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I hate my transmission!


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I downshift without the clutch all the time and that helps a bit but I also agree the random neutrals tend to happen at the worst time and its frustrating. I'd also like to hear about this shifting ratchet to see if its anything that can be fixed.

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The best thing to do is avoid going into 1st altogether, that is if its possible. For MX just start in second gear and use 2nd or 3rd in the corners with some clutch when needed.

For off road riding though, some tighter sections require 1st gear I assume... I guess the only option is you be sure to get a good clean downshift when passing by neutral.

Pretty much almost every MX bike I have ever owned has had a tendency to catch neutral (if your not careful) on a down shift from 2nd or a upshift from 1st.

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I find this happening on my 2003 250 in those "first gear or fall" technical trails/switchback, hills. I changed my gearing to a 13x50 (I'm also a heavier rider) and find 2nd works without having to bang 1st on all but the most technical (for my ability) scenarios. But yeah, so many times I hit a neutral instead of 1st... it's an 03 that was still new in 2008... so it has very little abuse on the tranny.

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I should have mentioned, it's an 07 250. How is the shifter ratchet/star accessed?

I believe he his referring to your shift detent lever, It is located behind the clutch. Yamaha puts a bearing on them and sometimes the bearing can go bad and the bearing race can get stuck under the linkage allowing it to not push down far enough. Will it shift back down from say 4th or 5th to 2nd?

here is a micro fish of the detent lever just to show you what your looking for when you take your clutch apart the detent arm is number 7. Like i said there should be a bearing on it. I would suggest putting a magnetic drain plug in if you dont have one already so you can see if there is any metal floating around in your transmission suggesting something is broken.

http://www.motosport.com/dirtbike/oem-parts/YAMAHA/2007/YZ250/?modelyearid=2305&typeid=1&groupId=96279

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On that diagram part #5, I always called the shift star. If you look between the detents they alll have a point except for between first and second. this is where the shift lever sits when in neutral. If you take this part out and grind down the neutral detent a little it makes a big difference. I had to do this on my 250f because I always hitting neutral. This made a huge difference, and neutral is still there, you just have to be a little more careful when finding it. There was a great write up on how to do it on www.thumperfaq.com, but I think the site is gone now.

Basically you just grind or file a little from the sides of the detent, this makes it more likely for the lever to pop down into first or second and not hang in neutral.

It is pretty easy and quick mod, plus if you do destroy the part, it is only $30 or so for a new one. I know it helpped my confidence on the 250f, and I won't hesitate to do it to my yz if I start having problems, but the rekluse seems to solve most of the issues.

Found it!

(From TT member Ken Sherer)

This is not technically a clutch modification but it does apparently help with the notchy shifting and accidental neutrals. This modification may help with the issues surrounding the "neutral" problems and "notchiness" on the 250Fs. This modification may help with the problem of accidentally finding neutral, and may improve the notchiness. Basically when you look at the ramps that you have to climb to shift from 1-2 and 2-1 its immediately obvious why its a notchy transmission. Basically neutral is just too damn big and easy to find. This is a death sentence on a motocross bike and a constant source of annoyance for tight trail riders.

The Part

The shift star wheel is located under the right side cover under the clutch. In order to remove it the clutch must come off. It costs about $35. The ONLY tricky thing to remember here is that its not a 2-stroke so there are a few o-rings and seals that connect the right side case to the engine. Without a correct reassembly you may not have full oil pressure. Also, almost forgot, what flops into each "slot" is a wheel held on the end of a spring loaded shaft. The "wheel" is almost the diameter of a dime. This assembly is called a shift detent mechanism.

Operating Theory

Note that there is a false neutral between 2-3, 3-4 and 4-5. All bikes have them because it is mechanically impossible for 2 gears to be engaged at once. If you get nothing else out of this remember that it is there. And remember that when you are doing a big 4th gear jump, especially when the gearsets are lightly loaded (ie; partial throttle) KEEP YOUR FOOT AWAY FROM THE SHIFTER. Because there is always that slight chance that you could unknowingly pull your tranny into one of these false neutrals, with just the weight of your boot, and execute a perfect forward somersault. Not fun. The tranny will work fine as long as you don't hambone it. That's why the false neutrals are located on "points" on the star wheel. It is meant to flop into one gear or the other. Do not interfere with this process when life and limb are at stake. If you still have doubts put your bike on a stand. Snick it into 3rd. Now rotate the back wheel back and forth as you ever so slowly pull the bike into 4th. At one point it will go into neutral. Now you know where you are: you are balanced on one of the "points" on the shifter star wheel.

Procedure

Here is the stock part with marks where is should be modified. I used a file to do it. Remember that the point here is to make the ramps on either side of neutral similar to the ramps for the other gears. You also want to reduce the size of neutral itself. But keep the 2 "points" as sharp as you can as you can so the shift detent wheel can't rest there.

Final notes and warnings:

Its an easily reversible modification as a replace part is relatively cheap.

Understand the process by shifting the bike when its apart. Its important to get the "feel" of things so you know how far you should proceed with the filing.

Neutral will become harder to find, of course. This is the goal you want.

There is a possibility that the shift detent can "balance" on the points between 1-2 or 2-1 after you are done filling. This could lead to some funny neutrals when the bike is idling by itself. I have had ZERO problems, in fact that's why I started filing in the first place. But be warned. I would not go revving the piss out of the engine (in neutral / clutch engaged) with your friend standing in front of the bike.

Two things we all get out of this (regardless as to whether you do the mod or not):

Watch the weight of your foot on the shifter when jumping.

Don't stand in front of a bike that is being revved to the moon with the clutch engaged. Neutral is a very, very relative thing. It can come and go at the worst possible moments!

Figure 1 Figure 2

Figure 3

Click images to enlarge

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On that diagram part #5, I always called the shift star. If you look between the detents they alll have a point except for between first and second. this is where the shift lever sits when in neutral. If you take this part out and grind down the neutral detent a little it makes a big difference. I had to do this on my 250f because I always hitting neutral. This made a huge difference, and neutral is still there, you just have to be a little more careful when finding it. There was a great write up on how to do it on www.thumperfaq.com, but I think the site is gone now.

Basically you just grind or file a little from the sides of the detent, this makes it more likely for the lever to pop down into first or second and not hang in neutral.

It is pretty easy and quick mod, plus if you do destroy the part, it is only $30 or so for a new one. I know it helpped my confidence on the 250f, and I won't hesitate to do it to my yz if I start having problems, but the rekluse seems to solve most of the issues.

Found it!

I'll need to bring some tools home from work to do this, what holds the star wheel on?

(From TT member Ken Sherer)

This is not technically a clutch modification but it does apparently help with the notchy shifting and accidental neutrals. This modification may help with the issues surrounding the "neutral" problems and "notchiness" on the 250Fs. This modification may help with the problem of accidentally finding neutral, and may improve the notchiness. Basically when you look at the ramps that you have to climb to shift from 1-2 and 2-1 its immediately obvious why its a notchy transmission. Basically neutral is just too damn big and easy to find. This is a death sentence on a motocross bike and a constant source of annoyance for tight trail riders.

The Part

The shift star wheel is located under the right side cover under the clutch. In order to remove it the clutch must come off. It costs about $35. The ONLY tricky thing to remember here is that its not a 2-stroke so there are a few o-rings and seals that connect the right side case to the engine. Without a correct reassembly you may not have full oil pressure. Also, almost forgot, what flops into each "slot" is a wheel held on the end of a spring loaded shaft. The "wheel" is almost the diameter of a dime. This assembly is called a shift detent mechanism.

Operating Theory

Note that there is a false neutral between 2-3, 3-4 and 4-5. All bikes have them because it is mechanically impossible for 2 gears to be engaged at once. If you get nothing else out of this remember that it is there. And remember that when you are doing a big 4th gear jump, especially when the gearsets are lightly loaded (ie; partial throttle) KEEP YOUR FOOT AWAY FROM THE SHIFTER. Because there is always that slight chance that you could unknowingly pull your tranny into one of these false neutrals, with just the weight of your boot, and execute a perfect forward somersault. Not fun. The tranny will work fine as long as you don't hambone it. That's why the false neutrals are located on "points" on the star wheel. It is meant to flop into one gear or the other. Do not interfere with this process when life and limb are at stake. If you still have doubts put your bike on a stand. Snick it into 3rd. Now rotate the back wheel back and forth as you ever so slowly pull the bike into 4th. At one point it will go into neutral. Now you know where you are: you are balanced on one of the "points" on the shifter star wheel.

Procedure

Here is the stock part with marks where is should be modified. I used a file to do it. Remember that the point here is to make the ramps on either side of neutral similar to the ramps for the other gears. You also want to reduce the size of neutral itself. But keep the 2 "points" as sharp as you can as you can so the shift detent wheel can't rest there.

Final notes and warnings:

Its an easily reversible modification as a replace part is relatively cheap.

Understand the process by shifting the bike when its apart. Its important to get the "feel" of things so you know how far you should proceed with the filing.

Neutral will become harder to find, of course. This is the goal you want.

There is a possibility that the shift detent can "balance" on the points between 1-2 or 2-1 after you are done filling. This could lead to some funny neutrals when the bike is idling by itself. I have had ZERO problems, in fact that's why I started filing in the first place. But be warned. I would not go revving the piss out of the engine (in neutral / clutch engaged) with your friend standing in front of the bike.

Two things we all get out of this (regardless as to whether you do the mod or not):

Watch the weight of your foot on the shifter when jumping.

Don't stand in front of a bike that is being revved to the moon with the clutch engaged. Neutral is a very, very relative thing. It can come and go at the worst possible moments!

Thanks for the great info! I'm definitely doing this mod when I get a little time.

So basically you just file off the "points" on each side of the detent so the little wheel is more likely to just roll past the detent rather than falling in it. Does that sound about right?

Edited by doggerdan1
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Don't stand in front of a bike that is being revved to the moon with the clutch engaged. Neutral is a very, very relative thing. It can come and go at the worst possible moments!

Funny you mention this , my YZ clicked into 1st all by itelf today while I was warming it in neutral. Hand wasnt on the clutch and it just stalled, If I was revving it like some tools do then I might have gone straignt into my truck.

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Bent shift fork or forks ๐Ÿ˜

I suppose it's possible one of the forks is bent, but it's very random, half the time there is no problem.

Today I pulled the little star wheel thingy out and filed off the points of the detent, we'll see if that works tomorrow.

I can see why that detent could cause a problem, it's deep and huge, very easy for the little bearing to get hung in it.

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It seems this mod has all but eliminated the false neutral problem. Only two missed shifts in 60 miles of trail.

There were times when I downshifted into first and fully expected to be in neutral but it was indeed in first gear.๐Ÿ˜

Time for a WR gear set now.

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