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2004 Gas Gas 300 Pro Shifting Problem

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I have been working on a shifting problem with my 04 GG 300 Pro after letting my nephews use if for their first dirt-bike lessons. I was the instructor so I knew they didn't abuse it except possibly stepping on the shift lever too hard.

The symptom I first noticed was when looking for and confirming first gear after one nephew complained about not being able to confirm the bike was in first.

In testing it, It didn't seem very precise so with a few stabs at the lever to confirm I was at the bottom of the shift pattern, I was greeted with a POP as the lever dropped well below where the first gear stop should have been. The bike ran well and I didn't notice any new noises nor any real problems shifting through all of the gears except for the stop at first.

I have been in conversation with Stu of Jack's Cycles, Dale of Gas Gas USA and by a couple emails with Laser17. We were all guessing or maybe it was hoping that the problem was with the shift shaft center locator on the right side under the clutch. A simple item to replace. But tests with it off as in the video below indicated I would get my first chance to use Jim Snell's video in the complete engine repair.

We finally came to the conclusion that the problem was INSIDE the transmission and I would have to split the cases. This is the first time in 17 years of owning Gas Gas motorcycles that I have had to remove an engine.

So here is a short video to show the symptom..

http://smg.photobucket.com/albums/v447/2Ply/Gas%20Gas%20300%20Transmission%20Repair/?action=view&current=GG-GearProblem.mp4

If you go to that page with the video, I believe PhotoBucket will allow you to see all of the other photos I posted about this lesson and what I found. :lol:

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So how is it going with the repair? I had my first experience with my 04 Pro that i had to split the cases ad replace the Output shaft and bearings, Kickstarter Gears etc. Turned around and Sold it, Now I have an 03 Edition and No Major Problems. Only the Rider

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So how is it going with the repair? I had my first experience with my 04 Pro that i had to split the cases ad replace the Output shaft and bearings, Kickstarter Gears etc. Turned around and Sold it, Now I have an 03 Edition and No Major Problems. Only the Rider

Well, 2 months after I bought it, the main shaft 2-piece bearing collapsed but GG USA made good on the warranty even though it was past the 30 day normal limit.

I have broken 2 kick-starter pawl gears on my 07 Raga but now I know how to tell if there is an impending problem. Learning that AND replacing the chewed up kick-start idler gear on the 07 has eliminated that problem. Seems there was a batch of improperly heat treated idler gears. My new gear shows no wear after over 2 years.

This current problem probably will turn out to be from brand new to dirt bike teenage family riders that probably stood on the shifter for lack of being able to stand on one foot while riding and shifting... I can vaguely remember having trouble doing that on my first couple of rides...

Anyway, I have added a final video showing what I found:

http://smg.photobucket.com/albums/v447/2Ply/Gas%20Gas%20300%20Transmission%20Repair/?action=view&current=Problem-Found.mp4

However, I must add that I have found this bike incredibly easy to work on. And with all of the detailed videos available form the USA Gas Gas crew, how much easier can it be?

Plus, I turned in the parts list yesterday and ALL of the needed parts are already on the way. But it really helps to have a spare bike when these things pop up.. :lol:

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2PLY,

Was that flamenco music I heard in homage to Jim Snell and all of his Gas Gas videos?

Ken

:) You caught that eh? I forgot to check the sound when I threw that video in the editor. And yes, that was Rumba Music by Jesse Cook. I've used quite a bit of his music in some of my video and on purpose... this time was by accident. :lol:

http://jessecook.com/#/home/

I went back and turned up the sound.. hahaha... I just grabbed that clip and trimmed both ends off to make it short but never turned on the sound on my computer, so my narration was chopped off too... I've been waiting for someone to chew me out for NOT wearing gloves... OOPS! BAD 2Ply!! Bad Boy!! No Biscuit!!

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I had to do the same repairs replacing the shifting pawl, kickstart gear and idler gear. Knowing now how expensive the parts are, I am very careful every time I shift and kick start. I don't let others ride my GG. I've seen experienced riders of Japanese bikes who are in the habit of jabbing hard on the shifter and doing multiple quick kickstarts damage the fragile GG engines.

Usually the the shift shaft center locator's crossbar "fuse" breaks before damaging the shifter pawl. I broke that fuse a couple of times, then that thin metal on the shifting pawl broke.

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..........

Usually the the shift shaft center locator's crossbar "fuse" breaks before damaging the shifter pawl. I broke that fuse a couple of times, then that thin metal on the shifting pawl broke.

We were hoping it was the fuse and I believe if the shifter is jammed UP in first by a rock strike or similar or up and down in any other gear, the fuse would come to the rescue. It's looking like it can't protect when in first gear and the force is down on the shifter.

Oh well, it has been a good experience as I have always dreaded splitting the cases but now find it almost fun if you have the place to work on it out of the rain.... AND if you have another bike as a back up like I do. :lol:

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So that's the ratchet mechanism that works on the drum, right? As soon as I saw the first video I was certain it was a rounded edge on one of the pawls, but that's what the assembly looks like on the Jap bikes I've worked on. Looks like the rollers serve the same function just a different design.

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So that's the ratchet mechanism that works on the drum, right? As soon as I saw the first video I was certain it was a rounded edge on one of the pawls, but that's what the assembly looks like on the Jap bikes I've worked on. Looks like the rollers serve the same function just a different design.

Jim Snell gets into the details of this at 4:40 in the video below

http://www.youtube.com/watch?v=pQ7OmoyATgU&list=FLKodxCtyK6SmiMQl4ndcQ1Q&feature=mh_lolz

And again at 6:30.

I actually had this video running as I worked on the engine. :lol:

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Jim Snell gets into the details of this at 4:40 in the video below

http://www.youtube.com/watch?v=pQ7OmoyATgU&list=FLKodxCtyK6SmiMQl4ndcQ1Q&feature=mh_lolz

And again at 6:30.

I actually had this video running as I worked on the engine. :lol:

Yep, that's pretty much what I was thinking although I couldn't quite picture how the rollers would disengage. I wasn't thinking of a feature in the case! In the image below is the assembly on a YZ250F, specifically the lower assembly in the drawing.

1254_shift_shaft.gif

Parts 8 are like the rollers, they pivot on the rounded edge, with the square edge engaging inside of part 1. You can see how a rounded edge on the downshift "pawl" would cause the same symptoms as your broken link. Part 3 is fixed to the case and performs the same function as the case on your GG for disengaging one of the pawls (or rollers on your GG) to shift in a given direction as described at 6:30 in your link.

Now I just have to see what the mechanism looks like in my Montesa! Yeah, I'm kind of a nerd when it comes to these things, that's why I like working on my bikes almost as much as I like riding them!... Almost...:)

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.....

the lower assembly in the drawing.

Parts 8 are like the rollers, they pivot on the rounded edge, with the square edge engaging inside of part 1.......

Hmmm... I can see the text part of the link (http://oem.thumpertalk.com/images/Yamaha/2004/Motorcycles/1254_shift_shaft.gif) but not the image

Regardless, here is the parts and list pages for my 2004 that apply to the problem:

CS001449.jpg

CS001449.jpg

In group 31, it was part number 14 that failed but I believe it's not available by itself so I get a new complete #31 assembly (Shift Shaft Set)

Interesting!! And I don't see the photo files I just added either.. I'll have to check my other computer to see if it's a Thumpertalk thing or just my computer... :lol:

Update: copied the screen shot to my PhotoBucket account.. Not sure why it's not working from my web space..

Hmmm... ??? Having some trouble controlling the display size of these too... should be much bigger so here is a closer view of the group:

CS001451.jpg

Edited by 2PLY

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Must be a problem just with the Trials forum as I can see posted photos in the Off-Road Techniques forum but not in the Trials Forum from EITHER of my computers... ???

NOPE, I take that back.. Seems to be a problem with any NEW photo links in other forums too.

Edited by 2PLY

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Yeah, weird I can't see either of the images you posted. But the image I posted shows up in your quote. Going to the URLs doesn't work either, maybe the site is down?

The image I posted is just the parts diagram from the TT OEM store for my 04 YZ250F's shift shaft assembly.

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That tranny problem is bummer. My brand new 07 280 gave me trouble downshifting right out of the crate, checked the adjuster and it was were it should be. Another trials friend had tranny problems with his new 280. We both sold ours, and I now sponser Montesa.

I hope you get your bike running properly.

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That tranny problem is bummer. My brand new 07 280 gave me trouble downshifting right out of the crate, checked the adjuster and it was were it should be. Another trials friend had tranny problems with his new 280. We both sold ours, and I now sponser Montesa.

I hope you get your bike running properly.

No problem. Parts have been shipped and will probably arrive tomorrow.

Actually, it's been somewhat fun and interesting. A really easy bike to work on and that's probably a really good thing.

I remember the instructions for splitting the case on my Bultaco Sherpa-T. I guess I've really dreaded it because of that engine, but this one is a piece of cake as long as you have a good place to work on it and this time, I do! :lol:

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All the pictures are working now BTW.

I think being able to fix your bike is almost as important as being able to ride it! Unless you're a pro and have your own personal mechanic you'll save a ton of money doing things yourself, too! Plus it's something to keep you occupied during the winter!

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All the pictures are working now BTW.

.

Yes, I saw that. However I had to place them in PhotoBucket before they would post. I have done a couple tests that I deleted right away and so far, other photos from my web space show, but just not the 2 screen shots of the PDF file. I was trying that from work so I'm not sure if it has something to do with the company server or not.. next test is to bring the files home and then upload them from here to my web space and THEN try to post them again..

Who needs VIDEO GAMES when you can have THIS much fun trying to solve the mysteries just from regular software..??? :lol:

BTW, my parts arrived from Jack's Cycles today.. Now for the second half of the fun! :)

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Follow up report:

Turns out the new shift shaft locator thingy (with the spring on it under the clutch) would not slip down the new shaft far enough to get the clip on. After many tries and comparisons with the old shaft and locator, it appeared that the slot in the end of the new shaft was not exactly centered. I discovered this on a Sunday evening at about 6:00 PM so decided to leave a voice message for Stu at Jack's Cycles (his time 9:00 PM). Lo and behold, he answered the phone!! I described the problem and the method I used to come to my conclusion and then later produced a video of the tests I did to help describe the reason for my conclusion.

Anyway, on Monday, he got the video and made some calls and confirmed some parts problems had been identified related to the shift shaft and locators. Next step was for TrialsPartsUSA to pre-fit test a new shaft and locator and ship it "next day" on Wednesday. I got the parts Thursday afternoon and shipped the flawed parts back in the same box.

So last Sunday (Dec 11) I went at it again and put the engine back together and into the bike ready to fire up but forgot the transmission oil. Came back Monday with the oil and BINGO!! It fired up on the third kick! On top of that, it runs and shifts perfectly!

This is the first time that I have gone deeper into the Gas Gas engine than the clutch and I can say that with the help of the videos and the simple design of the engine, it turned a dreaded task into an almost fun exploration. I have a much better understanding now of what takes place in the transmission and the rest of the engine..

Thanks to Stu of Jack's Cycles, Laser17 here on TT, Jim Snell's videos and the simple engine design of Gas Gas for a relatively painless experience on an otherwise serious problem. :bonk::thumbsup:

BTW 2 Gas Gas tools you should have on had are the flywheel puller and the swing arm shaft tool.. You could probably make your own swing arm shaft tool. It is essentially a long rod with the correct threads on the end of it so that you thread it into the end of the swing arm shaft and then pound on the end of the tool to drive the shaft out without damaging the threads in the swing arm shaft.

Here is the shaft out far enough to remove the engine:

IMG_2740.jpg

And here is the shaft tool still threaded into the swing arm shaft:

IMG_2739.jpg

Edited by 2PLY

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