KDX Knocking

[Brian]

My KDX 200 makes a knocking noise when
a) in neutral, rev slightly, let off, then knocking occurs.
b) on the trail, rev slightly, or under decelleration, then, there's the knocking.

Is this a jetting issue? I'm not sure what I'm jetted at right now, but I think it's stock. The bike is stock, except for the removal of the airbox snorkel. Does anyone know what this is? Thanks

 

[Perk]

Is this something that just started, or has it always done that? KDX's are generally very diesel sounding, especially at idle and low throttle.

 

[gooby]

it's probably the normal sewing machine sound they all make unless like perk says it's a new sound. hey perk

 

[Durt Cycler]

This might sound dumb but could this be fuel knocking? What octane are you using? Knocking occurs when fuel with too low of octane ignites before the spark fires.

 

[Perk]

Hey, what's up Gooby? My pipe should be getting here this Friday. I can't wait. I rode a buddies 220 over the weekend with a lot of goodies on it. He had a pipe, reeds, 49 rear sprocket, and some kick butt Factory Connection suspenders. WOW! That is the first time I have ridden a bike that really had the suspension for me. Trail nasties that normally kick me around, I never even noticed on his bike. Gotta start saving for that.

 

[someday]

Greg,
New springs alone will go along way. Get'm and I'll help you put them in. Decide to keep your old bike? Racing this Sunday?
Later,
Jeff

 

[Brian]

I just got it used, and it has done it since. I run premium pump gas with MC-1 @50:1. I thought only MX bikes needed octane booster, and that was just to get the ultimate max power out of one? Does it hurt it to ride it like this?

 

[Perk]

Yeah, I definitely need the new springs. I can bottom the front end just braking hard. And I will take all the help I can get. I'm a suspension virgin. Once I do somethign once and get the confidence I'm golden. I'll probably get a new counter sprocket, followed by reeds, then the springs. the springs have been bumped way up on my to do list after riding that other bike.

 

[Perk]

Stan,
What you are describing sounds like a normal thing for these bikes. They all do it. My brand new 220 just has a constant CLICK CLICK CLICK CLICK CLICK. So does my 93 200. Iwould hate for you to have something different though and wind up screwing up your bike. I would suggest having another KDX owner give it a listen and see if it sounds normal. I believe what that sound is is the power valves going through their motions. If you do a search on this, you will find that the same thing is posted by a new KDX owner about two or three times a week.

 

[Brian]

Perk and others,
Thanks for all the replies, and I did several searches on this, and I found out that they are noisy, but I'm still worried that mine might be exceptionally noisy. It rattles and clicks at idle, but thats not what I'm concerned about. It doesn't knock at idle, only when returning to idle after revving or whenever you let off the throttle under deceleration while riding. It's not loud enough to hear through my helmet, but you can hear it when putting around the pits, etc not wearing one. Does anyone have an audio clip of their bike? Maybe I'm just paranoid, but it is bothering me :think:

 

[KelvinKDX]

Try this Stan:

http://pages.globetrotter.net/mafil/kdx/soundclip.mp3

;) :debil: ;)

 

[Brian]

As amusing as that is, and I crack up everytime I hear it, I really would appreciate it if someone had a real clip of their bike :(

 

[vandean]

Hey Stan.Does it make the same noise if you pull in the clutch or is it the same as when released in neutral?

 

[Brian]

No, the clutch is a whole different noise. But the clutch does get loud when I pull it in at idle. I think the knocking is coming from the cylinder, but I can't imagine that it's jetted too rich because I think it's the stock jettting, and it spooges a lot.

 

[Kawierider]

stan,
try running a compression test. if the compression is low put in a new pioston and rings, if these are sloppy you will get a clicking or knocking noise. also, if your real paranoid or taking the cylinder off anyway check the side clearance and the lash on the lower rod bearing, basically if it can move an appreciabel amount wiht your hand the crank needs to be rebuilt. im having that problem with my kdx....be careful of this especially if the bike has high hours or was well used.
good luck
Tim

 

[Brian]

The bike is a '97 with very few hours, still has original tires, graphics, brake pads, etc... Everything is original, and is very clean. I doubt that it would really need a new top end or powervalve cleaning. I'm just wondering if it's something like jetting, or maybe more serious than that, or maybe nothing at all? I've never run a compression test, but it seems to have plenty when you slowly kick it over.

 

[Durt Cycler]

Could it possibly be piston slap?

 

[Brian]

It might be, but I highly doubt it, as the bike only has a few hours on it, but I will probably tear it down to inspect things, and replace the rings(and anything else it needs) pretty soon for insurance.

 

[russ_220]

my bike did the same thing for a while and then quit I asked the best mechanic I know and he said he had no clue and not to worry about it. He said his Gas-Gas 250 did it when he only had about 10 hours on the piston. I've heard some people say that its carbon build up in the cylinder anyway your not the only one that has heard the knocking

 

[Brian]

Well, I just re-jetted, and that did it :) The wierd thing is, though, that I rejetted, then put the 160 main back in just now, and it's still gone. It must've been the pilot or needle positioning, because I changed both of those, or, maybe my bike is just now getting broken in? Who knows, but I love this bike :)

 

[Robcolo]

Technically, preignition, known as "knocking" only occurs under a heavy load on the engine --either during full throttle acceleration or lugging it so this is not the cause of your [and my new kdx's] rattling. ONe of my KXs rattles loudly and the noise is caused by the free play in the KIPS valve allowing it to flop up & down. The KDX however has a different type KIPS valve which seems to fit tighter. The KDX has a considerably smaller piston skirt to cylinder contact area [than the KXs] so my suspicions are that we're hearing piston slap.

 

[toalco-kdx]

my bike kind of clicks when you let of the trottle whilr still moving and i was told it was just the clutch plates spinning. dont tke my word for it though.

 

[Brian]

Like I've said in previous posts, the KIPS valve rattles, and the clutch is noisy, but this was a totally different noise. I've gotten it under control, mostly was a jetting issue. The knocking is about 98% gone now, and KDX's are terribly noisy in general, so I'm not going to worry about it, especially since it has no effect on performance, has always run great, next is a pipe :)