RM250 '10 Transmission tear down, assistance needed with parts

Thedirtyrider
Edited Date/Time 10/19/2020 11:46am
Hi all,

I have torn down the transmission of my RM250 from 2010 (technically it's an 08), this is my first time doing it. The bike started to mis-shift, when switching into 3rd it went back to 1st or not grabbing 3rd at all, and then a rattling sound, so obviously something was wrong in there.

So opened it up, and the first clear view is that the 3rd drive cog has 3 missing teeth, fortunately, I could find all the pieces.

Now next to the 3rd gear, I need some guidance in what else needs to be replaced looking at the wear. I read a lot that this can happen because of bent shifter forks, but mine actually look fine, of course, I have no good eye as it is the first one I do. Also, don't want to just replace everything, only what is really necessary.

Here are some pictures, I hope you guys can help identify what to replace:
Shifter forks:
3rd gear drive:

4th gear drive:

5th gear drive:

1st gear driven:

2nd gear driven:



The drum and other gears look good.

Thanks!


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karlz
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karlz 10/1/2020 12:38pm
10/1/2020 12:38pm
All the gears shown need replacing as well as any other gears they select in to. Regards the forks hard to say without actually measuring them.

karlzracing
Paw Paw
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Paw Paw 10/1/2020 12:42pm
10/1/2020 12:42pm
That trans is shot as it shows a lot of wear and riding with broken parts in place. Replace it all and be done with it.

Paw Paw
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Thedirtyrider 10/1/2020 1:00pm
10/1/2020 1:00pm
All transmission parts were replaced new by a shop 3 years ago. I put about 60 hours on it since then, is it normal that it gets worn down that fast?
Paw Paw
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Paw Paw 10/1/2020 2:31pm
10/1/2020 2:31pm
3rd gear wear is normal. From what I see in your photos, yours has had a good bit of wear all the way up and down the gear train. Shift dogs and gears are real worn and broken. I would suggest that the shift forks are also worn.

Paw Paw

The Shop

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Thedirtyrider 10/2/2020 12:38am
10/2/2020 12:38am
Maybe it's because of my ridding, I do a lot of sand ridding and don't use the clutch much.

Thanks for the help, I'll order all gears and forks.
Paw Paw
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Paw Paw 10/2/2020 2:50pm
10/2/2020 2:50pm
Don't for get to also get the seals, gaskets and bearings.

Paw Paw
Polishhammer 10/6/2020 12:41pm
10/6/2020 12:41pm Edited Date/Time 10/6/2020 12:41pm
It sucks but it’s better to do it once and right then repeat later on.. Maybe look into cryo treating the trans parts for better durability.
Paw Paw
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Paw Paw 10/7/2020 6:08pm
10/7/2020 6:08pm
Maybe more frequent oil changes would also help as sand is very hard on every part of the bike.

Paw Paw
earnestT
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earnestT 10/10/2020 8:10am
10/10/2020 8:10am
u need to check each gear that are anchored to shaft, whether the gear turns or is anchored it needs as little side play as possible. this keeps the gear that slides into it from being pushed out from side play. now comming up with correct spacers thickness wise is hard to do. back in the day you could get your transmission dove tailed. the coggs on the slider gears would get machined so the gears pulled together under load. hard to shift under full throttle.
lecoen
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lecoen 10/19/2020 11:46am
10/19/2020 11:46am
I change the oil every 6 hours. Just going to replace the whole lot. Adding in extra shims is also something I was thinking about as cases might be a bit worn. But on the other hand I read and hear that it's quite common for these transmissions to let go after the amount of hours I put on it. 60 hours since the last time.

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