knock at idle

[ATC350X 85]

I have a basically stock 99 400ex with just a uni filter and a 152 main jet, fuel screw at 3.5 turns etc. After the bike is warm after a ride i can here what sounds like a rod knock, but I could be just paranoid about this because i recently bought this bike. It is consistent with rpm but the noise gets faint as the rpm is increased. It will not make this noise when cold. It seems to vibrate a little to when revving it out when riding it. I also had my uncle ride it and he thinks it vibrates somewhat as well. Is that a symptom of a rod knock? I have an Xr 400 that has the same noise but just not as pronounced so I am not sure if its normal or not. I compared the 2 motors side by side both bikes hot and I compared them both to my 85 350x and out of them all the 19 yr old ATC has the quietest motor and none of them have ever been rebuilt. JUst before i bought it they guy had the valves professionally adjusted so its not that, but I may check them to see. My xr valves are in spec with a recent adjustment and so is the atc. I think the best bet here is to compare my 400ex to someone elses. Anyone in ocean county nj?

i have a loud ticking knock noise that seems to be from bad rings...does it sopund liekl this video...right click link ......save as

right click....save as to see movie (http://www.imagestation.com/picture/sraid109/pfc6264b89e7072cc6b2adfd2fdca55ac/f9265cdc.mpg)

[2000400EX]

Mine kinda sounds like that too. :( How do you know it's from bad rings?

[mustang]

All ex's sound a little lumpy down bottom, no knocking though you probably just paranoid I thought the same thing with mine... Its not going to sound smooth like a car after all there is only 1 cylinder in it

[flattrack450]

for what it's worth... we just tore apart my bro's z440 because of a pronounced knock at idle. no valve noise. no pinging. a definite knock. started, idled, and rev'd just fine. i thought it might have been a bent rod due to hi compression. turns out one circlip (left side) holding the wirst pin in , had worked its way out.

scored the cyinder wall pretty good... need new piston kit.... but the worst part was splitting the lower cases to fish around with a magnet hoping to pull every last piece of that clip out before it found its way to any vitals. luckily we found most of the pieces on the magnets of the flywheel + stator, and a few on the oil drain plug.

first check valves.. if it continues it might not be a bad idea to pull the cylinder and check...

my valves were adjusted professionally about 2 riding hours ago from when I made this movie :(

[ATC350X 85]

i think mine is a little louder, but its kinda hard to tell over the net. If anything I think yours sounds normal.

[RED121572]

My damn Polaris started doing that. When at idle, I can hear and feel it knock sometimes. Im just gonna run it until she blows, scrap the motor and sell the rolling chasis.

[duncanracing400]

yea i listened to that movie, it sounds just like mine, it will do that when i start it up and let it run. then in 2 minutes it goes "CLINK!" and it doesnt do it anymore, but it did that also as soon as i bought it too, so i think maybe its just some normal thing that it does? i dunno, i dont think its your valves tho, cause i get mine adjusted at the honda shop, and when they start it up there and take it out, it makes that noise too, so i dont think its anyting to worry about, i mean if your header was red and hour piston shot out, lol, THEN ull have something to worry about j/p.. lol

im gonna keep riding thos untill it blows up...then ill get her bored to a 416 :eek2: .....if it doesnt blow then Ill leave it stock

[2000400EX]

Originally posted by Jumbo747
im gonna keep riding thos untill it blows up...then ill get her bored to a 416 :eek2: .....if it doesnt blow then Ill leave it stock


My thoughts exactly!;)

[miken]

Sounds normal, maybe just a slight cam chain rattle?
Mike -

Originally posted by miken
Sounds normal, maybe just a slight cam chain rattle?
Mike - thats what the mechanic said that I said messes up your stuff to get your business back....i dont know who I should let adjust it...is this a hard job?

[miken]

To be honest with you I'm not 100% sure about your Honda. I'm 95% sure mine (300ex) is an automatic cam chain tensioner with no adjustment. I don't think a mechanic can mess with it for return business, unless he takes it off and breaks the spring inside. For my DRZ I can get a manually adjustable tensioner. See if there are any aftermarket options for you. Some people (DRZ) say they tear the guts out of the auto-tensioner and replace with a bolt and 2 jam nuts to make it manual. Then you can adjust the tension until the rattle goes away. Do a web search for "manual cam chain tensioner".
Hope this helps?
Mike -

[RED121572]

Originally posted by Jumbo747
im gonna keep riding thos untill it blows up...then ill get her bored to a 416 :eek2: .....if it doesnt blow then Ill leave it stock

Just like mine did last year, you may get lucky and your bore will be completely shot. That way youll have a good excuse to step up to a 440. ;)

[UglyMotha™]

Originally posted by Jumbo747
im gonna keep riding thos untill it blows up...then ill get her bored to a 416 :eek2: .....if it doesnt blow then Ill leave it stock



really, that sounds like an awesome idea, maybe if your lucky enough the rod won't go with it too, and completely destroy your cases as if finishes it's last few revolutions with each last one it takes another chunk and then you'll only be spending 6 times the amount of money you could spend now and get it fixed, it's all bout luck, soooo good luck http://www.exriders.com/vbb/images/icons/icon14.gif

:eek2: sweet....iv'e ridden it about another 3 hours & no abnormal noises & everythings fine