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YZ250 2007 3rs slips out - Help with cogs n dogs n forks

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Sup people!

I love this bike, I cant and wont get rid of her and all she does at the mo is take my money but wouldnt be a dirt bike if it didnt hahaha.

So she started slipping in 3rd a while back, I looked at the the clutch plates and they were fine and I thought it may be a trans problem as all other gears pull fine.  I'm gonna open the engine yet again and have a look, luckily I have a spare complete trans from a 2006 I bought so may be able to swap out what I need to.  I've read on here that if it is the fork/3rd thats the problem you remove others that come in contact - does anyone know off the top of their head what they are?

Ta

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Yes I've had same thing happen to couple yz250's.  4 gears and a shiftfork every time.  You'll see the wear marks when split. Replace everything that shows wear. Also check your segment for wear. Pic below shows what to look for.

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OUCH :(

I'll get some pictures back to you to compare lol - thanks for that dude :thumbsup:

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13 minutes ago, nath125 said:

OUCH :(

I'll get some pictures back to you to compare lol - thanks for that dude :thumbsup:

Welcome man. Weak tranny compared to other brands. Everything is smaller and forks slide in cases instead of on pins like all others and older yz's. But rest of bike is pretty awesome lol

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I remember it looking ok but will double check, cheers.  Hoping to get it apart this weekend so will post an update.

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Life really gets in the way of a teardown lol. Anyway I managed to wake up early this morning and got everything out. I see that the forks look a bit crap, especially R. I also see some grind marks on the drum.



Can anyone see anything in the pics? I can take apart more if needed. Thanks for his guys, after all the problems I've had with her I'm hoping this is the last for a while
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Then two gears and check ones that mesh with them on other shaft. That shiftfork. Any gearthat shows any wear you wanna replace.  Not sure how marks on drum got there unless something was in there

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I dont really know what a new and used one looks like!  If I try to mesh them together nothing seems bad - but there has to be something!  Would it be easier if I took the tranny apart and showed?  Just want to make sure this is sorted before I put her together again

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6 hours ago, nath125 said:

I dont really know what a new and used one looks like!  If I try to mesh them together nothing seems bad - but there has to be something!  Would it be easier if I took the tranny apart and showed?  Just want to make sure this is sorted before I put her together again

Can see the wear in the pics you posted.  Any gear that has any sign of wear replace. Probably need 4 gears and the R fork. Witch is #1 in manual I believe have to look. I'm just leaving track now

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6 minutes ago, nath125 said:

Thanks matey, i have a manual at home so will take a peek.  Your a top bloke.

Lol top bloke?  Sry never heard before but you're welcome anyway. I've been threw alot of these trannys.  Was my biggest problem with the modern 250 . Yamaha compacted it down small and just isn't as reliable as other brands now.  But it does work good. Also inspect your segment real good and pawls for wear. One time lol i blew 3rd and replaced the gears ,fork that were bad and not long 4th went . But the segment was very worn from 2nd-4th and think that's what caused that failure but not sure. Once a gear starts slipping it's over just gets worse. I always tell customers it's better to be stuck in gear= less money. If you replace everything you see with wear marks it will be good to go

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So I can really only get my parts from fowlers in the UK (anyone know of any others/cheaper??) And the cost seems to be mounting up, its around £60 for each fork (as they all look like they have some wear), 3rd and I believe 5th that it goes into will need replacing and Im guessing there will be a few more gears aswell - all around £55-75.   Fowlers do not stock a few gears from my year as well which makes it more difficult.

The replacement tranny I got from an 06 has some signs of wear and different part no's so Im thinking that I may well have to bite the bullet and get a load of parts for around the £500 mark :( 

I know the engine has only had minor changes from 99 onwards but can I use the newer tranny parts from a 2016 bike to replace the parts in mine?  If thats the case I will order from the newer parts as they have them all in stock.  I also have a wr400 5th gear and pinion that I could put in there - I only use the bike for messing around on and off roading....

 

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On 5/21/2017 at 11:15 PM, Motox367 said:

Can see the wear in the pics you posted.  Any gear that has any sign of wear replace. Probably need 4 gears and the R fork. Witch is #1 in manual I believe have to look. I'm just leaving track now

Sorry to pester again - Do you know which gears I will need to replace?  Im confused looking at the manual and the trans....

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28 minutes ago, nath125 said:

Sorry to pester again - Do you know which gears I will need to replace?  Im confused looking at the manual and the trans....

Ya man taking set of ktm cases to welding shop when I get back home I'll help ya out.  If you can post pics of shafts next to each other so I can see witch dogs are wore exactly 

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Um... do you want the cogs off the shafts or pictures like above?

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1 hour ago, nath125 said:

Um... do you want the cogs off the shafts or pictures like above?

Close up of each axle whither dogs facing camera.  And slide them open . Need to see whitch gears have wear on dogs . Don't wanna tell you ones ya don't need this gets expensive.  Looks like you have two forks with wear spots I'd replace them also. R=shift fork 3, L=shift fork 1, c10= shift fork 2, you'll need those numbers to order them

Edited by Motox367

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So this is the current trans - where 3rd slips - I see most damage on the 5th gear dogs and 3rd gear nothches where 5th enters - they look quite shiny.  The forks don't look too special, a lot of rubbing especially on "R"

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I do have a spare from a 2006 which was breaking.  I have put 5th gear and pinion from a wr400 on them but have kept the 5th gar and pinion from the set.  Pictures below - If I can use this trans, or salvage any bits then it would make my bank and missus happier :)

 

Thanks again for this

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