Loud engine clicking around 5k RPM, but valves are in spec. Please Help!

Hello, I've spent the last hour reading and searching the forum about normal and abnormal engine sounds as well as valve clearance checking for my '99 WR400 (which I've owned for a month now).

Two weeks ago I noticed occasionally at 5,000 RPM (I have a Trail Tech tach..) there would be a relatively high pitched clicking that would sound randomly. (for those without a tach: around 40 mph with stock gearing in 5th gear). I know what valve knock sounds like in a car, but the WR has no rockers, so I don't know what valve lash sounds like. The sound on my bike is almost exactly like if you take two deep sockets (for a socket wrench) and hit them together (strange analogy, but it's true!!). Okay, now do that at 2,000 times/sec. j/k.

I kept on riding the bike (on the street primarily) and about a week later, or 150 miles, the sound is there ALWAYS at 5K, but now also from 4K to 6K and is loud. And it doesn't make the sound unles the engine is under a load (by revving in neutral).

The bike has been performing normally (starts, idles, power, all fine). I just checked the valve clearance and they are all in spec. I used those wide feeler gauges for cars, but they fit and I made sure that they were parallel to the valve bucket/cap. So hopefully I got correct numbers.

Soooo.. I guess I'm just wondering if, based on the sounds I described, my valves are actually out of spec or there is something else I should check (flywheel key, clutch basket, etc..).

I just thought it was the valves for sure because the sound was sensitive to engine RPM (something internal that was oscillating, not rotating..).

Please help, I can barely go a day without riding it. :thumbsup:.

THANK YOU!!!!!!!!!!!!!!!!!!!

Sorry for writing so much :worthy:.

Sounds like the crankshaft bearings are on their way out. My mate had a car that had a loud knocking that was only present at high RPM. As he kept using the car the RPM that the knocking could be heard got lower and lower until it was doing at idle. He had someone listen to it and they said it was a ticking timebomb. Unfortunately it's not going to be an easy fix, you probably going to have to split the crankcase which means it'll be off the road for at least a week, if of course you can definitively identify the problem.

I bet your just hearing the chain making noises.

The skidplate reflects noise back at you.

The valves get tighter from wear not looser.

In regards to the chain.. The chain slider (on the front of the swing arm) is worn through in one spot and the chain is just starting to wear on the swing arm. So I got a piece of the same type of plastic, cut it to shape and glued it to the bottom of the worn slider. Worked great and then fell off during one of my last few rides.. So mayyybe it's possible? I did do the mod kinda around the same time I started hearing the noise..

I'm pretty sure I know what chain slap sounds like (maybe..) and this isn't it. It sounds like hard, thick steel pinging against eachother.

I'm really hoping it's not the main bearings!! NOOOOOOOO!!

Do people here think its really the main bearings? Any othere ideas folks?

I agree with beezer - it's probably chain lash on the swingarm or the rear sub-frame and the bashplate amplifies it significantly.

You say the sound is not there when revving in neutral so I doubt it will be the bearings.

The fact that its in top gear between 4-6 when torquing it sounds to me just like the symptoms of chain lash.

Have a look at the rear subframe, about 1-2" above the chain and check for any wear or scratch marks as well.

Check and if required adjust your chain tension then test it again.

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