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5th gear AGAIN!


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OK this is getting ridiculous! This will make the 3rd time I have lost 5th gear in 3 years, this is my primary racebike for Desert and it has the WR trans 3-5.

 

Is there some solution for this, and does anybody else have this issue? Mind you I have put on over 300 hours on the bike during the past 2 years alone. 

 

I was racing in the 100s MC National Hare and Hound yesterday and it started popping out of 5th gear half way through the first loop and started getting worse to the point I stopped shifting into 5th anymore to keep from jacking up all my shift forks, etc... 

 

My bike in an 05' with 06' suspenders BTW.  

 

I am thinking about getting a new YZ so I can put all my aftermarket stuff on it.  I really wish they would make a YZ version of the KTM 300 damnit!!!  They would sell them all day long!

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I've been told by a Factory mechanic that they tumble the gears. I'm getting it done this winter. Supposedly shifts like butter after.

 

I change my bottom end oil every 3-5 hours tops.

Hmm might be worth a try, I was thinking the drum just isnt held tight enough by that little spur bearing ad allows the gears to start to slip, once that happens even once its downhill fast from there.

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I am thinking about getting a new YZ so I can put all my aftermarket stuff on it. I really wish they would make a YZ version of the KTM 300 damnit!!! They would sell them all day long!

I know I would be in line looking at one. I am hopeful with the release of the of the YZ250fx that a YZ300x will be in showrooms in a couple years and Yamaha will really go after the market KTM has there. Sorry it's off topic but really it stayed on longer than most threads...

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You have persistence, that's for sure.  But maybe it's time to buy a bike more suitable for your purposes.  I have 2 YZs and a KTM (and in the recent past have owned yellow, green, and red).  It's not like the yamaha is magic and all the others are crap.  The KTM has a 300 engine configuration with loads of flexibility in power output, and a WR transmission (now a 6 speed), that have both been around for years and years and are proven reliable.  Rebuild the YZ for the track and get a different bike for your desert bike.

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I've ridden many and they have such a tall seat height.

For me out of any bike I have owned or ridden the YZ just feels so much better.

Not sure I'm gonna have the YZ fixed in time for the next race, prolly just race the AF500. The YZ is gonna be a couple Benjamins at least to fix..

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OK this is getting ridiculous! This will make the 3rd time I have lost 5th gear in 3 years, this is my primary racebike for Desert and it has the WR trans 3-5.

Is there some solution for this, and does anybody else have this issue? Mind you I have put on over 300 hours on the bike during the past 2 years alone.

I was racing in the 100s MC National Hare and Hound yesterday and it started popping out of 5th gear half way through the first loop and started getting worse to the point I stopped shifting into 5th anymore to keep from jacking up all my shift forks, etc...

My bike in an 05' with 06' suspenders BTW.

I am thinking about getting a new YZ so I can put all my aftermarket stuff on it. I really wish they would make a YZ version of the KTM 300 damnit!!! They would sell them all day long!

Just out of curiosity, what oil do you run in the tranny?
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Could the groove in the shift drum that holds the fork be worn (have you replaced the drum?) is the bearing that holds the drum tight in the case?

 

Is your boot touching the shifter when riding but not shifting?

I had that happen on my 450, but I havent replaced it yet in the YZ, but I think I will just to keep it from happening again, the bearing was brand new at least last time I opened it.  My boot is normally clear of the shifter, but what "seems" to cause it is if I do a half assed shift into 5th and it pops out its done for.

 

Grind your dogs on the gears so they slightly hook into each other.

You also need to change out your shift forks as they will be bent and worn

Do you have a pic of this? And yeah I have changed shift forks every time

 

If u replace and don't have wr 450 sets which are suppose to b stronger, that might fix ur problems.

 

I have the WR gears already.

Just out of curiosity, what oil do you run in the tranny?

Rotella T-6. I use nothing but that in all my machines.  

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I had that happen on my 450, but I havent replaced it yet in the YZ, but I think I will just to keep it from happening again, the bearing was brand new at least last time I opened it.  My boot is normally clear of the shifter, but what "seems" to cause it is if I do a half assed shift into 5th and it pops out its done for.

 

 

As you know once the gear slips out the force applied at the tip of both the male dog and the female dog (the gear next to it) is concentrated at the sharp edge of the dog. one the edge of the dog rounds off there is little to keep them engaged.  The engagement face of each dog is ground at slight taper so the load applied by the engine force the two together and not apart.

 

Sounds like you have a good handle of what is happening inside so you may need a good magnifying glass for inspection of the dog tips.

 

I am not buying that the gears are not strong enough. at least the WR 426 i have has over 20k hard miles on the trans and the engine is bigger and the bike is much heavier. they work great in lots of bigger bikes.

 

Check the female dog carefully on the next gear (are you replacing them as a set?)

 

I guess you could use a wet stone on the vertical dog faces to sharpen the edge but the gear is hard so all you can do is remove a few high spots.

 

If you end up getting the ISF finish on the trans please show us a picture,

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As you know once the gear slips out the force applied at the tip of both the male dog and the female dog (the gear next to it) is concentrated at the sharp edge of the dog. one the edge of the dog rounds off there is little to keep them engaged.  The engagement face of each dog is ground at slight taper so the load applied by the engine force the two together and not apart.

 

Sounds like you have a good handle of what is happening inside so you may need a good magnifying glass for inspection of the dog tips.

 

I am not buying that the gears are not strong enough. at least the WR 426 i have has over 20k hard miles on the trans and the engine is bigger and the bike is much heavier. they work great in lots of bigger bikes.

 

Check the female dog carefully on the next gear (are you replacing them as a set?)

 

I guess you could use a wet stone on the vertical dog faces to sharpen the edge but the gear is hard so all you can do is remove a few high spots.

 

If you end up getting the ISF finish on the trans please show us a picture,

 

I always replace the mating gears, but once I split the cases I will shoot pics of the damaged parts, I guess I am behind the 8 ball on this but whats the ISF finish, is that the shot peening? 

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http://www.cvproducts.com/Powersports/  Check their catalog and look for" transmission Superfinishing"

It is a chemical milling process where all the hard gear and shaft parts have their surface polished smooth. it lowers friction and  heat caused my microscopic rough finish of mating hardened steel parts.

 

Its not really a repair for your trans but once you get it sorted out it will make it smother and more reliable.

 

All the big race teams use this on their trannys

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When you say Mating Gears

Do you mean the ones with the gear teeth that mesh? or the adjacent gears where the dogs mesh? maybe a new 5th gear is meshing into an adjacent gear with a worn slot for the dog on the side of the gear that holds it to the shaft once it slid over by the fork?

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When you say Mating Gears

Do you mean the ones with the gear teeth that mesh? or the adjacent gears where the dogs mesh? maybe a new 5th gear is meshing into an adjacent gear with a worn slot for the dog on the side of the gear that holds it to the shaft once it slid over by the fork?

I meant the dogs..the "teeth" are likely fine. Doesnt take much for these things to start popping out of gear.

The last couple times I had to replace 2 of the gears and all 3 f the shift forks. I'm gonna have to take a really close look at the drum, my CRF488 had a bad spot on the drum that caused gear failure.

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