RM250 3rd and 4th gears, Normal wear marks?

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5/2/2018 6:36 PM
Edited Date/Time: 5/2/2018 6:36 PM

I split the case on my RM250 2004 to change main bearings(and ended up changing crank as well) and found 3rd and 4th gear with a lot of marks. Any idea what they may be coming from? Normal wear?

Yes, I'll change them, new gears in the mail tomorrow.....

I have had the bike for 6-7 years and do frequent oil change (every 2-5 hours) but sure, I don't know what the bike been through before I got it.




5/3/2018 3:58 AM

That is kinda normal...lol it is casting flaws, there is nothing wrong with the gears. When they made the gear they pour liquid metal into a die cast and then machine them, when the liquid metal doesn't fill completely and they machine the rough cast that is what is left. It could be a quality control issue where it wasn't caught before it was put in the bike. In my opinion it shouldn't be that bad but the gear would be fine if it's lasted this long


5/3/2018 6:02 AM

My old 92 kx125 never had gears that worn as old as it was. looks like a piece of metal got between them and gouged them out or they were slamming together somehow. Good thing you found it before a tooth broke off


5/3/2018 9:26 AM

My friends 2006 RM had the same marks...although with 200+ hours. His third gear chippd a tooth and was rattling around in there for a bit. He changed them. I do not think that is at all normal, check your whole cluster for a chip before assembly.


Tomac and/or Anderson for 2020.....

5/3/2018 10:07 AM

Thanks for the input guys. I'll check one more time for any chips before I reassemble the transmission and closes up the cases.

I have new gears coming in and yes, it hurt the wallet, but I'm too deep in with investments("new" crank, main bearings, and a cylinder that recently got a millennium plating and Jeff Springman port work) on the engine at this point to go cheep and having a ticking bomb in there...

I can't wait to get the bike back on the track.... the fresh frame look so sad without the beast in here....