Rolling Marbles in Engine. Crank bearings?

95 wr250 (same engine as 94 yz). Noticed the noise as soon as I got her up and running, but it was so slight I thought it may be a vibration or wheel bearing. After about 350mi it has gotten 10x louder and only does it with the engine running.

It sounds like marbles rolling in the engine, doesn't really get worse with rpm or bike speed.

Is there any bearings in the trans that wear out? My guess is crank bearings...

I finally found the culprit! Turned out to be much easier than the crank bearings...one thing in the picture does not belong, can you spot it?

IMAG0511.jpg

How the heck did that get there haha? I guess putting stuff together and losing a washer without the carb installed might do it :p.

Good thing that it didn't get past the reeds! You'd have much worse sounds than marbles.

The sounds was present since the day I bought it, sometimes it was a lot more noticeable than others. The last ride I did in last October, I fired the bike up and my buddy said "what the heck is THAT noise?" I figured well shoot, I guess if he can hear it it's time to stop riding and fix it.

 

Stupid me I just assumed it was bearings and waited until I could afford the parts, I missed like 4 months of riding!! :(

 

All I can figure is when the previous owner put the filter in they put that washer in the wrong spot, There is some wear on the cage, but zero damage to the reeds, they are in excellent shape! I got a set of Boyeson power reeds so ill swap those in and put her back together!

The sounds was present since the day I bought it, sometimes it was a lot more noticeable than others. The last ride I did in last October, I fired the bike up and my buddy said "what the heck is THAT noise?" I figured well shoot, I guess if he can hear it it's time to stop riding and fix it.

 

Stupid me I just assumed it was bearings and waited until I could afford the parts, I missed like 4 months of riding!! :(

 

All I can figure is when the previous owner put the filter in they put that washer in the wrong spot, There is some wear on the cage, but zero damage to the reeds, they are in excellent shape! I got a set of Boyeson power reeds so ill swap those in and put her back together!

Lucky!.....

I couldn't believe how lucky, the size of the washer prevented it from being a HUGE failure. There was no way it could get through the reed block, and the wear inside the reed cage was absolutely minimal. It just did some small wearing on the gold coating was it.

 

Also found that the bolt that holds the exhaust valve linkage was barely hanging on with a few threads and the bolt itself was damaged and almost broken off!!

Got the bike back together and fired the bike up. Came to life after about 6 kicks and ran real nice, settled down to a mellow idle and rev'd easily.

So far I found:

Washer in the reed cage

Loose/damaged power valve bolt

Exhaust valve didn't operate properly

Loose clutch bolt, which allowed the kick starred to slip/not engage

Notches in clutch basket

Loose front sprocket bolt

Chain sliders destroyed

Replaced or fixed all those besides the sliders presently.

The noise is still present. It's like a waaaa waaaa waaa sound at idle. It almost sounds like a vibration. I have an aluminum skid plate that doesn't mount super snug, I'm thinking of pulling to see if it changes.

No significant metal material in the oil, still shifts and rides fine. Power is quite good now with the exhaust valve working properly!

Aluminum skid plates are a significant source of noise, or amplify engine sound back at the rider. Pull it, and let us know what you find.

Well it definitely amplified the noise, but its still there without the plate on it.

I can't tell where it is coming from exactly,even with the plate off. I think ill have to split the cases to find out what's going on. It's not in the top end out clutch side...

have you tried a stethoscope/piece of wood to help locate?

I have a set of earphones specially configured to listen to engine noise that I use for tuning car engines. I'll have to break those bad boys out next.

 

I've changed the trans oil 2x since I got the bike and there has not been significant metal shavings in the oil, but there is a little metallic flake in it each time. I havn't had a bike in so long I don't know if its normal or not to have a little bit in the oil or not though. I have done TONS of car engine work and for the most part I didn't see anything alarming though. No big chucks or anything, just enough to see in the sunlight

Edited by RalleyTuned

you'll always get some crap from the clutch in the oil but the metal sparklies should be minimum.  Got a magnetic drain plug?

Bike doesn't have one, but I intend to install one when I finish buying a bunch of engine rebuild parts haha

 

I'm gonna leave the bike together for a short bit and see if I can get someone local that knows 2 strokes better than myself to give it a listen. Going to break out the microphone ears and give it a listen too. Im super hesitant to pull it all apart because it runs so good now with all the bolts tight and the power valve working again, but I can't ignore the noise until I get someone with more experience to give it a listen...

Did a sound test today using these earphones

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I listened to multiple spots on the engine, nothing stood out in the bottom end but the main shaft area was def louder than the transmission or top end. It was about the same volume side to side also.

Well I brought over a friends 200exc and listened to his engine. There is no way some bearing isn't toast in mine. Time to tear it back down!

Let me know what you find I have a similar noise on my yz250 2004 I can't figure out

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