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2012 crf450r 2nd gear problem

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I am having an issue with my 2012 crf450r.  When in second gear there is a noise that sounds like grinding/slapping.  2nd gear is the only gear that does it and the noise is coming from the engine.  What could this be, and has anyone had this issue before?

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The noise is coming from inside the engine.  Only second gear has an issue.  It is not the chain slapping the engine or swingarm

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Well, Second is splined onto the main, and runs on a bushing on the counter. So when its in second, fourth is slipped over to take power and transfer it to the counter shaft. So Second and fourth are spinning the same speed(actually connected). Which leaves the right or center shift fork could possibly be bent, causing the dogs to drag, or its got a snap right that popped out allowing the dogs to tick off themselves.

Ive seen all manner of trans issues. Broke dogs, bent forks, I even found a counter shaft that was twisted in the spline just slightly, but enough to prevent a new gear from sliding down on it. I even recently found the backing plate screws on a Hinson steel basket that had popped the backing plate screws heads off, dumped the counter sunk heads into the trans and made one hell of a mess.

The only way to really figure out what's going on is to take it apart and really look.

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Yeah I'm going to start tearing it down tomorrow.  The noise is now worse than it was, and the engine stalls if I try to ride it.  It starts fine, clutch in its fine, then go to release the clutch and the trans kills the engine from lock up kind of. Transmission still is able to switch between gears fine but will not drive anymore

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Well when mine did similar the little kick back stop guide bracket on the kick starter had snapped in half and made its way around inside the clutch case then found a way over into the trans where it gave it a thrashing,  Bent two shafts smoked three gears ruined right side case cover, thanks to some skilled welder friends the right half case side was saved.  Now every time I have that side cover off it gets a new one (once so far) they are about $7 bucks, cheap as far as I'm concerned.  And we always kick it all the way through to the stop, we never give it half assed kicks and we try not to let it kick back, full to the stop kicks.  The guy who owned it before us was about 5'3" and said he hated starting it, maybe that was the start of the kick back damage because I don't now see any issues when I replaced it.

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15 hours ago, Mindfault said:

Yeah I'm going to start tearing it down tomorrow.  The noise is now worse than it was, and the engine stalls if I try to ride it.  It starts fine, clutch in its fine, then go to release the clutch and the trans kills the engine from lock up kind of. Transmission still is able to switch between gears fine but will not drive anymore

Its probably seized 3rd onto the counter shaft at this point. The reason I say third is that it was making the noise in 2nd. Third has to spin on the shaft when its in second. And when you put in into any gear, third has to spin.

You can probably verify this by clicking it up into third and then pulling in the clutch to see if the bike will roll. I wouldn't do it with the engine. You don't want to make things worse. But one of the gears that's supposed to spin when in its in another gear is locked onto its shaft. This may be a bucket of suck to get apart.

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Well, I've got the engine out and will be splitting the case tomorrow.  I guess we will see the damage once it's apart.  

20170627_201216.jpg

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Replace all the bushings when you start replacing gears. Ive never pulled an engine with the subframe still on. Never even occured to me. Getting the swinger and coil bracket out of the way is key.

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What caused it. Is the kickstart kick back stop still in place and in one piece

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if it was kickstarter kick back tab it is easy to see if its gone he should know by now.  I would bet one gear broken off bouncing around could do it.  One gear leads to two then looks like about 4-5.  When mine broke off and went over to the gear side it was not that bad.  Although it bent one shaft and kind of messed up three gears, I ended up putting in a used and so far good transplant tranny for around 180 I think.  It did get caught under the WP gear and went round and round for a while and ruined the right side case cover.

Edited by ramjetV8

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Where could I get a good used trans?  I was going to replace the damaged gears and bushings.  What I believe happened was 2nd gear broke a tooth off and damaged the rest

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I got mine off E-bay.  crap shoot I got lucky and so far all is good.  it was a full trans with shift drum and and all.  And be sure if you do rebuild it that the shafts are still true.  I had one bent

Edited by ramjetV8

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If you get a trans off ebay, make the seller take pics of the drive dogs on everything. I've had a couple customers bring me transmissions that weren't much better than the broken junk we were trying to fix.

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I hD good pictures came all assembled and wrapped tight in plastic. I was worried but it turned out fine knock on wood

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Honda changed something from 2012 to 2013, but I don't know if it was a huge dimensional shift or just a part number change on a couple specific pieces. But I do know that the bushing for 5th main is 2.3mm wider in 2013 than it was in 2012. But that doesn't mean the entire unit as a whole wouldn't slide into the cases. But I just don't know.

The ratios are the same.

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go to someplace online like rockymountain atv OEM and start COMPARING PART NUMBERS 2012 TO 2013.  I bet you will find enough info to tell you if its possible.  If shafts and shift forks etc match I bet it would work but I am not guaranteeing anything just saying I would be cross checking part numbers or find someone who has done it.

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