Was out riding with a buddy the other day and started hearing some strange metal on metal like noises coming from the motor... quickly shut it off and walked it in...

took the valve cover off and looked around... looked fine... valve clearances in spec... timing good...

pulled off the left side case cover next and found lots of brass like metal shavings... it's magnetic... have a look at the pictures below...


any recommendations for the next step??? main bearing cooked? new bottom end? won't know till I pull it apart???

btw... the top end has less than 20 hours on it... brand new head, valves, etc... from big bore thumpers... had some major issues (a valve spring broke in two places), but thats another story.

<<any recommendations for the next step??? main bearing cooked? new bottom end? won't know till I pull it apart???>>

Sorry to be the bearer of bad news; main bearings went.

Jim.

Those appear to be lower rod bearing pieces, not main bearing pieces. The counter balancer bearings can also wear and fail. Check those closely while you have the bottom end apart.

thanks guys... that's about what I was thinking... I've done four stroke top ends before... are the bottom ends much more complicated? Machine shop work needed?

not sure if its worth just taking to local honda shop or messing with it myself.

MX Tuner, on 06 February 2012 - 06:36 AM, said:

Your right. I was just looking at the brass, which is from the thrust washer and usually a sign of main bearing failure. But looking again, there does seem to be chunks of needle bearings in there as well.

Definitely need to split the cases no matter which and I would do everything to be safe. That's a lot of metal that was floating around in there .


Jim

It does look like there may be more than one bearing that failed.

The brass colored bearing material is coming from the big end of the rod, this link shows two brass thrust washers/bearings.
http://www.ebay.com/...=item35b9549277

achap, on 06 February 2012 - 03:40 PM, said:

The bottom end is alittle more involved than repacing a top end IMO. If you like doing this sort of thing and have a decent set of tools, a shop manual and some patience its not too bad. But if wrenching just isnt your thing I would suggest paying a shop to do it. Good luck!