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Steve93514

2020 Gas Gas TXT250 Shifting Issue

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I got my first trials bike. It is a 2020 Gas Gas TXT250. The bike seems great except when shifting from 4th gear to 5th gear. There is a bad gear grinding noise every time I shift from 4th to 5th unless the RPM's are extremely low. Like 25% of normal. I know  gears 1-4 are low ratio and gears 4-5 are high ratio so the jump between 4th and 5th is a big step. It seems that you would want to be able to shift out of 4th at a higher (or mid) RPM to make the jump to 5th easier. I need to be lugging down in 4th to be able to shift into 5th without getting the grinding noise.

Is this normal? The dealer is telling me that it is normal. 

Thanks, Steve

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Steve, how much have you ridden the bike? This 4th to 5th is a jump as you say and as a result is the necessity to make gentle changes possibly with lower revs, but positively as from memory the throw seems more on this change, if that makes sense?

There has been a big effort to get as far as possible a small and lightweight gearbox, so it definately needs a certain amount of sympathy and awarness. if it goes up and down ok and you get the gear every time then i wouldnt worry. Certainly do not consider clutchless changes. Have you ever droped the bike or bashed the gear lever on a rock?

The down side is I have had a problem like this a few years back and it started with 4th to 5th changes, upside the gearchange casette is aneasy and inexpensive cure.

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Hi Nigel, thank you for replying to my post. The bike is new. Less than two hours on the bike. I only did two short easy rides on it before I decided that the grinding noise could not be normal or a good thing. After the first ride I did change the gear oil with the specified gear oil. The gear changes did seem smoother on the 2nd ride but the grinding noise remained the same. I spent most of the 2nd ride carefully shifting through the gears from 1st to 6th then back down to 1st. All of the gear changes seemed fine with the exception of going from 4th to 5th. The grinding noise happened every time unless I was shifting at unusually low rpms. 

I returned the bike to the dealer after the 2nd ride. At first they said that there was a problem so they kept the bike. The dealer called me the following day to say that the noise is normal according to Gas Gas technical support. 

I suppose that I could live with the issue if it is "normal " but it seems like it will lead to a catastrophic failure of the gear box.

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Do the new bikes stll have the eccentric adjustment? Just curious.

Edited by lineaway

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Hi Lineaway, I don't know if the bike has that adjustment. The shifting feels really good with the exception of going from 4th to 5th. 

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Can you get a ride on another  Gasgas  to see if there is any difference . 4th/5th is horible

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As unpleasant as it may seem, I do believe that what you (mostly) describe is normal; I know that both of my 2008 GGs require "effort" to shift between 4th and 5th. I believe the effort is required because the compact design of the transmission requires that two sets of gears move when shifting between 4th and 5th, and there's just more moving parts which need to come together when making this transition.

My 4th to 5th issue can be mitigated by realizing that my tranny can never be "flicked" between those gears, and instead if I hold the lever (in 5th) before and during when I release the clutch when up-shifting things go better. Same with 4th; hold in 4th and then release the clutch when down-shifting.

I guess, basically try different shifting techniques.

But a grinding sound doesn't sound good. Have you ensured that you have correct free-play on your clutch? Are you getting a good disengagement?

Edited by d2w

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Maybe try getting video or sound of the gear change? Next time I have my '17 out I'll try to record mine shifting from 4th to 5th. As others state, mine is "loud" noise but I don't think it is a grinding noise.

 

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19 hours ago, Steve93514 said:

I got my first trials bike. It is a 2020 Gas Gas TXT250. The bike seems great except when shifting from 4th gear to 5th gear. There is a bad gear grinding noise every time I shift from 4th to 5th unless the RPM's are extremely low. Like 25% of normal. I know  gears 1-4 are low ratio and gears 4-5 are high ratio so the jump between 4th and 5th is a big step. It seems that you would want to be able to shift out of 4th at a higher (or mid) RPM to make the jump to 5th easier. I need to be lugging down in 4th to be able to shift into 5th without getting the grinding noise.

Is this normal? The dealer is telling me that it is normal. 

Thanks, Steve

it is NORMAL.  years back there was a diagram showing why there is a bunch of resistance in the 4-5 shift, it is because rotation of shaft speed and the fact that it isn't at much about gears meshing, but "Dogs" on the side of the 2 gears having to engage.  As you have noticed the 1st 4 gears are just slighty different each shift, but the 4 to 5 is a big step, then 5 to 6 is less of a step, so there is less perceived meshing "noises" on the other shifts. 

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Hi Sting32 I think this is the image you may have been referencing.

It is a little inaccurate because it doesn't show the shift discs engaged in the correct positions, it just shows the drive sequence. You are correct - gears are always in constant mesh, it is the shift discs that are moving and creating the drive sequence.

But from memory the 4 to 5th change all 3 disc are moving and need to relocate into the appropriate gears, hence the 'tougher' shift in the Gasser boxes in some gears and not others. Some changes only one or two discs are moving.

It is a great gearbox design, just needs to be understood that you can't be hamfisted with it. Saying that a clunky change is understandable knowing the mechanics of it, but it shouldn't be 'grinding' - that sounds like big bits of metal are being turned into small bits of metal!

 1777647811_ScreenShot2020-07-17at08_42_56.png.9ed077f8b819a05fea0c1a1c27a91078.png

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Thanks everyone for the responses. Unfortunately I don't have the bike right now. It is at the dealer that is over 200 miles away. I'll probably get it in a few days. It is looking like the dealer is confident that the grinding noise is normal and that there is not a problem with the bike. 

I have two KTM enduro bikes. I would say that I am a strong intermediate rider. I use clutch a lot to fine tune the power coming from the engine. Especially in technical terrain. With the Gas Gas the clutch and shifting seems really nice with the exception of the hideous grinding noise when shifting (using the clutch) from 4th to 5th. If one of my other bikes started making a noise like that I would stop riding it immediately. 

I will make a video of the problem and post it if it turns out ok. I'm going to try to find someone at KTM/Gas Gas that I can email the video to so that I can document that the issue was present during the 30 day warranty period. Which ends on July 25.

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Hi Arnoux, the sound is like the teeth of two cogs/gears are spinning in opposite directions and grinding against each other briefly before engaging 

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6 hours ago, Steve93514 said:

Thanks everyone for the responses. Unfortunately I don't have the bike right now. It is at the dealer that is over 200 miles away. I'll probably get it in a few days. It is looking like the dealer is confident that the grinding noise is normal and that there is not a problem with the bike. 

I have two KTM enduro bikes. I would say that I am a strong intermediate rider. I use clutch a lot to fine tune the power coming from the engine. Especially in technical terrain. With the Gas Gas the clutch and shifting seems really nice with the exception of the hideous grinding noise when shifting (using the clutch) from 4th to 5th. If one of my other bikes started making a noise like that I would stop riding it immediately. 

I will make a video of the problem and post it if it turns out ok. I'm going to try to find someone at KTM/Gas Gas that I can email the video to so that I can document that the issue was present during the 30 day warranty period. Which ends on July 25.

That I respectfully suggest could be the problem, you are used to an enduro slick change. Try to change positvely between 4 and 5th and insert more throw with you foot. Certainly as myself and others have said 4th to 5th isnt as smooth as all the others. is 5th to 4th ok?

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All the Gas gas pros I've owned have shifted 4/5 with a loud clonk,which is normal,which got worse with age .Never had a grinding noise,I'd be talking to the dealer.Difficult when you can't compare it with another bike and the dealers not local

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