize what is going on.  In addition I wlll tell you that HyVo chain should last as long as the engine quite easily.

 

That video audibly tells me you should get rid of that tensioner and either take a chance with another OEM or be sure with a manual unit.  Ask the guys who've done so and you will find most will go manual.

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Can you say "Cam chain tensioner"? I thought you could. I'm pretty much positive that noise is the cam drive. When you got close to the cam chain area with the camera the noise definitely became louder. If the noise comes from that area it is the tensioner. You can use a long handle screwdriver or a mechanic's stethoscope to trace noises. Put the tip in and around the area of the compression release, the cam cover and the tensioner, wherever the noise is loudest is where the problem is. On a KLX650 it doesn't even take that much. The cam drive will make the loudest noise on the left, loose valves higher and in the center front, the KACR will be on the right side and will usually definitely make a clacking at idle with a rough idle then get quiet with revs. When a KACR loses it's spring it will clack up to around 1200 rpm on the 650.

When it comes to the cam chain tensioner, the term "tensioner" is a bit of a misnomer. The chain should run with as little tension as possible, kind of like a drive chain. If it is too tight it will pull on the cams that are running in a plain bearing head (can you say "big dollars"?). On the other hand if the chain is loose it will be slapping around in the cylinder, possibly damaging the sliders, wearing out the chain with all the snatching, and possibly allow the cam timing to jump. That could damage the valves, head, and piston if they decide to occupy the same space at the same time.

If you pull out the OEM tensioner you may see some polishing on some teeth and three or four teeth with a wear pattern - that is where the rack is being snapped back skipping across and rounding the teeth of the rack and the pawl edge, then sliding back forward. Look at the back side and you will likely see wear and polishing showing it is sliding in and out. It's like when a worn set of shifter dogs allow a bike to pop out of gear. The tensioner is junk.

The spring in the tensioner is there only to put some relatively light pressure against the rack to allow it to index in (move a specific amount) and engage the next tooth. The pawl locking in the rack is what holds adjustment, not the spring. Problem is when the chain only seats in or wears enough to start to let the pawl snap into the next rack tooth - it doesn't seat and when under decel the momentum of the cam drive will push the rack back, hard, chipping and wearing teeth and pawl. That is happening over and over and over before you even realize it is starting.

Doing the short cut methods to force seating can put excess pressure on the cam drive - remember that expensive head where the cams run in a plain bearing machined surface? Break that oil film and they may get to share metal.

A manual tensioner is actually a manual adjuster. You turn in to take up the play, not to put tension on the cam drive. The object is to have as close to zero chain play as possible without having any tension when using a manual adjuster. It is easy to do. Finger tightening the adjuster will not overtighten the adjustment. Actually very simple. The other method is by sound with a fully warmed engine. The adjustment is done very slowly while carefully listening to the cam drive ticking. When the ticking just stops that is perfect adjustment. The engine should never drop rpm in this adjustment process. If it does the drive is too tight, back off immediately. I've actually found that the cold adjustment will be within a few thousandths of perfect and the play is so little it doesn't matter.

This is all basic reasoning and method for proper use of a chain drive in anything. Chains are not meant to run tight. Go flip a bicycle over, tighten a bicycle drive chain too tight then pedal it by hand - think of your cam drive and that very expensive head and cams. That is the best analogy to realize what is going on. In addition I wlll tell you that HyVo chain should last as long as the engine quite easily.

That video audibly tells me you should get rid of that tensioner and either take a chance with another OEM or be sure with a manual unit. Ask the guys who've done so and you will find most will go manual.

Yea, i know what the cam chain tensioner is. I helped my friend replace it on his DRZ. I mentioned before the video that it definitely did not sound that way. At idle, the bike sounds fine. And above acceleration at 6k rpm it sounds fine. Its just when you accelerate from idle to 6k when the engine knock occurs.

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Yea, i know what the cam chain tensioner is. I helped my friend replace it on his DRZ. I mentioned before the video that it definitely did not sound that way. At idle, the bike sounds fine. And above acceleration at 6k rpm it sounds fine. Its just when you accelerate from idle to 6k when the engine knock occurs.

 

 

It was more a bit of humor on the tensioner thing.  Also a fair part is for others who will read the thread.  You and I are not the only ones looking at this.  Others will learn from what people post in a thread, so a bit extra never hurts.  I will also tell you not all bikes have the same symptoms.  My KLX650 rattled all the time when it went bad (people telling me all Kaw engines were noisy cost me a new set of cam chains, two in the 650, and a rebuilt top end).  The KLX250s have a different range.  I have no idea for sure what it is for the DRz.  I just know if there is noise from the cam drive verified at any rpm there may be tensioner failure occurring.

 

What I was saying is that from your video it seems you have a tensioner issue.  From what I have learned of the KLX250/300 engines, the noise may not be there much at idle and the noise is loudest and strongest in the range from 4000-6000 range.  It is likely about the harmonics.  The thing I noticed in your video was the hard noise on decel, when the drive is actually pulling against the tensioner system pushing in against the plunger making a lot of slack in the front of the drive to slap around - the rattle.

 

Much has been said on the cam drive noise and the range in which it is heard in the Kawasaki forum where there is a strong following of KLX250 riders many of whom participate here.  It seems contrary to the constant noise the KLX650 made, the 250 has a range where the noise is strongest and I am learning from KLX300 riders that it is the same for them - of course the engines are the same in almost all ways other than electric start versus kick and the displacement.   The riders are where I learned the range of the cam drive noise as the tensioner startst to fail is between 4000-6000 rpm.  I have riders get with me for the manual unit with the same comments you have about the range of the noise.  For virtually all of them the solution has proven to be the tensioner.  And in my book it isn't the noise that needs fixed, it is keeping the cam chain slack under control to maintain proper timing and eliminate premature wear that needs fixed.

 

I am not out to sell tensioners as much as to keep riders from damaging engines.  I will tell people "don't fix what ain't broke".   My brother just bought a KLX250, I looked the bike over and bought it for him, then he paid me.  I reved the bike up through the range up to about 8 grand - no cam drive noise.  I told my brother no problems he didn't need to install a manual tensioner until it actually goes bad.  He still wants to put in the tensioner just because... his choice.  I wouldn't get to worried.  It isn't a catastrophic failure, but rather a progressive one.  You have time to fix it.  He's not the first I've told they didn't need to bother yet.

 

Your video makes me believe you are having tensioner failure.  Listen to it closely and verify where the noise is.  If it is focused in the cam drive area I am correct. 

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It was more a bit of humor on the tensioner thing. Also a fair part is for others who will read the thread. You and I are not the only ones looking at this. Others will learn from what people post in a thread, so a bit extra never hurts. I will also tell you not all bikes have the same symptoms. My KLX650 rattled all the time when it went bad (people telling me all Kaw engines were noisy cost me a new set of cam chains, two in the 650, and a rebuilt top end). The KLX250s have a different range. I have no idea for sure what it is for the DRz. I just know if there is noise from the cam drive verified at any rpm there may be tensioner failure occurring.

What I was saying is that from your video it seems you have a tensioner issue. From what I have learned of the KLX250/300 engines, the noise may not be there much at idle and the noise is loudest and strongest in the range from 4000-6000 range. It is likely about the harmonics. The thing I noticed in your video was the hard noise on decel, when the drive is actually pulling against the tensioner system pushing in against the plunger making a lot of slack in the front of the drive to slap around - the rattle.

Much has been said on the cam drive noise and the range in which it is heard in the Kawasaki forum where there is a strong following of KLX250 riders many of whom participate here. It seems contrary to the constant noise the KLX650 made, the 250 has a range where the noise is strongest and I am learning from KLX300 riders that it is the same for them - of course the engines are the same in almost all ways other than electric start versus kick and the displacement. The riders are where I learned the range of the cam drive noise as the tensioner startst to fail is between 4000-6000 rpm. I have riders get with me for the manual unit with the same comments you have about the range of the noise. For virtually all of them the solution has proven to be the tensioner. And in my book it isn't the noise that needs fixed, it is keeping the cam chain slack under control to maintain proper timing and eliminate premature wear that needs fixed.

I am not out to sell tensioners as much as to keep riders from damaging engines. I will tell people "don't fix what ain't broke". My brother just bought a KLX250, I looked the bike over and bought it for him, then he paid me. I reved the bike up through the range up to about 8 grand - no cam drive noise. I told my brother no problems he didn't need to install a manual tensioner until it actually goes bad. He still wants to put in the tensioner just because... his choice. I wouldn't get to worried. It isn't a catastrophic failure, but rather a progressive one. You have time to fix it. He's not the first I've told they didn't need to bother yet.

Your video makes me believe you are having tensioner failure. Listen to it closely and verify where the noise is. If it is focused in the cam drive area I am correct.

Yea, i appreciate the help. I think im confusing people. The video i posted is not actually mine. I posted to tell people that that is not what is occurring. I couldn't find a video of what is occurring, the exhaust is louder than the clack in videos. It also only occurs during accel. But yea, ill probably go ahead and change the tensioner. When i get the chance.

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Got it...  Sorry for my misunderstanding. 

 

I have to believe you know the scam when it's detonation.  Maybe you have an exhaust leak at the muffler joint?  I know it's pretty obvious, but sometimes it's simple.  Maybe at the head, making a loud ticking?  I remember the noise some cars with header leaks would make and I also remember when the packing at the joints on ATVs used to go bad on the Honda ATCs and TRXs.

 

If you don't hear the clatter at the cam drive the tensioner is doing fine.   If it ever does start making noise there is time to get it before anything really gets hurt as long as it isn't ignored for a long time.

 

Videos are a pain to help since you don't really get a good chance to listen around the bike.    I hope you figure out the noise, it's irritating as heck when you're not sure if a noise is damaging or just annoying.  Still, never buy the line that "that's the way they are.  It's normal."  That bit me in the butt once... never again. 

 

The KLX has a bit of a clack when reving a bit, but I know it's just the piston clicking when it goes over TDC on the power stroke.  That happened when the old Z1s were around in the 70s and the early Vulcan 1500s (where my piston came from).  The solution was to use a piston with a slight offset on the pin location to minimize the click, but it wasn't harmful.  So I'm good with it on my bike. Heck, it's done 30,000 miles like that so I'm not too worried.  I just hate to see someone miss a truly damaging situation. 

 

Later...

Edited by KLX678

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