2003 gas gas 280 pro transmission bench test

[Tacton]

Is there any way to bench test the transmission to make sure it cycles through all the gears, I have my lower gears but it doesn’t seem like I have my higher gears, I have heard they are difficult to bench test is this true or should you be able to get some gears on the bench, I’m not sure if there is anything that could be out of whack, everything went together nice, ?

[lineaway]

 Well more info is needed. Is it all the way together? By spinning the sprocket, you should be able to get all the gears. What did you replace?

[Tacton]

The cases are together with no clutch.

I replaced the shifter drum, same part numbers, compared to the old one they are the same, when I up shift I can get to 3rd gear then it seems to have no feel in the shifter, I’m wondering if I could get the secondary shaft is misaligned, I put it together with the transmission in neutral 

[d2w]

Hi from the Okanagan (the source of most of your smoke )

I recently rebuilt the tranny of my 2008 PRO; I'm assuming it's "close" to your tranny in design.

I too was unsure if it need to be in a certain gear during reassembly, but I eventually reasoned that it did not; the gears are positioned by the shift forks, and the forks are positioned according to the tracks/grooves in the shift drum. The drum only stops its rotation (first gear and sixth gear) when the forks are at the end of their travel in the drum tracks.  So the initial placement of the drum doesn't matter as the forks and gears will align correspondingly. Basically, the position of the tranny pieces are absolute.

I was able to manually "drive" my tranny through all gears. But I had to work at it, including rotating the tranny input shaft forward and back as well as rotating the tranny output shaft forward and back.. The operation was clunky.

If you can't get into the higher gears, do verify that both selector forks move when you rotate the shift drum. Try to identify what's stopping the higher gears from being selected. Does the tranny still rotate as expected when you're trying to get into the higher gears, or is there some interference/collision of gears, etc? Any chance you have a shift fork on "reversed/backwards"?

Jim Snell (or maybe Motobene) had a diagram of a PRO tranny which documented how the power was transferred through the tranny in each of the various gears (as its design is "clever" [some say like a grenade  ]). Dunno if it applies to your tranny. However it may help you better understand how yours should work and why it might not be working now.

Dale

With credit to Motobene and/or Jim Snell (as I see the Rising Sun Imports reference).:

Edited August 21, 2021 by d2w

[Tacton]

Thanks for the help I have some pictures, I’ve replaced the shifter drum because it was broken and I replaced the primary shift fork because the dowl  was missing the pictures were taken in neutral position the best of my knowledge

[lineaway]

 Did you rrplace the top hat and spring? With out the clutch on the shaft could the shaft move off the spring? Seems like it kept the shaft from moving. Been about 8 years since I did my last one. Good luck.

[d2w]

You wrote:

... and I replaced the primary shift fork because the dowl  was missing 

So did you ever find the missing dowel? Could it still be jammed in the tranny gears and preventing them from rotating and/or moving on the shafts as is required?
Can all gears and "discs-with-the-dawgs" (sorry, can't think of their name as the moment  ) rotate and move on the shafts as required? There are a number of needle bearings on the shafts on which the gears rotate. Have you checked them for being in good repair? Mine were minutes from grenade-ing; I touched mine and they fell apart (and not in a normal/correct way). If yours are gone perhaps a gear which is supposed to slide/rotate is now appearing to you to be (erroneously) secure?

Edited August 21, 2021 by d2w

[Tacton]

The top hat is all in good order gears all seem clean tight and smooth but what I’m thinking is I’m going to rotate my shift shaft 180 degrees , I bought the bike knowing that it had issues so I don’t know the history and I’ve never found anything in the the cases, 

thanks

[Tacton]

But I’m definitely going to take the gears out and do a very close inspection,

thanks again 

[d2w]

Tacton,

I found some photos of my tranny. My photos show the shift drum in the same orientation. That being said ... one thing that *may* have caught my eye when looking at your old photos above and comparing them to mine ... on the shaft with the two shaft with the two shift forks... is the lower one flipped? The beveled edge looks to be oriented different than mine? Bit perhaps it's just a photo angle thing since maybe the guide pin only allows the fork to be installed one way?

Anyways, here are some photos for reference. Again, these photos are from a 2008 GG PRO TXT300.