[Charecter1]

I just recently purchased a 2008 crf450r and I’m having a strange sound coming from the engine it seems. It happens at low RPM’s and it’s in neutral or in gear. It kind of sounds like a supercharger whistle as soon as you give it throttle and when it decelerates.
I changed the oil on both sides, new air filter, spark plug and I cleaned the carb but I still hear the noise. I’m coming off a 2003 crf450r that didn’t sound like this at all and I’m wondering if it’s a normal sound or something else.

Here’s a video

youtu.be/4Xy8sPgt4zo

[JimDirt]

Welcome to the site !!

It kind of sounds normal , but it also kind of sounds like the timing chain is doing it , its really hard to discern what exactly it is , it does not sound like a loose timing chain , but more like a over tightened one , at this point , also do a oil/filter change , and inspect the filter really close in the grooves , if you don't see any shavings , then it should be OK , but it is possible that the tensioner has somehow tightened up ,........... Undo the bolt in the center of the tensioner , and stick a small thin flat tipped screwdriver in and back off the screw so you feel tension on the screwdriver , then just release it , put the cover screw back in , fire it up and see if there is any difference , if there is not , then i would say just ride it

These engines make noise , and sometimes , its just the internal parts reflecting the noise off the aluminum , and some engines sound different than others even if they are the same engine but different years , and indoors they sound different from running them outside , and surroundings also affect any noise , metal buildings or the woods , will make a engine noisier or quieter , my 02 is noisy because i have a Aluminum Devol Skid Plate , it reflects the engine noise straight up to me , and i thought something was bad when i first got it , that was back in 08 , with the exception of a new piston and timing chain 2 seasons ago , its the same engine as it was back then , and its still noisy , unless i hear something clanging around , i generally do not worry too much about it , like i said , shavings in the filter , time to worry , if it starts right up and runs fine otherwise , then i would say its just engine noise , especially if the other items i mentioned check out good ........

[Charecter1]

Welcome to the site !!

It kind of sounds normal , but it also kind of sounds like the timing chain is doing it , its really hard to discern what exactly it is , it does not sound like a loose timing chain , but more like a over tightened one , at this point , also do a oil/filter change , and inspect the filter really close in the grooves , if you don't see any shavings , then it should be OK , but it is possible that the tensioner has somehow tightened up ,........... Undo the bolt in the center of the tensioner , and stick a small thin flat tipped screwdriver in and back off the screw so you feel tension on the screwdriver , then just release it , put the cover screw back in , fire it up and see if there is any difference , if there is not , then i would say just ride it

These engines make noise , and sometimes , its just the internal parts reflecting the noise off the aluminum , and some engines sound different than others even if they are the same engine but different years , and indoors they sound different from running them outside , and surroundings also affect any noise , metal buildings or the woods , will make a engine noisier or quieter , my 02 is noisy because i have a Aluminum Devol Skid Plate , it reflects the engine noise straight up to me , and i thought something was bad when i first got it , that was back in 08 , with the exception of a new piston and timing chain 2 seasons ago , its the same engine as it was back then , and its still noisy , unless i hear something clanging around , i generally do not worry too much about it , like i said , shavings in the filter , time to worry , if it starts right up and runs fine otherwise , then i would say its just engine noise , especially if the other items i mentioned check out good ........

Thanks for the advice! I’ll check my oil filter tomorrow. I figured it’s not a noise I should really be concerned about, it’s just more annoying than anything. I’m also going to replace the throttle slide seal between the slide and the vacuum plate and the exhaust crush gasket because I thought maybe I’m getting air in somewhere or I have an exhaust leak.
Also another note, I just replaced the spark plug and after a 4 hour ride, my spark plug is alredy carbon fouled, don’t know if this has anything to do with it

[JimDirt]

No problem , and yea , at this point I do not hear anything that sounds like its going to disintegrate , you might also want to look at the decompressor weight on the end of the cam as a possible source for the noise , or even the plunger and pin , sometimes they get sticky and clatter a little , just manually move the weight and see if it snaps back , and is not slowly returning , that could cause it to clatter a little as centrifugal force is supposed to engage and disengage it , as far as the fuel issue , are you noticing any popping on decel ?? , even though popping is associated with a lean condition , it can also be caused by a rich condition from unburnt fuel

What elevation are you at ?? , and what jets (main and pilot) are in the bike ?? (did you just clean , and if so , how ?? , or replace the jets ??) , and what is the fuel screw set at (turns out) ??

[Charecter1]

No problem , and yea , at this point I do not hear anything that sounds like its going to disintegrate , you might also want to look at the decompressor weight on the end of the cam as a possible source for the noise , or even the plunger and pin , sometimes they get sticky and clatter a little , just manually move the weight and see if it snaps back , and is not slowly returning , that could cause it to clatter a little as centrifugal force is supposed to engage and disengage it , as far as the fuel issue , are you noticing any popping on decel ?? , even though popping is associated with a lean condition , it can also be caused by a rich condition from unburnt fuel

What elevation are you at ?? , and what jets (main and pilot) are in the bike ?? (did you just clean , and if so , how ?? , or replace the jets ??) , and what is the fuel screw set at (turns out) ??

Oil filter checked out clean, no metal shavings on the filter or in the housing. I am in Phoenix so the elevation is around 1000. I’m not totally sure what jets are on the bike. I’m pretty sure it’s the stock jet sizes. I did clean it a little bit by taking the fuel bowl off and spraying carb cleaner through the jets and the bowl.
No popping on deceleration, fuel screw is set at 2.5 turns out. Also when the sound happens during the 1/4 throttle, it does seem to have a loss in power and bog a little bit until it gets into the higher Rpms

[JimDirt]

Good to hear the filter checked out , that confirms that at least at this point , its nothing major internally , for your elevation you should be at about a 45/165 , the 2-1/2 turns is within spec , so you are most likely good on jets , you can also pull the top off the carb , and pull the Needle(you remove the allen set screw to get to the needle) , pull it out with needle nose pliers and look at where the clip is on the needle (counting from the top down towards the tip) it should be on the 3rd from the top , if its on 4th or more , it could be dumping too much fuel too soon and giving you that bog/hesitation your feeling

Also (you need to have the subframe raised to do this) , look down the inlet to the carb (where it attaches to the airbox) and see if the AP squirt hits or misses the slide , what you do is give the throttle a twist while watching , the stream should just miss the slide and go into the venturi , if it hits the slide that will give a bog as well , you adjust it at the linkage under the black plastic cover where the cables attach , there is a spring loaded screw (not the idle screw attached to the cable , but a small phillips screw inside the cover) , you can adjust it there to "time" the squirt to just miss the slide as it rises ........ those are the main things I can think of off hand that would cause a rich condition , hopefully its one of those items .............. Also make sure the air filter is clean and NOT over oiled , as that can restrict airflow and cause a rich condition , especially if you use a oil like No-Toil (what I use) that is much thicker than some of the other brands , so you may have to adjust your fuel screw leaner (in) to compensate for the less air flow ......................

[Charecter1]

Good to hear the filter checked out , that confirms that at least at this point , its nothing major internally , for your elevation you should be at about a 45/165 , the 2-1/2 turns is within spec , so you are most likely good on jets , you can also pull the top off the carb , and pull the Needle(you remove the allen set screw to get to the needle) , pull it out with needle nose pliers and look at where the clip is on the needle (counting from the top down towards the tip) it should be on the 3rd from the top , if its on 4th or more , it could be dumping too much fuel too soon and giving you that bog/hesitation your feeling

Also (you need to have the subframe raised to do this) , look down the inlet to the carb (where it attaches to the airbox) and see if the AP squirt hits or misses the slide , what you do is give the throttle a twist while watching , the stream should just miss the slide and go into the venturi , if it hits the slide that will give a bog as well , you adjust it at the linkage under the black plastic cover where the cables attach , there is a spring loaded screw (not the idle screw attached to the cable , but a small phillips screw inside the cover) , you can adjust it there to "time" the squirt to just miss the slide as it rises ........ those are the main things I can think of off hand that would cause a rich condition , hopefully its one of those items .............. Also make sure the air filter is clean and NOT over oiled , as that can restrict airflow and cause a rich condition , especially if you use a oil like No-Toil (what I use) that is much thicker than some of the other brands , so you may have to adjust your fuel screw leaner (in) to compensate for the less air flow ......................

I’ll have to check to see if the stream hits the slide or not, thanks for all the help. If that is in spec, I’ll just have to deal with the noise because it’s nothing major. I am going to give the carb a good scrub though and check the valve clearance because I just recently bought the bike and I have no idea how long it’s been since they’ve been checked and the previous owner said the bike sat for 3 months

[JimDirt]

Generally , especially if the prior owner used Ethanol gas , it tends to start clogging stuff up in the fuel system when left sitting for more than about 2 months , usually this is followed by a severe Lean condition , but if a Air passage got blocked somehow , it would lead to a rich condition , the issue with bikes sitting is there are many variables that can affect how the bike runs or does not run afterwards .....

When checking the valves , take a look at the decompressor system as i mentioned , just to rule it out ......

[Charecter1]

Generally , especially if the prior owner used Ethanol gas , it tends to start clogging stuff up in the fuel system when left sitting for more than about 2 months , usually this is followed by a severe Lean condition , but if a Air passage got blocked somehow , it would lead to a rich condition , the issue with bikes sitting is there are many variables that can affect how the bike runs or does not run afterwards .....

When checking the valves , take a look at the decompressor system as i mentioned , just to rule it out ......

Okay I will take a look at it when looking at my valves. I will give an update after everything is done. Thank you

[Leardriver]

With the elevation and heat of Phoenix, you can run a 162 main, but your fuel screw needs to be just under 2 turns out, like 1 7/8. That will clean up your plug color.

[Charecter1]

Alright update on the bike, I took it to my local shop because I’ve been on call all week and didn’t have time to check it myself. He rand it through to see how it’s tuned and it’s actually tuned pretty close to spot on, he did tighten the fuel screw a little to lean it out more.

As for the noise, he didn’t tear into the engine because he said if I didn’t see any shavings, it’s nothing to worry about but he suggested maybe the cam bearing or the buckets are worn out, he also suggested maybe the cam chain guide is missing.

[JimDirt]

Cam bearings is a possibility , but i would think you would find fine silver metal in your filter , as for the buckets , you should be able to physically see the wear if there is any , the top where it contacts the cam lobe would be dished , as well as the cam itself would show signs of wear/deterioration , which once thru the surface of the cam lobe , it would disintegrate fairly quickly , again , this wear should be visible to the naked eye ..... On the guide , it could be excessively worn and if that were the issue you would hear the chain slapping when going from RPM to idle as the lash is increased , however if the guide was broken for some reason , you would hear the chain banging against the cylinder (aluminum) and you would see aluminum shrapnel in the oil and filter

And please do not think I am discrediting the Dealer tech , i am simply saying , although those are possibilities , and could very well be the case , i would think there would be more physical evidence showing up , and according to what you have described , there is none , so just make sure he is not trying to get you to go for a expensive full rebuild due to the fact that most techs work off commission , there job is to sell you parts and service as that is what their pay is based off , again , not saying this is the case , just be aware that this does happen , a lot

And that is why so many complain about the high cost of rebuilding a 4 stroke , because the "tech" "thought it best to just replace everything to be on the safe side " , but in reality , if done by yourself and a Factory Honda Service Manual , you can get away with half or more of the cost they would imply and have about the same outcome with only parts that "needed" to be replaced done , and unless you charge yourself labor , you will be saving a ton on that as well ...., that is what is nice about this place , no one is trying to sell you anything or get you to buy something unless its felt it would resolve issues , as all we are , is a bunch of enthusiasts just like yourself , aside from Ken the owner of this site , who does make a living off parts and service here , but in the end he is still a enthusiast just like the rest of us , and would not tell you to replace something just to sell something

My suggestion is to just go ahead and ride it for now , and see what it does , if you notice something , then act , or if nothing happens , wait till winter and tear it down for a seasonal go thru , which is what the majority of us here do , we redo our suspension , and freshen up things (normal wear parts like timing chains ,pistons , clutches , tires , etc) , so when spring comes around we have a fresh ready to go bike , that will most likely not give out on us on some distant trail or at the track hucking a jump ....

[Charecter1]

Cam bearings is a possibility , but i would think you would find fine silver metal in your filter , as for the buckets , you should be able to physically see the wear if there is any , the top where it contacts the cam lobe would be dished , as well as the cam itself would show signs of wear/deterioration , which once thru the surface of the cam lobe , it would disintegrate fairly quickly , again , this wear should be visible to the naked eye ..... On the guide , it could be excessively worn and if that were the issue you would hear the chain slapping when going from RPM to idle as the lash is increased , however if the guide was broken for some reason , you would hear the chain banging against the cylinder (aluminum) and you would see aluminum shrapnel in the oil and filter

And please do not think I am discrediting the Dealer tech , i am simply saying , although those are possibilities , and could very well be the case , i would think there would be more physical evidence showing up , and according to what you have described , there is none , so just make sure he is not trying to get you to go for a expensive full rebuild due to the fact that most techs work off commission , there job is to sell you parts and service as that is what their pay is based off , again , not saying this is the case , just be aware that this does happen , a lot

And that is why so many complain about the high cost of rebuilding a 4 stroke , because the "tech" "thought it best to just replace everything to be on the safe side " , but in reality , if done by yourself and a Factory Honda Service Manual , you can get away with half or more of the cost they would imply and have about the same outcome with only parts that "needed" to be replaced done , and unless you charge yourself labor , you will be saving a ton on that as well ...., that is what is nice about this place , no one is trying to sell you anything or get you to buy something unless its felt it would resolve issues , as all we are , is a bunch of enthusiasts just like yourself , aside from Ken the owner of this site , who does make a living off parts and service here , but in the end he is still a enthusiast just like the rest of us , and would not tell you to replace something just to sell something

My suggestion is to just go ahead and ride it for now , and see what it does , if you notice something , then act , or if nothing happens , wait till winter and tear it down for a seasonal go thru , which is what the majority of us here do , we redo our suspension , and freshen up things (normal wear parts like timing chains ,pistons , clutches , tires , etc) , so when spring comes around we have a fresh ready to go bike , that will most likely not give out on us on some distant trail or at the track hucking a jump ....

I do know the guy who is working on my bike so I don’t think he would try and sell me things the bike doesn’t need. He just made suggestions and said I should just ride it and it could be nothing. My problem is that it’s almost dune season and that already puts enough stress on 4 strokes and I want to make sure the bikes good to go.

[JimDirt]

That is why i said I am not discrediting the tech , I was just noting that "most" techs are there to make money and not really concerned about what the cost may be , as the more it costs , the more they make , but the "signs" of damage are just not present (if you have inspected the parts in question and visually noted they are not compromised) , which is why I mentioned to go ahead and ride it , and then during the winter , maybe do a rebuild or at the very least pull the head and check all the parts in question , including replacing the timing chain , and inspect the other parts , if nothing is found as far as visible damage , then just do the chain , and maybe the piston , and call it good , these engines take a lot of abuse before they let go , the worst thing you can do is allow dirt past the air filter , as that takes out the valves faster than they would normally wear , other than that , the timing chain and sometimes tensioner are about the main culprits in engine "noises" aside from the clutch

So as he and I suggested , go ahead and ride it (for the season) , and just keep a eye on the oil/filter for any shavings , if you have to for the next few rides , change them both after each ride , this way you can see any possible issues right away and catch it before it goes really bad and causes more damage , but from what i have followed from your description , I do not think the engine is going to grenade , at least not right now (there is no guarantee any engine will not blow at any time for any reason)

Because you are taking it to the dunes , it is very important that you do the filters (air and oil) after every ride (take at least 2-4 air filters with you for the weekend (not sure if your going every weekend or just occasionally), , and I would change the oil filter or at least inspect it after every ride (lay the bike on its right side so you don't lose oil while inspecting the filter) and make sure the air filters are oiled with a quality filter oil ** I personally use No-Toil Extreme filters and/or similar dual stage filters and No-Toil Green oil**) , due to the chance of dirt causing issues , the dunes will be the ultimate test as to the health of your engine , you can't really find a more punishing thing to do to it other than taking the throttle and holding it wide open until the engine grenades , its the ultimate test of durability , if anything can kill a engine , weather 2 or 4 stroke , its the dunes ... so if it survives your first dune ride , I would think it will be good to go and should ease your mind .....

[Charecter1]

That is why i said I am not discrediting the tech , I was just noting that "most" techs are there to make money and not really concerned about what the cost may be , as the more it costs , the more they make , but the "signs" of damage are just not present (if you have inspected the parts in question and visually noted they are not compromised) , which is why I mentioned to go ahead and ride it , and then during the winter , maybe do a rebuild or at the very least pull the head and check all the parts in question , including replacing the timing chain , and inspect the other parts , if nothing is found as far as visible damage , then just do the chain , and maybe the piston , and call it good , these engines take a lot of abuse before they let go , the worst thing you can do is allow dirt past the air filter , as that takes out the valves faster than they would normally wear , other than that , the timing chain and sometimes tensioner are about the main culprits in engine "noises" aside from the clutch

So as he and I suggested , go ahead and ride it (for the season) , and just keep a eye on the oil/filter for any shavings , if you have to for the next few rides , change them both after each ride , this way you can see any possible issues right away and catch it before it goes really bad and causes more damage , but from what i have followed from your description , I do not think the engine is going to grenade , at least not right now (there is no guarantee any engine will not blow at any time for any reason)

Because you are taking it to the dunes , it is very important that you do the filters (air and oil) after every ride (take at least 2-4 air filters with you for the weekend (not sure if your going every weekend or just occasionally), , and I would change the oil filter or at least inspect it after every ride (lay the bike on its right side so you don't lose oil while inspecting the filter) and make sure the air filters are oiled with a quality filter oil ** I personally use No-Toil Extreme filters and/or similar dual stage filters and No-Toil Green oil**) , due to the chance of dirt causing issues , the dunes will be the ultimate test as to the health of your engine , you can't really find a more punishing thing to do to it other than taking the throttle and holding it wide open until the engine grenades , its the ultimate test of durability , if anything can kill a engine , weather 2 or 4 stroke , its the dunes ... so if it survives your first dune ride , I would think it will be good to go and should ease your mind .....

I’m taking the valve cover off just to see if I can even seen any noticeable signs of wear and if not, I’m just going to ride her and keep up with the maintenance until riding season is over and I can get a rebuild done. I think it will do just fine in the dunes, I’m a firm believer that these Honda’s are bulletproof