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Good Morning

I am a new member from Durban, South Africa. I recently aquired myself a very good condition 2006 KDX 200. The bike is stock standard and runs like a dream. Its been meticulously maintained and is as clean as the day it left the dealership in 2008.

Yesterday I took it for its 1st proper ride, performance is great considering the stock pipe and the handling is superb. However, after about 30 minutes of playing around I started to hear a strange sound coming from the motor area, its hard to describe but I'd have to say its closer to a whistle that anything else. The 1st time I heard it was while out on the enduro circuit and it went away the moment I got back onto the powerband but returned after another few hundred meters of slow riding.

I made a small clip of the sound as it is with the bike idling and blipping the throttle, that can be found here

[youtube][/youtube]

Once the bike is cold again, the sound is gone.

My gut tells me thats air being sucked in somewhere, the doomsayers are saying its a dry bearing but I have my doubts.

If anyone has any suggestions or ideas as to what it could be, I would appreciate the input.

Please note that there was no performance loss whatsoever and no telltale knocking to suggest mechanical failure. The magneto is perfect and the gearbox oil level is spot on. Compression is perfect too.

Any idea's ?

Regards

Dave

Sounds kinda metallic

definitely something that spins

Wibbens might be on to something. It does sound weird, might be worth checking for something stupid rubbing before a tear down. ( Pipe touching the frame, loose silencer, loose skid plate, plugged exhaust, ect.)

ok, so i took the plug out and checked for any noises by turning the motor by hand using the magneto. engine is as smooth as butter, dropped 2 caps of 2 stroke oil in the plug hole and turned the motor over with the kick starter about 20 times or so.

the only odd sound i heard was the sucking sound from the carb when the inlet opens and a little rubber sounding squeak from the mag area. is there a rubber seal behind the magneto cover somewhere, maybe to seal it from the crankcase? i dont have access to a parts list to see if it could be a seal that maybe needs some grease.

engine starts and runs sweet, no noise after 15 minutes of idling and blipping ....

any further ideas?

im thinking i should ride it hard till it shows up again, then ride it harder till it goes away or breaks. that way i can identify the problem :)

here is the fiche
http://www.ronayers.com/Fiche/TypeID/26 ... del/KDX200

maybe just wear ear plugs

Crank bearings.

JoKDX220r wrote:Crank bearings.

I'd put some money on it

Definitely not normal, IMO.

I'm going to cast my vote for crank bearings as well.

Ok, so the general consensus is crank bearings. the obvious question is, do I ride it until it fails then open this pristine motor up or do I tear it apart now ?

I have no idea how a crank bearing will fail and what will happen when it does but it does not seem like it would be as catastrophic as a big end bearing failing for example.

I'm going to take the carb off this weekend and check the reed block etc. just to be sure and I'm putting it through a heat cycle tonight so I can drain the gearbox oil. I'm not sure what oil is in there but its green in color and seems a little thin to me so I think I'll change it and then re-evaluate if the noise comes back.

So far its been just under a week and no sign of it again... very frustrating.

Update:
Here's a small clip of the sound I heard while spinning the magneto by hand with no plug in. you can see from the clip that this motor is clean enough to use in a hospital so I'm really not too excited about opening it up :(

[youtube][/youtube]

Well I crank bearings fail, the engine will be the farthest thing from pristine. A failed crank bearing has the potential to destroy the entire engine.

Open it up, replace the bearings.

If its a crank bearing, It's already failed

Seals will be next

If you don't catch it time you could seize the cylinder too

Hi Stefan here from pretoria south africa with the same sound after a full moter rebuild.
I know its a old topic but what happend in the end?

skim wrote:Hi Stefan here from pretoria south africa with the same sound after a full moter rebuild.
I know its a old topic but what happend in the end?

check your up/down/in/out/front/back play at the flywheel. what that last video shows sounded like a slapping piston, loose flywheel, sheared key, or worst case, bad bearings.