Tapping noise

mmmbeergood · Jan 23, 2003

My '98 KDX 200 started making a steady, rapid tapping or rattling that seemed to be coming from the top end a few months ago. At first I thought it might be the FMF pipe hitting the frame as it was subtle, and only over rough terrain at speed. But it recently got louder, and I can now hear it at idle. The bike still runs strong, and starts on the first or second kick. The top end was rebuilt last year, and I perform routine maintenence, (Air filter,oil etc...). HELP!!!
Gordo

jpm200 · Jan 23, 2003

Sounds like it could be a big end bearing.

atc3434` · Jan 23, 2003

Piston slap??? Depends on how you hear tapping.... or slapping....

mmmbeergood · Jan 29, 2003

I took my bike to Cycle City, in Sumter,SC (1 1/2 hr away, bypassing 2 "dealers" cause the guy there owns a kdx 200 and is super cool). He heard my engine and says his does the same thing, and it goes away (or is overpowered) with revs. He has found nothing wrong with his rod or crank bearing, and it's not the piston or jug as he's replaced all that. My compression was 150. He says that everything is fine. My chain was a little loose and that the noise I heard over rough terrain was probably chain slap, and he was right, it's gone. But I'm still wondering if anyone else has this noise, that is distincly not combustion, but sounds more like a stick being run along a picket fence (really fast) but only at idle.
Thanks... Gordo

Patrick · Feb 12, 2003

Read my thread on "KIPS rattle in new 220". It sounds like the the same thing I'm hearing in my bike. When you take your top end apart for cleaning, advance the "main shaft" forward half way. Then put your finger on the "Flapper valve" located in between the subvalves. When I did this and felt the amount of play at this position, it was obvious that this was the source of the noise, since everything else was within spec. I have heard that this is normal. My friend's brand new KTM 300 EXC rattles like this also.

Kawierider · Feb 12, 2003

Hey, My bike made that sound....I thought it was the top-end too. When i pulled it off I found my lower rod bearing was toast...side clearance was twice what it should be and it could be visibly moved up and down with my fingers.
Pull your top-end and check for play and use a feeler gauge for side-clearance. Its relatively easy and cheap insurance.
Good luck

Speedy · Feb 13, 2003

Yup, My last KDX did the same thing. It was a rod bearing. The sound sounds like you had explained. A stick on the picket fence but had a air pushing sound to it. Not either way good luck and let us know if you find out what it is. Thanx

Speedy · Feb 13, 2003

Meant to say "Not good either way" Sorry

Jackpiner57 · Feb 13, 2003

I would only tear it down if the bike never made that noise before.

Speedy · Feb 14, 2003

True but if it is serious like a bearing. You keep riding it and it will cause a hell of alot more damage.

mmmbeergood · Feb 16, 2003

I just took her in for some work, a loud obnoxious noise in 4th gear, the mechanic thinks that a bolt may have come loose inside. with the gearbox open (I'm not touching it), we'll be able to get a better idea of what's going on.. I'll get back in a few days or so
Gordo

Tapping noise

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